Volume 164 Number 6, Part I
significant bleeding does not occur until the platelet count decreases below 30,000/mm3 , Therefore this value has become our cutoff point below which we protect patients with platelet transfusion whether they are to be delivered vaginally or abdominally, The overall incidence of transfusion is 60% in class I HELLP and 40% in class 2; virtually no patients in class 3 (platelet nadir> 100,000/mm' to :S 150,000/mm 3 ) receive blood products.
Progression and regression of HELLP syndrome
We believe that the class 3 group requires further study. For practicing clinicians I think the class 3 grouping functions as a "bright yellow flag," prodding obstetricians to notice that patients are about to get into trouble as they fall into the class 2 and then class I grouping.
Suture entrapment and secondary ureteral obstruction c. Robert Stanhope, MD, Timothy O. Wilson, MD, WiIliamJ. Utz, MD, Lynwood H. Smith, MD, and Peter C. O'Brien, PhD Rochester, Minnesota During the 6-year period ending in 1988, suture entrapment and secondary postoperative ureteral obstruction occurred in 18 (0.33%) of the 5379 patients who underwent major pelvic operations for benign conditions. Sixteen cases occurred after vaginal surgery and two after abdominal hysterectomy. Placement of the McCall suture or sutures for elevation of a bladder neck caused ureteral entrapment most frequently. Early diagnosis was facilitated by comparison of preoperative and postoperative serum creatinine levels. The mean change in serum creatinine level in patients with unilateral obstruction was an increase of 0.8 mg/dl. Treatment by either antegrade placement of ureteral stents or abdominal exploration with deligation or ureteroneocystotomy was successful in all cases. Retrograde placement of ureteral stents was unsuccessful. (AM J OBSTET GVNECOL 1991 ;164:1513-9.)
Key words: Postoperative ureteral obstruction, McCall's suture, high serum creatinine, percutaneous nephrostomy, antegrade ureteral stenting Ureteral injury occurs infrequently after pelvic surgery for benign disease; however, the risk can be minimized by understanding the relationship of the ureter to other pelvic organs and, whenever possible, by identifying the ureter at operation. Identification and exposure of the ureter is readily accomplished during abdominal surgery because the retroperitoneal space can be entered easily and safely and the ureter can be identified throughout its course. This is not possible during vaginal surgery, especially if the course of the ureter is distorted by marked pelvic relaxation or previous pelvic surgery. We have reviewed our recent experience with ureteral obstruction after pelvic surgery From the SectIOn of Gynecolofilc Surgery, the Department of Urology, the Dlvison of Nephrology and Internal Medlczne, and the SectIOn of Biostatistics, Ma.vo Clinic and Mayo Founatwn. Presented at the FiftY-eighth Annual Meetzng of the Central AssoCiatIOn ofObstetricians and Gynecologzsts, Louisville, Kentucky, October Il-I3, 1990. Also presented to the Minnesota Obstetrical and Gynecolofilcal Society, December 2, 1989. Reprint requests: C. Robert Stanhope, MD, SectIOn of Gynecolofilc Surgery, Mayo Clznic, 200 Flnt St. SW, Rochester, MN 55905. 6/6/28226
for benign conditions to determine the frequency with which this occurs, to identify means for early diagnosis, and to describe our current management. Patients and methods In the 6-year period ending in 1988, 5379 major pelvic operations were performed for therapy of benign conditions at the Mayo Clinic. Of this group 2546 were vaginal hysterectomies or operations for correction of vaginal prolapse and 2833 were abdominal hysterectomies or other gynecologic abdominal operations for therapy of pelvic conditions. Eighteen cases of suture entrapment and secondary postoperative ureteral obstruction (IS unilateral and 3 bilateral) were found for an overall incidence of 0.33%. The obstructions were attributable to entrapment by ureteral ligation or ureteral kinking by the placement of a periureteralligature. Ureteral perforation by a needle was not identified in any case. Sixteen cases occurred after vaginal operations, including repair of the vagina (incidence, 0.63%), and two occurred after pelvic operations done abdominally (incidence, 0.07%) (Table I). The site of 1513
1514
Stanhope et al.
June 1991 Am J ObSlCl Gynecol
Table I. Distribution of postoperative ureteral obstructions Ongmal ;urgical procedure
ObstructIOn (No.)
