Beyond the Target Sign: Two Cases of Low-Type Anal Atresia Diagnosed Prenatally With Fetal Perineal Imaging

Prenatal diagnosis of low-type anorectal malformations (ARMs) can be challenging, particularly when the target sign appears displaced or misleading. We report two fetuses-one male and one female-with isolated low-type anal atresia, both diagnosed prenatally through targeted axial and midsagittal transperineal ultrasound and confirmed postnatally. In the male fetus, an eccentrically located target sign and a hyperechoic tract suggested a perineoscrotal fistula. In the female fetus, the anal canal was anteriorly displaced, with a fistulous tract extending to the posterior vaginal introitus. Absence of bowel dilatation in both cases limited indirect signs, highlighting the value of direct anatomical assessment.