Utility of sonography for the evaluation of suspected urolithiasis in pregnancy

Abstract

Study objectives: We seek to evaluate the utility of sonography for the evaluation of suspected renal colic in pregnant patients. Methods: One radiologist retrospectively reviewed the radiology reports of all pregnant patients who presented to 1 institution during a 5-year period with suspected renal colic. All women who had at least 1 renal sonogram and the initial suspected diagnosis of renal colic were included. The official reports of the sonographic studies and of any additional relevant imaging studies were then reviewed. The presence or absence of a ureteral calculus, as well as hydronephrosis, was recorded. Potential indicators of ureteral obstruction on sonography, including abnormal color or power Doppler flow within the renal parenchyma, absence of ureteral jets, and elevated resistive indices of each kidney, were noted, if these observations were recorded. The results of any repeated sonographic studies during the course of the same pregnancy were also reviewed. The percentage of cases in which a ureteral stone was believed to be present was calculated. The percentage of cases in which a significant alternative diagnosis was believed to be established according to sonography was also calculated. Results: Seventy-seven women had at least 1 episode of suspected renal colic during pregnancy and also had at least 1 sonogram. Fifty-five of these women underwent a single study, and 22 underwent a total of 58 studies. Of the 22 women who underwent more than 1 study, 5 had 2 separate pregnancies in which sonography was performed for possible renal colic. There were only 2 women for whom a ureteral stone was reported at sonography (3.9% of women, 3.5% of examinations, 3.6% of pregnancies). The only alternative diagnosis established according to sonography was pyelonephritis, which was suggested in 1 woman and diagnosed in 2 others (3.9% of women, 2.7% of examinations, 3.6% of pregnancies). Only 1 woman had a magnetic resonance imaging urogram, which revealed no ureteral stone. Fifty-one percent of sonograms revealed some degree of unilateral or bilateral hydronephrosis. There was no consistent reporting of ureteral jets, resistive indices, or color or power Doppler analysis. Conclusion: Fewer than 5% of pregnant patients with suspected renal colic had that diagnosis established on sonography, fewer than 5% had an alternative diagnosis established, and only 1% underwent testing with a different imaging modality. Although the actual incidence of urolithiasis in these pregnant patients was unknown, the utility of routine sonography is questioned, and alternative testing such as magnetic resonance imaging urography should be considered when clinically indicated.