A 65-year-old woman comes to the emergency department due to the sudden onset of severe periumbilical pain, nausea, and vomiting. She has no fever, diarrhea, constipation, or urinary complaints. Her last menstrual period was 14 years ago. The patient has a history of coronary artery disease, a recent acute anterior myocardial infarction, hypertension, and hyperlipidemia. She had an appendectomy at age 18. She has a 20-pack-year smoking history. The patient drinks alcohol occasionally. Her temperature is 36.7 C (98 F), blood pressure is 120/76 mm Hg, pulse is 120/min and irregular, and respirations are 16/min. The abdomen is soft, nondistended, nontender, and has normoactive bowel sounds. There is no rebound tenderness or rigidity. Pelvic examination is within normal limits. ECG shows atrial fibrillation without other abnormal findings. Laboratory results are as follows: The other studies show normal serum lipase, slightly elevated serum amylase, and normal liver function tests. Urinalysis is normal. Fecal occult blood test is negative. Plain abdominal x-ray shows no abnormalities. Which of the following is the most likely diagnosis in this patient?

Question

A 65-year-old woman comes to the emergency department due to the sudden onset of severe periumbilical pain, nausea, and vomiting.  She has no fever, diarrhea, constipation, or urinary complaints.  Her last menstrual period was 14 years ago.  The patient has a history of coronary artery disease, a recent acute anterior myocardial infarction, hypertension, and hyperlipidemia.  She had an appendectomy at age 18.  She has a 20-pack-year smoking history.  The patient drinks alcohol occasionally.  Her temperature is 36.7 C (98 F), blood pressure is 120/76 mm Hg, pulse is 120/min and irregular, and respirations are 16/min.  The abdomen is soft, nondistended, nontender, and has normoactive bowel sounds.  There is no rebound tenderness or rigidity.  Pelvic examination is within normal limits.  ECG shows atrial fibrillation without other abnormal findings.  Laboratory results are as follows:  The other studies show normal serum lipase, slightly elevated serum amylase, and normal liver function tests.  Urinalysis is normal.  Fecal occult blood test is negative.  Plain abdominal x-ray shows no abnormalities.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c14e_7f00_8f63_89d339c17b67_MD0005_00 This patient's presentation is concerning for acute mesenteric ischemia likely due to atrial fibrillation leading to embolic phenomenon. Acute mesenteric ischemia is typically due to sudden occlusive or nonocclusive obstruction of intestinal blood flow (arterial or venous). Occlusive ischemia is most commonly due to embolic or thrombotic involvement of the superior mesenteric system (artery or vein), segmental intestinal strangulation, or volvulus. Emboli typically are due to a dislodged cardiac thrombus (eg, underlying atrial fibrillation) that occludes the superior mesenteric artery. Superior mesenteric venous occlusion is typically due to conditions such as hypercoagulable states, portal hypertension, and abdominal infections. Nonocclusive ischemia is usually due to hypoperfusion (eg, low cardiac output) leading to splanchnic hypoperfusion and vasoconstriction. Patients usually develop sudden onset of periumbilical abdominal pain with nausea and vomiting. The pain is often out of proportion to the examination findings; the initial abdominal examination is often normal (eg, soft, nontender, and nondistended) without peritoneal signs (eg, rebound tenderness, guarding). Progression of small-bowel ischemia to infarction leads to a grossly distended abdomen, absent bowel sounds, peritoneal signs, and blood in the stools (eg, positive fecal occult blood test). As a result, diagnosis requires a high index of clinical suspicion, especially in elderly patients with risk factors (eg, atrial fibrillation, peripheral vascular disease). Marked leukocytosis, hemoconcentration, and elevated lactate resulting in metabolic acidosis are common. CT of the abdomen shows signs of small-bowel ischemia (eg, focal or segmental bowel wall thickening, intestinal pneumatosis with portal vein gas, dilated bowel, mesenteric stranding) and is helpful in excluding other causes of abdominal pain. However, the diagnosis is best established with CT angiogram. Treatment involves fluid resuscitation, correction of metabolic acidosis, broad-spectrum antibiotics, and nasogastric tube for decompression. Surgical consultation is required. (Choice A) Acute colonic ischemia is usually due to transient reduction in blood flow to the colon due to hypovolemic states or transient ischemia to the bowel. It affects primarily the watershed areas (eg, splenic flexure, rectosigmoid). Patients usually have a more lateralized abdominal pain followed by bloody diarrhea. Pain is mild to moderate (as compared to the severe pain seen with acute mesenteric ischemia) because colonic ischemia is usually not due to obstructed blood flow to the colon. (Choice B) Acute diverticulitis usually causes a more localized pain, and physical examination would show left lower-quadrant tenderness. Patients may also develop diarrhea. (Choice C) Acute intermittent porphyria is a rare disease that usually presents with recurrent episodes of abdominal pain worsened by factors including medications (eg, phenytoin), menstruation, systemic illness, and surgery. Other findings can include peripheral neuropathy, tachycardia, and hyponatremia. However, porphyria more commonly occurs earlier in life, usually after puberty. (Choice E) Patients with intestinal obstruction usually have a history of absolute constipation. Examination usually shows a distended abdomen with hyperactive bowel sounds. As the distension worsens, the bowel sounds can become hypoactive. Plain abdominal radiographs typically show dilated loops of bowel with air fluid levels. Educational objective: Acute mesenteric ischemia is typically due to sudden occlusive or nonocclusive obstruction of intestinal blood flow (arterial or venous). Risk factors include older age, atrial fibrillation, congestive heart failure, and peripheral vascular disease. Sudden onset of periumbilical abdominal pain (out of proportion to examination), normal abdominal examination without peritoneal signs, and metabolic acidosis are early clues. References: Acute mesenteric ischemia. (http://www.ncbi.nlm.nih.gov/pubmed/24267504) The role of radiology in the diagnosis and treatment of mesenteric ischaemia. (http://www.ncbi.nlm.nih.gov/pubmed/23243151)

A 65-Year-Old Woman Comes to the Emergency Department Due to the Sudden