A 71-year-old man presents to the emergency department with a 4-day history of progressive… — USMLE Step 2 CK

A $71$ -year-old man presents to the emergency department with a $4$ -day history of progressive abdominal distension, crampy lower abdominal pain, and an inability to pass stool or flatus. He has had two episodes of bilious vomiting today. He has not seen a physician in over ten years and has never undergone colorectal cancer screening. Vital signs show a temperature of $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure of $138/86\text{ mmHg}$ , pulse of $88\text{/min}$ , and respirations of $16\text{/min}$ . Examination reveals marked abdominal distension with hyperactive, high-pitched bowel sounds. The abdomen is tympanic to percussion but soft, with no rebound tenderness, rigidity, or palpable masses. Digital rectal examination reveals an empty rectal vault and no gross blood. Assume advanced institutional capabilities (including interventional endoscopy) are available. Arrange the following steps in the most appropriate chronological sequence for the comprehensive evaluation and management of this patient's condition.

1Initiation of intravenous fluid resuscitation, electrolyte repletion, and nasogastric tube decompression
2Computed tomography of the abdomen and pelvis with intravenous contrast
3Endoscopic placement of a self-expanding metal stent (SEMS) across the obstructing lesion
4Completion of oncologic staging with computed tomography of the chest and baseline carcinoembryonic antigen (CEA) measurement
5Elective oncologic bowel resection with primary anastomosis

Answer

The correct sequence of management is: (1) Initiation of intravenous fluid resuscitation and nasogastric decompression, (2) Computed tomography of the abdomen and pelvis, (3) Endoscopic placement of a self-expanding metal stent, (4) Completion of oncologic staging with chest CT and CEA, and (5) Elective oncologic bowel resection with primary anastomosis.

The standard of care for a hemodynamically stable patient presenting with a suspected malignant large bowel obstruction begins with physiologic resuscitation and nasogastric decompression. Once stabilized, an abdominal CT scan is critical to confirm the diagnosis and rule out complications requiring immediate surgery (e.g., ischemia or free perforation). Because this patient has a soft abdomen and stable vitals, the optimal next step in an advanced center is endoscopic placement of a self-expanding metal stent (SEMS). This 'bridge to surgery' rapidly resolves the acute emergency, permitting the clinical team to safely complete oncologic staging (CT chest and CEA) before proceeding to an elective, curative-intent resection that allows for a primary anastomosis.

Step-by-Step Solution

Assess the clinical presentation and initiate supportive care.

The patient presents with an acute large bowel obstruction but is hemodynamically stable without peritonitis. Initial management requires IV fluids and NG tube decompression.

Decompression and fluid resuscitation mitigate the systemic effects of obstruction, treat third-spacing, and prevent pulmonary aspiration before further diagnostic imaging.

Obtain cross-sectional diagnostic imaging.

CT of the abdomen and pelvis with IV contrast is performed.

CT accurately differentiates small from large bowel obstruction, identifies the likely left-sided colonic transition point, and confirms the absence of bowel ischemia or perforation which would change management.

Perform interventions to relieve the acute mechanical obstruction.

Endoscopic placement of a self-expanding metal stent (SEMS) is chosen.

In a stable patient, a SEMS effectively decompresses a malignant colonic obstruction. This bridge to surgery avoids the high morbidity of an emergency laparotomy, which typically results in an end colostomy (Hartmann procedure).

Complete necessary workup for suspected malignancy.

CT of the chest and a baseline CEA level are obtained.

With the acute emergency resolved, full systemic staging is required to determine the presence of pulmonary or hepatic metastases, dictating whether the patient is a candidate for curative-intent surgery.

Perform definitive surgical management.

An elective segmental colectomy with primary anastomosis is performed.

Elective surgery on a decompressed colon allows for appropriate preoperative medical optimization and bowel preparation, significantly improving the safety and feasibility of a single-stage primary anastomosis.

Key Concept

The management of malignant large bowel obstruction involves initial decompression and resuscitation, followed by CT imaging. In stable patients without perforation, endoscopic stenting serves as a bridge to elective single-stage surgical resection.

Estimated Time:2m 0s

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