OC048: Physiology of fluid passage through the oesophagus and duodenum

To study the sonographic anatomy and physiology of the human fetal esophagus and duodenum during the midtrimester of pregnancy using a high-resolution linear transducer. This was a prospective observational study of the fetal esophagus and duodenum between 19 and 25 weeks' gestation. Each organ was studied in 60 consecutive and different fetuses, using a 5–13 MHz matrix array wide-band transducer. In the first 60 patients the collapsed esophagus was first visualized, and followed by a 5 minutes video recording in order to demonstrate luminal patency and peristaltic waves. In the last 60 patients the same method was used to visualize the duodenum. Complete anatomic visualization of the esophagus was possible in 52 patients (86.7%) and at least partial visualization in 58 (96.7%). Three different patterns of esophageal motility were observed: a simultaneous and short opening of the whole esophagus was found in 35 fetuses (58.3%); a segmental, peristalsis-like movement from the pharynx, through the mediastinum, and into the stomach was found in 18 fetuses (30%); and in 1 fetus reflux-like passage of solid contents from the stomach was observed. The mean time required for demonstration of esophageal patency was 96.1 seconds (range 10–300 seconds). Complete visualization of the duodenum was possible in only 12 patients (20%) and visualization of the first portion in 49 (81.7%). Demonstration of normal anatomy and physiologic activity of the fetal esophagus is feasible using appropriate transducers. The most commonly observed pattern of esophageal motility is the simultaneous relaxation of the upper and lower esophageal sphincters with concurrent opening of the esophageal lumen from the upper thorax to the stomach. Demonstration of the fetal duodenum is more difficult and time consuming but may be indicated in fetuses with suspected pyloric or duodenal anomalies.