531763 research-article2014
JFM0010.1177/1098612X14531763Journal of Feline Medicine and SurgeryKulendra et al
Original Article
Feline double pigtail ureteric stents for management of ureteric obstruction: short- and long-term follow-up of 26 cats
Journal of Feline Medicine and Surgery 1–7 © ISFM and AAFP 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1098612X14531763 jfms.com
Nicola Jayne Kulendra, Hattie Syme, Livia Benigni and Zoe Halfacree
Abstract
The objective of this study was to determine the outcome of cats with ureteric obstruction managed with double pigtail ureteric stents and to document the incidence of lower urinary tract signs at long-term follow-up. Data were obtained retrospectively from the medical records (2009–2012) of 26 cats that underwent ureteric stent placement. Owners were contacted for follow-up, and a quality of life questionnaire completed. Survival to discharge after stent placement was 85% (22/26). Prevalence of postoperative uroabdomen necessitating further surgery was 15% (4/26). Stents were replaced 4–28 months after the initial surgery in four cats because of migration, fracture, encrustation causing luminal obstruction or sterile cystitis, respectively. Nine cats were alive at follow-up, which was 3–28 months after the original surgery. Nine cats had azotaemic chronic kidney disease and nine had signs related to sterile cystitis; three of these cats were euthanased as a result of the severity of the signs. Preoperative serum creatinine of the survivors (9.4 mg/dl, n = 9) was not significantly different from that of the non-survivors (6.5 mg/dl, n = 13; P = 0.295). Quality of life was assigned a mean score of 8/10. Median survival of cats following discharge was 419 days (range 44–994 days). Signs consistent with sterile cystitis affected 35% of cats. It was concluded that ureteric stent placement in cats was associated with a 15% mortality rate before hospital discharge. Long-term management of ureteric stents is associated with a high rate of lower urinary tract signs. Accepted: 5 March 2014
Introduction Ureteric obstruction is an increasingly common diagnosis in cats and is usually caused by ureteroliths. Calcium oxalate urolithiasis is the most common cause of the condition in cats.1 Cats with calcium oxalate urolithiasis have the propensity to repeatedly form stones causing variable degrees of ureteric obstruction. Cats commonly present with a larger functional kidney acutely obstructed and a smaller previously obstructed kidney, which is end stage. As a result, these cats often have loss of a large proportion of their nephrons at initial presentation; as such, they are at risk of progressing to endstage chronic kidney disease (CKD). Traditional management of ureteroliths involved a ureterotomy to remove the stone and alleviate the obstruction. Previous studies have reported the survival to discharge following this procedure as 79%,2 and the rate of postoperative uroabdomen following ureterotomy was 16%3 and 6% respectively.2 Persistent ureteral
obstruction due to oedema, recurrence of stones and stricture formation are reported complications following this procedure.3 Kyles et al3 also reported that 10% of cats required a second surgical procedure and 40% of the cats with ureterotomies had recurrence of ureteral obstruction on follow-up examination. Because of the small size of the ureter, surgery can be particularly challenging, and microsurgical techniques are often employed. Recent management of ureteric obstruction has involved the placement of ureteric stents.4–6 They have Royal Veterinary College, Hatfield, UK Corresponding author: Nicola Jayne Kulendra BVetMed (Hons) MVetMed CertVDI DECVS MRCVS, The Royal Veterinary College, Hatfield, AL10 9QT, UK Email: [email protected]
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Case information recorded included signalment, presenting signs, physical examination findings, initial biochemical data, methods of diagnosis, surgical procedure performed, maximum urine output postoperatively, time to discharge, time to follow-up and survival. Information regarding reasons for euthanasia, where applicable, was recorded.
Figure 1 Placement of a 22-gauge intravenous catheter into the renal pelvis allowing advancement of a guide wire
been used in humans for over 20 years and are typically placed to prevent or relieve ureteral obstruction secondary to a variety of intrinsic or extrinsic aetiologies that include obstructing ureteral calculi, ureteral strictures, congenital anomalies, neoplasia, trauma or iatrogenic injury.7 They are also used to maintain ureteric luminal patency following ureteroscopy and lithotripsy, and following renal transplantation.7 Because of patient discomfort associated with voiding, and abdominal pain in around 50% patients, stents are typically removed 2–3 days after a procedure.6 There have been limited reports of ureteric stents in the veterinary literature.4–9 One review described the placement of over 150 stents.4 A recent case series of nine cats with ureteric stents placed reported no cases of uroabdomen, despite all cats having the ureteric lumen opened.5 Eight out of nine cats were alive at follow-up and two cats had signs related to dysuria. Stents have also been used for the management of malignant ureteric obstruction, ureteric strictures or stenosis.5,6,8 The aim of this retrospective study was to report the clinical outcomes of cats undergoing ureteral stent placement and to evaluate their long-term quality of life using telephone-based questionnaires. The secondary aim was to document the incidence of sterile cystitis in this population of cats and compare it with the human literature.
Materials and methods Case details from all cats undergoing placement of ureteric stents from June 2009 until July 2012 were included in the study. Medical records were searched retrospectively, and cats were included if one or more ureteric stents were placed at surgery following diagnosis of ureteric obstruction.
Procedure Initially, all cats received medical management until ureteric obstruction was diagnosed. Medical treatment varied, but generally included some combination of intravenous fluid therapy, analgesia and antimicrobials. Cats were investigated using a combination of abdominal ultrasonography, survey abdominal radiography, percutaneous antegrade pyelography and intravenous urography (IVU). In-house serum biochemistry was performed, including measurement of serum creatinine and urea concentrations, as well as packed cell volume (PCV). For percutaneous antegrade pyelography, the procedure was performed under ultrasound guidance using a 23-gauge needle connected to an extension set and threeway tap. The needle was inserted via the greater curvature of the kidney into the renal pelvis, and urine was collected for bacterial culture and urinalysis. A volume of non-ionic iodinated contrast (Iohexol; Omnipaque, GE Healthcare) equal to 75–100% of the urine volume that was removed was injected. Lateral and ventrodorsal fluoroscopic images were obtained immediately, at 5 mins and approximately 15 mins postinjection. For cats with a diagnosis of ureteric obstruction, an exploratory laparotomy was performed. Immediate decompression of the obstructed kidney was performed by passing a 22-gauge intravenous catheter through the cranio-lateral aspect of the greater curvature into the renal pelvis, which allowed urine to drain into the abdominal cavity. A 0.018-gauge hydrophilic guide wire (Weasel Wire; Infiniti Medical) was passed through the catheter into the pelvis in an attempt to pass the wire into the ureter in an antegrade fashion (Figure 1). If this was not possible, a ventral cystotomy extending to the proximal urethra was performed in order to visualise the ureteric openings at the trigone. The hydrophilic guide wire was placed, in a retrograde manner, through the ureteric openings into the ureters and past the obstruction into the renal pelvis. In cats in which the guide wire could not be advanced past the site of obstruction, ureterotomy or ureteric resection and anastomosis were performed. For obstructions that occurred in the distal ureter where it was not possible to pass the stent, a neoureterocystostomy was performed. If possible, a dilator was passed over the guide wire and removed prior to stent placement. A ureteric stent (Figure 2) was placed over the guide wire so that the proximal aspect of the stent sat within the renal pelvis. The guide wire was removed and fluoroscopy
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Figure 2 Multiple fenestrated 2.5-French double pigtail soft ureteric stent
used to confirm the position of the proximal pigtail of the stent within the renal pelvis. The stents were double pigtail, multiple fenestrated polyurethane stents (Vet stentUreter; Infinity Medical); the first three cats had 2.5- or 3-French hard stents placed. Subsequently, 2.5-French soft stents were available and so these were placed. If a ureterotomy or ureterectomy was performed, it was sutured over the stent using either 5/0 or 6/0 polydioxanone (PDS II; Ethicon). Surgical loupes were used according to surgeon preference. Postoperative radiographs were taken to document stent location if the cat was stable enough to tolerate an increased anaesthesia time (Figure 3). In cats that were inappetent or anorexic, an esophagostomy tube was placed and maintained until the cat began eating independently. Postoperatively, a urethral catheter was placed to monitor urine output and evaluate fluid balance in all cats apart from one in which it was not placed at the surgeon’s discretion. All cats recovered in the intensive care unit where their heart rate, respiratory rate, blood pressure and urine output was monitored. Cats received medical therapy consisting of intravenous fluid therapy, opioid analgesia and other medications as necessary. Prevalence of postoperative complications, perioperative death rate and number of cats requiring further surgeries were recorded. Cats alive at follow-up that were azotaemic were staged according to the International Renal Interest Society (IRIS) grading system.10
Statistical analysis A Shapiro–Wilk test revealed that the data were normally distributed; this was confirmed by visual inspection of a histogram for each data set. The Kaplan–Meier method was used to document survival times. The 6-, 12- and 24-month survival rates were calculated; survival times are recorded as median values. An independent sample t-test was performed to identify any relationship between creatinine at presentation and survival. For all statistical analyses, values of P 10 times daily and had signs of straining.
