Symptomatic nephrolithiasis complicating pregnancy.

OBJECTIVE: To review our experiences with diagnosis and management of symptomatic nephrolithiasis complicating pregnancy and to ascertain the efficacy of renal sonography for initial diagnosis compared with plain x-rays or single-shot intravenous pyelography.
METHODS: Perinatal outcomes were evaluated for all pregnant women admitted to Parkland Hospital for nephrolithiasis from 1986 to 1999. Diagnostic studies and management of nephrolithiasis were also evaluated.
RESULTS: During the 13-year study period, 57 pregnant women had 73 admissions for symptomatic nephrolithiasis. Symptomatic nephrolithiasis complicated 1 in 3300 (0.03%) deliveries at our institution. Only 12 women (20%) had a history of renal calculi. Mean gestational age at diagnosis was 23 weeks. Imaging techniques included renal ultrasonography, plain abdominal x-ray, and single-shot intravenous pyelography. Calculi were visualized in 21 of 35 (60%) renal ultrasonographic examinations and 4 of 7 (57%) abdominal x-ray studies when these were performed as the initial test. In contrast, urolithiasis was discovered in 13 of 14 (93%) instances in which intravenous pyelography was performed as the initial diagnostic test. When sonography was negative (n = 14), renal calculi were confirmed by single-shot intravenous pyelography (n = 8). Although 43 of 57 (75%) of symptomatic episodes responded to conservative management, 10 women required ureteral stents, 3 needed percutaneous nephrostomy tubes, and 2 underwent ureteral laser lithotripsy for resolution.
CONCLUSION: Although the convenience and safety of ultrasonography to initially diagnose nephrolithiasis are indisputable, 40% of calculi were missed when this method alone was used. Thus, if nephrolithiasis is still suspected clinically despite ultrasonographic findings, single-shot pyelography is recommended.