Urolithiasis is the most common cause of nonobstetrical abdominal pain that requires hospitalization among pregnant patients. ^{[1, 2]} The relative incidence and rate of recurrent calculi in pregnant patients (1 per 1500 pregnant patients) is similar to that in nonpregnant patients. ^[3]Symptomatic stones are found in the ureter twice as often as in the renal pelvis and affect both ureters in equal frequency. Eighty to ninety percent are diagnosed after the first trimester.

Urolithiasis in pregnancy is often a diagnostic and therapeutic challenge for multiple reasons. First, potential adverse effects of anesthesia, radiation, and surgery often complicate traditional diagnostic and treatment modalities. Second, many signs and symptoms of urolithiasis can be found in a normal pregnancy or may be associated with broad differential diagnoses of other sources of abdominal pathology.Appendicitis, diverticulitis, or placental abruption was mistakenly diagnosed in 28% of patients in a 1992 study by Stothers and Lee.

Finally, most stones (64-84%) pass spontaneously with conservative treatment. However, if the calculus does not pass, it may initiatepremature labor, produce intractable pain, cause urosepsis in the setting of urinary tract infection, or interfere with the progression of normal labor.

Of the various imaging modalities currently available, renal ultrasonography has become the first-line screening test for urolithiasis in pregnant patients, while limited intravenous pyelography (IVP) or CT scanning is reserved for more complex cases. Ideally, no ionizing radiation should be used in the first or second trimesters, if at all possible. MRI has limited utility in urinary stone disease, and nuclear renography is reserved for functional studies to direct treatment. These are of limited value during pregnancy.

Treatment of stones in pregnancy ranges from conservative management (eg, bed rest, hydration, analgesia) to more invasive measures (eg, stent placement, ureteroscopy with stone manipulation,percutaneous nephrostomy). With appropriate diagnosis and management, the outcome for both the mother and baby is excellent.

Prophylaxis

Prevention is the best cure for urolithiasis, and multiple investigators have suggested prophylactic measures to prevent the difficult course of treating urolithiasis in pregnancy. Denstedt and Razvi (1992) suggested prophylactic treatment of asymptomatic caliceal stones in women of childbearing age who are planning pregnancies. Biyani and Joyce (2002) recommended metabolic evaluation in known stone formers, as well as prophylactic treatment of asymptomatic stones prior to pregnancy. ^[4] In support of their recommendation, they sited Glowacki et al (1992), whose study monitored 107 asymptomatic patients with renal calculi over 31.6 months. They found that 31.8% became symptomatic over that period.

Women with cystinuria who desire pregnancy should seek genetic counseling, and management of their disease should begin prior to pregnancy.