Vaginal hysterectomy and repair for total procidentia Vaginal hysterectomy and repair for grade 2 or 3 uterine prolapse or stress urinary incontinence Vaginal repair of posthysterectomy vaginal vault prolapse Total abdominal hysterectomy
7
6 3
2 18
TOTAL
Table II. Sites of ureteral obstruction
Fig. I. Excretory urogram demonstrating ureteral obstruction after suture entrapment.
obstruction was the distal ureter in each case; the left side was involved more often than the right (Table II). Flank pain, fever, or both occurred in 13 patients (72o/c) in the immediate postoperative period, and difficult micturition was noted in two patients. No patient experienced hematuria. Bilateral involvement was promptly recognized by anuria in three patients. Signs of unilateral ureteral obstruction within the first 36 to 48 hours included an early transient increase in serum creatinine value in 17 of the 18 patients; one patient did not have a postoperative serum creatinine determination within that interval. In the evaluable patients with unilateral obstruction, the mean serum creatinine value was 0.93 mg/dl before operation and 1.65
Site
No.
Unilateral Left Right Bilateral
15 9 6 3
mg/dl at 36 to 48 hours after operation. The mean change in serum creatinine level in patients with unilateral obstruction was an increase of 0.8 mg/ dl (range, 0.3 to 1.4 mg/dl). Excretory urography, percutaneous nephrostography, or renal pelvic ultrasonography was used to confirm partial or complete unilateral ureteral obstruction (Figs. I and 2). Three age- and procedure-matched controls for each of 13 cases of unilateral ureteral entrapment were identified. Serum creatinine levels increased markedly more in the cases than in the controls (p < 0.00 I; two-tailed paired t test) (Fig. 3). In a number of instances in the control cases, the postoperative creatinine value decreased slightly, presumably related to operative and immediate postoperative hydration. Etiology. Although the ureter can be palpated during vaginal surgery and excluded from the vascular pedicles, it easily can become entrapped by the suture used to ligate a pedicle, to repair descent of the bladder neck, or to plicate the uterosacral ligaments. Plication sutures at the base of the bladder approximate the pubovesicocervical fascia and correct the bladder neck descent while restoring the posterior urethral vesicle angle. It is our practice to place at least one McCall's suture to plicate the uterosacral ligaments and to obliterate any potential enterocele space in every patient undergoing vaginal hysterectomy or repair of vault prolapse. Often, two or more McCall's sutures are placed when there is significant enterocele or marked vaginal vault prolapse. At least one McCall's suture was used in every vaginal case; however, two were used in five cases and three sutures were used in three cases. Either the McCall
Volume 164 I'\umber 6, r"rt I
Postoperative ureteral obstruction
1515
Fig. 2. LTltrasonograms of renal pelvis (A) and ureter (B), demomtrating dilation of renal pelvis and ureter in association with ureteral obstruction cdused by suture entrapment.
suture or the sutures used to repair bladder neck descent caused partial or complete obstruction in 14 cases. In one vaginal case a suture on a uterine artery pedicle caused entrapment, and in one vaginal case an infundibulopelvic ligament tie caused entrapment. After abdominal hysterectomy a Moschcowitz uterosacral plication suture caused ureteral entrapment in one patient and a pelvic peritonealization suture caused entrapment at the pelvic brim in the second (Table III). Rarely was the ureter actually encircled by a suture. Most commonly, the ureter was merely kinked by suture placement in the periureteral tissues. Results
Attempted retrograde passage of a ureteral catheter at cystoscopy in 10 cases was unsuccessful. Retrograde ureteroscopy was attempted in one case but was not successful. Percutaneous nephrostomy was performed in eight cases to achieve drainage of the affected renal unit, as well as to attempt antegrade passage of a ureteral catheter; subsequent stenting in this fashion was successful in six cases. Ten patients underwent early reoperation by the transperitoneal approach to mobilize the involved ureter(s) and, when indicated, to place ureteral stents through a cystotomy incision. Two patients required ureteroneocystostomy because the ureter was damaged or its vascular supply was compromised. Segmental ureterectomy and ureteroureterostomy were not indicated. No patient had a subsequent fistula, and all patients subsequently had normal renal function as measured by serum creatinine level. Subsequent excretory urography, performed in only a small group of patients, showed postoperative changes with no significant abnormalities. Comment
The early recognition of ureteral obstruction is impOl'tant because the degree to which nephron function
