The duodenum is mainly located in the upper abdomen and is the main organ connecting the stomach and jejunum. The upper part of the duodenum is connected to the anatomical part of the pylorus, and the lower part is connected to the upper part of the jejunum. The duodenum is mainly divided into bulbous, descending, horizontal and ascending parts. The bulb of the duodenum is mainly prone to duodenal bulb ulcers and is a common site for gastrointestinal bleeding. The descending part of the duodenum is tubular in shape, and the inner part of the descending part of the duodenum has openings for the bile and pancreatic ducts, called the duodenal papilla. Below the descending part is the horizontal part of the duodenum, followed by the ascending part of the duodenum. The ascending part of the duodenum has the duodenal flexor ligament compressing the duodenum, and when symptoms are more pronounced, abdominal pain and fullness can occur, also known as duodenal stasis.