Per-oral esophageal myotomy (POEM)

Per-oral esophageal myotomy (POEM) is a natural orifice endoscopic surgery that has been gaining increasing use as an alternative to traditional esophageal myotomies (e.g. Heller myotomy and Nissen fundoplication) to treat achalasia by weakening the lower esophageal sphincter.

Technique

The endoscopist insufflates the esophagus with CO₂ then creates a 2 cm opening approximately 12 cm above the squamocolumnar junction. A submucosal path is created through the opening to the lower esophageal sphincter and usually into the cardia of the stomach. The sphincter/ circular muscle is then incised (myotomy). The endoscope is withdrawn and the mucosal opening is closed with staples. The whole procedure is performed beneath the mucosa under general anesthesia.

Radiographic features

Most patients receive a fluoroscopic esophageal swallow study either immediately after the procedure or soon after the procedure.

The most common scope approach is anteriorly in the esophagus, so the RPO position is often best to profile the clips ². 

Water-soluble contrast (e.g. Gastrografin) is usually used first in case there is an occult perforation.

Normal findings

• clips at the surface of the esophagus, indicating the entrance to the submucosal tunnel (clips usually fall off with time)

• small amounts of pneumoperitoneum,  pneumomediastinum, intramural gastric pneumatosis, retroperitoneal gas, as well as intramural dissection and contrast leak are common findings post procedure

  • due to leakage from CO₂ instillation through the scope during the procedure

  • these usually resolve spontaneously and no further intervention is required

Treatment and prognosis

Complications

• contrast leak outside the esophagus (perforation)

• a large amount of pneumoperitoneum (concerning for perforation)

• distal sphincter dilatation less than 5 mm post POEM is considered poor response