Figure 3 Postoperative radiograph of cat illustrating bilateral ureteric stents, urethral catheter and oesophagostomy tube
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Results Twenty-six cats had ureteric stents placed; five cats had stents placed bilaterally. Fourteen cats were female (12 were neutered) and 12 cats were male neutered. The cats were aged from 2 to 12 years (mean 6 years). Ten cats were domestic shorthairs, three were domestic longhairs, two were British shorthairs, and there was one each of the following breeds: Birman, Burmese, Burmilla, Chinchilla, Exotic, Manx, Oriental, Persian, Ragdoll, Russian Blue and Siamese. The majority of cats had stents placed secondary to obstruction by ureteric calculi (n = 21); four cats had obstruction secondary to ureteric strictures and one cat had traumatic obstruction of both ureters. Of the cats with ureterolithiasis, uroliths were removed and submitted for analysis in 14 cats. Thirteen cats had calcium oxalate ureteroliths and one cat had xanthine uroliths. Four cats had a stricture causing the obstruction; in all of these cats, uroliths were visible at other sites in the urinary tract. Presenting signs included vomiting (n = 9), inappetance (n = 6), anorexia (n = 3), lethargy (n = 10), weight loss (n = 7), polyuria/polydipsia (n = 5), haematuria (n = 2), vocalising (n = 2), dysuria (n = 1), oliguria (n = 1), collapse (n = 1), cough (n = 1), hypersalivation (n = 1), depression (n = 1), weakness (n = 1), constipation (n = 1), pollakiuria (n = 1), stranguria (n = 1) and urethral obstruction (n = 1). Two cats had ureteric obstruction discovered as an incidental finding; one had azotaemia discovered on routine biochemistry, the other had a ureterolith discovered on a computed tomographic scan for investigation of hypervitaminosis D. Physical examination findings included heart murmur (n = 9), renal asymmetry (n = 5), painful kidneys (n = 5), abdominal pain (n = 4), irregular kidneys (n = 3), bilateral renomegaly (n = 3), unilateral renomegaly (n = 3), bradycardia (n = 2), tachycardia (n = 2), bilaterally small kidneys (n = 1), firm kidneys (n = 1), abdominal bruising (n = 1), obtundation (n = 1), pulmonary crackles (n = 1), hypovolemia (n = 1), hypothermia (n = 1), unilaterally small kidney (n = 1), dehydration (n = 1) and a gallop rhythm (n = 1). Two cats were normal on physical examination. Twenty-five cats had urine culture or culture of the urolith performed. Enterococcus faecalis was cultured in one cat and Escherichia coli was cultured in another cat; both cats had an indwelling urethral catheter placed prior to referral. Mean PCV at presentation was 28 ± 6% (15–36%). Mean creatinine was 7.6 ± 5.5 mg/dl (154–1408 mg/dl). Urea was off the scale in 11 cats; in the remainder, the mean urea was 31.5 ± 21.6 mmol/l (7.2–64.3 mmol/l). Mean potassium at presentation was 5.06 ± 1.58 mEq/l (2.65–8.50 mEq/l); 14/26 cats were hyperkalaemic (potassium >4.6 mEq/l).
Diagnostic imaging was performed in all cats: 25 had abdominal ultrasonography, 19 had survey abdominal radiography, 10 had percutaneous antegrade pyelography and four cats had IVU. Twelve cats had left ureteric obstruction: nine had right ureteric obstruction and in five cats it was bilateral. The stents were placed in an antegrade direction in four ureters. Ureterotomy was performed in 11 ureters, and resection and anastomosis was performed in six ureters; in these cats, it was not possible to pass the stent past the site of obstruction and so the stent was placed over a guide wire inserted proximally and distally through the ureterotomy and ureteric resection and anastomosis sites so that one end of the wire ended up in the renal pelvis and the other exited the ureter through the trigone. In one cat with bilateral ureteric obstruction, a stent was placed retrograde in one ureter and antegrade and via a ureterotomy in the other. In two cats the site of obstruction was very distal and ureteric re-implantation was performed when the stent was unable to be passed beyond the site of obstruction. One case had a very distal obstruction and a sphinctoroplasty was performed. Jackson–Pratt abdominal drains (Infusion Concepts; Sowerby Bridge) were placed in seven cats; six cats had a ureterotomy performed—in one cat the guide wire inadvertently penetrated the wall of the ureter. Surgical time was 182 mins (range 90–370 mins) and anaesthesia time was 315 mins (range 155–485 mins). Postoperatively, two cats received a fresh whole blood transfusion and one cat received a transfusion of oxyglobin. In all cats in which urine output was recorded (n = 22), mean urine output was 9 ml/kg/h (range 0–22.9 ml/kg/h). Two cats suffered a cardiopulmonary arrest on recovery from the anaesthetic; one cat had pulmonary oedema following fluid overload prior to referral; the other had severe hypotension, hypoglycaemia and anuria. Twenty-two cats survived to discharge; the mean number of days to discharge was 8 (range 2–14 days). Of the four cats that did not survive to discharge, two died in the perioperative period and two died 9 and 48 h postoperatively respectively; one cat became anuric, profoundly azotaemic and hyperkalaemic in the absence of renal pelvis dilation on ultrasound, and so acute renal failure was suspected. One cat developed uroabdomen 24 h postoperatively and a second laparotomy was performed; the cat became hypotensive and acidotic, and suffered cardiopulmoary arrest on recovery from anaesthesia. Additional surgical procedures Five cats developed uroabdomen between 3 and 48 h postoperatively; a diagnosis was made by documentation of higher creatinine within the abdominal fluid compared with serum creatinine. Four cats had a second
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5 60%, 44% and 20% respectively. The median survival of cats after surgery was 265 days (range 0–1071 days).
