Definition

Peritonitis is an inflammation of the membrane
which lines the inside of the abdomen and all of the internal
organs. This membrane is called the peritoneum.

Description

Peritonitis may be primary (meaning that it occurs
spontaneously, and not as the result of some other medical
problem) or secondary (meaning that it results from
some other condition). It is most often due to infection
by bacteria, but may also be due to some kind of a
chemical irritant (such as spillage of acid from the stomach,
bile from the gall bladder and biliary tract, or
enzymes from the pancreas during the illness called
pancreatitis). Peritonitis has even been seen in patients
who develop a reaction to the cornstarch used to powder
gloves worn during surgery. Peritonitis with no evidence
of bacteria, chemical irritant, or foreign body has
occurred in such diseases as systemic lupus erythematosus,
porphyria, and familial Mediterranean
fever. When the peritoneum is contaminated by blood,
the blood can both irritate the peritoneum and serve as a
source of bacteria to cause an infection. Blood may leak
into the abdomen due to a burst tubal pregnancy, an
injury, or bleeding after surgery.

Causes and symptoms

Primary peritonitis usually occurs in people who
have an accumulation of fluid in their abdomens (ascites).
Ascites is a common complication of severe cirrhosis of
the liver (a disease in which the liver grows increasingly
scarred and dysfunctional). The fluid that accumulates
creates a good environment for the growth of bacteria.

Secondary peritonitis most commonly occurs when
some other medical condition causes bacteria to spill into
the abdominal cavity. Bacteria are normal residents of a
healthy intestine, but they should have no way to escape
and enter the abdomen, where they could cause an infection.

Bacteria can infect the peritoneum due to conditions
in which a hole (perforation) develops in the stomach
(due to an ulcer eating its way through the stomach wall)
or intestine (due to a large number of causes, including a
ruptured appendix or a ruptured diverticulum). Bacteria
can infect the peritoneum due to a severe case of pelvic
inflammatory disease (a massive infection of the female
organs, including the uterus and fallopian tubes). Bacteria
can also escape into the abdominal cavity due to an
injury that causes the intestine to burst, or an injury to an
internal organ which bleeds into the abdominal cavity.

Symptoms of peritonitis include fever and abdominal
pain. An acutely ill patient usually tries to lie very still,
because any amount of movement causes excruciating
pain. Often, the patient lies with the knees bent, to
decrease strain on the tender peritoneum. There is often
nausea and vomiting. The usual sounds made by the
active intestine and heard during examination with a
stethoscope will be absent, because the intestine usually
stops functioning. The abdomen may be rigid and boardlike.
Accumulations of fluid will be notable in primary
peritonitis due to ascites. Other signs and symptoms of the
underlying cause of secondary peritonitis may be present.

Diagnosis

A diagnosis of peritonitis is usually based on symptoms.
Discovering the underlying reason for the peritonitis,
however, may require some work. A blood sample
will be drawn in order to determine the white blood cell
count. Because white blood cells are produced by the
body in an effort to combat foreign invaders, the white
blood cell count will be elevated in the case of an infection.
A long, thin needle can be used to take a sample of
fluid from the abdomen in an effort to diagnose primary
peritonitis. The types of immune cells present are usually
characteristic in this form of peritonitis. X-ray films may
be taken if there is some suspicion that a perforation
exists. In the case of a perforation, air will have escaped
into the abdomen and will be visible on the picture. When
a cause for peritonitis cannot be found, an open exploratory
operation on the abdomen (laparotomy) is considered
to be a crucial diagnostic procedure, and at the same time
provides the opportunity to begin treatment.

Treatment

Treatment depends on the source of the peritonitis,
but an emergency laparotomy is usually performed. Any
perforated or damaged organ is usually repaired at this
time. If a clear diagnosis of pelvic inflammatory disease
or pancreatitis can be made, however, surgery is not usually
performed. Peritonitis from any cause is treated with
antibiotics given through a needle in the vein, along with
fluids to prevent dehydration.

Prognosis

Prognosis for untreated peritonitis is poor, usually
resulting in death. With treatment, the prognosis is variable,
dependent on the underlying cause.

Prevention

There is no way to prevent peritonitis, since the diseases
it accompanies are usually not under the voluntary
control of an individual. However, prompt treatment can
prevent complications.