DOI: 10.5301/urologia.5000048

Urologia 2014 ; 81 ( 1): 12-15

REVIEW

Etiology, diagnosis and treatment of renal colic during pregnancy Angelica Anna Chiara Grasso, Gabriele Cozzi Department of Urology, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, Milano - Italy

Objectives: To assess the incidence and causes of renal stones in pregnant women, investigate the reliability and accuracy of diagnostic investigations and to consider the various therapeutic options available. Methods: A review of the literature was conducted, searching for relevant papers on the physiology of urinary apparatus changes during pregnancy, as well as the etiology, diagnosis and management of renal colic in pregnant women. Results: Standards of care in renal colic during pregnancy include accurate diagnosis primarily with ultrasound, or MRI if necessary, conservative therapy and careful surgical approach for urinary drainage in the first place or ureterorenoscopy when needed. Conclusions: Renal colic during pregnancy is potentially troublesome and likely to lead to serious adverse effects on both mother and fetus. A multi-disciplinary approach is needed, which includes experts in the fields of Urology, Obstetrics, Radiology and Anesthesiology, to ensure the optimal care of this delicate cohort of patients. Key words: Pregnancy, Renal colic, Renal stones Parole chiave: Gravidanza, Colica renale, Litiasi renale Accepted: November 14, 2013

Introduction Physiological pregnancy causes profound changes on a woman’s body in order to accommodate the demands and necessities of the fetus; these changes involve the urinary apparatus as well. The kidney size increases by 1 to 1.5 cm (1); hydronephrosis and ureteral dilatation, more prominent on the right than the left side, can be found in up to 80% of pregnant women (2). This results from hormonal effects (progesterone), mechanical external compression, and intrinsic changes in the ureteral wall (3). Urinary protein excretion rises and microscopic hematuria is not uncommon. Glomerular filtration rate (GFR) rises during pregnancy, primarily due to elevations in cardiac output and renal blood 12

flow. Due to the physiologic increase in GFR during pregnancy, serum creatinine concentration decreases, approximately of 0.4 mg/dL. Therefore a serum creatinine of 1.0 mg/dL, while normal in a non-pregnant woman, reflects some kind of kidney failure in a pregnant individual. The development of a symptomatic renal colic due to a stone during pregnancy is a rare event, affecting about 1 in every 1500 to 3000 pregnancies (4, 5), with almost the same probability of occurring in a non-pregnant woman (6); nevertheless it is potentially troublesome, leading to hospitalization, invasive investigations and treatment, and adverse effects on both mother and fetus. Some uncertainty still remains on how to best differentiate nephrolithiasis from physiological pregnancy hydronephrosis, and on the safety of various urological procedures when medical therapy may not be resolving.

© 2014 Wichtig Publishing - ISSN 0391-5603

Grasso and Cozzi

Materials and Methods A review of the literature was performed in September 2013, searching Medline, Embase and Scopus databases for articles dealing with renal colic during pregnancy and its diagnosis and management. The key terms used for the search were: pregnancy, renal colic, renal stones, ureteral stones; 110 articles were retrieved. Only articles in English were fully reviewed. An explanation of the physiological changes occurring to the urinary apparatus is offered in order to focus on the challenging problems when diagnosing and the potential complications during pregnancy.

Results Patients present more frequently in the second or third trimester, only 20% in the first trimester, with acute flank pain (90%), which often radiates to the lower abdomen. Hematuria is present in 75 to 95% of women (but it is fundamental to remember that microscopic hematuria is common among pregnant women), only approximately 25% of these have gross hematuria; less than 40% have pyuria (4, 5).

Etiology Physiological pregnancy is characterized by a bland increase in urine calcium excretion, minor increases in urine citrate and magnesium excretion (which protect against stone formation), and a rise in urine pH (7). The urine content of calcium oxalate is similar to the one seen in non-pregnant women with calcium stones. Urinary stasis may also contribute to stone formation. Calcium phosphate proves to be the principal component of stones during pregnancy (8). Most pregnant women presenting with renal colic do not have a prior history of renal stone disease.

Diagnostic tools Currently, the preferred imaging modality during pregnancy is ultrasound: it is non invasive and free of ionizing radiations (9).

