# A 6-month-old infant is brought to the emergency department by parents who report the child has been experiencing severe coughing episodes for the past week. Which assessment finding would be most characteristic of pertussis (whooping cough) in this infant?

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## 문제

A 6-month-old infant is brought to the emergency department by parents who report the child has been experiencing severe coughing episodes for the past week. Which assessment finding would be most characteristic of pertussis (whooping cough) in this infant?

## 보기

1. Fever with chills and profuse sweating episodes
2. Barking cough with audible inspiratory stridor
3. Paroxysmal coughing followed by a high-pitched inspiratory whoop **✔ 정답**
4. Productive cough with thick, purulent sputum production

**정답: 3**

## 해설

Paroxysmal coughing followed by a high-pitched inspiratory whoop is the classic sign of pertussis. Other options represent symptoms more typical of other respiratory infections like pneumonia or croup.

## 심화 해설

Understanding Intussusception

Intussusception is a serious pediatric abdominal emergency where one segment of the intestine telescopes into an adjacent distal segment [1]. This process leads to compression of the mesenteric vessels, causing bowel wall edema, venous congestion, and if not promptly treated, can progress to arterial obstruction, bowel ischemia, and necrosis [1]. The classic clinical presentation in an infant includes sudden, severe, colicky abdominal pain that causes the child to draw up their legs and cry inconsolably, often alternating with periods of lethargy.

Analysis of Assessment Findings

The most characteristic assessment finding for intussusception is the passage of currant jelly-like stools, which are a mixture of blood and mucus [1,3]. This finding is a hallmark sign resulting from the ischemic bowel mucosa sloughing off and mixing with intestinal secretions. While this is a classic and highly specific sign, it is often a later finding and its absence does not rule out the condition [1].

Let's examine why the other options are less characteristic for this specific condition:

- Projectile vomiting immediately after feeding is more classically associated with hypertrophic pyloric stenosis, a condition typically presenting in infants 2-8 weeks old, not at 6 months. In intussusception, vomiting is a common symptom, but it is usually non-bilious initially and may become bilious as the obstruction progresses, rather than being specifically projectile and immediately postprandial [3].

- An olive-shaped mass in the epigastric area is the pathognomonic finding for hypertrophic pyloric stenosis, not intussusception. In intussusception, a palpable abdominal mass is often described as a "sausage-shaped" mass, typically located in the right upper quadrant, reflecting the telescoped segment of bowel [1].

- High-pitched bowel sounds throughout the abdomen are a general sign of a mechanical bowel obstruction and are not specific to intussusception. While they may be present, they do not carry the same diagnostic specificity as the currant jelly stool. The bowel sounds in intussusception can vary, and the abdomen may be distended with a palpable mass [1].

Clinical Reasoning and Diagnostic Confirmation

When an infant presents with the triad of colicky abdominal pain, a palpable abdominal mass, and currant jelly stools, the clinical suspicion for intussusception is extremely high. The definitive diagnosis is typically made with abdominal ultrasound, which will reveal a characteristic "target sign" or "pseudo-kidney sign" on transverse and longitudinal views, respectively, representing the layers of the telescoped bowel [3]. Prompt recognition is critical because the first-line treatment is often non-operative hydrostatic or pneumatic enema reduction, which has a higher success rate when performed early in the disease course [2,4]. Delays in diagnosis increase the risk of enema reduction failure and the need for surgical intervention due to complications like bowel ischemia or perforation [2,4].References (research sources)

- [1]High risk and low incidence diseases: Pediatric intussusception.Research articleLong B, Easter J, Koyfman A. (2025) · DOI: 10.1016/j.ajem.2025.02.020

- [3]A rare case of intusscusception in a 6-month-old baby.Research articleFiagbedzi E, Arkorful J, Appiah E, Otumi N, Ofori I, Gorleku PN. (2024) · DOI: 10.1016/j.radcr.2024.06.080

## 임상 시나리오

Clinical Practice Guide: Pertussis in Infancy

The classic presentation of pertussis in a 6-month-old involves the paroxysmal stage, which typically begins after 1-2 weeks of nonspecific catarrhal symptoms. The hallmark is a series of rapid, forceful coughs during a single expiration, followed by a sudden, high-pitched inspiratory whoop as air rushes past a narrowed glottis. Post-tussive emesis and exhaustion are common. However, clinicians must recognize that infants under 6 months may not produce the characteristic whoop and instead present with apnea, cyanosis, or gasping, making a high index of suspicion critical.

Key nursing actions include immediate isolation with droplet precautions, continuous cardiopulmonary monitoring for apnea and oxygen desaturation, and gentle supportive care to avoid triggering paroxysms. Suction equipment and emergency airway supplies must be at the bedside. Nasopharyngeal swab for PCR or culture confirms the diagnosis. Macrolide antibiotics (e.g., azithromycin) are initiated early to reduce infectivity, though they do not alter the disease course once the paroxysmal phase has started. All close contacts require post-exposure chemoprophylaxis regardless of immunization status.

## 핵심 개념

- **Pertussis** — A highly contagious respiratory infection caused by Bordetella pertussis, characterized by severe coughing fits.
- **Paroxysmal cough** — Sudden, intense, uncontrollable episodes of coughing, a hallmark of the paroxysmal stage of pertussis.
- **Inspiratory whoop** — A high-pitched sound produced when a patient forcefully inhales against a partially closed glottis after a coughing fit.
- **Croup** — A viral infection causing upper airway inflammation and edema, leading to a characteristic barking cough and stridor.
- **Bordetella pertussis** — The gram-negative coccobacillus bacterium that causes whooping cough.

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