A 64-year-old female is brought to the emergency department after the sudden onset of excr… — USMLE Step 3

A 64-year-old female is brought to the emergency department after the sudden onset of excruciating abdominal pain that began 3 hours ago. She has a history of nonvalvular atrial fibrillation but stopped taking her prescribed rivaroxaban one month ago. On physical examination, the patient appears distressed and is writhing on the stretcher. Her abdomen is soft and mildly tender to deep palpation, without guarding, rigidity, or rebound tenderness. Her temperature is $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), blood pressure is $135/82\text{ mmHg}$ , heart rate is $112\text{/min}$ and irregular, and respiratory rate is $22\text{/min}$ . Laboratory studies show a leukocyte count of $17,200\text{/mm}^3$ and a serum lactate level of $5.4\text{ mmol/L}$ . Based on the suspected diagnosis, arrange the following procedural and management steps in the most appropriate chronological sequence for this patient.

1Initiation of intravenous fluid resuscitation, broad-spectrum antibiotics, and systemic anticoagulation
2Computed tomography angiography (CTA) of the abdomen and pelvis
3Exploratory laparotomy with superior mesenteric artery embolectomy and resection of necrotic bowel
4Second-look laparotomy 24 to 48 hours after the initial operation

Cevap

The correct sequence is: (1) Initiation of intravenous fluid resuscitation, broad-spectrum antibiotics, and systemic anticoagulation, (2) Computed tomography angiography (CTA) of the abdomen and pelvis, (3) Exploratory laparotomy with superior mesenteric artery embolectomy and resection of necrotic bowel, and (4) Second-look laparotomy 24 to 48 hours after the initial operation.

The clinical presentation of severe abdominal pain out of proportion to exam findings, along with elevated lactate and a history of untreated atrial fibrillation, is highly suspicious for acute mesenteric ischemia. Management must follow a logical, stepwise approach prioritizing life-saving stabilization before definitive procedures. Step 1 is medical stabilization, which includes aggressive fluid resuscitation (to correct third-spacing), broad-spectrum antibiotics (to cover bacterial translocation from ischemic gut), and systemic anticoagulation with intravenous heparin (to halt thrombus propagation). Step 2 is obtaining a computed tomography angiography (CTA) of the abdomen and pelvis. Because this patient is hemodynamically stable, imaging is essential to confirm the diagnosis, locate the occlusion (e.g., superior mesenteric artery), and plan the surgical approach. Step 3 is emergent exploratory laparotomy to perform an embolectomy, re-establish blood flow, and resect any frankly necrotic bowel. Step 4 is a planned second-look laparotomy. Reperfusion injury and progressive thrombosis can cause marginal bowel left behind during the first operation to necrose over the next day; therefore, re-evaluating the abdomen 24 to 48 hours later is a mandatory standard of care.

Adım Adım Çözüm

Recognize the clinical presentation of acute mesenteric ischemia

Identify pain out of proportion to physical exam findings and elevated lactate in a patient with untreated atrial fibrillation.

Establishing the suspected diagnosis guides the entire management sequence.

Prioritize initial medical stabilization

Select fluid resuscitation, antibiotics, and anticoagulation as the first intervention.

Patients with acute mesenteric ischemia are at high risk for systemic toxicity and clot propagation; stabilization must occur before leaving the department for imaging.

Determine the appropriate diagnostic modality

Select CTA of the abdomen and pelvis as the second step.

CTA is the gold standard for confirming the diagnosis and localizing the occlusion in a hemodynamically stable patient.

Sequence surgical interventions

Place exploratory laparotomy first, followed by a scheduled second-look laparotomy.

Initial surgery re-establishes perfusion and removes dead tissue, while the second-look procedure evaluates borderline tissue after reperfusion has occurred.

Anahtar Kavram

The management of acute mesenteric ischemia requires immediate medical stabilization (fluids, antibiotics, anticoagulation), followed by diagnostic confirmation with CTA in hemodynamically stable patients, emergent surgical revascularization and resection, and a mandatory second-look laparotomy.

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