Grenier reported a sensitivity of 34-95% in detecting stones in pregnant women (10); Stothers reported 34% sensitivity and 86% specificity in detecting abnormal findings in the presence of stones (4). During pregnancy, being hydronephrosis a common finding, the use of Doppler ultrasonography may increase the sensitivity in detecting ureteral obstruction, by adding a functional element to the evaluation of obstruction. In a study conducted on 22 patients Shokeir et al. found the use of Color Doppler Ultrasonography helpful in differentiating ureteral obstruction from physiological hydronephrosis (11). The comparison of ureteral jets may be useful to distinguish obstruction from physiological hydronephrosis. If both ureteral jets are present and symmetric on Doppler ultrasonography, unilateral ureteral obstruction is unlikely (12). In his study on 57 pregnant women, Butler reported 60% sensitivity in detecting stones with ultrasound (5). If further diagnosis is required, MRI is safe during pregnancy since it does not involve radiation exposure; however, limitations to this technique include limited visualization of small stones and its relatively high cost (13, 14). White reported on the use of low-dose CT scanning for the evaluation of flank pain in the pregnant population, although these low-dose CT protocols have great sensitivity, their effects have not been fully evaluated (15) and anyway low-dose CT can be used in the second and third trimester but not the first one, when the fetus is most susceptible to radiation-induced injury.

Therapeutic options The several papers studied report that up to 80% of patients pass stones spontaneously during pregnancy, partly due to the normally dilated urinary tract in pregnant women, and 50% of the remaining patients expel their stones in the post-partum period (4). The first-line management is conservative, including hydration, analgesia and antibiotics. The safety of medical expulsive therapies during pregnancy has not been established. Surgical intervention is needed if conservative therapy fails or the patient suffers any of the following conditions: febrile urinary tract infections, sepsis, obstructive uropathy, acute renal failure or obstruction of a solitary kidney (16). Urinary drainage can be achieved with placement of a ureteral stent or percutaneous nephrostomy.

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Renal colic during pregnancy

Cystoscopy and retrograde ureteral stent placement can be performed under local anesthesia using ultrasound guidance, however the presence of a double-J stent can lead to urinary tract infections, hematuria and pain. Furthermore, due to the increased hypercalciuria and hyperuricosuria during pregnancy, the stent needs to be changed every 4-8 weeks to prevent its encrustation, therefore causing multiple interventions to the pregnant woman (17). Percutaneous nephrostomy can also be performed with ultrasound guidance using local anesthesia; the disadvantages of this technique include the risk of bleeding, encrustation, bacterial colonization of the catheter and dislocation. There is only one reported case of epidural anesthesia administered to facilitate stone passage in a pregnant woman. The anesthesia was maintained for 18 hours, with resolution of symptoms, although definitive passage of the stone was not confirmed (18). Various authors have evaluated the efficacy and safety of ureterorenoscopy during pregnancy. Semins performed a systematic review on ureteroscopy during pregnancy, comparing the complication rate of the procedure among pregnant and non-pregnant women, and reported that complications were uncommon in both cases, with no significant differences between the two cohorts (19). Bozkurt et al. describe their experience with 32 patients who underwent ureteroscopy during pregnancy; stones were fragmented by pneumatic lithotripter or holmium laser. Postoperatively, sepsis developed in 1 patient, dysuria and pain were observed in 2 patients and urinary infections developed in 4 patients (20). Isen et al. report their experience on 36 patients; for 12 of them, conservative management failed and 9 underwent ureteroscopy. No significant complications were observed (21). Pregnancy remains a strict contraindication to shock wave lithotripsy (SWL). Animal studies have confirmed fetal death after exposure to SWL (22, 23).

