1. 
   

   What are the important features in the history and physical examination that can help to determine the cause of acute abdominal pain?

   
   
2. 
   

   What tests have the greatest impact in the diagnosis of patients with acute abdominal pain?

   
   
3. 
   

   What are the important metabolic/endocrine disorders that cause acute abdominal pain simulating an acute abdomen?

   
   
4. 
   

   What are the important hematologic/immunologic disorders that cause acute abdominal pain simulating an acute abdomen?

Acute abdominal pain, particularly when severe, requires an expeditious evaluation because a missed or delayed diagnosis may lead to significant morbidity and mortality. The first step is to determine whether the patient has a life-threatening cause of acute abdominal pain. After the patient has been stabilized, the emergency physician or hospitalist must then determine whether the patient needs emergent surgery. The decision to obtain an emergency surgical consultation depends on the history and physical examination (with ancillary radiographic examinations of secondary importance), and when signs of an acute abdomen are present, a surgical consult should be requested, with concurrent diagnostic testing as appropriate. In other instances, a thorough history and physical examination is required with close observation and repeat examinations are often needed. Elderly patients and very young patients may present with atypical or nonspecific signs and symptoms that otherwise might be dismissed as insignificant.

Appendicitis, cholecystitis and choledocholithiasis, intestinal obstruction, pancreatitis, mesenteric ischemia, bowel perforation, and diverticulitis account for two-thirds of hospital admissions for acute abdominal pain and are associated with significant morbidity and mortality. In addition, physicians must be mindful of complications following procedures.

Patients may experience visceral pain, parietal pain, and/or referred abdominal pain.

Visceral pain is typically dull or crampy in character. It is caused by stretching, torsion, distention, or contraction of organs. The visceral innervation of the gut and accessory organs comes via the -anchoring mesentery, so pain does not always localize to the quadrant in which the pathology resides, and is often midline. Pain innervation corresponds to dermatomes that match the innervations of the injured organ. Epigastric visceral pain corresponds with organs proximal to the ligament of Treitz, including the hepatobiliary system and the spleen. Periumbilical visceral pain corresponds with injury to organs distal to the ligament of Treitz and the hepatic flexure of the colon. Lower abdominal visceral pain corresponds to injury to organs distal to the hepatic flexure.

Parietal pain is sharp in character and localized to the site of peritoneal inflammation or capsular. This pain is similar to skin and muscle pain and lateralization occurs due to unilateral parietal innervations.

Referred pain is typically well localized. It occurs because visceral afferent nerves carrying stimuli from an inflamed organ enter the spinal cord at the same level as somatic afferent nerves from remote locations.

Did This Patient’s Abdominal Pain Occur Abruptly?

Pain that occurs suddenly increases the likelihood of intestinal, ureteral, or biliary obstruction, an acute vascular problem such as an aortic dissection or rupture or hemorrhage into the retroperitoneal space, or perforation of a viscus. Intermittent, colicky pain is more suggestive of obstruction of a viscus rather than the severe, persistent, or worsening pain of a perforation. The onset of pain associated with inflammation such as appendicitis is more gradual and in the early stages may not cause severe pain. Appendicitis should be considered in all patients with acute abdominal pain.

Women should always be asked about the menstrual cycle, possible pregnancy, and birth control pills.

Did This Patient’s Abdominal Pain Localize?

Localization of pain may be useful in determining its cause.

Diffuse pain may result from gastroenteritis, peritonitis, perforation, gastrointestinal hemorrhage, abdominal abscess, acute pancreatitis, intestinal obstruction, early appendicitis, ileocolitis, sigmoid diverticulitis, strangulated hernia, inflammatory bowel disease, mesenteric ischemia, aortic dissection or rupture, and traumatic injury. Angioedema of the bowel (hereditary, idiopathic or medication induced), familial Mediterranean fever, sickle cell crisis, acute porphyria, diabetic ketoacidosis, uremia, hypercalcemia, opiate withdrawal, and heavy metal intoxication may also cause diffuse pain.

Mid upper abdominal pain may be caused by peptic ulcer disease; pancreatic cancer, pancreatitis; biliary colic, cholecystitis, or ascending cholangits; esophagitis, gastroesophageal reflux disease, or pill-induced esophagitis, myocardial ischemia or pericarditis, mesenteric ischemia, rupture or dissection of the aorta, and traumatic injury.

Periumbilical pain may arise from early appendicitis, obstruction of the small bowel, gastroenteritis, mesenteric ischemia, aortic aneurysm rupture or dissection, and traumatic injury.

Right upper quadrant pain may result from acute cholecystitis, ascending cholangitis or biliary colic, acute hepatitis, hepatic abscess, hepatic congestion secondary to congestive heart failure, perforated duodenal ulcer, acute pancreatitis, retrocecal appendicitis, colitis, right-sided diverticulitis, myocardial ischemia, pericarditis, right lower lobe pneumonia, pulmonary embolism, subphrenic abscess, pyelonephritis, renal calculi, perinephric abscess, and traumatic injury.

Right lower quadrant pain suggests appendicitis, inflammatory bowel disease, right-sided diverticulitis, ileocolitis, ischemic colitis, gastroenteritis, hernia, Merckel diverticulosis, cecal diverticulosis, mesenteric adenitis, incarcerated strangulated groin hernia, leaking aneurysm, ruptured ectopic pregnancy, twisted ovarian cyst, pelvic inflammatory disease, salpingitis, Mittelschmerz, endometriosis, gynecologic cancer, pyelonephritis, renal calculi, prostatitis, seminal vesiculitis, psoas abscess, and traumatic injury.

