Acute abdomen

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Acute abdomen refers to a sudden, severe pain in the abdomen that is less than 24 hours in duration. It is in many cases an emergency condition requiring urgent and specific diagnosis, and the treatment usually involves surgery.

Classification

Peritonitis

Acute abdomen is occasionally used synonymously with peritonitis. This is not incorrect; however, peritonitis is the more specific term, referring to inflammation of the peritoneum. It is diagnosed on physical examination as rebound tenderness, or pain upon removal of pressure rather than application of pressure to the abdomen. Peritonitis may result from several diseases, notably appendicitis and pancreatitis.

Ischemic Acute abdomen

Vascular disorders are more likely to affect the small bowel than the large bowel. Arterial supply to the intestines is provided by the superior and inferior mesenteric arteries, (SMA and IMA respectively) both of which are direct branches of the aorta.

The superior mesenteric artery supplies:

1. Small bowel
2. Ascending and proximal 2/3 of the transverse colon

The inferior mesenteric artery supplies:

1. Distal 1/3 of the transverse colon
2. Descending colon
3. Sigmoid colon

Of note, the splenic flexure, or the junction between the transverse and descending colon, is supplied by the most distal portions of both the inferior mesenteric artery and superior mesenteric artery. It is referred to medically as a watershed area, or an area especially vulnerable to ischemia during periods of systemic hypoperfusion, such as in shock (medical).

Acute abdomen of the ischemic variety is usually due to:

1. A thromboembolism from the left side of the heart, such as may be generated during atrial fibrillation, occluding the SMA.
2. Nonocclusive ischemia, such as that seen in hypotension secondary to heart failure may also contribute, but usually results in a mucosal or mural infarct, as contrasted with the typically transmural infarct seen in thromboembolus of the SMA.
3. Primary mesenteric vein thromboses may also cause ischemic acute abdomen, usually precipitated by hypercoagulable states such as polycythemia vera.

Causes

Common Causes

• Acute appendicitis
• Acute peptic ulcer and its complications
• Acute cholecystitis
• Acute pancreatitis
• Acute intestinal ischemia
• Diabetic ketoacidosis
• Acute diverticulitis
• Ectopic pregnancy with tubal rupture
• Acute peritonitis
• Bowel perforation with free air or bowel contents in the abdominal cavity
• Acute ureteral colic
• Bowel volvulus

Causes by Organ System

Cardiovascular	No underlying causes
Chemical/Poisoning	No underlying causes
Dental	No underlying causes
Dermatologic	No underlying causes
Drug Side Effect	Clomifene
Ear Nose Throat	No underlying causes
Endocrine	No underlying causes
Environmental	No underlying causes
Gastroenterologic	No underlying causes
Genetic	No underlying causes
Hematologic	No underlying causes
Iatrogenic	No underlying causes
Infectious Disease	No underlying causes
Musculoskeletal/Orthopedic	No underlying causes
Neurologic	No underlying causes
Nutritional/Metabolic	No underlying causes
Obstetric/Gynecologic	No underlying causes
Oncologic	No underlying causes
Ophthalmologic	No underlying causes
Overdose/Toxicity	No underlying causes
Psychiatric	No underlying causes
Pulmonary	No underlying causes
Renal/Electrolyte	No underlying causes
Rheumatology/Immunology/Allergy	No underlying causes
Sexual	No underlying causes
Trauma	No underlying causes
Urologic	No underlying causes
Miscellaneous	No underlying causes

Diagnosis

History and Symptoms

Patients with an Ischemic type of acute abdomen present with symptoms of:

• Diffuse abdominal pain
• Bowel distension
• Bloody diarrhea

Physical Examination

Abdomen

In cases of ischemic acute abdomen, bowel sounds will be absent.

Laboratory Findings

In cases of ischemic acute abdomen, laboratory tests reveal:

• Neutrophilic leukocytosis, sometimes with a left shift assessed through a complete blood count
• Increased serum amylase.

CT

A CT scan can provide a differential diagnosis between simple and complex pathologies causing the Acute abdomen. The scan can also provide evidence to the doctor whether surgical intervention is necessary.

Other Imaging Findings

In cases of ischemic acute abdomen, abdominal radiography will show many air-fluid levels, as well as widespread edema.

Treatment

Surgery

Acute ischemic abdomen is a surgical emergency. Typically, treatment involves removal of the region of the bowel that has undergone infarction, and subsequent anastomosis of the remaining healthy tissue.