A 74-year-old man is evaluated on the postoperative wards on hospital day 5 following an u… — USMLE Step 2 CK

A $74$ -year-old man is evaluated on the postoperative wards on hospital day $5$ following an urgent open reduction and internal fixation of a right femoral neck fracture. For the past $3$ days, he has experienced progressive abdominal distension, nausea, and a failure to pass flatus or stool. $48$ hours ago, all opioid analgesics were discontinued, and he was placed on bowel rest with nasogastric tube decompression and intravenous fluid support. Despite these measures, his symptoms have worsened. His temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), pulse is $88/\text{min}$ , blood pressure is $138/82 \text{ mmHg}$ , and respirations are $16/\text{min}$ . The abdomen is massively distended and tympanitic to percussion. It is mildly tender diffusely, but there is no guarding, rigidity, or rebound tenderness. Bowel sounds are absent. Laboratory studies show a leukocyte count of $8,000/\text{mm}^3$ , potassium of $4.2 \text{ mEq/L}$ , and magnesium of $2.1 \text{ mEq/L}$ . An electrocardiogram shows normal sinus rhythm. Computed tomography of the abdomen and pelvis with intravenous contrast reveals marked dilation of the colon extending from the cecum to the splenic flexure, with a maximal cecal diameter of $11.8 \text{ cm}$ . There is no discrete transition point, obstructing mass, or pneumoperitoneum. Which of the following is the most appropriate next step in management?

Intravenous neostigmineCevap
B
Colonoscopic decompression
C
Immediate exploratory laparotomy
D
Oral polyethylene glycol
E
Intravenous piperacillin-tazobactam

Cevap

Intravenous neostigmine is the most appropriate next step for this patient's acute colonic pseudo-obstruction.

The correct answer is intravenous neostigmine. This patient has acute colonic pseudo-obstruction (Ogilvie syndrome), characterized by massive dilation of the colon in the absence of a mechanical obstruction. It classically occurs in elderly, hospitalized patients following surgery or severe medical illness. Initial management consists of conservative measures: bowel rest, nasogastric and rectal tube decompression, correction of electrolyte abnormalities (especially hypokalemia and hypomagnesemia), and discontinuation of offending medications (e.g., opioids, anticholinergics). If a patient fails

24

48

hours of conservative management, or if the cecal diameter rapidly approaches or exceeds

12 \text{ cm}

(which poses a high risk of ischemia and perforation), active decompression is indicated. The first-line active intervention is intravenous neostigmine, an acetylcholinesterase inhibitor that stimulates colonic motility. Since this patient has failed

48

hours of conservative therapy and has a cecal diameter of

11.8 \text{ cm}

with a normal EKG (no bradycardia to contraindicate the drug), neostigmine is the most appropriate next step.

Adım Adım Çözüm

Analyze the clinical presentation and imaging findings.

The patient has massive colonic dilation (

11.8 \text{ cm}

) without a mechanical transition point in the postoperative setting.

Establishing the diagnosis of acute colonic pseudo-obstruction (Ogilvie syndrome) and ruling out mechanical small or large bowel obstruction.

Evaluate the response to initial therapies.

The patient has already undergone

48

hours of appropriate conservative management (NPO, NG tube, IV fluids, electrolyte correction, discontinuation of opioids) without improvement.

Determines whether to continue supportive care or escalate to active decompression.

Assess the severity of dilation and check for contraindications to specific therapies.

The cecal diameter is critically enlarged (approaching

12 \text{ cm}

), warranting active decompression. The EKG shows normal sinus rhythm, indicating no bradycardic contraindication to acetylcholinesterase inhibitors.

Guides the selection of pharmacologic versus endoscopic decompression.

Anahtar Kavram

Management of Acute Colonic Pseudo-obstruction (Ogilvie Syndrome)

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

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