The fetal esophagus: anatomical and physiological ultrasonographic characterization using a high-resolution linear...

To study the sonographic anatomy and physiology of the human fetal esophagus during the mid-trimester of pregnancy using a high-resolution linear transducer.

This was a prospective observational study of the fetal esophagus between 19 and 25 weeks' gestation. The study was performed in 60 consecutive fetuses, after a normal anatomy scan, using a 5-13-MHz matrix array wide-band transducer. During the examination the collapsed esophagus was first visualized, and followed by a 5-min video recording in order to demonstrate luminal patency and peristaltic waves.

Complete anatomical visualization of the esophagus was possible in 52 (86.7%) patients and at least partial visualization in 58 (96.7%) patients. Three different patterns of esophageal motility were observed: a simultaneous and short opening of the whole esophagus was found in 35 (58.3%) fetuses; a segmental, peristalsis-like movement from the pharynx, through the mediastinum, and into the stomach was found in 18 (30%) fetuses; and in one fetus reflux-like passage of solid contents from the stomach was observed. The mean time required for demonstration of esophageal patency was 96.1 (range, 10-300) s.

Demonstration of normal anatomy and physiological activity of the fetal esophagus is feasible using appropriate transducers. The most commonly observed pattern of esophageal motility in the mid-trimester of pregnancy 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 a patent esophagus may be helpful in fetuses with suspected esophageal atresia.