Serosa of esophagus

The serosa of oesophagus (serous coat) is the peritoneum that encloses the abdominal part of the oesophagus.

The esophagus is unique among the gastrointestinal tract because most of its length is not covered by a true serosa. Instead, the cervical and thoracic portions are surrounded by an adventitia, a layer of connective tissue that anchors the esophagus to adjacent structures in the neck and posterior mediastinum. Only the short abdominal segment of the esophagus below the diaphragm, is covered by a partial serosal layer derived from the visceral peritoneum, which is present mainly on its anterior and lateral surfaces.

Clinical significance of absence of serosa in the cervical and abdominal parts of esophagus

The absence of a complete serosa is of considerable clinical importance, as it facilitates the spread of infection, inflammation, and malignant tumours into surrounding mediastinal tissues. Consequently, esophageal perforation can rapidly result in mediastinitis, a serious and potentially lifethreatening condition. Histologically, the wall of the esophagus consists of the mucosa, submucosa, muscularis externa, and an outer adventitial layer throughout most of its course, with serosa being present only over the distal abdominal portion.