Free air in the abdominal cavity (med. peritoneal cavity) is also called pneumoperitoneum. A pneumoperitoneum can be artificially created by a physician, for example during an operation, and is in this case called a pseudopneumoperitoneum. However, pathological processes or injuries of the abdominal cavity can also lead to this clinical picture.
The causes
Normally, the air in the abdominal cavity is only in hollow organs, such as the intestines or the bladder. Air outside hollow organs does not occur in healthy people. Doctors then refer to this air as “free air”.
A pneumoperitoneum can also be artificially created by a doctor. This occurs during minimally invasive procedures, such as laparoscopy. In this case, the surgeon pumps up the abdomen with a gas in order to obtain better visibility and more space during an operation.
This air can remain in the patient’s abdomen for several days and has no disease value. The cause of free air in the abdominal cavity is a perforation (piercing) or injury to a hollow organ. An example is the perforation of a stomach ulcer or the perforation of an inflamed appendix.
Diverticulitis is another high risk of perforation of a hollow organ. This is an inflammatory protrusion of the colon. Especially older patients are affected by this disease.
If a perforation occurs, the patient suffers from severe abdominal pain and the abdominal wall is hard as a board (so-called acute abdomen). A perforation can also be caused by an invasively growing tumor. Free air can also accumulate in the abdominal cavity if the outer covering of the abdomen is damaged and air can enter the body from outside.
During an operation in the abdomen, the abdominal cavity is opened and the surgical procedure is performed. This procedure is also called laparotomy. After the abdominal wall is sutured and closed, there may be free air in the abdomen.
A common cause of air in the abdominal cavity is a laparoscopy, the laparoscopy. More and more operations are being performed minimally invasive nowadays. This means that only small incisions are made during the operation so that the body can recover more quickly afterwards.
At the beginning of the laparoscopy, three to five liters of carbon dioxide are pumped into the patient’s abdominal cavity using a special machine. For this purpose, the patient’s abdomen is punctured with a needle and the gas is introduced through it. This causes the patient to inflate, the abdominal wall rises and the organs separate from each other.
As a result, the surgeons have a better overview of the abdominal organs and enough space to operate. At the end of the operation, the gas is pumped out, but not all of the carbon dioxide can be removed and a residue remains in the abdomen as free air. This air can remain there for up to two weeks before it is gradually absorbed through the intestinal wall and finally breathed out by the patient.
Patients typically feel bloated after the procedure and feel a feeling of pressure in the abdomen. In general, carbon dioxide is considered a suitable gas and has established itself as the preferred gas in surgery over helium and nitrous oxide. In rare cases, however, complications can arise due to the formation of the pneumoperitoneum.
The introduced gas exerts a certain pressure in the abdomen, which compresses the large venous blood vessels and can disrupt the return flow of blood to the heart. As a result, heart function may be restricted. This method is therefore unsuitable for people with heart disease.
Even patients with limited lung function (asthma or chronic obstructive pulmonary disease) cannot be operated on minimally invasively because they cannot sufficiently exhale the remaining CO2. In a caesarean section, the abdominal cavity is surgically opened and the child is removed from the uterus. As with all operations in the abdominal cavity, air gets into the abdomen, which accumulates and can still be detected a few days after the operation. However, this is completely normal and does not require further treatment, but women often feel bloated and suffer from abdominal pain.
