Sonographic Assessment of Fetal Sex: More than External Genitalia.

Early identification of fetal sex is possible due to both improved ultrasound resolution and the incorporation of cell-free DNA testing into routine prenatal screening services. While ultrasound assessment of the external genitalia generally suffices, there are instances where identification of the internal genitalia becomes vital to allow accurate prenatal diagnosis and comprehensive counseling. This manuscript outlines the methodology and clinical utility of assessing fetal genitalia beyond conventional sonography from the second trimester onward and is the first to describe direct visualization of the fetal vagina.