GI Emergencies

Abdominal pain accounts for over five million visits annually to Emergency Departments. Between 20-40% of these patients will require inpatient admission. However, it is often difficult to arrive at the etiology of abdominal pain in the course of the ED visit. In particular, women who are of child-bearing age or pregnant, children and elderly patients create a diagnostic challenge (due to atypical presentations). Unfortunately, many of the disease processes share similar clinical presentations and may be difficult to sort out by history alone. Physical examination and laboratory evaluation can both lack sensitivity, making the job of the emergency physician difficult. Therefore, the diagnosis of abdomen pain of unclear etiology is a common diagnosis made in cases where the underlying pathology is not clear. This obligates the physician to provide patients with adequate reexamination to monitor the progression of the process.

While the discussion of abdominal disorders in this chapter is not exhaustive, the most common etiologies are reveiwed.

As a general rule, elderly patients presenting with abdominal pain form a unique group. Despite lack of identification of a focal disease process on initial presentation, at least half will have a disorder requiring surgical intervention. Physical examination will often lack sensitivity, as will laboratory evaluation. Women of child-bearing age and young children will have atypical presentations of common disorders, such as appendicitis and may require more observation time.

Despite technology in imaging and laboratory diagnostics, a large portion of patients will still have undifferentiated abdominal pain, requiring close follow-up and referral.

Mesenteric Ischemia

Risk Factors/Etiology

• Age >50 yr old
• Occlusive disease (80% of mesenteric ischemia) occurs 50% of the time from the sudden occlusion of the superior mesenteric artery originating from a proximal source and 25% of the time as local thrombosis. Mesenteric venous thrombosis is the cause only 5% of the time. Prolonged occlusion can result in both proximal and distal reactive vasospasm, esophageal emergencies, further aggravating the insult to the intestines.
• Occlusive disease often results from the propagation of left atrial or ventricular thrombi that fragment during or after a dysrhythmia or from atherosclerotic disease at the origin of the SMA itself. Thus, the major risk factors are recent MI, peripheral vascular disease, and cardiac dysrhythmias. Mesenteric venous thrombosis occurs during the classic hypercoagulable states as well as during malignancy, abdominal trauma, and estrogen therapy.
• Nonocclusive disease (20% of mesenteric ischemia) occurs during low flow states, such as cardiogenic shock, hypovolemia, or sepsis resulting in reactive vasoconstriction of the splanchnic circulation. Additionally, regional vasospasm can result from use of vasoactive medications, such as digoxin, diuretics, cocaine, or vasopressin.

• The historical factors may be nonspecific, but the diagnosis should be pursued in any person >50 yr old with sudden onset of acute abdominal pain and with an associated low flow, atherosclerotic, or hypercoaguable disease state.
• Historical factors include abdominal angina, recent weight loss, or recent change in bowel habits.
• Signs and symptoms include nausea and vomiting, colicky, severe, diffuse abdominal pain associated with repeated bowel movements, and a diffusely tender abdomen. As the disease progresses peritoneal signs occur and are an ominous finding. Abdominal distention and rectal bleeding may be the only initial complaint in up to 25% of the cases. The only initial abnormality on physical exam may be the presence of fecal occult blood, occurring in over half of the cases.
• Laboratory tests are nonspecific. An elevated WBC count is common, but a normal count does not exclude the diagnosis. Additionally, metabolic acidosis with a base deficit, an elevated amylase, and evidence of hemoconcentration are sensitive (present in more than half the cases) but nonspecific findings.
• Plain radiographs are often normal early on but may be used to rule out other pathology. They may show pneumatosis intestinalis, portal vein gas, or thumb printing in late disease. CT scan and ultrasound may show edema of the bowel wall and mesentery, ascites, abnormal gas patterns, and evidence of mesenteric venous thrombosis. CT is 82% sensitive and 93% specific and is better than angiography for venous obstruction. Ultrasound is only 28% sensitive.
• Angiography remains the diagnostic gold standard with a sensitivity of 88% (92% arterial and 50% venous). Angiography is contraindicated in shock states or with patients on vasopressor therapy because they confound the diagnosis of nonocclusive mesenteric ischemia. False negative studies are common with mesenteric venous thrombosis.
• The differential diagnosis is large and includes all sources of acute abdominal pain, especially ruptured abdominal aortic aneurysm, perforated dudodenal ulcer, strangulated bowel obstruction, and urolithiasis. Common initial misdiagnoses include constipation, gastroenteritis, ileus, and small bowel obstruction.

• Stabilization of the patient is of the utmost priority, with initial focus on the ABCs. Hypovolemia is common and should be corrected. Vasoactive drugs should be discontinued. CHF and dysrhythmias should be managed. A nasogastric tube should be placed for early decompression. Broad spectrum antibiotics should be begun early.
• Surgical consultation should be obtained immediately.