Left upper quadrant pain may be caused by gastritis or peptic ulcer disease; acute pancreatitis or pancreatic cancer; splenic enlargement or infarction, rupture, infarction or aneurysm, myocardial ischemia, pulmonary embolism, subphrenic abscess, left lower lobe pneumonia, pyelonephritis, renal calculi, perinephric abscess, and traumatic injury.

Left lower quadrant pain may result from sigmoid diverticulitis, ischemic colitis, inflammatory bowel disease, ileocolitis, gastroenteritis, incarcerated or strangulated groin hernia, regional enteritis, leaking aneurysm, ruptured ectopic pregnancy, Mittelschmerz, twisted ovarian cyst or torsion, gynecologic cancer, salpingitis, pelvic inflammatory disease, endometriosis; pyelonephritis, perinephris abscess, ureteral calculi, seminal vesiculitis, prostatitis, psoas abscess, and traumatic injury.

With any lateralizing pain location (any of the four quadrants), particularly when there is a lack of clinical evidence for an intra-abdominal process, the physician should think about the possibility of herpes zoster (lateralizing sharp pain, classically band like along a dermatome, sometimes preceded by tingling), which may arise prior to development of the classic eruption. Abdominal wall processes and muscular processes (including hematoma, infection, and muscle strain) should also be considered in the appropriate setting.

Does This Pain Radiate?

Gallbladder pain, liver disease, and referred pain from diaphragmatic irritation typically radiate to the back and/or shoulder. Liver disease and gallbladder disease may also radiate to the tip of the scapula. Pancreatitis, posterior perforation of an ulcer, kidney disease, and dissecting aneurysm can cause severe back pain due to inflammation in the retroperitoneum, occasionally with radiation to the shoulder. Other retroperitoneal structures such as kidney or ureter may also cause abdominal or flank pain that radiates to the back. Abdominal pain radiating to the groin/testicles may be due to an obstructing renal stone in the ureter.

What Is the Severity of This Patient’s Pain Near the Time of Onset?

Although pain is experienced subjectively, there are certain types of pain that are classically intense within seconds or minutes of onset. Acute vascular insufficiency from torsion of a visceral structure or an acute embolic event (eg, in a patient with atrial fibrillation), perforation, hemorrhage, and dissection will often present with intense, acute pain. Renal colic also can present acutely, but waxes and wanes often with near-complete resolution between pain peaks.

How Does the Patient Describe the Quality of Pain?

Abdominal pain in a patient with bowel obstruction is colicky in nature. Repeated episodes of colicky abdominal pain may suggest internal hernias as the cause of intermittent or acute intestinal obstruction. An intraabdominal hernia occurs when an anomalous fold or outpocketing of the peritoneum traps an intestinal loop. Acute strangulation of the intestinal loop may result in compression of the vasculature or gangrene of the bowel (50% of patients) or volvulus (14% of patients).

Biliary colic is a misnomer, the pain does not wax and wane but builds over 15 to 60 minutes, then is steady for several hours and dissipates slowly (visceral pain).

Pain in cholecystitis usually lasts longer than 6 hours and is located in the right upper quadrant due to progressive inflammation (parietal pain).

Although peptic ulcer disease may be asymptomatic and occasionally a patient may report crampy abdominal pain, most patients characterize the pain as burning/gnawing pain.

Visceral pain in diverticulitis is initially crampy in character, followed by parietal pain as the inflammation progresses.

Pain in acute mesenteric ischemia is acute in onset and severe. The patient reports periumbilical visceral pain out of proportion to the physical examination. Parietal pain and localizing exam findings are ominous findings in mesenteric ischemia, suggesting that the bowel may have infarcted or perforated. A dissecting aneurysm usually manifests with sudden severe pain, sometimes described as tearing/ripping sensation that radiates to the back. The onset may be in the epigastric region but then may progress to involve the lower quadrants as the dissection proceeds. Often the intense pain occurs intermittently as new tearing episodes occur.

How Has the Pain Progressed?

Has the patient experienced similar episodes in the past? If so, have the patient describe them, and determine what prior evaluation has been performed and what presumptive diagnoses were obtained.

What Are the Associated Signs and Symptoms?

Is there a history of systemic symptoms, such as fever, anorexia, weight loss? Acute inflammatory symptoms such as fever, particularly when infectious diarrhea is not suspected, may suggest the need for urgent imaging. Fever may be due to a loss of bowel wall integrity (perforation or severe mucosal injury) or due to infection in other abdominal structures (eg, cholecystitis). Weight loss may suggest a chronic inflammatory condition, mesenteric ischemia, malignancy, a problem with absorption, or a stricture. Sometimes food avoidance due to fear of pain may be the cause of weight loss.

Vomiting preceding the pain suggests the diagnosis of gastroenteritis, intestinal obstruction, biliary colic, or ureteral colic. Gastroenteritis, however, is usually associated with diarrhea. In appendicitis, vomiting rarely precedes pain. Bilious vomiting suggests mechanical obstruction.

Obstruction caused by a tumor, diverticulitis, stricture, or less commonly by a colonic volvulus, may have nausea, vomiting, -abdominal distention, and pain.

Dark urine and pale stools suggest biliary obstruction. Be cautious in interpreting these complaints, however, since loose stools in general are often paler than formed stools, and truly acholic stools are uncommon. Further, dehydration—common with poor oral intake—leads to concentrated urine, so the clinician should specifically seek a history of brown or tea colored urine rather than simply asking if the urine is “dark. ” Jaundice is often not present early on after a biliary obstruction since scleral icterus reflects bilirubin levels from days earlier.