A 67-year-old white woman presents to the emergency department with generalized abdominal pain that began this morning. Following the algorithm, you check her for cough, shortness of breath, and an unusual odor to her breath, and find none of these signs. She is not aware of being bitten by a spider, and you do not find any bite-like lesions on her body. Her blood pressure is 95/60 and her pulse is 110 per minute, so you keep in mind the possibility of an inferior wall myocardial infarct.

Examination of the abdomen reveals generalized rebound tenderness and guarding and hypoactive bowel sounds. You perform a rectal examination and find bloody stools. You suspect a mesenteric thrombosis and you would be correct.

1. Where is the pain located? If it is diffuse, one should consider pancreatitis, mesenteric artery occlusion, or ruptured peptic ulcer. In addition, another viscus may be perforated, such as a ruptured ectopic, and there may be peritonitis. Pain out of proportion to the objective findings suggests mesenteric artery occlusion. If it is focal, we need to know what quadrant it is in. For example, acute cholecystitis is in the right upper quadrant, whereas diverticulitis is usually in the left lower quadrant (LLQ).

2. What is the nature of the pain? Colicky abdominal pain suggests intestinal obstruction, renal calculus, and cholelithiasis or common duct stone, whereas constant pain is typical of pancreatitis, a ruptured peptic ulcer, appendicitis, diverticulitis, and a ruptured ectopic pregnancy.

3. Does the pain radiate? The pain of acute cholecystitis typically radiates to the right scapula or right shoulder. The pain of a ruptured peptic ulcer may also radiate to the shoulder. The pain of acute renal calculus may radiate to the testicle.

4. What are the associated signs and symptoms? Shock with generalized tenderness and rebound and diminished or absent bowel sounds should suggest a ruptured peptic ulcer or acute pancreatitis. However, acute right upper quadrant pain with nausea and vomiting should suggest acute cholecystitis. On the other hand, appendicitis is more insidious in onset and is associated with anorexia and nausea, rarely vomiting, as well as constipation. Renal colic presents with hematuria.

5. Could this patient’s abdominal pain be caused by an extra-abdominal condition? Remember, lobar pneumonia, myocardial infarction, diabetic acidosis, and porphyria may be responsible for acute abdominal pain. There are numerous other conditions that need to be considered.

6. If the patient is an infant, is there projectile vomiting or current jelly stools? Projectile vomiting suggests pyloric stenosis, whereas bloody stools would suggest intussusception.

Except in patients with obvious gastroenteritis, it is wise to consult a general surgeon at the outset. All patients with acute abdominal pain should have a stat, flat, and upright plate of the abdomen; a chest x-ray to rule out pneumonia; an electrocardiogram (EKG) to rule out myocardial infarction; and a complete blood count (CBC), urinalysis, amylase, lipase, lactic acid, and chemistry panel. In cases of trauma, the
radiological examination of choice is a computed tomography (CT) scan with and without contrast as well as CT angiography (CTA), although abdominal ultrasound is also used to demonstrate blood in the peritoneal cavity. Sometimes, lateral decubitus films of the abdomen are necessary to show the step ladder pattern of intestinal obstruction. A pregnancy test is ordered when age and sex dictate it!

When these tests fail to confirm the clinical diagnosis, x-ray contrast studies or ultrasound may be necessary. For example, a CT scan of the abdomen can be done for a suspected renal calculus. Serial cardiac enzymes may confirm a myocardial infarction. Gallbladder ultrasound can be done to confirm cholecystitis and cholelithiasis. A nuclear scan of the gallbladder with iminodiacetic acid derivatives is very accurate in detecting acute cholecystitis. An angiogram is done for suspected mesenteric thrombosis. Ultrasonography may also help diagnose impending rupture of an abdominal aneurysm, appendicitis, or ectopic pregnancy. A peritoneal tap may diagnose a ruptured ectopic pregnancy. Laparoscopy should also be considered. A urine porphobilinogen helps exclude porphyria. A double enema may help diagnose intestinal obstruction. Magnetic resonance imaging (MRI) can be done when the diagnosis remains obscure, but it is cheaper to consult a general surgeon first.