Abdominal Pain: General Considerations

Causes and PathogenesisTop

Abdominal pain is a nonspecific symptom in many diseases.

1. Acute abdominal pain: A sudden-onset somatic abdominal pain (due to stimulation of pain receptors in the parietal peritoneum and the abdominal wall) with an intensity that may increase over several hours or days. The pain is usually well localized and aggravated by movement, coughing, deep breathing, and changes in body position. It is most severe over the disease-affected area and may be accompanied by abdominal guarding and other signs of peritonitis caused by inflammation of the parietal peritoneum. Acute abdominal pain can be a symptom of acute illness, which may pose a health risk or be life threatening and require prompt medical intervention, often including emergency surgery; also see Adynamic Ileus, see Mechanical Intestinal Obstruction, see Acute Appendicitis, see Gastrointestinal Bleeding.

Causes:

1) Gastrointestinal (GI) diseases: Perforated peptic ulcer, appendicitis, intestinal perforation, bowel obstruction, acute gastroenteritis, diverticulitis or perforated colonic diverticula, Meckel diverticulitis.

2) Hepatobiliary diseases: Biliary colic, acute cholecystitis, acute cholangitis, acute hepatic congestion (hepatic vein thrombosis, heart failure).

3) Acute pancreatitis.

4) Acute splenic rupture.

5) Genitourinary diseases: Nephrolithiasis, acute pyelonephritis, acute cystitis, ectopic pregnancy, adnexal torsion or cyst, acute adnexitis.

6) Metabolic diseases: Diabetic ketoacidosis (DKA), porphyria, uremia.

7) Vascular diseases: Mesenteric arterial embolism, mesenteric venous thrombosis, abdominal aortic dissection, systemic vasculitis (eg, IgA-associated vasculitis [Henoch-Schönlein purpura]).

8) Diseases of the intrathoracic organs: Coronary artery disease (particularly inferior wall acute myocardial infarction), myocarditis, pericarditis, pneumonia with pleuritis, pulmonary embolism.

9) Endocrine diseases: Thyrotoxic crisis, diabetic enteropathy, adrenal crisis, hypercalcemic crisis.

10) Allergic diseases: Food allergy, angioedema.

11) Poisoning: Lead, arsenic, mercury, mushrooms.

2. Chronic abdominal pain is usually visceral (caused by stimulation of pain receptors in the internal organs and visceral peritoneum) and may persist for months or years. The pain is dull and difficult to localize. Its intensity may fluctuate. It is often accompanied by features of autonomic nervous system stimulation (nausea, vomiting, sweating) or discomfort. The pain is often located symmetrically on both sides of the midline and its intensity may increase at rest.

Causes:

1) Functional disorders: Irritable bowel syndrome (IBS), functional dyspepsia, chronic functional abdominal pain.

2) GI diseases: Chronic gastroduodenitis, peptic ulcer disease (PUD), gastroesophageal reflux disease (GERD), Crohn disease, ulcerative colitis, ischemic or radiation-induced enteritis, bowel inflammation in the course of systemic connective tissue diseases, infectious or parasitic bowel disease (tuberculosis, actinomycosis, giardiasis, teniasis, ascariasis, trichomoniasis, schistosomiasis, Whipple disease), diverticulitis, celiac disease.

3) Cholelithiasis and choledocholithiasis.

4) Chronic pancreatitis.

5) Abdominal tumors.

6) Nervous system diseases: Multiple sclerosis, herpes zoster, neuralgia.

3. Referred pain is perceived superficially in the skin or muscles at a location distant from the affected organ. An example of referred pain is pain in the back and over the right scapula that accompanies disorders of the biliary system.

DiagnosisTop

Determine the location, type (acute, chronic), quality (stabbing, burning, dull, gnawing, colicky, cramp-like), and intensity of pain as well as triggering or modifying factors (especially food, drinking, vomiting, bowel movements, body position). The most frequent causes of abdominal pain by location: Table 1 and Figure: The character of pain and abdominal guarding in certain conditions associated with adynamic ileus. During physical examination assess the patient’s general appearance, vital signs (respirations, pulse, blood pressure), skin color, and check for the presence of hernias, ascites, abdominal distension, scars, collateral venous circulation, point of maximal tenderness, presence of tumors, abdominal guarding and other signs of peritonitis, presence and nature of intestinal peristaltic sounds, and presence of liver dullness on percussion.

Exclude features indicating an organic cause that requires immediate diagnostic workup or surgical treatment:

1) Acute abdominal pain with vomiting or sudden stool retention is suggestive of intestinal obstruction.

2) Acute abdominal pain with GI bleeding may be suggestive of a gastric or duodenal ulcer, acute hemorrhagic gastropathy, intestinal ischemia, or very rarely even a ruptured abdominal aortic aneurysm.

3) Acute abdominal pain with rapid deterioration of the patient’s general condition (hypotension, altered mental status, breathing disorders) may be suggestive of, among others, GI perforation, acute pancreatitis, intra-abdominal hemorrhage, acute liver failure, or sepsis from obstruction of the bowel, kidney, or biliary tree.

4) Chronic abdominal pain accompanied by the presence of blood in stool or weight loss may be a symptom of cancer or inflammatory bowel disease.

5) Abdominal pain accompanied by abnormal physical findings (eg, jaundice, abdominal mass).

6) Abdominal pain waking the patient at night.

Order the basic diagnostic studies: Complete blood count (CBC); serum electrolyte, creatinine, and glucose levels; urinalysis; electrocardiography (ECG). Further blood, urine, and stool tests should be performed on the basis of the initial diagnosis and the necessary differential diagnosis and may include serum levels of amylase, bilirubin, cardiac troponin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and calprotectin, as well as a fecal occult blood test. The initial imaging studies include ultrasonography (may reveal free fluid in the abdominal cavity, urinary stones or gallstones, abnormalities of the abdominal aorta) and plain abdominal radiography (may reveal free intraperitoneal air, air-fluid levels in the bowel loops, urinary stones). A computed tomography (CT) scan of the abdomen is increasingly being used, depending on the suspected cause. Surgical consultation should be considered early.

TablesTop