Pneumoperitoneum is pneumatosis (abnormal presence of air or other gas) in the peritoneal cavity, a potential space within the abdominal cavity. The most common cause is a perforated abdominal organ, generally from a perforated peptic ulcer, although any part of the bowel may perforate from a benign ulcer, tumor or abdominal trauma. A perforated

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seldom causes a pneumoperitoneum. Spontaneous pneumoperitoneum is a rare case that is not caused by an abdominal organ rupture. This is also called an idiopathic spontaneous pneumoperitoneum when the cause is not known. In the mid-twentieth century, an "artificial" pneumoperitoneum was sometimes intentionally administered as a treatment for a hiatal hernia. This was achieved by insufflating the abdomen with

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

. The practice is currently used by surgical teams in order to aid in performing laparoscopic surgery.

Causes

* Perforated duodenal ulcer – The most common cause of rupture in the abdomen. Especially of the anterior aspect of the first part of the duodenum. * Perforated peptic ulcer * Bowel obstruction * Ruptured diverticulum * Penetrating trauma * Ruptured inflammatory bowel disease (e.g., megacolon) * Necrotising enterocolitis/pneumatosis coli * Bowel cancer *

Ischemic bowel Ischemic bowel may refer to: *Ischemic colitis, ischemia of the large bowel *Mesenteric ischemia Intestinal ischemia is a medical condition in which injury to the large or small intestine occurs due to not enough blood supply. It can come on sud ...

* Steroids * After laparotomy * After laparoscopy * Breakdown of a surgical anastomosis * Bowel injury after endoscopy * Peritoneal dialysis (PD), although the prevalence of pneumoperitoneum is estimated to be less than 4% among people with PD in a more recent study in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

. * Vaginal insufflation (air enters via the fallopian tubes; e.g., water-skiing, oral sex) * Colonic or peritoneal

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable d ...

* From chest (e.g., bronchopleural fistula) * Non-invasive PAP (positive airway pressure) can force air down duodenum as well as down trachea.

Spontaneous pneumoperitoneum

A spontaneous pneumoperitoneum is a rare case that is not caused by an abdominal organ rupture. This is also called an idiopathic spontaneous pneumoperitoneum when the cause is not known. Causes of a spontaneous pneumoperitoneum, with no peritonitis include a barotrauma due to mechanical ventilation, and a tracheal rupture following an emergency intubation. In the ventilation case, air had passed from the chest into the abdominal cavity through the diaphragm. In the tracheal rupture air had passed along the great vessels.

Diagnosis

When present, pneumoperitoneum can often be seen on projectional radiography, but small amounts are often missed, and

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

is nowadays regarded as a criterion standard in the assessment of a pneumoperitoneum. CT can visualize quantities as small as 5 cm³ of air or gas. Signs that can be seen on projectional radiography are shown below: The ''double wall sign'' marks the presence of air on both sides of the intestine. However, a false double wall sign can result from two loops of bowel being in contact with one another. The sign is named after Leo George Rigler. It is not the same as Rigler's triad. The ''football sign'' is when the abdomen appears as a large oval

radiolucency Radiodensity (or radiopacity) is opacity to the radio wave and X-ray portion of the electromagnetic spectrum: that is, the relative inability of those kinds of electromagnetic radiation to pass through a particular material. Radiolucency or hyp ...

reminiscent of an

American football American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team wit ...

on a supine projectional radiograph. The football sign is most frequently seen in infants with spontaneous or iatrogenic

gastric perforation Gastrointestinal perforation, also known as ruptured bowel, is a hole in the wall of part of the gastrointestinal tract. The gastrointestinal tract includes the esophagus, stomach, small intestine, and large intestine. Symptoms include severe ab ...

causing pneumoperitoneum. It is also seen in bowel obstruction with secondary perforation, as in

Hirschprung disease Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Symptoms usu ...

, midgut volvulus, meconium ileus and intestinal atresia. Iatrogenic causes like endoscopic perforation may also give football sign. The ''Cupola sign'' is seen when air is accumulated under the central tendon of the diaphragm. Image:Pneumoperitoneum chest X-ray.jpg, Another pneumoperitoneum on chest X-ray. Image:Pneumoperitoneum lateral decubitus.jpg, Pneumoperitoneum seen on X-ray with the patient lying on his left side. File:Double wall sign annotated.jpg, Double wall sign. This is a secondary sign of pneumoperitoneum. Patient is supine, and air within the abdomen and lumen of the bowel accentuate both sides of the bowel wall. File:UOTW 68 - Ultrasound of the Week 2.webm, Ultrasound finding of pneumoperitoneum known as "peritoneal stripe sign"

Differential diagnosis

As differential diagnoses, a

subphrenic abscess Subphrenic abscess is a disease characterized by an accumulation of infected fluid between the diaphragm, liver, and spleen. This abscess develops after surgical operations like splenectomy. Presents with cough, increased respiratory rate with sh ...

, bowel interposed between diaphragm and liver (

Chilaiditi syndrome Chilaiditi syndrome is a rare condition when pain occurs due to transposition of a loop of large intestine (usually transverse colon) in between the diaphragm and the liver, visible on plain abdominal X-ray or chest X-ray. Normally this causes no ...

), and linear atelectasis at the base of the lungs can simulate free air under the diaphragm on a chest X-ray.

Treatment

Treatment depends on the cause of the condition.

Terminology

Pneumoperitoneum can be described as peritoneal emphysema, just as pneumomediastinum can be called mediastinal emphysema, but ''pneumoperitoneum'' is the usual name.

References

External links

{{Digestive system diseases Disorders of fascia Peritoneum disorders