Diagnosis of urolithiasis and rate of spontaneous passage during pregnancy

Purpose: Due to imaging limitations little is known about the true rate of spontaneous stone passage during pregnancy. We evaluated the accuracy of urolithiasis diagnosis during pregnancy and the rate of spontaneous passage. Materials and Methods: We retrospectively reviewed the records of patients diagnosed with urolithiasis during pregnancy from 1997 to 2009. Patients were evaluated for a confirmed stone event, defined as a stone visualized on imaging or at surgery, or passed with visualization. Results: We identified 112 women diagnosed with urolithiasis during pregnancy, including 5 with multiple episodes for a total of 117 events. Stones were visualized by imaging in 63 of 117 events. Another 22 patients without imaging confirmation passed a stone spontaneously. In 1 patient the stone was diagnosed at surgical removal during pregnancy and postpartum imaging identified another 4 patients. Thus, 90 of 117 events (77%) represented confirmed stones. Of the 90 patients 27 (30%) underwent temporizing or definitive surgical intervention during pregnancy. Postpartum definitive surgical management was necessary in 29 women (25%). Overall only 43 of 90 women (48%) spontaneously passed the stone. Mean followup of those with confirmed stones was 51 months. Urolithiasis recurred in 26 of the 90 patients (29%). The most common primary component of analyzed stones was calcium phosphate (81%). Conclusions: We found that almost a quarter of pregnant women diagnosed with urolithiasis are diagnosed inaccurately. The inappropriate diagnosis of urolithiasis may contribute to the misconception that most stones pass with conservative management during pregnancy.