EP10.01: Prenatal prediction of fecal continence in fetuses diagnosed with anal atresia

Anal atresia (AA) is divided into; high-lying, or low-lying anomalies. Postnatal surgery for Low AA has an excellent prognosis resulting in fecal continence in contrast to high AA usually resulting in fecal incontinence. We demonstrate a 2D sonographic method to diagnose AA and differentiate between high and low AA. Cases with suspected AA were examined using a sagittal infracoccygeal approach as well as the traditional tangential view of the fetal perineum. A sagittal view of the fetal pelvis showing the rectum and anal canal was obtained. Normal anatomy was determined when the anal canal was continuous with the rectum towards the skin. High AA was suspected when a blind ended rectal pouch was demonstrated. Low AA was suspected when a rectal pouch was seen to be continuous with an anteriorly deflected fistula to the vestibule in female fetuses and to the base of the scrotum in males. Following birth or termination, verification of the diagnosis was conducted by direct visualisation of the fistula, radiographic studies, surgery and pathologic examination. 13 fetuses were prenatally diagnosed with AA, six suspected to have low AA and seven high AA. The median gestational age at diagnosis was 23 weeks (range 14-36 weeks). In all cases, additional anatomic malformations were detected. Nine of the cases had termination of pregnancy (TOP); three low and six high AA. Three cases were excluded due to inability to determine the diagnosis after TOP, leaving 10 cases for final analysis, 6 low AA and 4 high AA. All 10 cases of AA confirmed to be diagnosed correctly prenatally, rendering 100% sensitivity and 100% specificity (p < 0.001). It is feasible to differentiate high AA from low AA using the infracoccygeal sagittal approach and thus to predict postnatal continence.