Gastrointestinal Oncology and Endoscopy
This domain tests endoscopy quality, lesion selection for endoscopic resection, and recognition of procedural complications. It overlaps oncology staging but focuses on the endoscopist's decisions.
Endoscopy quality metrics
- Cecal intubation rate 90% or higher; adenoma detection rate 25% or higher overall (30% or more in men, 20% or more in women); withdrawal time at least 6 minutes in a normal colon; adequate bowel preparation using the Boston Bowel Preparation Scale (segment score 2 or more, total 6 or more).
- Photodocument landmarks and use high-definition white light; dye-based or virtual chromoendoscopy improves polyp characterization.
- Report lesion size, location, morphology (Paris classification) and completeness of resection.
Endoscopic resection and oncology
- Cold snare polypectomy for lesions under 10 mm; hot snare or EMR for larger; ESD for lesions with suspected superficial submucosal invasion, fibrosis, or recurrent adenoma.
- Early gastric cancer suitable for ESD: intramucosal, differentiated, 2 cm or less, ulcer-negative. Early esophageal squamous lesions and Barrett neoplasia are managed with EMR or ESD plus ablation of residual Barrett.
- Staging: TNM for colorectal and esophageal cancer; EUS for locoregional staging of esophageal, gastric and pancreatic lesions; EUS-FNA for tissue confirmation.
- Tumor markers: CEA for colorectal follow-up, not screening; CA19-9 for pancreatic prognosis; AFP in hepatocellular carcinoma.
Procedural complications and prevention
- Post-ERCP pancreatitis: prophylaxis with rectal indomethacin and aggressive periprocedural hydration in average and high-risk patients; pancreatic stent in high-risk cases.
- Post-sphincterotomy bleeding: managed with injection, clips or thermal therapy; reverse anticoagulation where possible.
- Perforation after colonoscopy: recognize post-procedure pain; CT confirms; small perforations may be clipped, larger ones need surgery.
- Capsule endoscopy retention risk: obtain patency capsule or cross-sectional imaging in suspected stricture; retained capsules may require surgical or endoscopic retrieval.
Worked example
A 45-year-old undergoes screening colonoscopy in which a 25 mm laterally spreading lesion in the cecum is found. It is not obviously invasive on narrow-band imaging. Refer for piecemeal EMR or ESD rather than snare polypectomy, and document site and Paris classification for surveillance planning.
Traps
- Snaring a large laterally spreading lesion that needs EMR or ESD.
- Reporting adenoma detection rate without confirming cecal intubation.
- Omitting rectal NSAIDs for post-ERCP pancreatitis prophylaxis.
- Using CEA to screen for colorectal cancer.