Obstetrics and Gynecology
Nephrolithiasis, renal colic, kidney stones
1. What every clinician should know
Lifetime risk for renal colic is 7% for U.S. women; peak age of occurrence is 35-45 y.o.
Risk factors include white race, higher socioeconomic status, family history, prior history
Recurrence rates after 1 st episode: 14%, 35%, and 52% at 1, 5, and 10 years, respectively
Approximately 20% of patients require hospitalization
Incidence of nephrolithiasis during pregnancy is 0.03%
Types of calculi are calcium (75%), struvite (15%), uric acid (6%), and cysteine (2%)
Calculi can cause obstruction in different locations including the kidney, ureteral-pelvic junction, ureter, or bladder.
Chronic UTIs with gram-negative rods (Proteus, Pseudomonas,and Klebsiellaspecies) increase risk for struvite stones. Urine pH is greater than 7 in these cases.
Uric acid stones are associated with high purine intake or malignancy. Urine p H is less than 5.5 in these cases. Approximately 25% of patients with uric acid stones have gout.
2. Diagnosis and differential diagnosis
Signs and symptoms of nephrolithiasis include:
Sudden onset of severe pain, arising from the flank and radiating to the groin
Possible writhing and pacing, depending on level of obstruction
Nausea and vomiting (one-half of patients)
CVA (costovertebral angle) tenderness
CBC with differential
Serum calcium, phosphorus, uric acid and creatine
Urine culture and sensitivity
Non-invasive, safe in pregnancy, most sensitive when larger stones are present, approximate detection rate 30%, dependent on operator experience.
Plain Radiography (flat plate or KUB)
Detect calcium-containing stones (because they are radiopaque)
May not have adequate visualization due to uterus and fetus
Computed Tomography Scanning
In non-pregnant patients, has replaced IVP as most accurate imaging test
Can be done without contrast and has fast acquisition time
May assess other intra-abdominal pathology
Detect stones 3mm or greater with routine studies
Con: radiation exposure to fetus
Preterm labor (absence of cervical change and contractions decrease probability)
Pyelonephritis (usually accompanied by fever, flank tenderness, elevated WBC count, bacteruria and less hematuria)
Appendicitis (may have nausea and vomiting, anorexia, fever, less rhythmic colicky pain, RUQ tenderness)
Cholecystitis (may have fever, RUQ pain, gallstones, dilation of biliary tract, elevated liver enzymes)
Pancreatitis (nausea and vomiting, less colicky pain, upper mid-abdominal tenderness elevated amylase or lipase)
Viral gastroenteritis (nausea and vomiting, fever, malaise, less colicky pain)
If there is suspicion for surgical abdomen (e.g. appendicitis, cholecystitis) consultation with general surgery may be appropriate.
Discussion with radiologist regarding optimal imaging techniques during pregnancy may be useful (diagnostic performance of some studies, e.g. ultrasound, may be affected by operator experience).
If ureteral obstruction persists, then consultation with urology for possible ureteral stents or percutaneous nephrostomy.
Obtain IV access and aggressive hydration (patients often have dehydration due to vomiting and decrease po intake).
IV narcotics (Morphine, meperidine, or butorphanol are most common) for pain control.
Assessment for the presence of obstruction and/or infection.
Continue aggressive IV hydration to facilitate passage of stone.
If evidence of infection, then IV antibiotic therapy.
Continuous epidural anesthesia has been used for pain control in some cases.
Surgical therapy: if obstruction continues or recurrent obstruction develops, placement of ureteral stents or even percutaneous nephrostomy may be required if medical therapy fails (most stones less than 4 mm will pass spontaneously).
Lithotripsy contraindicated during pregnancy.
UTIs and progression to pyelonephritis can occur with obstructing calculi.
Chronic renal insufficiency can develop due to recurrent/repetitive pyelonephritis associated with calculi.
Acute renal failure extremely uncommon.
If ureteral stents required, require replacement 4-6 week intervals.
If percutaneous nephrostomy placed, can develop migration of catheter and need for replacement; also risk of cellulitis.
5. Prognosis and outcome
75-85% of renal stones pass spontaneously.
May require dietary modifications or chronic medical therapy if underlying condition is present (e.g. gout, hyperparathyroidism).
May need antibiotic suppression through pregnancy due to risks of pyelonephritis.
Need to avoid dehydration to decrease risk of recurrence. If chronic oral narcotic required during pregnancy, there is a risk of neonatal abstinence syndrome (NAS).
6. What is the evidence for specific management and treatment recommendations
Burgess, KL, Gettman, MT, Rangel, LJ, Krambeck, AE. "Diagnosis of urolithiasis and rate of spontaneous passage during pregnancy". J Urol. vol. 186. 2011. pp. 2280-4.
Butler, EL, Cox, SM, Eberts, EG, Cunningham, FG. "Symptomatic nephrolithiasis complicating pregnancy". Obstet Gynecol. vol. 96. 2000. pp. 753-6.
Maikranz, P, Coe, FL, Parks, J, Lindheimer, MD. "Nephrolithiasis in pregnancy". Am J Kidney Dis. vol. 9. 1987. pp. 354-8.
Riley, JM, Dudley, AG, Semins, MJ. "Nephrolithiasis and Pregnancy: Has the Incidence Been Rising?". J Endourol. 2013 Dec 17.
Rosenberg, E, Sergienko, R, Abu-Ghanem, S, Wiznitzer, A, Romanowsky, I. "Nephrolithiasis during pregnancy: characteristics, complications, and pregnancy outcome". World J Urol. vol. 29. 2011. pp. 743-7.
Ross, AE, Handa, S, Lingeman, JE, Matlaga, BR. "Kidney stones during pregnancy: an investigation into stone composition". Urol Res. vol. 36. 2008. pp. 99-102.
Srirangam, SJ, Hickerton, B, Van Cleynenbreugel, B. "Management of urinary calculi in pregnancy: a review". J Endourol. vol. 22. 2008. pp. 867-75.
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