Discussion Renal stones in pregnant women are a rare event and occur more frequently during the second and third trimester. Imaging modalities in pregnancy are limited, due to the risks on the fetus related to ionizing radiation; however, 14

ultrasonography and MRI are proven to be safe and they are most of the times sufficient to confirm diagnosis and guide therapy. Conservative treatment including hydration, analgesia and antibiotics represent the first-line preferred therapy. Some commonly used antibiotics must, however, be used with extreme caution during pregnancy and, in some cases, must be completely avoided. Cephalosporins and penicillins are generally safe to use. Animal studies of ciprofloxacin showed alterations in the joint cartilages; neither adverse effects on cartilage nor an increase in congenital malformations have been documented from its use during human pregnancy. Trimethoprim and nitrofurantoin are avoided in the first trimester because of a potential increased incidence of congenital malformations, although no documented cases have been reported in humans. Aminoglycosides carry the risk of inducing fetal (and maternal) ototoxicity and nephrotoxicity, but should not be withheld in cases of life-threatening infections. Sulphonamide may elevate the levels of free bilirubin, crossing the placenta and competing with bilirubin for albumin binding sites, thus increasing the risk of kernicterus. Tetracyclines have been associated with transient suppression of bone growth and with staining of developing teeth (24). If needed surgery must lead to immediate urinary drainage, avoiding invasive procedures, even though ureterorenoscopy with stone fragmentation did not prove to cause higher complications in pregnant compared to non-pregnant women.

Conclusions Renal colic during pregnancy is potentially troublesome and likely to lead to serious adverse effects on both mother and fetus. Various imaging techniques, antibiotics and surgical procedures have not yet been proved to be completely riskfree; further studies are needed to assess their safety for both mother and child. Before safety is clearly assessed, surgical procedures must be performed only if mandatory. Careful consideration of gestational age, comorbidities and the patient’s clinical situation must be taken into account in a pregnant woman.

© 2014 Wichtig Publishing - ISSN 0391-5603

Grasso and Cozzi

A multi-disciplinary approach is needed, which includes experts in the fields of Urology, Obstetrics, Radiology and Anesthesiology, to ensure the optimal care of this delicate cohort of patients. Disclaimers

Corresponding Author: Angelica Anna Chiara Grasso Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico Università degli Studi di Milano Via Pergolesi 24 20124 Milano, Italy [email protected]

Informed consent: The manuscript does not report the results of an experimental investigation on human subjects. Financial support: No financial support has been received for this study. Conflict of Interest: No conflict of interest is present.

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13. Duncan KR. The development of magnetic resonance imaging in obstetrics. Br J Hosp Med. 1996;55:178. 14. Kirkinen P, Partanen K, Vainio P, Ryynänen M. MRI in obstetrics: a supplementary method for ultrasonography. Ann Med. 1996;28:131. 15. White WM, et al. Low-dose computed tomography for the evaluation of flank pain in the pregnant population. J Endourol. 2007;21:1255-1260. 16. Fallon BDD. Urologic issues during pregnancy. Hosp Physician. 2007;14:1-12. 17. Goldfarb RA, et al. Management of acute hydronephrosis of pregnancy by ureteral stenting: risk of stone formation. J Urol. 1989;141:921-922. 18. Ready LB, Johnson ES. Epidural block for treatment of renal colic during pregnancy. Canad Anaesth Soc. J 1981;28: 77-9. 19. Semins MJ, et al. The safety of ureteroscopy during pregnancy: a systematic review and meta-analysis. J Urol. 2009;181:139. 20. Bozkurt Y, et al. The efficacy and safety of ureteroscopy for ureteral calculi in pregnancy: our experience in 32 patients. Urol Res. 2012;40:531-535. 21. Isen K, et al. Experience with the diagnosis and management of symptomatic ureteric stones during pregnancy. Urology. 2012;79(3):508-12. 22. Yalcin O, et al. Effects of shock waves on the rat fetus. Scand J Urol Nephrol. 1998;32:167-70. 23. Streem S. Contemporary clinical practice of shock wave lithotripsy: a reevaluation of contraindications. J Urol. 1997; 157:1197-203. 24. Maclean AB, McAllister T. Antimicrobial therapy in obstetrics and gynaecology. In: MacLean AB, ed. Clinical Infection in Obstetrics and Gynaecology. Oxford: Blackwell, 1990.

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Etiology, diagnosis and treatment of renal colic during pregnancy.

To assess the incidence and causes of renal stones in pregnant women, investigate the reliability and accuracy of diagnostic investigations and to con...
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