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CHAPTER 113: The Acute Abdomen and Intra-abdominal Sepsis 1079

TABLE 113-2 Classification of intra-abdominal Sepsis by Source
Primary peritonitis
Infected ascites
Infected peritoneal dialysis catheter
Miscellaneous (eg, tuberculosis)
Secondary peritonitis
Intraperitoneal
Biliary tree
Gastrointestinal tract
Female reproductive system
Retroperitoneal
Pancreas
Urinary tract
Visceral abscess
Liver
Spleen

The importance of prompt diagnosis and treatment cannot be
overemphasized. This is one of the few prognostic variables that physi-
cians can control, and prompt treatment has been shown repeatedly to
FIGURE 113-2. CT scan diagnostic of a localized intra-abdominal abscess. The patient decrease mortality. 5-8
has a rim enhancing collection with an air-fluid level (arrow) secondary to acute diverticulitis.
The sigmoid in the area is thick walled and has many diverticula. ■ PRIMARY PERITONITIS
Primary peritonitis is a group of diseases characterized by infection in
depends on timely diagnosis and the close collaboration of the intensivist the peritoneal cavity without an obvious source such as a gastrointestinal
and the surgeon. (GI) tract perforation. This occurs most frequently in patients with
9,10
ascites secondary to cirrhosis, congestive heart failure, and peritoneal
THE INTENSIVE CARE UNIT MANAGEMENT dialysis, among other disorders. Patients suffering from primary peri-
OF THE PATIENT WITH AN ACUTE ABDOMEN tonitis rarely require intensive care. However, primary peritonitis may
occur in patients requiring intensive care for other reasons. For example,
Most patients with an acute abdomen are diagnosed outside the ICU, a cirrhotic patient with portal hypertension and ascites may develop
and require treatment in an ICU for one of five reasons: primary peritonitis that precipitates hepatic decompensation, leading to
1. Nonoperative: The patient is very ill but may not require surgical variceal bleeding and hypovolemic shock necessitating ICU admission.
intervention (eg, severe pancreatitis). The clinical presentation is usually one of fevers and physical signs of
2. Preoperative: The patient requires rapid stabilization or investiga- peritoneal irritation: involuntary guarding, rebound tenderness, shake
and cough tenderness. However, approximately one-third of patients
tion before urgent operation. with primary peritonitis have no sign or symptom of sepsis referable to
3. Postoperative: The patient requires intensive care for unrelated the abdomen. Diagnosis is based on clinical suspicion, the patient’s pre-
medical problems (eg, chronic lung disease) following definitive sentation, and the Gram stain and culture results obtained from ascitic
surgical treatment of an acute abdominal condition. fluid aspiration. Culture of infected ascitic fluid usually yields facultative
4. Postoperative: The patient requires intensive care because of severe anaerobic enteric organisms such as Escherichia coli; however, approxi-
10
sepsis or other condition following definitive surgical treatment of mately 35% of patients will have negative ascitic fluid cultures. Blood
an acute abdominal condition. cultures may be positive in these patients. Primary bacterial peritonitis
5. Interim: The patient requires stabilization before planned reoperation may be assumed to be present when the ascitic fluid neutrophil count is
over the next 24 to 72 hours (eg, “damage control” surgery for trauma). >250/µL. The diagnosis may be confirmed in culture-negative patients
by a response to appropriate antibiotic treatment within 48 hours char-
A classification of the sources of IAS appears in Table 113-2. acterized by clinical improvement and a decrease in the number of white
Abdominal infections originating in the pancreas, and infections arising blood cells present in the ascitic fluid.
in the urinary tract, are discussed in other chapters. It is essential to distinguish primary from secondary bacterial peri-
The key components of treatment of IAS are tonitis, which is caused by contamination from the gut lumen, and in
which multiple microbial species are usually found in the ascitic fluid
1. Prompt diagnosis and resuscitation Gram stain or culture. 9-10 Patients with secondary bacterial peritonitis
2. Prompt treatment of the underlying pathology and mechanical are unlikely to respond to antibiotic administration alone, and will
cleansing of the peritoneal cavity (“source control”) usually need surgical treatment to survive.
3. Timely, appropriate antibiotic administration Antibiotic treatment should be initiated on clinical suspicion of primary
4. Supportive care of the patient peritonitis and before culture and sensitivity results are available.
Primary bacterial peritonitis tends to be caused by a single pathogen,
5. Vigilant detection and aggressive treatment of complications arising usually an enteric gram-negative rod but sometimes gram positive such
from the underlying condition or its treatment as Streptococcus pneumoniae, or staphylococcal or Candida species if a
6. Close collaboration among all physicians caring for the patient dialysis catheter is present. Empiric antibiotics should therefore cover

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