First-trimester diagnosis of sirenomelia. A case report.

We report a case of sirenomelia diagnosed at 13 gestational weeks. This rare malformation sequence is characterized by fusion and rotation of the lower limbs to various degrees and anorectal atresia, usually associated with absence of bladder and agenesis or dysgenesis of the kidneys. Diagnosis is commonly made later in the second trimester of pregnancy with oligohydramnios as the alerting sign. Survival is extremely rare, and only possible in the absence of bilateral renal agenesis. In view of the dismal prognosis, early diagnosis allows for earlier and less traumatic therapeutic abortion. Copyright 2001 S. Karger AG, Basel