April 18, 2008 — Guidelines for the evaluation of acute abdominal pain in adult patients presenting to primary care are reviewed in the April 1 issue of the American Family Physician. This review mandates a thorough and logical approach to the diagnosis of abdominal pain in this setting.

"Abdominal pain is a common presentation in the outpatient setting and is challenging to diagnose," write Sarah L. Cartwright, MD, and Mark P. Knudson, MD, MSPH, from the Wake Forest University School of Medicine in Winston-Salem, North Carolina. "Abdominal pain is the presenting complaint in 1.5 percent of office-based visits and in 5 percent of emergency department visits. Although most abdominal pain is benign, as many as 10 percent of patients in the emergency department setting and a lesser percentage in the outpatient setting have a severe or life-threatening cause or require surgery."

Acute abdominal pain may be caused by a variety of conditions ranging from benign and self-limited disease to surgical emergencies. An optimal approach to diagnose the basis for abdominal pain should rely on the likelihood of disease, complaints, and other features of patient history, findings on physical examination, laboratory tests, and imaging studies.

The location of abdominal pain is a useful starting point that should guide further workup; for example, right lower quadrant pain strongly suggests appendicitis. Although certain findings on history taking and physical examination are helpful, others are of limited value. For example, constipation and abdominal distension are strong indicators of bowel obstruction, but anorexia is of low diagnostic value for appendicitis.

In patients with abdominal pain, symptoms that suggest surgical or emergent conditions include fever, protracted vomiting, syncope or presyncope, and evidence of gastrointestinal tract blood loss.

Special populations may also be at risk for certain conditions causing abdominal pain, and these should be sought after in these subgroups. For example, women are at risk for genitourinary tract disease, and the elderly population may present with atypical symptoms of a disease.

Based on the location of abdominal pain, different imaging studies are recommended by the American College of Radiology as part of the diagnostic workup. Ultrasonography is preferred for evaluation of right upper quadrant pain and suprapubic pain vs computed tomography (CT) for right and left lower quadrant pain. CT with intravenous contrast media is recommended for workup of right lower quadrant pain, and CT with oral and intravenous contrast media is preferred for left lower quadrant pain.

In addition to considering location of abdominal pain, categorizing causes of abdominal pain by organ system and then by specific cause may also be helpful in differential diagnosis. Biliary causes of right upper quadrant pain include cholecystitis, cholelithiasis, and cholangitis; colonic causes are colitis or diverticulitis; and hepatic causes are abscess, hepatitis, or mass. Pulmonary causes are pneumonia or embolus, and renal causes are nephrolithiasis or pyelonephritis.

For epigastric pain, biliary causes are cholecystitis, cholelithiasis, and cholangitis. Cardiac causes are myocardial infarction or pericarditis; gastric causes include esophagitis, gastritis, and peptic ulcer; and early appendicitis may be a colonic cause. Pancreatic causes are mass or pancreatitis, whereas vascular causes are aortic dissection or mesenteric ischemia.

For left upper quadrant pain, cardiac, gastric, pancreatic, renal, and vascular causes are similar to those listed in the previous 2 paragraphs. Periumbilical sources of pain may be early appendicitis, vascular causes may be aortic dissection or mesenteric ischemia, or gastric causes may include small-bowel mass or obstruction in addition to those listed in the previous paragraph.

In the right or lower quadrant or suprapubic region, renal and colonic causes are as listed previously. Additional colonic sources are inflammatory bowel disease (IBD) or irritable bowel syndrome, and gynecologic sources of pain are ectopic pregnancy, fibroids, ovarian mass, torsion, or pelvic inflammatory disease.

In any location, pain originating from the abdominal wall may include herpes zoster, muscle strain, or hernia. Bowel obstruction, mesenteric ischemia, peritonitis, narcotic withdrawal, sickle cell crisis, porphyria, IBD, or heavy metal poisoning may cause diffuse or nonspecifically localized abdominal pain.

"When possible, the history should be obtained from a nonsedated patient," the study authors write. "The initial differential diagnosis can be determined by a delineation of the pain's location, radiation, and movement (e.g., appendicitis-associated pain usually moves from the periumbilical area to the right lower quadrant of the abdomen). After the location is identified, the physician should obtain general information about onset, duration, severity, and quality of pain and about exacerbating and remitting factors."

Specific clinical recommendations for practice, all of level of evidence rating C, are as follows:

• Appendicitis cannot be ruled out by a normal white blood cell count.
• In patients with epigastric pain, simultaneous amylase and lipase measurements are recommended.
• For evaluation of patients with acute right upper quadrant abdominal pain, ultrasonography is the imaging study of choice.
• For evaluating patients with acute right lower quadrant or left lower quadrant abdominal pain, CT is the imaging study of choice.

"Presentation may differ in older patients, and poor patient recall or a reduction in symptom severity may cause misdiagnosis," the reviewers conclude. "There are several diseases that should be considered in all older patients with abdominal pain because of the increased incidence and high risk of morbidity and mortality in these patients. Occult urinary tract infection, perforated viscus, and ischemic bowel disease are potentially fatal conditions commonly missed or diagnosed late in older patients."

The study authors have disclosed no relevant financial relationships.

Am Fam Physician. 2008;77:971-978.

Clinical Context

Pearls for Practice

• The initial evaluation of acute abdominal pain in adults depends on the location; symptoms consistent with severe or surgical conditions include fever, persistent emesis, syncope, and gastrointestinal tract bleeding.
• Recommended imaging studies for adults with acute abdominal pain include ultrasonography for right upper quadrant pain and CT for right or left lower quadrant pain.

CME/CE Test