A 28-year-old woman, gravida 1 para 0, at 18 weeks gestation, is evaluated in the intensiv… — USMLE Step 2 CK

A 28-year-old woman, gravida 1 para 0, at 18 weeks gestation, is evaluated in the intensive care unit. She was admitted three days ago for a severe exacerbation of pan-ulcerative colitis characterized by 15 bloody bowel movements daily. Upon admission, she was initiated on intravenous hydrocortisone, aggressive fluid resuscitation, and empiric intravenous ciprofloxacin and metronidazole. Blood cultures drawn on admission have since grown $Bacteroides fragilis$ that is susceptible to metronidazole. Today, the patient is lethargic. Her temperature is $39.5^\circ\text{C}$ ( $103.1^\circ\text{F}$ ), pulse is $138\text{/min}$ , blood pressure is $80/50\text{ mmHg}$ , and respirations are $28\text{/min}$ . Physical examination reveals a gravid uterus consistent with gestational age. The abdomen is markedly distended, tympanic, and exhibits diffuse rigidity with rebound tenderness. Laboratory studies show:

Leukocyte count: $26,000/\text{mm}^3$
Hemoglobin: $10.8\text{ g/dL}$

Arterial blood gas (room air):
pH: $7.18$
$\text{pCO}_2$ : $42\text{ mmHg}$
$\text{HCO}_3^-$ : $15\text{ mEq/L}$

An abdominal radiograph (performed with appropriate fetal shielding) demonstrates a continuous segment of transverse colon dilated to $9.5\text{ cm}$ with complete loss of haustral markings. No free intraperitoneal air is visualized.

Which of the following is the most appropriate next step in the management of this patient?

Emergency subtotal colectomy with end ileostomyCevap
B
Initiate intravenous infliximab therapy
C
Discontinue current antibiotics and initiate intravenous meropenem
D
Administer intravenous sodium bicarbonate
E
Transfuse packed red blood cells

Cevap

Emergency subtotal colectomy with end ileostomy is the most appropriate next step because the patient has developed toxic megacolon with shock and peritonitis, rendering further medical management unsafe.

The correct action is emergency subtotal colectomy with end ileostomy. This patient presents with classic signs of toxic megacolon (fever, tachycardia, leukocytosis, and colonic dilation

>6\text{ cm}

) complicating a severe ulcerative colitis flare. Despite aggressive initial medical management with intravenous corticosteroids and antibiotics, she has developed worsening toxicity, distributive shock, and peritonitis (abdominal rigidity and rebound tenderness). In the setting of toxic megacolon with hemodynamic instability, impending perforation, or peritonitis, medical therapy must be immediately abandoned in favor of life-saving surgical intervention. A subtotal colectomy with an end ileostomy is the procedure of choice.

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Analyze the clinical presentation and abdominal radiograph findings.

The patient has a fever, tachycardia, leukocytosis, shock, peritonitis, and a transverse colon dilated to

9.5\text{ cm}

These findings definitively diagnose toxic megacolon complicating her severe ulcerative colitis flare.

Evaluate the patient's hemodynamic status and response to medical therapy.

Despite 72 hours of intravenous steroids and antibiotics, she has deteriorated into distributive shock with rigid peritonitis.

Toxic megacolon that progresses to shock, peritonitis, or fails to improve within 24-72 hours of medical therapy is an absolute indication for surgery.

Determine the definitive intervention.

Subtotal colectomy with end ileostomy is required.

Surgical removal of the diseased, dilated colon is the only life-saving measure to prevent imminent perforation and resolve the toxic state.

Analyze the laboratory distractors.

Identify that the hemoglobin is physiologically normal for pregnancy and the acid-base derangement is a mixed metabolic and respiratory acidosis.

Recognizing physiologic changes of pregnancy and correctly applying Winter's formula prevents the selection of inappropriate medical interventions (transfusion or bicarbonate) in a surgical emergency.

Anahtar Kavram

Toxic megacolon complicating inflammatory bowel disease requires immediate surgical intervention (subtotal colectomy) if the patient develops peritonitis, hemodynamic instability, or fails to improve on targeted medical therapy.

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