Fetal MRI compared with ultrasound for the diagnosis of obstructive genital malformations

To compare the accuracy of magnetic resonance imaging (MRI) and ultrasound (US) to diagnose and characterize congenital obstructive genital abnormalities.

Retrospective cohort of 20 fetuses who underwent a fetal MRI following a US diagnosis of obstructive urogenital malformation. We compared MRI and US findings and their correlation with the definitive diagnosis.

The correct diagnosis was obtained in 6/20 (30%) cases and 19/20 cases (95%) with US and MRI, respectively. MRI revealed additional information to US in 15/20 cases (75%) and modified the prenatal management in 14 fetuses (70%). The identification rates of the most important anatomical landmarks for the diagnosis, using US and MRI, were compared. Bladder: US 17/20 (85%) vs MRI 20/20 (100%) P = 0.23; vagina: US 6/19 (31.5%) vs MRI 19/19 (100%) P < 10^-4 ; uterus: US 11/19 (57.8%) vs MRI 19/19 (100%) P = 0.003, kidneys: US: 40/40 (100%) MRI: 40/40 (100%) P = 1, ureters: US 14/40 (35%) vs MRI 30/40 (75%) P=0.001, rectum: US 6/20 (30%) MRI 20/20 (100%) P < 10^-4 , and sacrum: US 20/20 (100%) vs MRI 17/20 (85%) P = 0.23.

In fetuses with obstructive urogenital malformations, MRI facilitates assessment of major pelvic organs and provides significant information that may alter the prenatal management.