Correlation between the five-layer echo pattern and histologic layers of the normal gastrointestinal wall

On endoscopic ultrasound, the normal intestinal wall is visualized as five alternating hyperechoic (bright) and hypoechoic (dark) bands that correspond to five distinct histologic layers of the intestinal wall. In the stomach and duodenum, the fifth histologic layer is the serosa. In the esophagus and in the rectum, the fifth histologic layer is the adventitia.