is lost irreversibly is directly related to the duration and completeness of the obstruction. There are four areas within the pelvis where suture entrapment is most likely to occur: (1) the point where the ureter crosses the iliac vessels, (2) the point where the ureter comes into close proximity to the adnexa near the pelvic brim, (3) the point where the ureter is crossed by the uterine vessels, and (4) the base of the bladder where traction on the interuretel'ic ligament may obstruct the ureter. The relationship of the ureter to other pelvic structures during vaginal surgery has been examined during operating conditions. I The ureter is a mean of 1.0 cm from the clamp placed on the infundibulopelvic ligament when the tube and ovary are removed and a mean of 0.9 em from the plication sutures used to provide support to the base of the bladder. However, despite this close proximity, ligation of the ureter or kinking is an uncommon occurrence. However, when it happens, it rarely is recognized during the operative procedure. The frequency of postoperative ureteral obstruction reponed in the literature ranges from 0.1 % to 2.4%.:1" Most of the reponed cases involve injury occurring during abdominal hysterectomy for benign conditions. The present study differs in that only rarely (2/18) did the injury occur during abdominal hysterectomy, and the vaginal surgery associated with injury involved uterine or vaginal prolapse in every case. Early recognition of ureteral obstruction in the postoperative period, even before flank pain or fever develops, is possible by detecting subtle increases in the serum creatinine value, which can begin as early as 24 hours after operation. The serum creatinine value may return to nearly normal by 72 hours after operation. This phenomenon has been observed under experimental conditions in the case of unilateral ureteral obstruction. ' With total unilateral obstruction, initially there will be a transient increase in renal blood flow, lasting 1 to 2 hours. This will be followed by vaosconstriction and
1516 Stanhope et al.
June 1991 Am J Obstet Gvnecol
1.2 1.0 0.8
en Q) en
ctS ()
0.6 0.4 0.2
•
.. ... •
•
•
P50% of the injuries? Does the author feel that the test he describes is sufficiently useful that paired creatinine levels should be collected on all pelvic surgical patients? REFERENCES
J. Gynaekologische Operationslehre. Berlin: Urban and Schwarzenberg, 1932: 172. 2. Symmonds RE. Uteral injuries associated with gynecologic surgery: prevention and management. Clin Obstet Gynecol 1. Halban
1976; 19:623-43.
3. Moody TE, Vaughn ED Jr, Gillenwater JV. Relationship between renal blood flow and ureteral pressure during 18 hours of total unilateral ureteral occlusion: implications for changing sites of increased renal resistance. Invest Ural 1975;13:246-51.
DR. PEDRO A. POMA, Melrose Park, Illinois. I have two questions. First, did the authors review all the other cases of elevated creatinine, follow them, and find out
Volume 164 1\ umber 6. Part 1
how many had ureteral obstruction? Second, what is the influence of dehydration, blood loss, and fever in relationship to the postoperative creatinine levels? DR. DANIEL RIGHTMIRE, Springfield, Illinois. I wanted to ask how often do the authors believe that unilateral entrapment of the ureter goes undetected, because that's certainly important in this case. Second, may I suggest that the change in serum creatinine data be submitted to receiver operating characteristic curve analysis? DR. STANHOPE (Closing). I would like to thank Drs. Drukker and Rogers and Drs. Poma and Rightmire from Illinois for their comments. Concerning Dr. Drukker's first concern, the probable and more likely site for ureteral entrapment is compression of the interureteric ligament. The McCall suture also has been documented to cause entrapment, and I have taken photographs of this. But I believe the greatest risk is traction on the interureteric ligaments, causing the ureter to kink. The McCall suture, as described in 1957 and published in the Green Journal, consisted of three silk sutures designed to approximate the uterosacral ligaments from their posterior and lateral perirectal positions. If you draw an imaginary transverse line, bisecting the surgical field, and place the sutures well below that line, you can be reasonably assured entrapment will not occur. Dr. Drukker's second concern was how we expose the ureter during abdominal operations where the ovaries or just the uterus is removed. It is our practice to open the broad ligament and identify visually the course of the ureter down to where the uterine artery crosses it. Then, when a clamp is placed on the uterus at the level of the uterine artery, we palpate the ureter. We do this in every case. This report just dealt with surgery for benign conditions. However, our frequency of ureteral entrapment or obstruction after surgery for malignant conditions is less, related to the fact that most surgery for cancer is abdominal and the ureter is often completely dissected in cancer operations.
