3 ABDOMINAL PAIN
Harrison’s Manual of Medicine
Acute, Catastrophic Abdominal Pain
Numerous causes, ranging from acute, life-threatening emergencies to chronic functional disease and disorders of several organ systems, can generate abdominal pain. Evaluation of acute pain requires rapid assessment of likely causes and early initiation of appropriate therapy. A more detailed and time-consuming approach to diagnosis may be followed in less acute situations. Table 3-1 lists the common causes of abdominal pain.
Table 3-1 Common Etiologies of Abdominal Pain
Approach to the Patient
Historic features are of critical diagnostic importance. Physical examination may be unrevealing or misleading and laboratory and radiologic exams delayed or unhelpful.
Characteristic Features of Abdominal Pain
Duration and Pattern These provide clues to nature and severity, although acute abdominal crisis may occasionally present insidiously or on a background of chronic pain.
Type and location provide a rough guide to nature of disease. Visceral pain (due to distention of a hollow viscus) localizes poorly and is often perceived in the midline. Intestinal pain tends to be crampy; when originating proximal to the ileocecal valve, it usually localizes above and around the umbilicus. Pain of colonic origin is perceived in the hypogastrium and lower quadrants. Pain from biliary or ureteral obstruction often causes pts to writhe in discomfort. Somatic pain (due to peritoneal inflammation) is usually sharper and more precisely localized to the diseased region (e.g., acute appendicitis; capsular distention of liver, kidney, or spleen), exacerbated by movement, causing pts to remain still. Pattern of radiation may be helpful: right shoulder (hepatobiliary origin), left shoulder (splenic), midback (pancreatic), flank (proximal urinary tract), groin (genital or distal urinary tract).
Factors That Precipitate or Relieve Pain Ask about its relationship to eating (e.g., upper GI, biliary, pancreatic, ischemic bowel disease), defecation (colorectal), urination (genitourinary or colorectal), respiratory (pleuropulmonary, hepatobiliary), position (pancreatic, gastroesophageal reflux, musculoskeletal), menstrual cycle/menarche (tuboovarian, endometrial, including endometriosis), exertion (coronary/intestinal ischemia, musculoskeletal), medication/ specific foods (motility disorders, food intolerance, gastroesophageal reflux, porphyria, adrenal insufficiency, ketoacidosis, toxins), and stress (motility disorders, nonulcer dyspepsia, irritable bowel syndrome).
Associated Symptoms Look for fevers/chills (infection, inflammatory disease, infarction), weight loss (tumor, inflammatory diseases, malabsorption, ischemia), nausea/vomiting (obstruction, infection, inflammatory disease, metabolic disease), dysphagia/odynophagia (esophageal), early satiety (gastric), hematemesis (esophageal, gastric, duodenal), constipation (colorectal, perianal, genitourinary), jaundice (hepatobiliary, hemolytic), diarrhea (inflammatory disease, infection, malabsorption, secretory tumors, ischemia, genitourinary), dysuria/hematuria/vaginal or penile discharge (genitourinary), hematochezia (colorectal or, rarely, urinary), skin/joint/eye disorders (inflammatory disease, bacterial or viral infection).
Predisposing Factors Inquire about family history (inflammatory disease, tumors, pancreatitis), hypertension and atherosclerotic disease (ischemia), diabetes mellitus (motility disorders, ketoacidosis), connective tissue disease (motility disorders, serositis), depression (motility disorders, tumors), smoking (ischemia), recent smoking cessation (inflammatory disease), ethanol use (motility disorders, hepatobiliary, pancreatic, gastritis, peptic ulcer disease).
Evaluate abdomen for prior trauma or surgery, current trauma; abdominal distention, fluid, or air; direct, rebound, and referred tenderness; liver and spleen size; masses, bruits, altered bowel sounds, hernias, arterial masses. Rectal examination for presence and location of tenderness, masses, blood (gross or occult). Pelvic examination in women is essential. General examination: evaluate for evidence of hemodynamic instability, acid-base disturbances, nutritional deficiency, coagulopathy, arterial occlusive disease, stigmata of liver disease, cardiac dysfunction, lymphadenopathy, and skin lesions.
Routine Laboratory and Radiologic Studies
Choices depend on clinical setting (esp. severity of pain, rapidity of onset): may include CBC, serum electrolytes, coagulation parameters, serum glucose, and biochemical tests of liver, kidney, and pancreatic function; CXR to determine the presence of diseases involving heart, lung, mediastinum, and pleura; ECG is helpful to exclude referred pain from cardiac disease; plain abdominal radiographs to evaluate bowel displacement, intestinal distention, fluid and gas pattern, free peritoneal air, liver size, and abdominal calcifications (e.g., gallstones, renal stones, chronic pancreatitis).
These include abdominal ultrasonography (to visualize biliary ducts, gallbladder, liver, pancreas, and kidneys); CT to identify masses, abscesses, evidence of inflammation (bowel wall thickening, mesenteric “stranding,” lymphadenopathy), aortic aneurysm; barium contrast radiographs (barium swallow, upper GI series, small-bowel follow-through, barium enema; upper GI endoscopy, sigmoidoscopy, or colonoscopy; cholangiography (endoscopic, percutaneous, or via MRI), angiography (direct or via CT or MRI), and radionuclide scanning. In selected cases, percutaneous biopsy, laparoscopy, and exploratory laparotomy may be required.
ACUTE, CATASTROPHIC ABDOMINAL PAIN
Intense abdominal pain of acute onset or pain associated with syncope, hypotension, or toxic appearance necessitates rapid yet orderly evaluation. Consider obstruction, perforation, or rupture of hollow viscus, dissection or rupture of major blood vessels (esp. aortic aneurysm), ulceration, abdominal sepsis, ketoacidosis, and adrenal crisis.
BRIEF HISTORY AND PHYSICAL EXAMINATION These should focus on presence of fever or hypothermia, hyperventilation, cyanosis, direct or rebound abdominal tenderness, pulsating abdominal mass, abdominal bruits, ascites, rectal blood, rectal or pelvic tenderness, and evidence of coagulopathy. Useful laboratory studies include hematocrit (may be normal with acute hemorrhage or misleadingly high with dehydration), WBC, arterial blood gases, serum electrolytes, BUN, creatinine, glucose, lipase or amylase, and UA. Radiologic studies should include supine and upright abdominal films (left lateral decubitus view if upright unobtainable) to evaluate bowel caliber and presence of free peritoneal air, cross-table lateral film to assess aortic diameter; CT (when available) to detect evidence of bowel perforation, inflammation, solid organ infarction, retroperitoneal bleeding, abscess, or tumor. Abdominal paracentesis (or peritoneal lavage in cases of trauma) can detect evidence of bleeding or spontaneous peritonitis. Abdominal ultrasound (when available) reveals evidence of abscess, cholecystitis, biliary obstruction, or hematoma and is used to determine aortic diameter.
Intravenous fluids, correction of life-threatening acid-base disturbances, and assessment of need for emergent surgery are the first priority; careful follow- up with frequent reexamination (when possible, by the same examiner) is essential. The use of narcotic analgesia is controversial. Traditionally, narcotic analgesics were withheld pending establishment of diagnosis and therapeutic plan, since masking of diagnostic signs may delay needed intervention. However, evidence that narcotics actually mask a diagnosis is sparse.
For a more detailed discussion, see Silen W: Abdominal Pain, Chap. 14, p. 67, in HPIM-15.