The main manifestations of peritonitis are acute
abdominal pain,
abdominal tenderness,
abdominal guarding,
rigidity, which are exacerbated by moving the
peritoneum, e.g., coughing (forced cough may be used as a test), flexing one's hips, or eliciting the
Blumberg's sign (meaning that pressing a hand on the abdomen elicits less pain than releasing the hand abruptly, which will aggravate the pain, as the peritoneum snaps back into place). Rigidity is highly
specific for diagnosing peritonitis (specificity: 76–100%).[7] The presence of these signs in a person is sometimes referred to as peritonism.[8] The localization of these manifestations depends on whether peritonitis is localized (e.g.,
appendicitis or
diverticulitis before perforation), or generalized to the whole
abdomen. In either case, pain typically starts as a generalized abdominal pain (with involvement of poorly localizing
visceral innervation of the
visceral peritoneal layer), and may become localized later (with involvement of the
somatic innervation of the parietal peritoneal layer). Peritonitis is an example of an
acute abdomen.[9]
Other symptoms
Diffuse abdominal rigidity (
abdominal guarding) is often present, especially in generalized peritonitis
Spontaneous bacterial peritonitis (SBP) is a peculiar form of peritonitis occurring in the absence of an obvious source of contamination. It occurs in people with
ascites, including children.
Intra-peritoneal dialysis predisposes to peritoneal infection (sometimes named "primary peritonitis" in this context).
Systemic infections (such as
tuberculosis) may rarely have a peritoneal localisation.
Sterile abdominal surgery, under normal circumstances, causes localised or minimal generalised peritonitis, which may leave behind a
foreign body reaction or fibrotic
adhesions. However, peritonitis may also be caused by the rare case of a
sterile foreign body inadvertently left in the abdomen after
surgery (e.g.,
gauze,
sponge).
A diagnosis of peritonitis is based primarily on the clinical manifestations described above. Rigidity (involuntary contraction of the abdominal muscles) is the most specific exam finding for diagnosing peritonitis.[14] If focal peritonitis is detected, further work-up should be done. If diffuse peritonitis is detected, then urgent surgical consultation should be obtained, and may warrant surgery without further investigations.
Leukocytosis,
hypokalemia,
hypernatremia, and
acidosis may be present, but they are not specific findings. Abdominal
X-rays may reveal dilated, edematous intestines, although such X-rays are mainly useful to look for
pneumoperitoneum, an indicator of
gastrointestinal perforation. The role of whole-abdomen
ultrasound examination is under study and is likely to expand in the future.
Computed tomography (CT or CAT scanning) may be useful in differentiating causes of abdominal pain. If reasonable doubt still persists, an exploratory
peritoneal lavage or
laparoscopy may be performed. In people with
ascites, a diagnosis of peritonitis is made via
paracentesis (abdominal tap): More than 250
polymorphonuclear cells per μL is considered diagnostic. In addition, Gram stain is almost always negative, whereas culture of the peritoneal fluid can determine the microorganism responsible and determine their sensitivity to antimicrobial agents.[15][16]
Pathology
In normal conditions, the peritoneum appears greyish and glistening; it becomes dull 2–4 hours after the onset of peritonitis, initially with scarce
serous or slightly
turbid fluid. Later on, the
exudate becomes creamy and evidently
suppurative; in people who are dehydrated, it also becomes very inspissated. The quantity of accumulated exudate varies widely. It may be spread to the whole peritoneum, or be walled off by the
omentum and
viscera.
Inflammation features infiltration by
neutrophils with fibrino-purulent exudation.[17]
Treatment
Depending on the severity of the person's state, the management of peritonitis may include:
Antibiotics are usually administered intravenously, but they may also be infused directly into the peritoneum. The empiric choice of
broad-spectrum antibiotics often consist of multiple drugs, and should be targeted against the most likely agents, depending on the cause of peritonitis (see above); once one or more agents grow in cultures isolated, therapy will be target against them.[18]
Gram-positive and Gram-negative organisms must be covered. Out of the
cephalosporins,
cefoxitin and
cefotetan can be used to cover Gram-positive bacteria, Gram-negative bacteria, and anaerobic bacteria. Beta-lactams with beta-lactamase inhibitors can also be used; examples include
ampicillin/sulbactam,
piperacillin/
tazobactam, and
ticarcillin/
clavulanate.[19]Carbapenems are also an option when treating primary peritonitis as all of the carbapenems cover Gram-positives, Gram-negatives, and anaerobes except for
ertapenem. The only fluoroquinolone that can be used is moxifloxacin because this is the only fluoroquinolone that covers anaerobes.
Tigecycline is a
tetracycline that can be used due to its coverage of Gram-positives and Gram-negatives. Empiric therapy will often require multiple drugs from different classes.[20]
Surgery (
laparotomy) is needed to perform a full exploration and lavage of the
peritoneum, as well as to correct any gross anatomical damage that may have caused peritonitis.[21] The exception is
spontaneous bacterial peritonitis, which does not always benefit from surgery and may be treated with antibiotics in the first instance.
Prognosis
If properly treated, typical cases of surgically correctable peritonitis (e.g., perforated peptic ulcer, appendicitis, and diverticulitis) have a
mortality rate of about <10% in otherwise healthy people. The mortality rate rises to 35% in peritonitis patients who develop sepsis, and patients who have underlying renal insufficiency and complications have a higher mortality rate.[22]
Etymology
The term "peritonitis" comes from
Greek περιτόναιον peritonaion "
peritoneum, abdominal membrane" and
-itis "inflammation".[23]
^Nishijima, D. K., Simel, D. L., Wisner, D. H., & Holmes, J. F. (2012). Does this adult patient have a blunt intra-abdominal injury?. JAMA, 307(14), 1517–1527.
https://doi.org/10.1001/jama.2012.422