A 62-year-old man comes to the emergency department due to periumbilical abdominal pain. The patient says, "The pain suddenly began one hour ago and has been constant. I never had such severe pain in my life, and nothing makes it better. I also have nausea, and I vomited green-colored liquid once." Two weeks ago, the patient was hospitalized after experiencing chest and epigastric pain and was diagnosed with ST elevation myocardial infarction. He underwent percutaneous coronary intervention with stenting to the left anterior descending artery. He has been taking dual antiplatelet therapy since then. The patient's other medical conditions include hypertension, hyperlipidemia, and obstructive sleep apnea. He is a former smoker with a 20-pack-year smoking history and does not use alcohol or illicit drugs. On examination, the patient appears to be in significant pain. Temperature is 37.2 C (99 F), blood pressure is 140/85 mm Hg, pulse is 90/min, and respirations are 22/min. Lungs are clear to auscultation, and heart sounds are normal with no murmur. The abdomen is nondistended and soft with mild generalized tenderness. There is no guarding or rebound tenderness. Bowel sounds are normal. Stool testing for occult blood is negative. Laboratory results are as follows: ECG shows normal sinus rhythm with deep Q waves in the anterior leads. Which of the following is most likely to establish the diagnosis in this patient?

Question

A 62-year-old man comes to the emergency department due to periumbilical abdominal pain.  The patient says, "The pain suddenly began one hour ago and has been constant.  I never had such severe pain in my life, and nothing makes it better.  I also have nausea, and I vomited green-colored liquid once."  Two weeks ago, the patient was hospitalized after experiencing chest and epigastric pain and was diagnosed with ST elevation myocardial infarction.  He underwent percutaneous coronary intervention with stenting to the left anterior descending artery.  He has been taking dual antiplatelet therapy since then.  The patient's other medical conditions include hypertension, hyperlipidemia, and obstructive sleep apnea.  He is a former smoker with a 20-pack-year smoking history and does not use alcohol or illicit drugs.  On examination, the patient appears to be in significant pain.  Temperature is 37.2 C (99 F), blood pressure is 140/85 mm Hg, pulse is 90/min, and respirations are 22/min.  Lungs are clear to auscultation, and heart sounds are normal with no murmur.  The abdomen is nondistended and soft with mild generalized tenderness.  There is no guarding or rebound tenderness.  Bowel sounds are normal.  Stool testing for occult blood is negative.  Laboratory results are as follows:  ECG shows normal sinus rhythm with deep Q waves in the anterior leads.  Which of the following is most likely to establish the diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bf43_935d_8f63_61901e2784c7_MD0005_00 This older patient who recently had a myocardial infarction and now has severe abdominal pain out of proportion to his benign examination findings, along with an anion gap metabolic acidosis (Na − (HCO₃^- + Cl) = 141 − (18 + 104) = 19), should be considered to have acute mesenteric ischemia until proven otherwise. ₃^- Mesenteric ischemia occurs when the bowel does not obtain the necessary blood flow. The most common cause is superior mesenteric artery occlusion due to embolic disease; other causes include arterial and venous thrombosis due to atherosclerotic disease and watershed infarctions of areas with limited collateral vessels, generally during periods of hypotension from other causes. Patients with recent myocardial infarctions, arrhythmias, or heart failure are particularly high risk due to the ease of formation of ventricular thrombi and potential for poor perfusion. Other risk factors include hypercoagulable states and hypovolemia, including trauma or hemodialysis. Acute ischemia (similar to acute myocardial ischemia) presents as sudden-onset severe abdominal pain out of proportion to the examination findings (eg, patient has severe pain but abdominal examination shows only mild tenderness), often with nausea and vomiting; in contrast, chronic ischemia (similar to chronic angina) presents with cramping abdominal pain after eating. Patients with acute mesenteric ischemia generally do not demonstrate peritoneal signs initially on examination; they will often (but not always) have grossly bloody stool. Classic laboratory results, helpful in diagnosis, include anion gap lactic acidosis (due to intestinal cell hypoperfusion) and elevated amylase (seen in about ~50% of patients and likely reflecting intraabdominal inflammation). However, these findings are neither sensitive nor specific; therefore, normal results should not delay imaging if the diagnosis is suspected. CT angiography is the imaging modality of choice, but MR angiography can be used in patients with contrast allergy. Untreated acute mesenteric ischemia may cause bowel infarction, sepsis, and death. Mortality in this case may be as high as 60%. (Choice B) CT with oral contrast can be used in cases of suspected intestinal obstruction, which would cause a distended abdomen with hyperactive or absent bowel sounds. Oral contrast should be avoided with acute mesenteric ischemia as it can obscure the vasculature. (Choice C) Cholescintigraphy (HIDA scan) is used to evaluate for patency of the biliary tree and the presence of gallstones or cholecystitis. Cholecystitis or cholangitis would also present with abdominal pain and leukocytosis, but pain is generally located in the right upper quadrant, worsens with eating, and, in the case of cholangitis, would be associated with liver function test abnormalities and fevers. (Choice D) Acute myocardial infarction, which classically presents as left-sided pressure-like chest pain, diaphoresis, nausea, and shortness of breath, can sometimes present with abdominal pain. However, abdominal pain out of proportion to the examination findings and anion gap acidosis are more consistent with mesenteric ischemia. The patient's deep Q waves are likely due to his recent myocardial infarction. (Choice E) Esophagogastroduodenoscopy is useful for diagnosis of peptic ulcer disease (PUD), which may present with similar abdominal pain. However, PUD would not cause acidosis, anemia may be present, and stool would likely contain blood from the upper gastrointestinal tract. Educational objective: Patients with acute onset of severe abdominal pain and physical examination findings that do not match the severity of pain should be considered to have acute mesenteric ischemia until proven otherwise. The presence of metabolic acidosis further supports this diagnosis. The diagnostic test of choice is CT angiography. References: Mesenteric ischemia: Pathogenesis and challenging diagnostic and therapeutic modalities (http://www.ncbi.nlm.nih.gov/pubmed/26909235)

A 62-Year-Old Man Comes to the Emergency Department Due to Periumbilical