Harrison's Manual of Medicine

Abdominal Pain

Approach to the Patient

History: History is of critical diagnostic importance. Physical exam 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 or 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 disease, 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).

Physical examination: 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 assesses 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) and may include complete blood count, serum electrolytes, coagulation parameters, serum glucose, and biochemical tests of liver, kidney, and pancreatic function; chest x-ray to determine the presence of diseases involving heart, lung, mediastinum, and pleura; electrocardiogram 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).

Special studies: 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.

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 43-1 lists the common causes of abdominal pain.

TABLE 43-1 COMMON ETIOLOGIES OF ABDOMINAL PAIN

Mucosal or muscle inflammation in hollow viscera: Peptic disease (ulcers, erosions, inflammation), hemorrhagic gastritis, gastroesophageal reflux, appendicitis, diverticulitis, cholecystitis, cholangitis, inflammatory bowel diseases (Crohn's, ulcerative colitis), infectious gastroenteritis, mesenteric lymphadenitis, colitis, cystitis, or pyelonephritis

Visceral spasm or distention: Intestinal obstruction (adhesions, tumor, intussusception), appendiceal obstruction with appendicitis, strangulation of hernia, irritable bowel syndrome (muscle hypertrophy and spasm), acute biliary obstruction, pancreatic ductal obstruction (chronic pancreatitis, stone), ureteral obstruction (kidney stone, blood clot), fallopian tubes (tubal pregnancy)

Vascular disorders: Mesenteric thromboembolic disease (arterial or venous), arterial dissection or rupture (e.g., aortic aneurysm), occlusion from external pressure or torsion (e.g., volvulus, hernia, tumor, adhesions, intussusception), hemoglobinopathy (esp. sickle cell disease)

Distention or inflammation of visceral surfaces: Hepatic capsule (hepatitis, hemorrhage, tumor, Budd-Chiari syndrome, Fitz-Hugh-Curtis syndrome), renal capsule (tumor, infection, infarction, venous occlusion), splenic capsule (hemorrhage, abscess, infarction), pancreas (pancreatitis, pseudocyst, abscess, tumor), ovary (hemorrhage into cyst, ectopic pregnancy, abscess)

Peritoneal inflammation: Bacterial infection (perforated viscus, pelvic inflammatory disease, infected ascites), intestinal infarction, chemical irritation, pancreatitis, perforated viscus (esp. stomach and duodenum), reactive inflammation (neighboring abscess, incl. diverticulitis, pleuropulmonary infection or inflammation), serositis (collagen-vascular diseases, familial Mediterranean fever), ovulation (mittelschmerz).

Abdominal wall disorders: Trauma, hernias, muscle inflammation or infection, hematoma (trauma, anticoagulant therapy), traction from mesentery (e.g., adhesions)

Toxins: Lead poisoning, black widow spider bite

Metabolic disorders: Uremia, ketoacidosis (diabetic, alcoholic), Addisonian crisis, porphyria, angioedema (C1 esterase deficiency), narcotic withdrawal

Neurologic disorders: Herpes zoster, tabes dorsalis, causalgia, compression or inflammation of spinal roots, (e.g., arthritis, herniated disk, tumor, abscess), psychogenic

Referred pain: From heart, lungs, esophagus, genitalia (e.g., cardiac ischemia, pneumonia, pneumothorax, pulmonary embolism, esophagitis, esophageal spasm, esophageal rupture)

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

Historic features of importance include age; time of onset of the pain; activity of the pt when the pain began; location and character of the pain; radiation to other sites; presence of nausea, vomiting, or anorexia; temporal changes; changes in bowel habits; and menstrual history. Physical exam should focus on the pt's overall appearance [writhing in pain (ureteral lithiasis) vs. still (peritonitis, perforation)], position (a pt leaning forward may have pancreatitis or gastric perforation into the lesser sac), presence of fever or hypothermia, hyperventilation, cyanosis, bowel sounds, 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 with differential count, arterial blood gases, serum electrolytes, BUN, creatinine, glucose, lipase or amylase, and UA. Females of reproductive age should have a pregnancy test. 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 peritonitis. Abdominal ultrasound (when available) reveals evidence of abscess, cholecystitis, biliary or ureteral obstruction, or hematoma and is used to determine aortic diameter.

DIAGNOSTIC STRATEGIES

The initial decision point is based on whether the pt is hemodynamically stable. If not, one must suspect a vascular catastrophe such as a leaking abdominal aortic aneurysm. Such pts receive limited resuscitation and move immediately to surgical exploration. If the pt is hemodynamically stable, the next decision point is whether the abdomen is rigid. Rigid abdomens are most often due to perforation or obstruction. The diagnosis can generally be made by a chest and plain abdominal radiograph.

If the abdomen is not rigid, the causes may be grouped based on whether the pain is poorly localized or well localized. In the presence of poorly localized pain, one should assess whether an aortic aneurysm is possible. If so, a CT scan can make the diagnosis; if not, early appendicitis, early obstruction, mesenteric ischemia, inflammatory bowel disease, pancreatitis, and metabolic problems are all in the differential diagnosis.

Pain localized to the epigastrium may be of cardiac origin or due to esophageal inflammation or perforation, gastritis, peptic ulcer disease, biliary colic or cholecystitis, or pancreatitis. Pain localized to the right upper quadrant includes those same entities plus pyelonephritis or nephrolithiasis, hepatic abscess, subdiaphragmatic abscess, pulmonary embolus, or pneumonia, or it may be of musculoskeletal origin. Additional considerations with left upper quadrant localization are infarcted or ruptured spleen, splenomegaly, and gastric or peptic ulcer. Right lower quadrant pain may be from appendicitis, Meckel's diverticulum, Crohn's disease, diverticulitis, mesenteric adenitis, rectus sheath hematoma, psoas abscess, ovarian abscess or torsion, ectopic pregnancy, salpingitis, familial fever syndromes, uterolithiasis, or herpes zoster. Left lower quadrant pain may be due to diverticulitis, perforated neoplasm, or other entities previously mentioned.

TREATMENT

IV 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. Relieve the pain. 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

For a more detailed discussion, see Silen W: Abdominal Pain, Chap. 13, p. 108, in HPIM-18.

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