Pneumoperitoneum is

pneumatosis Pneumatosis is the abnormal presence of air or other gas within tissues. In the lungs, emphysema involves enlargement of the distal airspaces,

(abnormal presence of air or other gas) in the peritoneal cavity, a potential space within the

abdominal cavity The abdominal cavity is a large body cavity in humans and many other animals that contains many organs. It is a part of the abdominopelvic cavity. It is located below the thoracic cavity, and above the pelvic cavity. Its dome-shaped roof is th ...

. 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 A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

or abdominal trauma. A perforated

appendix Appendix, or its plural form appendices, may refer to: __NOTOC__ In documents * Addendum, an addition made to a document by its author after its initial printing or publication * Bibliography, a systematic list of books and other works * Index (pu ...

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 Peptic ulcer disease (PUD) is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines i ...

– 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 In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

Penetrating trauma Penetrating trauma is an open wound injury that occurs when an object pierces the skin and enters a tissue of the body, creating a deep but relatively narrow entry wound. In contrast, a blunt or ''non-penetrating'' trauma may have some deep da ...

* Ruptured

inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine, Crohn's disease and ulcerative colitis being the principal types. Crohn's disease affects the small intestine and large intestine, as well ...

(e.g., megacolon) * Necrotising enterocolitis/pneumatosis coli * Bowel cancer * Ischemic bowel *

Steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

* After

laparotomy A laparotomy is a surgical procedure involving a surgical incision through the abdominal wall to gain access into the abdominal cavity. It is also known as a celiotomy. Origins and history The first successful laparotomy was performed without ane ...

* After laparoscopy * Breakdown of a

surgical anastomosis A surgical anastomosis is a surgical technique used to make a new connection between two body structures that carry fluid, such as blood vessels or bowel. For example, an arterial anastomosis is used in vascular bypass and a colonic anastomosis ...

* Bowel injury after

endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inse ...

* 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 continental mainland. It comprises England, Scotland, Wales and ...

. * Vaginal insufflation (air enters via the

fallopian tubes The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...

; 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 di ...

* 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 Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretching the tissues in tensi ...

due to

mechanical ventilation Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV), is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move a ...

, 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 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 The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans an ...

. 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 Leo George Rigler (16 October 1896, Minneapolis – 25 October 1979) was an American radiologist remembered for describing Rigler's sign. Biography Leo Rigler attended the University of Minnesota, receiving a B.S. in 1917, B.M. in 1919 and ...

. It is not the same as

Rigler's triad Rigler's triad is a combination of findings on an abdominal radiograph of people with gallstone ileus, a condition where a large gallstone causes bowel obstruction. Rigler's triad consists of: (1) small bowel obstruction, (2) a gallstone outside ...

. The ''football sign'' is when the abdomen appears as a large oval radiolucency 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 wi ...

on a supine projectional radiograph. The football sign is most frequently seen in

infant An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used t ...

s with spontaneous or iatrogenic gastric perforation causing pneumoperitoneum. It is also seen in bowel obstruction with secondary perforation, as in Hirschprung disease, midgut volvulus, meconium ileus and

intestinal atresia Intestinal atresia is any congenital malformation of the structure of the intestine that causes bowel obstruction. The malformation can be a narrowing (stenosis), absence or malrotation of a portion of the intestine. These defects can either occur ...

. 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 s ...

, bowel interposed between diaphragm and liver ( Chilaiditi syndrome), and linear

atelectasis Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange. It is usually unilateral, affecting part or all of one lung. It is a condition where the alveoli are deflated down to little or no volume, as distinct ...

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