This study is performed to assess the efficacy and outcomes of Gastric Per Oral Endoscopic Myotomy "G-POEM" in patients presenting with gastroparesis.

Gastroparesis is a chronic digestive disorder best defined as severe nausea, vomiting, bloating, and abdominal pain in the setting of objectively delayed gastric emptying without mechanical gastric outlet obstruction. The most common etiology is idiopathic. Some of the identifiable etiologies include diabetes and post-surgical.

Endoscopic techniques to reduce pyloric tone mainly consisted of Botulinum toxin injection but failed to demonstrate significant symptom improvement compared to placebo. Another endoscopic method was transpyloric stenting which yielded symptomatic relief but is prone to stent migration and therefore is unlikely to provide a viable long term solution.

Surgical pyloroplasty has shown to be effective in reducing gastroparesis symptoms, but is associated with a risk of leakage and potential further narrowing of gastric outlet. It also carried all the risks of general anesthesia and requires advanced laparoscopic suturing skills. Therefore, the development of a less invasive reliable method of improving gastric emptying is highly desirable.

An endoscopic submucosal myotomy technique may be applied to divide the pyloric sphincter without surgical access. Such endoscopic technique may provide the benefits of a natural orifice procedure, and improve gastric emptying in gastroparetic patients. Gastric Per-Oral Endoscopic Myotomy (G-POEM) is feasible and can be performed by using techniques similar to those of esophageal per-oral endoscopic myotomy. Endoscopists who are experienced in esophageal per-oral endoscopic myotomy should be able to perform G-POEM because both use similar techniques, principles, and equipment.

The investigators theorize that a subset of patients with refractory gastroparesis, diabetic gastroparesis or post-surgical gastroparesis, may respond to endoscopic pyloromyotomy.

Inclusion Criteria:

• Adult patient age greater than 18 years old who are undergoing a standard-of-care G-POEM procedure.

Exclusion Criteria:

• Previous surgery of the esophagus or stomach which has resulted in a resection of the antrum and pylorus
• Known active gastroesophageal malignancy
• Prior surgical or laparoscopic pyloromyotomy

Individuals who initially approach the study team from outside the institution (e.g. responding to the clinicaltrials.gov listing) or patients seen in the gastroenterology clinic.