What is the procedure for performing Per-Oral Endoscopic Myotomy (POEM)?

Per-Oral Endoscopic Myotomy (POEM) Procedure

Per-Oral Endoscopic Myotomy (POEM) is a minimally invasive endoscopic procedure performed by creating a submucosal tunnel to access and divide the muscular layers at the esophagogastric junction or pylorus, effectively treating conditions like achalasia or gastroparesis. 1

Patient Preparation

• Patients should maintain a liquid diet for at least 24 hours before the procedure to minimize residual contents in the stomach/esophagus 1
• Periprocedural antibiotics effective against enteric pathogens must be administered 1
• The procedure is performed under general anesthesia with the patient in either supine or left lateral position (supine position preferred to facilitate management of potential capnoperitoneum) 1

Equipment Requirements

• High-definition gastroscope with waterjet capability and a clear distal cap attachment 1
• Low-flow CO2 insufflation (room air must be completely avoided) 1
• Modern electrosurgical generator capable of modulating power based on tissue resistance 1
• Endoscopic knives and hemostatic devices 1

Procedural Steps for Esophageal POEM

1. Mucosal Entry and Tunnel Creation:

   • Create a mucosal incision 10-15 cm proximal to the lower esophageal sphincter (LES) 1
   • Develop a submucosal tunnel extending distally 2-4 cm onto the gastric cardia 1

2. Myotomy Technique:

   • Begin the circular muscle myotomy at least 2-3 cm distal to the mucosotomy 1
   • Extend the myotomy to the distal point of cardia dissection 1
   • A second endoscope may be used in challenging cases to ensure complete gastric myotomy by providing a retroflexed view of the gastric cardia 2

3. Closure:

   • Close the mucosal entry site using endoscopic clips or suturing techniques 1

Procedural Steps for Gastric POEM (G-POEM)

1. Submucosal Injection and Entry:

   • Create a submucosal bleb 4-5 cm proximal to the pylorus, typically along the greater curvature, using saline with 0.25% indigo carmine or methylene blue 1
   • Make a 1.5-2 cm longitudinal or transverse mucosal incision 1

2. Tunnel Creation:

   • Introduce the endoscope into the submucosal space 1
   • Create a submucosal tunnel through repeated injection and dissection until reaching the pyloric ring 1
   • Use blended-cutting current for mucosal incision and blended-coagulation settings for tunnel creation 1
   • Coagulate large vascular complexes using hemostatic forceps before division 1
   • Periodically deflate the stomach to minimize endoscope looping and facilitate advancement toward the pylorus 1

3. Myotomy:

   • Once the pyloric ring is exposed, perform a single myotomy extending proximally 1-3 cm into the antrum 1
   • Perform full-thickness pyloromyotomy of circular and oblique muscle bundles while preserving the serosal layer 1
   • An insulated-tip knife may increase safety margin, especially for beginners 1

4. Closure:

   • Close the mucosal incision using endoscopic clips or endoscopic suturing 1

Post-Procedural Care

• Overnight observation is recommended after POEM 1
• Start with clear liquids if no adverse events are detected 1
• Consider upper gastrointestinal contrast study the day after POEM to ensure no contrast leakage 1
• Progress to full-liquid diet for 5-7 days, then advance to 5-6 small meals per day of low-fiber, low-fat solid foods 1
• Prescribe 8 weeks of proton pump inhibitor therapy to decrease acid secretion and aid mucosal healing 1
• A short course of oral antibiotics is suggested 1
• Monitor for gastroesophageal reflux disease after POEM, as reflux occurs in approximately 16-58% of patients 1, 3

Potential Complications and Management

• Capnoperitoneum can be managed with percutaneous needle decompression 1
• Serious adverse events include perforation, pneumothorax, and bleeding, occurring in approximately 0.5-3.2% of cases 1, 3
• Patients with post-procedural abdominal pain, tachycardia, or fever should undergo CT scan or upper gastrointestinal contrast study 1
• Gastroesophageal reflux is common after POEM and requires monitoring and appropriate management 1

Clinical Outcomes

• POEM has shown success rates >90% for achalasia treatment 1, 4
• The procedure results in significant reduction in symptom scores and lower esophageal sphincter pressures 3
• POEM appears more effective than pneumatic dilation and comparable to laparoscopic Heller myotomy for treating achalasia 1

POEM represents a significant advancement in the treatment of esophageal and gastric motility disorders, with excellent clinical outcomes and acceptable procedural risks when performed by properly trained interventional endoscopists 1, 3.