Pneumoperitoneum

Abnormal presence of free gas within the peritoneal cavity, most commonly resulting from perforation of a hollow viscus, but also occurring secondary to postoperative, traumatic, iatrogenic, thoracic, or gynecologic conditions.

Causes

• Gastrointestinal perforation

  • Perforated peptic ulcer

  • Diverticulitis with perforation

  • Bowel obstruction with perforation

  • Ischemic bowel

  • Inflammatory bowel disease with perforation

  • Perforated colorectal or gastric cancer

  • Perforated appendicitis

  • Traumatic bowel perforation

• Postoperative and iatrogenic causes

  • Recent abdominal surgery

  • Endoscopy

  • Colonoscopy

  • Laparoscopy

  • Peritoneal dialysis

• Thoracic causes

  • Mechanical ventilation with barotrauma

  • Cardiopulmonary resuscitation (CPR)

  • Pneumothorax

  • Pneumomediastinum with dissection of air into the peritoneal cavity

• Gynecologic causes

  • Air entering through the vagina and passing via the fallopian tubes into the peritoneal cavity

  • Pelvic instrumentation

  • Hysterosalpingography

• Other causes

  • Penetrating abdominal trauma

  • Gas-producing intra-abdominal infection (rare)

  • Intra-abdominal fistulas