Minimally Invasive Surgery & Endoscopy: ABSITE 2026 Review

Electrosurgery Principles

• 💡 Electrosurgery uses radio frequency alternating current to raise tissue temperature, converting electromagnetic energy into kinetic and then thermal energy for coagulation or cutting.
• ⚡ Cutting involves continuous low voltage energy, while coagulation uses high voltage for a short duration, with only 5-6% of the duty cycle active.
• ⚠️ The dispersive electrode (Bovie pad) should not be placed on bony prominences, hairy areas, scar tissue, pressure points, areas with skin discoloration, previous injury, or limbs with circulatory compromise.
• 🏥 For patients with implanted cardiac devices, the dispersive electrode placement should ensure the energy vector avoids the device's pathway to the heart.

CO2 Pneumoperitoneum Effects

• 🫁 CO2 pneumoperitoneum increases central venous pressure, decreasing venous return and cardiac output, while increasing systemic vascular resistance, blood pressure, heart rate, and pulmonary artery pressure.
• 📉 It also decreases splanchnic perfusion due to vessel compression and increases mean airway pressure, peak inspiratory pressure, and end-tidal CO2, while decreasing functional residual capacity.
• 💧 Renal blood flow decreases, leading to reduced urine output and increased renin and ADH production.
• ⚠️ Cardiopulmonary dysfunction can begin at intra-abdominal pressures greater than 20 mmHg; normal is 10-15 mmHg.
• 💓 The vagal nerve response to insufflation can cause extreme bradycardia, treated by immediate abdominal deflation; atropine or glycopyrrolate may be considered if persistent.

Endoscopy Pearls

• 💊 Prophylactic antibiotics for EGDs are indicated for immunocompromised patients, cirrhotic patients, those with advanced hematologic malignancies, and for specific procedures like PEG placement, variceal bleeding control, ERCP for cholangitis, or endoscopic ultrasound with FNA.
• 📍 Within the ampulla of Vater, the pancreatic duct is at the 1:00 position and the biliary duct is at the 11:00 position.
• ☠️ Alkali injuries cause liquefactive necrosis, extending rapidly through the esophageal mucosa, and are worse than acid injuries, which cause superficial coagulation necrosis.
• 📌 Physiologically narrower esophageal regions prone to foreign body impaction include the upper esophageal sphincter, the aortic crossover, and the lower esophageal sphincter.
• 🚨 Emergent endoscopy is required for complete esophageal obstruction, inability to handle secretions, button batteries, or sharp objects lodged in the esophagus.
• ⏳ Urgent endoscopy (within 24 hours) is indicated for non-sharp objects lodged in the esophagus, non-obstructing food impaction, magnets, or sharp objects in the stomach/duodenum, or objects greater than 2 cm in length in the stomach/duodenum.

Lower GI & Bronchoscopy Insights

• ✅ High-quality colonoscopies are measured by cecal intubation in >90% of cases, average withdrawal time >6 minutes, perforation rates <1 in 1000 (screening) or <1 in 500 (overall), and post-polypectomy bleeding managed non-operatively in >90% of cases.
• 🤒 Post-polypectomy syndrome presents with fever and localized pain the day after a thermal injury, without actual perforation, managed conservatively unless free air is present on imaging.
• 💨 Bronchospasm during bronchoscopy is treated with a beta-2 agonist like albuterol.
• 🦠 A quantitative BAL diagnostic threshold for pneumonia is over 100,000 colony-forming units per milliliter.
• 🥜 Peanut aspirations can cause intense pneumonitis due to the release of peanut oil upon breakdown.

Operating Room Safety & Quick Hits

• 🔥 OR fires require an ignition source (e.g., monopolar energy), fuel (e.g., chloroprene), and an oxidizer (e.g., oxygen).
• 🩸 Bipolar energy can safely seal blood vessels up to 7 mm in diameter.
• 💨 A sudden rise in end-tidal CO2 followed by a drop and hypotension may indicate a CO2 embolus, managed by placing the patient in Trendelenburg and left lateral decubitus positions, and attempting aspiration.
• ⚠️ Neck crepitus after an upper endoscopic procedure suggests a perforation, managed with a water-soluble esophagogram.
• 🗣️ Physical exam findings prompting endotracheal intubation after suspected caustic agent or foreign body ingestion include dysphagia, drooling, stridor, or hoarseness.