Hydrocolpos may be associated with a lower urinary tract obstruction in a spectrum of urorectal malformations ranging from persistent urogenital sinus to cloacal dysgenesis. As cloacal dysgenesis carries the worst postnatal prognosis, detailed prenatal ultrasound should focus on the fetal pelvic anatomy to provide the parents with appropriate prenatal counseling. We report three cases of fetal hydrocolpos associated with low urinary tract obstructions, including two with a normal appearance of the anal canal and rectum on prenatal ultrasound and one with a complex cloacal malformation which contributed to the precise prenatal assignment of the malformation in each case within the spectrum of urogenital sequence malformations.