Percent survival
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50
0
0
500
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Figure 4 Kaplan–Meier survival curve of cats following ureteric stent placement. Cats were censored at time of death
laparotomy, three cats had leakage from a ureterotomy site and one cat had leakage from the cystotomy site. One cat with a uroabdomen had a Jackson–Pratt drain placed at the original surgery site, which involved a ureterotomy and therefore, when diagnosed with a uroabdomen, did not require a second surgery. Stents needed to be replaced 4–28 months after the initial surgery in five cats because of migration, fracture, mineralisation causing luminal obstruction or sterile cystitis. The cat with sterile cystitis was urinating every 1–2 h with marked dysuria that was refractory to treatment with prednisolone at 1 mg/kg. Long-term follow-up Of the 22 cats that were alive at discharge, nine were alive at follow-up which was 3–28 months after the original surgery; one of these cats was lost to follow-up. Five cats had azotaemia, and, owing to its temperament, one cat had no recent biochemistry results. Of the cats with azotaemia, five were classified as IRIS stage 2 and two were IRIS stage 3. Six cats were diagnosed with sterile cystitis. Of the cats not alive at follow-up, eight were euthanased because of marked azotaemia, three were euthanased because of severe dysuria that was refractory to medical management and one was euthanased for unknown reasons, although it had previously documented severe azotaemia. One cat with recent biochemical evidence of severe azotaemia died; necropsy was declined. Statistical analysis The creatinine levels of the survivors (9.4 mg/dl, n = 9) was not significantly different from that of the non-survivors (6.5 mg/dl, n = 13; P = 0.295). A Kaplan–Meier survival curve depicts the survival characteristics of the cats following the surgery (Figure 4). The 1-, 6-, 12- and 24-month survival rates were 84%,
Quality of life assessment Telephone follow-up was performed between 3 and 36 months after the surgery. Eleven owners answered the questionnaire. Quality of life was scored as 8/10 (range 5–10). Three owners believed their cat’s mood was different since the surgery; two owners believed that the mood was affected occasionally. The behaviour of three cats had been negatively affected since the surgery; two cats were occasionally negatively affected. When asked whether the cat had experienced changes in urination (pollakiuria, stranguria or dysuria), six cats were affected and one cat occasionally had difficulty urinating; one cat was an outdoor cat and so it was not possible to document changes in urination patterns. With regard to the number of times per day each cat urinated, one cat urinated 1–2 times daily, three cats urinated 3–5 times daily, one cat urinated 6–9 times daily and three cats urinated >10 times daily. Eight cats visited a veterinarian frequently since the surgery for blood tests or management of cystitis, one cat visited the veterinarian for routine appointments only and two cats went infrequently. Three cats had received medical management from the local veterinarian to manage straining to urinate. One cat appeared uncomfortable when being picked up. One cat had changes in posture following the surgery. Three cats groomed the flank, perineum or lower abdomen more frequently after the surgery. When asked if owners worried about the cat since the surgery to place the stent, four answered yes and four answered occasionally. Four owners felt they had been restricted or limited in terms of what they would like to do, such as going on holidays, going away for weekends or evenings, or going to work; one owner felt restricted occasionally. Three owners chose not to leave their cat in a cattery or with family members or friends since the surgery. Four owners worried about the cost of the surgery and ongoing care, two owners worried occasionally. Ten out of 11 owners would choose to have the surgery performed again should they have a cat with the same condition.
Discussion Ureteric stents are an integral part of urological practice in human surgery, and are typically placed to prevent or relieve ureteral obstruction secondary to instrinsic or extrinsic aetiologies, including calculi, strictures, congenital anomalies, neoplasia or trauma.12 In addition, stents can be placed prophylactically after ureteric surgery or extracorporeal shock wave lithotripsy to prevent ureteral obstruction. Ureteral stents in humans are associated with frequent side effects, including irritating voiding symptoms in 40–55% of patients.13 In one study,11
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6 flank pain was noted in 42%, and 45% of patients reported impairment in their quality of life. In humans, stents are generally removed between 2 days and 2 weeks after placement.7 Owners of cats in this study recorded a favourable quality of life score, with a median value of 8/10. However, based upon the previous described grading system, the cats alive at follow-up had mild dysuria (3/11; 27%), moderate dysuria (1/11; 9%) and severe dysuria (3/11; 27%). One report described removal of a stent owing to persistent stranguria.5 One cat with traumatic ureteric obstruction in this study developed acute ureteric obstruction after stent removal; therefore, careful monitoring of cats following stent removal is advised.14 Although removing stents after a few weeks following ureteric surgery may prevent the dysuria, one of the benefits of having stents placed is to prevent re-obstruction and to allow passive ureteric dilation in these cats with persistent stone formation.4 The incidence of dysuria in this study was higher than in the current literature.4,5,7 The classification of mild dysuria as cats that urinate 2–5 times a day may be tolerable in some cats. In addition, cats may urinate more frequently owing to azotaemic CKD. In a review article,4 dysuria was reported in a minority of cats and was reported as self limiting or responsive to glucocorticoids. A retrospective study reported only one case of sterile cystitis out of nine cats.5 Cats in this study with persistent cystitis were started on anti-inflammatory doses of prednisolone; however, the urinary tract signs of some of the cats were refractory to glucocorticoids. The ureteropelvic junction in the cat is located relatively caudal and we suspect that the distal coil of the stent irritates the trigone and proximal urethra. A ventral cystotomy was performed in this study; it is possible that the location of the suture line opposite to the ureterovesicular junction contributed to the dysuria. A ventral cystotomy was performed in this study as it allows easier catheterisation of both ureters;15 a dorsal cystotomy may have reduced the incidence of dysuria and would be an interesting extension of the study. In the study by Nicoli et al,5 a neocystoureterostomy was performed in 8/9 cats and so it is possible that the distal aspect of the stent exited more cranially and therefore further away from the trigone. After diagnosis of ureteric obstruction, all cats were treated with a similar protocol of medical management prior to surgery. Surgery was performed shortly after diagnosis based on previous evidence that complete ureteric obstruction causes irreversible kidney damage from 7 days.16 While no statistically significant difference was seen between survivors and non-survivors, it was notable that some of the survivors had extremely elevated creatinine concentrations (range 1.74–20.00 mg/dl). A high serum creatinine at presentation may represent a situation in which complete ureteric obstruction has occurred in a kidney that was, until recently, functioning well, and if the obstruction is
relieved there may be adequate functional renal parenchyma to allow recovery of adequate renal function; that is, it was the relative contribution of acute versus chronic disease that predicted the improvement in azotaemia after relief of the obstruction. Ultrasound proved to be a useful preoperative imaging modality as it confirmed renal pelvis dilation and hydroureter. In many cases, a ureterolith could be identified by distal acoustic shadowing. Radiographs were useful in some cases, particularly where radio-opaque ureteroliths were present. Initially, an IVU was performed in cases in which the diagnosis of ureteric obstruction was questionable. However, it became apparent that there was poor opacification of the upper urinary tract secondary to reduced glomerular filtration of contrast; subsequently, in cases in which the diagnosis of ureteric obstruction was not certain, an antegrade pyelograde was performed. In some cases, intraoperative fluoroscopy was used to image the urinary tract and to guide positioning of the guide wire or stent. Ureteric stents are a useful way of relieving ureteric rupture or obstruction. The prognosis for cats with stents placed remains guarded primarily because of CKD, but also because of dysuria, stent migration or fracture. Survival to discharge was similar to a previous study involving ureterolithotomy.2 A study comparing medical and surgical management of ureteric obstruction in cats found a 12-month survival rate of 66% with medical management and 91% with surgical management.3 Surgical management in the study by Kyles et al3 included ureterotomy with and without nephrostomy tube placement and ureteroneocystotomy. Our study found that the 12-month survival rate was less favourable, with only 52% cats alive at 12 months. It is possible that the cat population in the study by Kyles et al3 differed from the population of cats in the present study or they presented later in the disease process. Another reason why the cats in the present study had a worse 12-month survival may be related to the long anaesthetic and surgical time (mean surgery time 182 mins). Renal blood flow and glomerular function may be depressed as a result of hypotension and renal vasoconstriction secondary to anaesthesia,17 and an increased length of anaesthetic required to place the stents compared with traditional surgery may have caused additional damage to the remaining nephrons. In addition, three cats in this study were euthanased as a result of dysuria, which makes the long-term results less favourable than the study by Kyles et al.3 Another reason why cats in this study had a worse 12-month survival compared with other studies may represent presentation at a later stage in the disease process, for example more advanced CKD. A high proportion of our cats presented with lethargy and one was collapsed at presentation. Additionally, three cats in this study were euthansed as a result of refractory sterile cystitis, which had an impact on the long-term outcome.
