Renal Colic in Pregnancy

Background

• Renal colic describes acute abdominal and lumbar pain caused by renal or ureteral calculi (kidney stones).
• In pregnancy, renal colic is reported to affect up to 1 in 200 (0.5%)-3,000 (0.03%) pregnancies, with 80%-90% of stones occurring in women in the second and third trimester.
• Once identified, stones are characterized in terms of complexity (as it relates to renal anatomy), size, position within the collecting system, etiology, composition, and radiographic degree of lucency.
• Renal colic in pregnancy may be caused by either the presence of renal or ureteral calculi or physiologic hydronephrosis caused by compression of the ureter by the gravid uterus.
• Certain anatomical and functional changes to the genitourinary system occur during normal pregnancy that may increase risk of nephrolithiasis. A number of medications can also increase the risk.
• Intermittent ("colicky") flank pain that may radiate to the lower abdomen or groin is nearly ubiquitous in patients presenting with renal colic. Accompanying symptoms may also include nausea, vomiting, dysuria, urinary frequency, fever, and hematuria.

Evaluation

• Suspect renal colic in a pregnant woman with acute flank pain, possibly associated with nausea, vomiting, and hematuria.
• The diagnosis of renal colic is confirmed by imaging.
  • Renal and pelvic ultrasound is the preferred initial imaging test (Strong Recommendation).
  • Magnetic resonance imaging (MRI) is the second-line imaging modality, especially in the first trimester (Strong Recommendation).
  • Low-dose computed tomography (CT) is a last-line option, and only in the second or third trimester (Strong Recommendation).
• Routine laboratory testing should include (Strong Recommendation):
  • serum creatinine, uric acid, (ionized) calcium, sodium, potassium, blood cell count, and C-reactive protein
  • urinalysis and urine culture
• Perform stone composition analysis in all patients with first stone using a valid analytical procedure (such as x-ray diffraction or infrared spectroscopy) (Strong Recommendation).

Management

• Pain management:
  • Acetaminophen (paracetamol) is the analgesic drug of choice for pain during pregnancy.
  • Exercise caution when considering other analgesics which may pose risks to the woman and fetus (often trimester-dependent).
• Treat all uncomplicated cases of urolithiasis in pregnancy conservatively, unless there are clinical indications for intervention (Strong Recommendation).
  • Consider medical expulsion therapy (MET) as an adjunct to conservative management in pregnant women.
  • MET options considered safe in pregnant women include alpha blockers (tamsulosin, doxazosin, terazosin, alfuzosin, naftopidil, and silodosin) and calcium channel blockers (nifedipine).
• Consider ureteroscopic stone removal or temporary drainage for decompression of the renal collecting system by placement of either indwelling ureteral double-J stents or percutaneous nephrostomy for pregnant women with nephrolithiasis refractory to conservative management.
• A urinary tract infection must be excluded or treated with antibiotics prior to endourologic stone removal (Strong Recommendation); most antibiotics are considered safe during pregnancy.
• Percutaneous nephrolithotomy is generally contraindicated during pregnancy but can be considered on an individual basis during pregnancy and should only be performed in experienced centers.
• Shock wave lithotripsy is absolutely contraindicated in pregnancy.
• Consider open surgery for septic patients with symptoms when endourological techniques have failed or are unavailable.