Several pathogenetic mechanisms have been suggested to explain the syndrome of deficiency of anterior abdominal muscles and genitourinary abnormalities which is usually seen in males. Four such fetuses were recently seen, 2 males and 2 females, all of which showed obstruction of the lower urinary tract, with dilatation proximally. Apparently atrophy of abdominal muscles occurs following venous infarction, due to gross overdistension of the abdomen.