Contents
Presence of free air within the peritoneal cavity
Aetiology
Surgical pneumoperitoneum: Pneumoperitoneum induced Peritonitis
Leak of air and visceral contents contaminates the peritoneal cavity producing peritonitis that mandates surgery
- Inflammatory conditions
- Traumatic injury: Intra-abdominal viscus perforation (M/C, 90% cases)
- Neoplasia
- Anastomotic leak
- Vascular causes
Non-surgical/spontaneous pneumoperitoneum (SP):
Presence of free air in the peritoneum with intact gut
- Intrathoracic causes: Intermittent positive-pressure ventilation, asthma, chronic obstructive pulmonary disease (COPD), cardiopulmonary resuscitation, and severe coughing spells
- Intra-abdominal causes: Pneumatosis cystoides intestinalis, following abdominal surgery and endoscopy
- Gynecologic causes: Sexual intercourse, predominantly post-hysterectomy, vaginal douching, insufflation, and pelvic inflammatory disease (PID)
- Idiopathic pneumoperitoneum
Clinical features
The clinical presentation of the patients varies according to the site of perforation.
Features of peritonitis (if present):
- Abdominal pain, vomiting, abdominal distension, constipation, fever, diarrhea
- Tachycardia (pulse >110/min)
- Hypotension (systolic blood pressure <100 mmHg)
- Oliguria (<30 mL/h)
- Tachypnea (respiratory rate >20/min).
Diagnosis
Chest radiograph:
- Peritoneal ligament signs:
- Silver’s sign/falciform ligament sign: Air outlines the falciform ligament.
- Inverted V sign: Air outlining lateral umbilical ligaments (inferior epigastric vessels).
- Football sign: Seen in massive pneumoperitoneum, where the abdominal cavity is outlined by gas.
- Urachus sign: Outline of middle umbilical ligament.
- Bowel signs:
- Telltale triangle sign: Triangular air pocket between three loops of bowel.
- Rigler’s sign/bas-relief sign/double-wall sign: Air outlining both sides of the bowel wall.
- RUQ signs:
- Cupola/saddlebag/mustache sign (supine radiograph): Air accumulation underneath the central tendon of the diaphragm in the midline.
- Doge’s cap sign: Triangular collection of gas in Morison pouch.
- Lucent liver sign: Reduction of liver opacity due to air located anterior to the liver.
Computerized tomography (CT):
Managmenet
- Surgical pneumoperitoneum: Surgery
- Spontaneous pneumoperitoneum: Often managed conservatively, and exploratory surgery is warranted only if the clinical features of peritonitis are present.