US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal US is the first-line study for diagnosis of maternal hydronephrosis or renal anatomic abnormalities [5,17,43]. In the pregnant patient with known, symptomatic hydronephrosis, specific findings on US including anteroposterior 21 Hydronephrosis on Prior Imaging-Unknown Cause diameter of the renal pelvis and renal RI can help differentiate benign pregnancy-related hydronephrosis and pathologic obstruction and can help predict the need for intervention. In a prospective single-center study of 1,026 pregnant patients including 295 with hydronephrosis, Bayraktar et al [5] reported a correlation between anteroposterior diameter of the renal pelvis on US and requirement for intervention for symptomatic patients. Ercil et al [9] report the same finding in a retrospective single-center series of 246 pregnant patients with symptomatic hydronephrosis, noting that a diameter above 21 mm on the right had a sensitivity of 91% and a specificity of 84% for predicting intervention, and a diameter above 25 mm on the left had a sensitivity and specificity of 100%. Demir et al [45] reported in a study of 227 pregnant women with symptomatic hydronephrosis that intervention was found to be necessary with renal pelvis anteroposterior diameter >16.5 mm in the first two trimesters and >27.5 mm in the third trimester.
Hydronephrosis on Prior Imaging Unknown Cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal US is the first-line study for diagnosis of maternal hydronephrosis or renal anatomic abnormalities [5,17,43]. In the pregnant patient with known, symptomatic hydronephrosis, specific findings on US including anteroposterior 21 Hydronephrosis on Prior Imaging-Unknown Cause diameter of the renal pelvis and renal RI can help differentiate benign pregnancy-related hydronephrosis and pathologic obstruction and can help predict the need for intervention. In a prospective single-center study of 1,026 pregnant patients including 295 with hydronephrosis, Bayraktar et al [5] reported a correlation between anteroposterior diameter of the renal pelvis on US and requirement for intervention for symptomatic patients. Ercil et al [9] report the same finding in a retrospective single-center series of 246 pregnant patients with symptomatic hydronephrosis, noting that a diameter above 21 mm on the right had a sensitivity of 91% and a specificity of 84% for predicting intervention, and a diameter above 25 mm on the left had a sensitivity and specificity of 100%. Demir et al [45] reported in a study of 227 pregnant women with symptomatic hydronephrosis that intervention was found to be necessary with renal pelvis anteroposterior diameter >16.5 mm in the first two trimesters and >27.5 mm in the third trimester.