Postoperative ureteral obstruction
1519
Finally, about retrograde ureteral studies, we don't attempt retrograde stent placement at all anymore. But there is a new procedure, called ureteroscopy. With a fiberoptic instrument the urologist can get into the ureter, advance a guide wire that can turn and maneuver around an apparent kink, and position a ureteral stent. Ureteroscopy may playa future role. Dr. Rogers had expressed concern about obtaining serum creatinine levels. Serum creatinine levels were obtained preoperatively in all of our patients as part of our preanesthetic medical evaluation. We get postoperative electrolyte studies that also include serum creatinine. So, for a number of years, we have had this information available for both the preoperative and the postoperative periods. I believe that this test is significant, with a high observed sensitivity of 100% and an observed specificity of 92%, and that we should obtain paired serum creatinine levels preoperatively and postoperatively, as you indicated, in patients undergoing hysterectomy or surgery where ureteral injury could occur. I think we should follow through on this. Dehydration can cause an increase in the serum creatinine level. Serum creatinine may be elevated in the preoperative period when the patient has fasted, and then postoperatively, after hydration, it may be lower than the preoperative value. Obviously, there are other causes for elevated creatinine, for example, the use of aminoglycosides. I think that in our series there are probably undetected incidences where ureteral entrapment has occurred. We were not trying to look at that. We got the idea for this study from a nephrologist who indicated that this phenomenon occurred in patients who had unilateral ureteral stones and that these patients were found to have transient rises in serum creatinine. I noted that we frequently saw a rise after ureteral entrapment from vaginal surgery, so we decided to look at this in more detail. I will take your suggestion for further statistical analysis.
significant bleeding does not occur until the platelet count decreases below 30,000/mm3 , Therefore this value has become our cutoff point below which we protect patients with platelet transfusion whether they are to be delivered vaginally or abdominally, The overall incidence of transfusion is 60% in class I HELLP and 40% in class 2; virtually no patients in class 3 (platelet nadir> 100,000/mm' to :S 150,000/mm 3 ) receive blood products.
Progression and regression of HELLP syndrome
We believe that the class 3 group requires further study. For practicing clinicians I think the class 3 grouping functions as a "bright yellow flag," prodding obstetricians to notice that patients are about to get into trouble as they fall into the class 2 and then class I grouping.
Suture entrapment and secondary ureteral obstruction c. Robert Stanhope, MD, Timothy O. Wilson, MD, WiIliamJ. Utz, MD, Lynwood H. Smith, MD, and Peter C. O'Brien, PhD Rochester, Minnesota During the 6-year period ending in 1988, suture entrapment and secondary postoperative ureteral obstruction occurred in 18 (0.33%) of the 5379 patients who underwent major pelvic operations for benign conditions. Sixteen cases occurred after vaginal surgery and two after abdominal hysterectomy. Placement of the McCall suture or sutures for elevation of a bladder neck caused ureteral entrapment most frequently. Early diagnosis was facilitated by comparison of preoperative and postoperative serum creatinine levels. The mean change in serum creatinine level in patients with unilateral obstruction was an increase of 0.8 mg/dl. Treatment by either antegrade placement of ureteral stents or abdominal exploration with deligation or ureteroneocystotomy was successful in all cases. Retrograde placement of ureteral stents was unsuccessful. (AM J OBSTET GVNECOL 1991 ;164:1513-9.)