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Five cats in our study developed a uroabdomen postoperatively. Postoperative diuresis produced a urine output of up to 22 ml/kg/h in some cats. We suspect that in cats in which a ureterotomy or ureteric resection and anastomosis has been performed, the high volume of urine produced in the immediate postoperative period may cause an increased risk of leakage from the ureter. It was initially suspected that the presence of a stent may help to decrease the incidence of uroabdomen postoperatively. However, the rate of uroabdomen in this study was, in fact, higher than that in other studies in which ureterotomies or ureterectomies were performed without stents (16%).3 It subsequently became protocol to place a Jackson–Pratt drain whenever a ureterotomy or ureteric resection and anastomosis was performed. This allowed any urine produced to be evacuated from the abdomen; it also allowed biochemical analysis of the abdominal fluid to be performed. The drains were removed when the volume decreased or plateaued and there was no evidence of urine leakage. By nature, as a retrospective study, there were numerous limitations, including incomplete record-keeping, leading to missing data and inconsistent management protocols. There may have been confounding variables that were not identified. In addition, the surgeries were performed by a number of surgeons with variable experience in the procedure. We were only able to follow up on a small number of cases for the questionnaire part of the study; a larger number of cases may have altered the results.
Conclusions Ureteric stents may reduce the incidence of certain complications of ureteric surgery, such as stricture formation and subsequent obstruction and uroabdomen if a Jackson–Pratt drain is placed concurrently. However, they may be associated with novel complications, such as stent fracture, migration and, in particular, dysuria. It is possible that altering the location of the distal aspect of the stent away from the trigone may reduce the incidence of dysuria, for example by performing a ureteroneocystotomy or using a device such as a subcutaneous ureteral bypass (SUB) system (Norfolk Medical). The SUB consists of a nephrostomy tube connected to a cystostomy tube via a subcutaneous port; the location of the cystostomy tube is at the apex of the bladder. The prognosis of cats with stent placement secondary to ureteric obstruction remains guarded due to concurrent CKD. Conflict of interest The authors do not have any potential conflicts of interest to declare.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
References 1 Kyles AE, Hardie EM, Wooden BG, et al. Clinical, clincopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984–2002) J Am Vet Med Assoc 2005; 226: 932–936. 2 Roberts SF, Aronson LR and Brown DC. Postoperative mortality in cats after ureterolithotomy. Vet Surg 2011; 40: 438–443. 3 Kyles AE, Hardie EM, Wooden BG and Adin CA. Management and outcome of cats with ureteral calculi: 153 cases (1984–2002). J Am Vet Med Assoc 2005; 226: 937–944. 4 Berent AC. Ureteral obstructions in dogs and cats: a review of traditional and new interventional diagnostic and therapeutic options. J Vet Emerg Crit Care (San Antonio) 2011; 21: 86–103. 5 Nicoli S, Morello E, Martano M, et al. Double-J ureteral stenting in nine cats with ureteral obstruction. Vet J 2012; 194: 60–65. 6 Lam JS and Gupta M. Ureteral stents. In: Stoller ML and Meng MV (eds). Urinary stone disease: the practical guide to medical and surgical management. 1st ed. Totowa: Humana Press, 2007, p 465. 7 Horowitz C, Berent A, Weisse C, et al. Predictors of outcome for cats with ureteral obstructions after interventional management using ureteral stents or a subcutaneous ureteral bypass device. J Feline Med Surg 2013; 15: 1052–1062. 8 Zaid MS, Berent AC, Weisse C and Caceres A. Feline ureteral strictures: 10 cases (2007–2009). J Vet Intern Med 2011; 25: 222–229. 9 Berent AC, Weisse C, Beal MW, et al. Use of indwelling, double-pigtail stents for treatment of malignant ureteral obstruction in dogs: 12 cases (2006–2009). J Am Vet Med Assoc 2011; 238: 1017–1025. 10 International Renal Interest Society staging of CKD, http:// www.iris-kidney.com/pdf/IRIS2009_Staging_CKD.pdf (accessed March 2013). 11 Niessen SJ, Powney S, Guitian J, et al. Evaluation of a quality-of-life tool for cats with diabetes mellitus. J Vet Intern Med 2010; 24: 1098–1105. 12 Manassero M, Decambron A, Viateau V, et al. Indwelling double pigtail ureteral stent combined or not with surgery for feline ureterolithiasis. J Feline Med Surg. Epub ahead of print 4 December 2013. 13 Leibovici D, Cooper A, Lindner A, et al. Ureteral stents: morbidity and impact on quality of life. Isr Med Assoc J 2005; 7: 491–494. 14 Kulendra ER, Kulendra NJ and Halfacree ZJ. Management of bilateral ureteric trauma in a cat with ureteral stenting and subcutaneous ureteral bypass. J Feline Med Surg. Epub ahead of print 30 October 2013. DOI: 10.1177/1098612X13509098. 15 Waldron DR. Urinary bladder. In: Slatter D (ed). Textbook of small animal surgery. 3rd ed. Philadelphia: Saunders, 1993, p 1635. 16 Kerr WS. Effect of complete ureteral obstruction for one week on kidney function. J Appl Physiol 1954; 6: 762–772. 17 Mason DE. Urinary system. In: Slatter D (ed). Textbook of small animal surgery. 3rd ed. Philadelphia: Saunders, 1993, p 2548.
