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 The peritoneal cavity is a potential space between the parietal peritoneum (the peritoneum that surrounds the abdominal wall) and visceral peritoneum (the peritoneum that surrounds the internal organs). The parietal and visceral peritonea are lay ...

, a

potential space In anatomy, a potential space is a space between two adjacent structures that are normally pressed together (directly apposed). Many anatomic spaces are potential spaces, which means that they are potential rather than realized (with their realiz ...

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 the th ...

. The most common cause is a perforated

abdominal organ The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

, generally from a perforated

peptic 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 ...

, although any part of the

bowel 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 and ...

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 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 A hiatal hernia or hiatus hernia is a type of hernia in which abdominal organs (typically the stomach) slip through the diaphragm into the middle compartment of the chest. This may result in gastroesophageal reflux disease (GERD) or laryngop ...

. 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 transpar ...

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

laparoscopic surgery Laparoscopy () is an operation performed in the abdomen or pelvis using small incisions (usually 0.5–1.5 cm) with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.Medl ...

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 ...

– The most common cause of rupture in the abdomen. Especially of the anterior aspect of the first part of the duodenum. * Perforated

Bowel obstruction Bowel obstruction, also known as intestinal obstruction, is a mechanical or Ileus, functional obstruction of the Gastrointestinal tract#Lower gastrointestinal tract, intestines which prevents the normal movement of the products of digestion. Eith ...

* 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 dama ...

* Ruptured

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

(e.g.,

megacolon Megacolon is an abnormal dilation of the colon (also called the large intestine). This leads to hypertrophy of the colon. The dilation is often accompanied by a paralysis of the peristaltic movements of the bowel. In more extreme cases, the feces ...

) *

Necrotising enterocolitis Necrotizing enterocolitis (NEC) is a devastating intestinal disease that affects premature or very low birth weight infants.Gephart S.M., Quinn M. A call to action to fight for equity and end necrotizing enterocolitis disparities. ''Adv. Neonata ...

/pneumatosis coli *

Bowel cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel m ...

* 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 a ...

* 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 Laparoscopy () is an operation performed in the abdomen or pelvis using small incisions (usually 0.5–1.5 cm) with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.Medli ...

* 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 i ...

* 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 insert ...

Peritoneal dialysis Peritoneal dialysis (PD) is a type of dialysis which uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood. It is used to remove excess fluid, correct electrolyte pro ...

(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 North ...

. * 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 dise ...

* From chest (e.g., bronchopleural

fistula A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow or ...

) * 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 Peritonitis is inflammation of the localized or generalized peritoneum, the lining of the inner wall of the abdomen and cover of the abdominal organs. Symptoms may include severe pain, swelling of the abdomen, fever, or weight loss. One part or ...

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 tens ...

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 air ...

, and a tracheal rupture following an emergency

intubation Intubation (sometimes entubation) is a medical procedure involving the insertion of a tube into the body. Patients are generally anesthetized beforehand. Examples include tracheal intubation, and the balloon tamponade with a Sengstaken-Blakemo ...

. 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 Great vessels are the large vessels that bring blood to and from the heart. These are: *Superior vena cava *Inferior vena cava *Pulmonary arteries * Pulmonary veins *Aorta Transposition of the great vessels is a group of congenital heart defec ...

Diagnosis

When present, pneumoperitoneum can often be seen on

projectional radiography Projectional radiography, also known as conventional radiography, is a form of radiography and medical imaging that produces two-dimensional images by x-ray radiation. The image acquisition is generally performed by radiographers, and the images ...

, 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 ...

. 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 Radiodensity (or radiopacity) is opacity (optics), 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. Radi ...

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 with ...

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 to ...

s with spontaneous or

iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence. "Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 2 ...

gastric perforation causing pneumoperitoneum. It is also seen in bowel obstruction with secondary perforation, as in Hirschprung disease, midgut volvulus,

meconium ileus Meconium is the earliest stool of a mammalian infant resulting from defecation. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, amniotic ...

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, 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 Pneumomediastinum (from Greek ''pneuma'' – "air", also known as mediastinal emphysema) is pneumatosis (abnormal presence of air or other gas) in the mediastinum, the central part of the chest cavity. First described in 1819 by René Laennec, ...

can be called mediastinal emphysema, but ''pneumoperitoneum'' is the usual name.

References

External links

{{Digestive system diseases Disorders of fascia Peritoneum disorders