Key words: Postoperative ureteral obstruction, McCall's suture, high serum creatinine, percutaneous nephrostomy, antegrade ureteral stenting Ureteral injury occurs infrequently after pelvic surgery for benign disease; however, the risk can be minimized by understanding the relationship of the ureter to other pelvic organs and, whenever possible, by identifying the ureter at operation. Identification and exposure of the ureter is readily accomplished during abdominal surgery because the retroperitoneal space can be entered easily and safely and the ureter can be identified throughout its course. This is not possible during vaginal surgery, especially if the course of the ureter is distorted by marked pelvic relaxation or previous pelvic surgery. We have reviewed our recent experience with ureteral obstruction after pelvic surgery From the SectIOn of Gynecolofilc Surgery, the Department of Urology, the Dlvison of Nephrology and Internal Medlczne, and the SectIOn of Biostatistics, Ma.vo Clinic and Mayo Founatwn. Presented at the FiftY-eighth Annual Meetzng of the Central AssoCiatIOn ofObstetricians and Gynecologzsts, Louisville, Kentucky, October Il-I3, 1990. Also presented to the Minnesota Obstetrical and Gynecolofilcal Society, December 2, 1989. Reprint requests: C. Robert Stanhope, MD, SectIOn of Gynecolofilc Surgery, Mayo Clznic, 200 Flnt St. SW, Rochester, MN 55905. 6/6/28226
for benign conditions to determine the frequency with which this occurs, to identify means for early diagnosis, and to describe our current management. Patients and methods In the 6-year period ending in 1988, 5379 major pelvic operations were performed for therapy of benign conditions at the Mayo Clinic. Of this group 2546 were vaginal hysterectomies or operations for correction of vaginal prolapse and 2833 were abdominal hysterectomies or other gynecologic abdominal operations for therapy of pelvic conditions. Eighteen cases of suture entrapment and secondary postoperative ureteral obstruction (IS unilateral and 3 bilateral) were found for an overall incidence of 0.33%. The obstructions were attributable to entrapment by ureteral ligation or ureteral kinking by the placement of a periureteralligature. Ureteral perforation by a needle was not identified in any case. Sixteen cases occurred after vaginal operations, including repair of the vagina (incidence, 0.63%), and two occurred after pelvic operations done abdominally (incidence, 0.07%) (Table I). The site of 1513
1514
Stanhope et al.
June 1991 Am J ObSlCl Gynecol
Table I. Distribution of postoperative ureteral obstructions Ongmal ;urgical procedure
ObstructIOn (No.)
Vaginal hysterectomy and repair for total procidentia Vaginal hysterectomy and repair for grade 2 or 3 uterine prolapse or stress urinary incontinence Vaginal repair of posthysterectomy vaginal vault prolapse Total abdominal hysterectomy
7
6 3
2 18
TOTAL
Table II. Sites of ureteral obstruction
Fig. I. Excretory urogram demonstrating ureteral obstruction after suture entrapment.
obstruction was the distal ureter in each case; the left side was involved more often than the right (Table II). Flank pain, fever, or both occurred in 13 patients (72o/c) in the immediate postoperative period, and difficult micturition was noted in two patients. No patient experienced hematuria. Bilateral involvement was promptly recognized by anuria in three patients. Signs of unilateral ureteral obstruction within the first 36 to 48 hours included an early transient increase in serum creatinine value in 17 of the 18 patients; one patient did not have a postoperative serum creatinine determination within that interval. In the evaluable patients with unilateral obstruction, the mean serum creatinine value was 0.93 mg/dl before operation and 1.65
Site
No.
Unilateral Left Right Bilateral
15 9 6 3
mg/dl at 36 to 48 hours after operation. The mean change in serum creatinine level in patients with unilateral obstruction was an increase of 0.8 mg/ dl (range, 0.3 to 1.4 mg/dl). Excretory urography, percutaneous nephrostography, or renal pelvic ultrasonography was used to confirm partial or complete unilateral ureteral obstruction (Figs. I and 2). Three age- and procedure-matched controls for each of 13 cases of unilateral ureteral entrapment were identified. Serum creatinine levels increased markedly more in the cases than in the controls (p < 0.00 I; two-tailed paired t test) (Fig. 3). In a number of instances in the control cases, the postoperative creatinine value decreased slightly, presumably related to operative and immediate postoperative hydration. Etiology. Although the ureter can be palpated during vaginal surgery and excluded from the vascular pedicles, it easily can become entrapped by the suture used to ligate a pedicle, to repair descent of the bladder neck, or to plicate the uterosacral ligaments. Plication sutures at the base of the bladder approximate the pubovesicocervical fascia and correct the bladder neck descent while restoring the posterior urethral vesicle angle. It is our practice to place at least one McCall's suture to plicate the uterosacral ligaments and to obliterate any potential enterocele space in every patient undergoing vaginal hysterectomy or repair of vault prolapse. Often, two or more McCall's sutures are placed when there is significant enterocele or marked vaginal vault prolapse. At least one McCall's suture was used in every vaginal case; however, two were used in five cases and three sutures were used in three cases. Either the McCall
Volume 164 I'\umber 6, r"rt I
Postoperative ureteral obstruction
1515
Fig. 2. LTltrasonograms of renal pelvis (A) and ureter (B), demomtrating dilation of renal pelvis and ureter in association with ureteral obstruction cdused by suture entrapment.