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JFM0010.1177/1098612X14531763Journal of Feline Medicine and SurgeryKulendra et al
Original Article
Feline double pigtail ureteric stents for management of ureteric obstruction: short- and long-term follow-up of 26 cats
Journal of Feline Medicine and Surgery 1–7 © ISFM and AAFP 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1098612X14531763 jfms.com
Nicola Jayne Kulendra, Hattie Syme, Livia Benigni and Zoe Halfacree
Abstract
The objective of this study was to determine the outcome of cats with ureteric obstruction managed with double pigtail ureteric stents and to document the incidence of lower urinary tract signs at long-term follow-up. Data were obtained retrospectively from the medical records (2009–2012) of 26 cats that underwent ureteric stent placement. Owners were contacted for follow-up, and a quality of life questionnaire completed. Survival to discharge after stent placement was 85% (22/26). Prevalence of postoperative uroabdomen necessitating further surgery was 15% (4/26). Stents were replaced 4–28 months after the initial surgery in four cats because of migration, fracture, encrustation causing luminal obstruction or sterile cystitis, respectively. Nine cats were alive at follow-up, which was 3–28 months after the original surgery. Nine cats had azotaemic chronic kidney disease and nine had signs related to sterile cystitis; three of these cats were euthanased as a result of the severity of the signs. Preoperative serum creatinine of the survivors (9.4 mg/dl, n = 9) was not significantly different from that of the non-survivors (6.5 mg/dl, n = 13; P = 0.295). Quality of life was assigned a mean score of 8/10. Median survival of cats following discharge was 419 days (range 44–994 days). Signs consistent with sterile cystitis affected 35% of cats. It was concluded that ureteric stent placement in cats was associated with a 15% mortality rate before hospital discharge. Long-term management of ureteric stents is associated with a high rate of lower urinary tract signs. Accepted: 5 March 2014
Introduction Ureteric obstruction is an increasingly common diagnosis in cats and is usually caused by ureteroliths. Calcium oxalate urolithiasis is the most common cause of the condition in cats.1 Cats with calcium oxalate urolithiasis have the propensity to repeatedly form stones causing variable degrees of ureteric obstruction. Cats commonly present with a larger functional kidney acutely obstructed and a smaller previously obstructed kidney, which is end stage. As a result, these cats often have loss of a large proportion of their nephrons at initial presentation; as such, they are at risk of progressing to endstage chronic kidney disease (CKD). Traditional management of ureteroliths involved a ureterotomy to remove the stone and alleviate the obstruction. Previous studies have reported the survival to discharge following this procedure as 79%,2 and the rate of postoperative uroabdomen following ureterotomy was 16%3 and 6% respectively.2 Persistent ureteral
obstruction due to oedema, recurrence of stones and stricture formation are reported complications following this procedure.3 Kyles et al3 also reported that 10% of cats required a second surgical procedure and 40% of the cats with ureterotomies had recurrence of ureteral obstruction on follow-up examination. Because of the small size of the ureter, surgery can be particularly challenging, and microsurgical techniques are often employed. Recent management of ureteric obstruction has involved the placement of ureteric stents.4–6 They have Royal Veterinary College, Hatfield, UK Corresponding author: Nicola Jayne Kulendra BVetMed (Hons) MVetMed CertVDI DECVS MRCVS, The Royal Veterinary College, Hatfield, AL10 9QT, UK Email: [email protected]
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Case information recorded included signalment, presenting signs, physical examination findings, initial biochemical data, methods of diagnosis, surgical procedure performed, maximum urine output postoperatively, time to discharge, time to follow-up and survival. Information regarding reasons for euthanasia, where applicable, was recorded.
Figure 1 Placement of a 22-gauge intravenous catheter into the renal pelvis allowing advancement of a guide wire
been used in humans for over 20 years and are typically placed to prevent or relieve ureteral obstruction secondary to a variety of intrinsic or extrinsic aetiologies that include obstructing ureteral calculi, ureteral strictures, congenital anomalies, neoplasia, trauma or iatrogenic injury.7 They are also used to maintain ureteric luminal patency following ureteroscopy and lithotripsy, and following renal transplantation.7 Because of patient discomfort associated with voiding, and abdominal pain in around 50% patients, stents are typically removed 2–3 days after a procedure.6 There have been limited reports of ureteric stents in the veterinary literature.4–9 One review described the placement of over 150 stents.4 A recent case series of nine cats with ureteric stents placed reported no cases of uroabdomen, despite all cats having the ureteric lumen opened.5 Eight out of nine cats were alive at follow-up and two cats had signs related to dysuria. Stents have also been used for the management of malignant ureteric obstruction, ureteric strictures or stenosis.5,6,8 The aim of this retrospective study was to report the clinical outcomes of cats undergoing ureteral stent placement and to evaluate their long-term quality of life using telephone-based questionnaires. The secondary aim was to document the incidence of sterile cystitis in this population of cats and compare it with the human literature.
Materials and methods Case details from all cats undergoing placement of ureteric stents from June 2009 until July 2012 were included in the study. Medical records were searched retrospectively, and cats were included if one or more ureteric stents were placed at surgery following diagnosis of ureteric obstruction.
Procedure Initially, all cats received medical management until ureteric obstruction was diagnosed. Medical treatment varied, but generally included some combination of intravenous fluid therapy, analgesia and antimicrobials. Cats were investigated using a combination of abdominal ultrasonography, survey abdominal radiography, percutaneous antegrade pyelography and intravenous urography (IVU). In-house serum biochemistry was performed, including measurement of serum creatinine and urea concentrations, as well as packed cell volume (PCV). For percutaneous antegrade pyelography, the procedure was performed under ultrasound guidance using a 23-gauge needle connected to an extension set and threeway tap. The needle was inserted via the greater curvature of the kidney into the renal pelvis, and urine was collected for bacterial culture and urinalysis. A volume of non-ionic iodinated contrast (Iohexol; Omnipaque, GE Healthcare) equal to 75–100% of the urine volume that was removed was injected. Lateral and ventrodorsal fluoroscopic images were obtained immediately, at 5 mins and approximately 15 mins postinjection. For cats with a diagnosis of ureteric obstruction, an exploratory laparotomy was performed. Immediate decompression of the obstructed kidney was performed by passing a 22-gauge intravenous catheter through the cranio-lateral aspect of the greater curvature into the renal pelvis, which allowed urine to drain into the abdominal cavity. A 0.018-gauge hydrophilic guide wire (Weasel Wire; Infiniti Medical) was passed through the catheter into the pelvis in an attempt to pass the wire into the ureter in an antegrade fashion (Figure 1). If this was not possible, a ventral cystotomy extending to the proximal urethra was performed in order to visualise the ureteric openings at the trigone. The hydrophilic guide wire was placed, in a retrograde manner, through the ureteric openings into the ureters and past the obstruction into the renal pelvis. In cats in which the guide wire could not be advanced past the site of obstruction, ureterotomy or ureteric resection and anastomosis were performed. For obstructions that occurred in the distal ureter where it was not possible to pass the stent, a neoureterocystostomy was performed. If possible, a dilator was passed over the guide wire and removed prior to stent placement. A ureteric stent (Figure 2) was placed over the guide wire so that the proximal aspect of the stent sat within the renal pelvis. The guide wire was removed and fluoroscopy
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Figure 2 Multiple fenestrated 2.5-French double pigtail soft ureteric stent
used to confirm the position of the proximal pigtail of the stent within the renal pelvis. The stents were double pigtail, multiple fenestrated polyurethane stents (Vet stentUreter; Infinity Medical); the first three cats had 2.5- or 3-French hard stents placed. Subsequently, 2.5-French soft stents were available and so these were placed. If a ureterotomy or ureterectomy was performed, it was sutured over the stent using either 5/0 or 6/0 polydioxanone (PDS II; Ethicon). Surgical loupes were used according to surgeon preference. Postoperative radiographs were taken to document stent location if the cat was stable enough to tolerate an increased anaesthesia time (Figure 3). In cats that were inappetent or anorexic, an esophagostomy tube was placed and maintained until the cat began eating independently. Postoperatively, a urethral catheter was placed to monitor urine output and evaluate fluid balance in all cats apart from one in which it was not placed at the surgeon’s discretion. All cats recovered in the intensive care unit where their heart rate, respiratory rate, blood pressure and urine output was monitored. Cats received medical therapy consisting of intravenous fluid therapy, opioid analgesia and other medications as necessary. Prevalence of postoperative complications, perioperative death rate and number of cats requiring further surgeries were recorded. Cats alive at follow-up that were azotaemic were staged according to the International Renal Interest Society (IRIS) grading system.10
Statistical analysis A Shapiro–Wilk test revealed that the data were normally distributed; this was confirmed by visual inspection of a histogram for each data set. The Kaplan–Meier method was used to document survival times. The 6-, 12- and 24-month survival rates were calculated; survival times are recorded as median values. An independent sample t-test was performed to identify any relationship between creatinine at presentation and survival. For all statistical analyses, values of P 10 times daily and had signs of straining.
