Gastrointestinal perforation

Etiology & Pathophysiology - The Breach

• Common Causes:

  • Peptic Ulcer Disease (PUD): Most frequent, esp. anterior duodenal ulcers.
  • Diverticulitis: Particularly sigmoid colon.
  • Appendicitis: Rupture leading to peritonitis.
  • Malignancy: Gastric or colorectal tumors eroding the wall.
  • Trauma: Blunt or penetrating injuries.
  • Iatrogenic: Post-procedural (e.g., colonoscopy, ERCP) or surgical.
  • Bowel Obstruction: Ischemic necrosis or cecal blowout.
  • Inflammatory Bowel Disease (IBD): Crohn's (transmural), toxic megacolon (UC).

• Pathophysiology Cascade:

  • Breach of GI wall → Leakage of luminal contents (air, bacteria, enzymes, feces).
  • Chemical peritonitis → Bacterial peritonitis → Systemic inflammation (SIRS).
  • Fluid shift to peritoneum ("third spacing") → Hypovolemia & septic shock.

⭐ The most common cause of pneumoperitoneum is a perforated duodenal ulcer. Free air under the diaphragm on an upright chest X-ray is the classic sign.

Clinical Presentation & Diagnosis - The Alarm Bells

• History & Symptoms:
  • Sudden, severe, diffuse abdominal pain (“thunderclap” onset).
  • Syncope can occur due to profound vagal response.
  • Referred shoulder pain (Kehr's sign) from diaphragmatic irritation.
• Physical Exam Findings:
  • Signs of peritonitis: guarding, rigidity, rebound tenderness.
  • Classic "board-like" abdomen is pathognomonic.
  • Systemic signs: Tachycardia, hypotension, fever (SIRS).

⭐ On exam, diminished liver dullness to percussion can be an early clue to pneumoperitoneum before imaging is even done.

Management - The Fix-It Crew

Immediate resuscitation is key. The approach follows a structured algorithm, often leading to surgical intervention.

• Initial Stabilization (The ABCs):

  • NPO (Nil Per Os) & Nasogastric (NG) tube for gastric decompression.
  • Aggressive IV fluid resuscitation (crystalloids).
  • Broad-spectrum IV antibiotics (e.g., Piperacillin-Tazobactam) to cover gram-negatives and anaerobes.
  • Insert a Foley catheter to monitor urine output.

• Definitive Treatment:

  • The primary goal is source control (closing the perforation) and peritoneal lavage.

⭐ For a perforated peptic ulcer, an omental patch repair (Graham patch) is a common and effective technique. This involves suturing a piece of the omentum over the perforation to seal it.

High‑Yield Points - ⚡ Biggest Takeaways

• Peptic ulcer disease, particularly duodenal ulcers, is the leading cause of GI perforation.
• The classic presentation is sudden-onset, severe, diffuse abdominal pain followed by a rigid, board-like abdomen from peritonitis.
• An upright chest X-ray is the best initial test to detect pneumoperitoneum (free air under the diaphragm).
• Abdominal CT scan is the most sensitive imaging modality for diagnosis.
• Management is an emergency: IV fluids, broad-spectrum antibiotics, and immediate exploratory laparotomy.