suture or the sutures used to repair bladder neck descent caused partial or complete obstruction in 14 cases. In one vaginal case a suture on a uterine artery pedicle caused entrapment, and in one vaginal case an infundibulopelvic ligament tie caused entrapment. After abdominal hysterectomy a Moschcowitz uterosacral plication suture caused ureteral entrapment in one patient and a pelvic peritonealization suture caused entrapment at the pelvic brim in the second (Table III). Rarely was the ureter actually encircled by a suture. Most commonly, the ureter was merely kinked by suture placement in the periureteral tissues. Results
Attempted retrograde passage of a ureteral catheter at cystoscopy in 10 cases was unsuccessful. Retrograde ureteroscopy was attempted in one case but was not successful. Percutaneous nephrostomy was performed in eight cases to achieve drainage of the affected renal unit, as well as to attempt antegrade passage of a ureteral catheter; subsequent stenting in this fashion was successful in six cases. Ten patients underwent early reoperation by the transperitoneal approach to mobilize the involved ureter(s) and, when indicated, to place ureteral stents through a cystotomy incision. Two patients required ureteroneocystostomy because the ureter was damaged or its vascular supply was compromised. Segmental ureterectomy and ureteroureterostomy were not indicated. No patient had a subsequent fistula, and all patients subsequently had normal renal function as measured by serum creatinine level. Subsequent excretory urography, performed in only a small group of patients, showed postoperative changes with no significant abnormalities. Comment
The early recognition of ureteral obstruction is impOl'tant because the degree to which nephron function
is lost irreversibly is directly related to the duration and completeness of the obstruction. There are four areas within the pelvis where suture entrapment is most likely to occur: (1) the point where the ureter crosses the iliac vessels, (2) the point where the ureter comes into close proximity to the adnexa near the pelvic brim, (3) the point where the ureter is crossed by the uterine vessels, and (4) the base of the bladder where traction on the interuretel'ic ligament may obstruct the ureter. The relationship of the ureter to other pelvic structures during vaginal surgery has been examined during operating conditions. I The ureter is a mean of 1.0 cm from the clamp placed on the infundibulopelvic ligament when the tube and ovary are removed and a mean of 0.9 em from the plication sutures used to provide support to the base of the bladder. However, despite this close proximity, ligation of the ureter or kinking is an uncommon occurrence. However, when it happens, it rarely is recognized during the operative procedure. The frequency of postoperative ureteral obstruction reponed in the literature ranges from 0.1 % to 2.4%.:1" Most of the reponed cases involve injury occurring during abdominal hysterectomy for benign conditions. The present study differs in that only rarely (2/18) did the injury occur during abdominal hysterectomy, and the vaginal surgery associated with injury involved uterine or vaginal prolapse in every case. Early recognition of ureteral obstruction in the postoperative period, even before flank pain or fever develops, is possible by detecting subtle increases in the serum creatinine value, which can begin as early as 24 hours after operation. The serum creatinine value may return to nearly normal by 72 hours after operation. This phenomenon has been observed under experimental conditions in the case of unilateral ureteral obstruction. ' With total unilateral obstruction, initially there will be a transient increase in renal blood flow, lasting 1 to 2 hours. This will be followed by vaosconstriction and
1516 Stanhope et al.
June 1991 Am J Obstet Gvnecol
1.2 1.0 0.8
en Q) en
ctS ()
0.6 0.4 0.2
•
.. ... •
•
•
P50% of the injuries? Does the author feel that the test he describes is sufficiently useful that paired creatinine levels should be collected on all pelvic surgical patients? REFERENCES
J. Gynaekologische Operationslehre. Berlin: Urban and Schwarzenberg, 1932: 172. 2. Symmonds RE. Uteral injuries associated with gynecologic surgery: prevention and management. Clin Obstet Gynecol 1. Halban
1976; 19:623-43.
