ABSTRACT
The primary role for volume sonography in the fetal genitourinary system has been gender assignment, renal pelvis volumetry, urine production, and characterizing other genitourinary abnormalities. Hydronephrosis is a marker for chromosomal aberrations and exists in a continuum of gradations. The amniotic fluid index may be measured in several ways, and the importance of quantifying the amniotic fluid lies in its ability to indicate adequate fetal vascularization, in the absence of fetal hypoxia, reflected by good urine production. The major limitation with volume sonography in the genitourinary system is false diagnoses, especially in cases of ambiguous genitalia. Surface rendering aids in visualizing the external genitalia; however, navigating through a volume, looking for other signs such as the tulip sign and the distance between the bladder and rectum, provides more conclusive information.
