Pneumoperitoneum
Free air within the peritoneal cavity, often seen as subdiaphragmatic lucency on upright films
Pneumoperitoneum means free air in the peritoneal cavity and can be an urgent clue to perforated bowel or another abdominal emergency.
Pneumoperitoneum means air is present in the abdominal cavity outside the bowel. On upright radiographs, it may collect under the diaphragm and can be a sign of perforation.
Representative X-ray
Representative annotated X-ray not available for this topic yet.
We only show a representative image when there is a clean corresponding source in the current reference set.
What it is
- This is a radiographic finding of free intraperitoneal gas
- It often raises concern for perforation of a hollow viscus, although postoperative or procedural causes can also produce it
How it appears on chest X-ray
- On upright chest or abdominal X-ray, pneumoperitoneum may appear as crescent-shaped lucency beneath one or both hemidiaphragms or as other signs of free air outlining abdominal structures
What radiologists look for
- Radiologists look for definite free air, distribution beneath the diaphragm, interval change, and whether the appearance fits perforation versus a less urgent postoperative explanation
How X-ray helps
- Upright radiographs can reveal free air quickly and may trigger urgent abdominal imaging or surgical evaluation
Common causes
- Causes include perforated ulcer, bowel perforation, diverticulitis, trauma, ischemic bowel, recent surgery, and endoscopic or procedural complications
Symptoms / associated symptoms
- Symptoms may include severe abdominal pain, guarding, distension, fever, vomiting, or sepsis, though postoperative patients may have different context
Risk factors
- Risk factors depend on the cause and may include ulcer disease, inflammatory bowel disease, diverticular disease, trauma, surgery, infection, or ischemia
Why it can matter clinically
- If caused by perforation, complications can include peritonitis, sepsis, shock, and death without urgent treatment
When to seek medical care
- Severe abdominal pain, rigid abdomen, fever, fainting, vomiting, or sudden worsening can represent an emergency and should be evaluated urgently
Evaluation and diagnosis
- Evaluation often includes abdominal examination, labs, surgical review, and CT imaging to confirm the source and severity
Treatment approaches
- Treatment may include urgent surgery, IV fluids, antibiotics, bowel rest, and source control depending on the cause
Medication classes clinicians may use
Management is driven by the underlying cause and usually involves hospital-level care rather than simple outpatient medication.
Treatment modalities commonly paired with medication decisions
- Urgent surgical evaluation
- Source control
- Broad-spectrum antibiotics when indicated
- Supportive inpatient care
Broad-spectrum antibiotics
Often started when bowel perforation or intra-abdominal infection is suspected.
- piperacillin-tazobactam
- ceftriaxone plus metronidazole
FAQ
Is pneumoperitoneum always an emergency?
It often is, because perforation is a key concern, but recent surgery or procedures can also explain free air in some settings.
Can chest X-ray detect it?
Yes. Upright chest X-ray can show free air beneath the diaphragm and may be the first imaging clue.