Figure 3 Postoperative radiograph of cat illustrating bilateral ureteric stents, urethral catheter and oesophagostomy tube
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Results Twenty-six cats had ureteric stents placed; five cats had stents placed bilaterally. Fourteen cats were female (12 were neutered) and 12 cats were male neutered. The cats were aged from 2 to 12 years (mean 6 years). Ten cats were domestic shorthairs, three were domestic longhairs, two were British shorthairs, and there was one each of the following breeds: Birman, Burmese, Burmilla, Chinchilla, Exotic, Manx, Oriental, Persian, Ragdoll, Russian Blue and Siamese. The majority of cats had stents placed secondary to obstruction by ureteric calculi (n = 21); four cats had obstruction secondary to ureteric strictures and one cat had traumatic obstruction of both ureters. Of the cats with ureterolithiasis, uroliths were removed and submitted for analysis in 14 cats. Thirteen cats had calcium oxalate ureteroliths and one cat had xanthine uroliths. Four cats had a stricture causing the obstruction; in all of these cats, uroliths were visible at other sites in the urinary tract. Presenting signs included vomiting (n = 9), inappetance (n = 6), anorexia (n = 3), lethargy (n = 10), weight loss (n = 7), polyuria/polydipsia (n = 5), haematuria (n = 2), vocalising (n = 2), dysuria (n = 1), oliguria (n = 1), collapse (n = 1), cough (n = 1), hypersalivation (n = 1), depression (n = 1), weakness (n = 1), constipation (n = 1), pollakiuria (n = 1), stranguria (n = 1) and urethral obstruction (n = 1). Two cats had ureteric obstruction discovered as an incidental finding; one had azotaemia discovered on routine biochemistry, the other had a ureterolith discovered on a computed tomographic scan for investigation of hypervitaminosis D. Physical examination findings included heart murmur (n = 9), renal asymmetry (n = 5), painful kidneys (n = 5), abdominal pain (n = 4), irregular kidneys (n = 3), bilateral renomegaly (n = 3), unilateral renomegaly (n = 3), bradycardia (n = 2), tachycardia (n = 2), bilaterally small kidneys (n = 1), firm kidneys (n = 1), abdominal bruising (n = 1), obtundation (n = 1), pulmonary crackles (n = 1), hypovolemia (n = 1), hypothermia (n = 1), unilaterally small kidney (n = 1), dehydration (n = 1) and a gallop rhythm (n = 1). Two cats were normal on physical examination. Twenty-five cats had urine culture or culture of the urolith performed. Enterococcus faecalis was cultured in one cat and Escherichia coli was cultured in another cat; both cats had an indwelling urethral catheter placed prior to referral. Mean PCV at presentation was 28 ± 6% (15–36%). Mean creatinine was 7.6 ± 5.5 mg/dl (154–1408 mg/dl). Urea was off the scale in 11 cats; in the remainder, the mean urea was 31.5 ± 21.6 mmol/l (7.2–64.3 mmol/l). Mean potassium at presentation was 5.06 ± 1.58 mEq/l (2.65–8.50 mEq/l); 14/26 cats were hyperkalaemic (potassium >4.6 mEq/l).
Diagnostic imaging was performed in all cats: 25 had abdominal ultrasonography, 19 had survey abdominal radiography, 10 had percutaneous antegrade pyelography and four cats had IVU. Twelve cats had left ureteric obstruction: nine had right ureteric obstruction and in five cats it was bilateral. The stents were placed in an antegrade direction in four ureters. Ureterotomy was performed in 11 ureters, and resection and anastomosis was performed in six ureters; in these cats, it was not possible to pass the stent past the site of obstruction and so the stent was placed over a guide wire inserted proximally and distally through the ureterotomy and ureteric resection and anastomosis sites so that one end of the wire ended up in the renal pelvis and the other exited the ureter through the trigone. In one cat with bilateral ureteric obstruction, a stent was placed retrograde in one ureter and antegrade and via a ureterotomy in the other. In two cats the site of obstruction was very distal and ureteric re-implantation was performed when the stent was unable to be passed beyond the site of obstruction. One case had a very distal obstruction and a sphinctoroplasty was performed. Jackson–Pratt abdominal drains (Infusion Concepts; Sowerby Bridge) were placed in seven cats; six cats had a ureterotomy performed—in one cat the guide wire inadvertently penetrated the wall of the ureter. Surgical time was 182 mins (range 90–370 mins) and anaesthesia time was 315 mins (range 155–485 mins). Postoperatively, two cats received a fresh whole blood transfusion and one cat received a transfusion of oxyglobin. In all cats in which urine output was recorded (n = 22), mean urine output was 9 ml/kg/h (range 0–22.9 ml/kg/h). Two cats suffered a cardiopulmonary arrest on recovery from the anaesthetic; one cat had pulmonary oedema following fluid overload prior to referral; the other had severe hypotension, hypoglycaemia and anuria. Twenty-two cats survived to discharge; the mean number of days to discharge was 8 (range 2–14 days). Of the four cats that did not survive to discharge, two died in the perioperative period and two died 9 and 48 h postoperatively respectively; one cat became anuric, profoundly azotaemic and hyperkalaemic in the absence of renal pelvis dilation on ultrasound, and so acute renal failure was suspected. One cat developed uroabdomen 24 h postoperatively and a second laparotomy was performed; the cat became hypotensive and acidotic, and suffered cardiopulmoary arrest on recovery from anaesthesia. Additional surgical procedures Five cats developed uroabdomen between 3 and 48 h postoperatively; a diagnosis was made by documentation of higher creatinine within the abdominal fluid compared with serum creatinine. Four cats had a second
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5 60%, 44% and 20% respectively. The median survival of cats after surgery was 265 days (range 0–1071 days).
