The goals of this study were to determine whether anal sphincter dysfunction in spina bifida develops during fetal life or after birth and whether it reflects the severity of spina bifida and therefore can be used as a criterion to select the cases that could benefit from in utero surgery. Total protein and digestive enzyme activities [γ-glutamyl transpeptidase (GGTP), aminopeptidase M (AMP), and alkaline phosphatase isoenzymes including the intestinal form (iALP)] were assayed retrospectively in amniotic fluid from 80 myelomeningocele spina bifida cases without unrelated associated malformation (gestational age 14-33 wk). A normal enzyme activity profile was observed in 46 of the 80 cases. Two abnormal profiles were observed: 1) bilious vomiting, characterized by abnormally high GGTP and AMP activities but normal iALP, and 2) digestive enzyme leakage, characterized by abnormally high activities of GGTP, AMP, and iALP, typical of anal incontinence. No relation was observed between these enzyme activity profiles and the different secondary signs of spina bifida or the level of the damage. In concluson, anal sphincter dysfunction in spina bifida revealed by amniotic fluid digestive enzyme activities occurred before 24 wk in fetal life in 28.7%of cases. This criterion may be indicative of the severity of spina bifida and therefore perhaps could be used to select cases that are suited to in utero surgery. It could also be used to establish the potential benefit of this surgery in fecal incontinence.u001a The goals of this study were to determine whether anal sphincter dysfunction in fetal life or after birth and whether it reflects the severity of spina bifida and therefore can be used as a criterion to select the cases that could benefit from in utero surgery . Total protein and digestive enzyme activities [γ-glutamyl transpeptidase (GGTP), aminopeptidase M (AMP), and alkaline phosphatase isoenzymes including the intestinal form (iALP)] were assayed retrospectively in amniotic fluid from 80 myelomeningocele spina bifida cases without unrelated associated malformation A normal enzyme activity profile was observed in 46 of the 80 cases. Two abnormal profiles were observed: 1) bilious vomiting, characterized by abnormally high GGTP and AMP activities but normal iALP, and 2) digestive enzyme leakage, characterized by abnormally high activity of GGTP, AMP, and iALP, typical of anal incontinence. No relation was observed between the se enzyme activity profiles and the different secondary signs of spina bifida or the level of the damage. In concluson, anal sphincter dysfunction in spina bifida revealed by amniotic fluid digestive enzyme activities occurred before 24 wk in fetal life in 28.7% of cases. This criterion may be indicative of the severity of spina bifida and therefore perhaps could be used to select cases that are suited to in utero surgery. It u alsoa be able to establish the potential benefit of this surgery in fecal incontinence.