A 12-day-old female neonate is evaluated in the neonatal intensive care unit for sudden-on… — USMLE Step 2 CK

A 12-day-old female neonate is evaluated in the neonatal intensive care unit for sudden-onset lethargy and temperature instability. She was born at 28 weeks of gestation via spontaneous vaginal delivery secondary to preterm premature rupture of membranes. Her birth weight was 1,050 g, and Apgar scores were 5 and 7 at 1 and 5 minutes, respectively. Over the past week, she had been tolerating incrementally advanced nasogastric feeds with premature infant formula. Current vital signs show a temperature of $35.4^\circ\text{C}$ ( $95.7^\circ\text{F}$ ), heart rate of 175/min, and respiratory rate of 68/min with occasional apneic pauses. Physical examination reveals an ill-appearing neonate with a tensely distended abdomen and prominent abdominal wall erythema. Bowel sounds are absent. A recent diaper change revealed a grossly bloody stool.

Laboratory studies are as follows:

Laboratory Test	Result
Leukocyte count	$2,500/\text{mm}^3$
Hemoglobin	$12.5\text{ g/dL}$
Platelet count	$85,000/\text{mm}^3$
C-reactive protein	$45\text{ mg/L}$
Venous blood gas pH	$7.28$
$\text{pCO}_2$	$42\text{ mmHg}$
$\text{HCO}_3^-$	$16\text{ mEq/L}$

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

Discontinuation of enteral feeds, initiation of intravenous fluids, and abdominal radiographyCevap
B
Immediate exploratory laparotomy and placement of a peritoneal drain
C
Upper gastrointestinal series with water-soluble contrast
D
Transition of enteral feeds to an extensively hydrolyzed elemental formula
E
Initiation of empiric oral amoxicillin and continuation of current enteral feeds

Cevap

Discontinuation of enteral feeds, initiation of intravenous fluids, and abdominal radiography

The correct option outlines the standard initial management for suspected necrotizing enterocolitis (NEC). This patient's presentation of temperature instability, apnea, feeding intolerance, and bloody stools in the context of prematurity is the classic presentation of NEC. The physical finding of abdominal wall erythema indicates underlying peritonitis or necrotic bowel. Because the gut is severely compromised, immediate bowel rest (discontinuation of feeds) and intravenous fluids are essential. An abdominal radiograph is the most important initial diagnostic test to look for pneumatosis intestinalis (air in the bowel wall), portal venous gas, or pneumoperitoneum (free air).

Adım Adım Çözüm

Analyze the demographic and historical risk factors.

The patient is a premature, very low birth weight neonate who is receiving enteral formula feeds.

Prematurity and formula feeding are the two most significant risk factors for necrotizing enterocolitis (NEC).

Interpret the clinical presentation and laboratory findings.

The patient has systemic signs of sepsis (apnea, temperature instability, leukopenia, thrombocytopenia, metabolic acidosis) combined with gastrointestinal catastrophes (bloody stools, abdominal distension, absent bowel sounds, and abdominal wall erythema).

These findings are highly specific for NEC. The abdominal wall erythema specifically suggests severe bowel inflammation or underlying ischemic necrosis.

Determine the next best step in management.

The immediate priority is bowel rest (stopping enteral feeds), hemodynamic stabilization (IV fluids), broad-spectrum IV antibiotics, and diagnostic imaging (abdominal radiograph).

An abdominal radiograph is necessary to confirm the diagnosis (looking for pneumatosis intestinalis or portal venous gas) and to rule out frank perforation (pneumoperitoneum), which would dictate the need for surgical intervention.

Anahtar Kavram

Diagnosis and initial management of necrotizing enterocolitis (NEC)

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