Percent survival
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Figure 4 Kaplan–Meier survival curve of cats following ureteric stent placement. Cats were censored at time of death
laparotomy, three cats had leakage from a ureterotomy site and one cat had leakage from the cystotomy site. One cat with a uroabdomen had a Jackson–Pratt drain placed at the original surgery site, which involved a ureterotomy and therefore, when diagnosed with a uroabdomen, did not require a second surgery. Stents needed to be replaced 4–28 months after the initial surgery in five cats because of migration, fracture, mineralisation causing luminal obstruction or sterile cystitis. The cat with sterile cystitis was urinating every 1–2 h with marked dysuria that was refractory to treatment with prednisolone at 1 mg/kg. Long-term follow-up Of the 22 cats that were alive at discharge, nine were alive at follow-up which was 3–28 months after the original surgery; one of these cats was lost to follow-up. Five cats had azotaemia, and, owing to its temperament, one cat had no recent biochemistry results. Of the cats with azotaemia, five were classified as IRIS stage 2 and two were IRIS stage 3. Six cats were diagnosed with sterile cystitis. Of the cats not alive at follow-up, eight were euthanased because of marked azotaemia, three were euthanased because of severe dysuria that was refractory to medical management and one was euthanased for unknown reasons, although it had previously documented severe azotaemia. One cat with recent biochemical evidence of severe azotaemia died; necropsy was declined. Statistical analysis The creatinine levels of the survivors (9.4 mg/dl, n = 9) was not significantly different from that of the non-survivors (6.5 mg/dl, n = 13; P = 0.295). A Kaplan–Meier survival curve depicts the survival characteristics of the cats following the surgery (Figure 4). The 1-, 6-, 12- and 24-month survival rates were 84%,
Quality of life assessment Telephone follow-up was performed between 3 and 36 months after the surgery. Eleven owners answered the questionnaire. Quality of life was scored as 8/10 (range 5–10). Three owners believed their cat’s mood was different since the surgery; two owners believed that the mood was affected occasionally. The behaviour of three cats had been negatively affected since the surgery; two cats were occasionally negatively affected. When asked whether the cat had experienced changes in urination (pollakiuria, stranguria or dysuria), six cats were affected and one cat occasionally had difficulty urinating; one cat was an outdoor cat and so it was not possible to document changes in urination patterns. With regard to the number of times per day each cat urinated, one cat urinated 1–2 times daily, three cats urinated 3–5 times daily, one cat urinated 6–9 times daily and three cats urinated >10 times daily. Eight cats visited a veterinarian frequently since the surgery for blood tests or management of cystitis, one cat visited the veterinarian for routine appointments only and two cats went infrequently. Three cats had received medical management from the local veterinarian to manage straining to urinate. One cat appeared uncomfortable when being picked up. One cat had changes in posture following the surgery. Three cats groomed the flank, perineum or lower abdomen more frequently after the surgery. When asked if owners worried about the cat since the surgery to place the stent, four answered yes and four answered occasionally. Four owners felt they had been restricted or limited in terms of what they would like to do, such as going on holidays, going away for weekends or evenings, or going to work; one owner felt restricted occasionally. Three owners chose not to leave their cat in a cattery or with family members or friends since the surgery. Four owners worried about the cost of the surgery and ongoing care, two owners worried occasionally. Ten out of 11 owners would choose to have the surgery performed again should they have a cat with the same condition.
Discussion Ureteric stents are an integral part of urological practice in human surgery, and are typically placed to prevent or relieve ureteral obstruction secondary to instrinsic or extrinsic aetiologies, including calculi, strictures, congenital anomalies, neoplasia or trauma.12 In addition, stents can be placed prophylactically after ureteric surgery or extracorporeal shock wave lithotripsy to prevent ureteral obstruction. Ureteral stents in humans are associated with frequent side effects, including irritating voiding symptoms in 40–55% of patients.13 In one study,11
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Journal of Feline Medicine and Surgery
6 flank pain was noted in 42%, and 45% of patients reported impairment in their quality of life. In humans, stents are generally removed between 2 days and 2 weeks after placement.7 Owners of cats in this study recorded a favourable quality of life score, with a median value of 8/10. However, based upon the previous described grading system, the cats alive at follow-up had mild dysuria (3/11; 27%), moderate dysuria (1/11; 9%) and severe dysuria (3/11; 27%). One report described removal of a stent owing to persistent stranguria.5 One cat with traumatic ureteric obstruction in this study developed acute ureteric obstruction after stent removal; therefore, careful monitoring of cats following stent removal is advised.14 Although removing stents after a few weeks following ureteric surgery may prevent the dysuria, one of the benefits of having stents placed is to prevent re-obstruction and to allow passive ureteric dilation in these cats with persistent stone formation.4 The incidence of dysuria in this study was higher than in the current literature.4,5,7 The classification of mild dysuria as cats that urinate 2–5 times a day may be tolerable in some cats. In addition, cats may urinate more frequently owing to azotaemic CKD. In a review article,4 dysuria was reported in a minority of cats and was reported as self limiting or responsive to glucocorticoids. A retrospective study reported only one case of sterile cystitis out of nine cats.5 Cats in this study with persistent cystitis were started on anti-inflammatory doses of prednisolone; however, the urinary tract signs of some of the cats were refractory to glucocorticoids. The ureteropelvic junction in the cat is located relatively caudal and we suspect that the distal coil of the stent irritates the trigone and proximal urethra. A ventral cystotomy was performed in this study; it is possible that the location of the suture line opposite to the ureterovesicular junction contributed to the dysuria. A ventral cystotomy was performed in this study as it allows easier catheterisation of both ureters;15 a dorsal cystotomy may have reduced the incidence of dysuria and would be an interesting extension of the study. In the study by Nicoli et al,5 a neocystoureterostomy was performed in 8/9 cats and so it is possible that the distal aspect of the stent exited more cranially and therefore further away from the trigone. After diagnosis of ureteric obstruction, all cats were treated with a similar protocol of medical management prior to surgery. Surgery was performed shortly after diagnosis based on previous evidence that complete ureteric obstruction causes irreversible kidney damage from 7 days.16 While no statistically significant difference was seen between survivors and non-survivors, it was notable that some of the survivors had extremely elevated creatinine concentrations (range 1.74–20.00 mg/dl). A high serum creatinine at presentation may represent a situation in which complete ureteric obstruction has occurred in a kidney that was, until recently, functioning well, and if the obstruction is
relieved there may be adequate functional renal parenchyma to allow recovery of adequate renal function; that is, it was the relative contribution of acute versus chronic disease that predicted the improvement in azotaemia after relief of the obstruction. Ultrasound proved to be a useful preoperative imaging modality as it confirmed renal pelvis dilation and hydroureter. In many cases, a ureterolith could be identified by distal acoustic shadowing. Radiographs were useful in some cases, particularly where radio-opaque ureteroliths were present. Initially, an IVU was performed in cases in which the diagnosis of ureteric obstruction was questionable. However, it became apparent that there was poor opacification of the upper urinary tract secondary to reduced glomerular filtration of contrast; subsequently, in cases in which the diagnosis of ureteric obstruction was not certain, an antegrade pyelograde was performed. In some cases, intraoperative fluoroscopy was used to image the urinary tract and to guide positioning of the guide wire or stent. Ureteric stents are a useful way of relieving ureteric rupture or obstruction. The prognosis for cats with stents placed remains guarded primarily because of CKD, but also because of dysuria, stent migration or fracture. Survival to discharge was similar to a previous study involving ureterolithotomy.2 A study comparing medical and surgical management of ureteric obstruction in cats found a 12-month survival rate of 66% with medical management and 91% with surgical management.3 Surgical management in the study by Kyles et al3 included ureterotomy with and without nephrostomy tube placement and ureteroneocystotomy. Our study found that the 12-month survival rate was less favourable, with only 52% cats alive at 12 months. It is possible that the cat population in the study by Kyles et al3 differed from the population of cats in the present study or they presented later in the disease process. Another reason why the cats in the present study had a worse 12-month survival may be related to the long anaesthetic and surgical time (mean surgery time 182 mins). Renal blood flow and glomerular function may be depressed as a result of hypotension and renal vasoconstriction secondary to anaesthesia,17 and an increased length of anaesthetic required to place the stents compared with traditional surgery may have caused additional damage to the remaining nephrons. In addition, three cats in this study were euthanased as a result of dysuria, which makes the long-term results less favourable than the study by Kyles et al.3 Another reason why cats in this study had a worse 12-month survival compared with other studies may represent presentation at a later stage in the disease process, for example more advanced CKD. A high proportion of our cats presented with lethargy and one was collapsed at presentation. Additionally, three cats in this study were euthansed as a result of refractory sterile cystitis, which had an impact on the long-term outcome.