3. Moody TE, Vaughn ED Jr, Gillenwater JV. Relationship between renal blood flow and ureteral pressure during 18 hours of total unilateral ureteral occlusion: implications for changing sites of increased renal resistance. Invest Ural 1975;13:246-51.
DR. PEDRO A. POMA, Melrose Park, Illinois. I have two questions. First, did the authors review all the other cases of elevated creatinine, follow them, and find out
Volume 164 1\ umber 6. Part 1
how many had ureteral obstruction? Second, what is the influence of dehydration, blood loss, and fever in relationship to the postoperative creatinine levels? DR. DANIEL RIGHTMIRE, Springfield, Illinois. I wanted to ask how often do the authors believe that unilateral entrapment of the ureter goes undetected, because that's certainly important in this case. Second, may I suggest that the change in serum creatinine data be submitted to receiver operating characteristic curve analysis? DR. STANHOPE (Closing). I would like to thank Drs. Drukker and Rogers and Drs. Poma and Rightmire from Illinois for their comments. Concerning Dr. Drukker's first concern, the probable and more likely site for ureteral entrapment is compression of the interureteric ligament. The McCall suture also has been documented to cause entrapment, and I have taken photographs of this. But I believe the greatest risk is traction on the interureteric ligaments, causing the ureter to kink. The McCall suture, as described in 1957 and published in the Green Journal, consisted of three silk sutures designed to approximate the uterosacral ligaments from their posterior and lateral perirectal positions. If you draw an imaginary transverse line, bisecting the surgical field, and place the sutures well below that line, you can be reasonably assured entrapment will not occur. Dr. Drukker's second concern was how we expose the ureter during abdominal operations where the ovaries or just the uterus is removed. It is our practice to open the broad ligament and identify visually the course of the ureter down to where the uterine artery crosses it. Then, when a clamp is placed on the uterus at the level of the uterine artery, we palpate the ureter. We do this in every case. This report just dealt with surgery for benign conditions. However, our frequency of ureteral entrapment or obstruction after surgery for malignant conditions is less, related to the fact that most surgery for cancer is abdominal and the ureter is often completely dissected in cancer operations.
Postoperative ureteral obstruction
1519
Finally, about retrograde ureteral studies, we don't attempt retrograde stent placement at all anymore. But there is a new procedure, called ureteroscopy. With a fiberoptic instrument the urologist can get into the ureter, advance a guide wire that can turn and maneuver around an apparent kink, and position a ureteral stent. Ureteroscopy may playa future role. Dr. Rogers had expressed concern about obtaining serum creatinine levels. Serum creatinine levels were obtained preoperatively in all of our patients as part of our preanesthetic medical evaluation. We get postoperative electrolyte studies that also include serum creatinine. So, for a number of years, we have had this information available for both the preoperative and the postoperative periods. I believe that this test is significant, with a high observed sensitivity of 100% and an observed specificity of 92%, and that we should obtain paired serum creatinine levels preoperatively and postoperatively, as you indicated, in patients undergoing hysterectomy or surgery where ureteral injury could occur. I think we should follow through on this. Dehydration can cause an increase in the serum creatinine level. Serum creatinine may be elevated in the preoperative period when the patient has fasted, and then postoperatively, after hydration, it may be lower than the preoperative value. Obviously, there are other causes for elevated creatinine, for example, the use of aminoglycosides. I think that in our series there are probably undetected incidences where ureteral entrapment has occurred. We were not trying to look at that. We got the idea for this study from a nephrologist who indicated that this phenomenon occurred in patients who had unilateral ureteral stones and that these patients were found to have transient rises in serum creatinine. I noted that we frequently saw a rise after ureteral entrapment from vaginal surgery, so we decided to look at this in more detail. I will take your suggestion for further statistical analysis.