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Five cats in our study developed a uroabdomen postoperatively. Postoperative diuresis produced a urine output of up to 22 ml/kg/h in some cats. We suspect that in cats in which a ureterotomy or ureteric resection and anastomosis has been performed, the high volume of urine produced in the immediate postoperative period may cause an increased risk of leakage from the ureter. It was initially suspected that the presence of a stent may help to decrease the incidence of uroabdomen postoperatively. However, the rate of uroabdomen in this study was, in fact, higher than that in other studies in which ureterotomies or ureterectomies were performed without stents (16%).3 It subsequently became protocol to place a Jackson–Pratt drain whenever a ureterotomy or ureteric resection and anastomosis was performed. This allowed any urine produced to be evacuated from the abdomen; it also allowed biochemical analysis of the abdominal fluid to be performed. The drains were removed when the volume decreased or plateaued and there was no evidence of urine leakage. By nature, as a retrospective study, there were numerous limitations, including incomplete record-keeping, leading to missing data and inconsistent management protocols. There may have been confounding variables that were not identified. In addition, the surgeries were performed by a number of surgeons with variable experience in the procedure. We were only able to follow up on a small number of cases for the questionnaire part of the study; a larger number of cases may have altered the results.
Conclusions Ureteric stents may reduce the incidence of certain complications of ureteric surgery, such as stricture formation and subsequent obstruction and uroabdomen if a Jackson–Pratt drain is placed concurrently. However, they may be associated with novel complications, such as stent fracture, migration and, in particular, dysuria. It is possible that altering the location of the distal aspect of the stent away from the trigone may reduce the incidence of dysuria, for example by performing a ureteroneocystotomy or using a device such as a subcutaneous ureteral bypass (SUB) system (Norfolk Medical). The SUB consists of a nephrostomy tube connected to a cystostomy tube via a subcutaneous port; the location of the cystostomy tube is at the apex of the bladder. The prognosis of cats with stent placement secondary to ureteric obstruction remains guarded due to concurrent CKD. Conflict of interest The authors do not have any potential conflicts of interest to declare.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
References 1 Kyles AE, Hardie EM, Wooden BG, et al. Clinical, clincopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984–2002) J Am Vet Med Assoc 2005; 226: 932–936. 2 Roberts SF, Aronson LR and Brown DC. Postoperative mortality in cats after ureterolithotomy. Vet Surg 2011; 40: 438–443. 3 Kyles AE, Hardie EM, Wooden BG and Adin CA. Management and outcome of cats with ureteral calculi: 153 cases (1984–2002). J Am Vet Med Assoc 2005; 226: 937–944. 4 Berent AC. Ureteral obstructions in dogs and cats: a review of traditional and new interventional diagnostic and therapeutic options. J Vet Emerg Crit Care (San Antonio) 2011; 21: 86–103. 5 Nicoli S, Morello E, Martano M, et al. Double-J ureteral stenting in nine cats with ureteral obstruction. Vet J 2012; 194: 60–65. 6 Lam JS and Gupta M. Ureteral stents. In: Stoller ML and Meng MV (eds). Urinary stone disease: the practical guide to medical and surgical management. 1st ed. Totowa: Humana Press, 2007, p 465. 7 Horowitz C, Berent A, Weisse C, et al. Predictors of outcome for cats with ureteral obstructions after interventional management using ureteral stents or a subcutaneous ureteral bypass device. J Feline Med Surg 2013; 15: 1052–1062. 8 Zaid MS, Berent AC, Weisse C and Caceres A. Feline ureteral strictures: 10 cases (2007–2009). J Vet Intern Med 2011; 25: 222–229. 9 Berent AC, Weisse C, Beal MW, et al. Use of indwelling, double-pigtail stents for treatment of malignant ureteral obstruction in dogs: 12 cases (2006–2009). J Am Vet Med Assoc 2011; 238: 1017–1025. 10 International Renal Interest Society staging of CKD, http:// www.iris-kidney.com/pdf/IRIS2009_Staging_CKD.pdf (accessed March 2013). 11 Niessen SJ, Powney S, Guitian J, et al. Evaluation of a quality-of-life tool for cats with diabetes mellitus. J Vet Intern Med 2010; 24: 1098–1105. 12 Manassero M, Decambron A, Viateau V, et al. Indwelling double pigtail ureteral stent combined or not with surgery for feline ureterolithiasis. J Feline Med Surg. Epub ahead of print 4 December 2013. 13 Leibovici D, Cooper A, Lindner A, et al. Ureteral stents: morbidity and impact on quality of life. Isr Med Assoc J 2005; 7: 491–494. 14 Kulendra ER, Kulendra NJ and Halfacree ZJ. Management of bilateral ureteric trauma in a cat with ureteral stenting and subcutaneous ureteral bypass. J Feline Med Surg. Epub ahead of print 30 October 2013. DOI: 10.1177/1098612X13509098. 15 Waldron DR. Urinary bladder. In: Slatter D (ed). Textbook of small animal surgery. 3rd ed. Philadelphia: Saunders, 1993, p 1635. 16 Kerr WS. Effect of complete ureteral obstruction for one week on kidney function. J Appl Physiol 1954; 6: 762–772. 17 Mason DE. Urinary system. In: Slatter D (ed). Textbook of small animal surgery. 3rd ed. Philadelphia: Saunders, 1993, p 2548.
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