A 4-week-old, full-term boy is brought to the office due to vomiting. Since birth, he has had small spit-ups with feeding. However, for the past few days he has had forceful emesis after every feed that is worsening. The emesis consists of formula and is neither bilious nor bloody. Despite this, the patient has an excellent appetite and "always seems hungry." He passes one small stool every other day, and his last bowel movement was yesterday. Weight today is down 0.5 kg (1.1 lb) from a well-child visit 2 weeks ago. On examination, the patient is awake and alert. His anterior fontanelle is sunken and he has decreased skin turgor. Capillary refill is 3 seconds. The abdomen is soft, nontender, and nondistended. The scrotum has no erythema, and the testes are descended. Which of the following is the best next step in management of this patient?

Question

A 4-week-old, full-term boy is brought to the office due to vomiting.  Since birth, he has had small spit-ups with feeding.  However, for the past few days he has had forceful emesis after every feed that is worsening.  The emesis consists of formula and is neither bilious nor bloody.  Despite this, the patient has an excellent appetite and "always seems hungry."  He passes one small stool every other day, and his last bowel movement was yesterday.  Weight today is down 0.5 kg (1.1 lb) from a well-child visit 2 weeks ago.  On examination, the patient is awake and alert.  His anterior fontanelle is sunken and he has decreased skin turgor.  Capillary refill is 3 seconds.  The abdomen is soft, nontender, and nondistended.  The scrotum has no erythema, and the testes are descended.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d680_44b3_bc81_99b487042c44_MD0003_00 This patient with emesis and weight loss has gastric outlet obstruction due to infantile hypertrophic pyloric stenosis. First-born boys are at higher risk for this condition, as well as newborns exposed to macrolide antibiotics (eg, erythromycin). Also, compared with breastfed infants, formula-fed infants have slower gastric emptying and typically consume more volume in less time. This increased gastric burden may stimulate pyloric muscle growth. Pyloric stenosis most commonly presents at age 3-5 weeks with postprandial projectile vomiting followed by hunger (eg, "hungry vomiter"). Emesis is nonbilious as the obstruction is proximal to the bile duct. Infants have poor weight gain and are often dehydrated (eg, sunken fontanelle, decreased skin turgor, delayed capillary refill). The classic olive-shaped abdominal mass is not always palpable as retained gastric contents can obscure the mass. The abdomen will otherwise be soft and nondistended because minimal air passes the gastric outlet. When the diagnosis is suspected based on clinical presentation, the best next step in management is abdominal ultrasonography. The presence of a thick and elongated pylorus confirms the diagnosis. Definitive treatment is pyloromyotomy. thick and elongated pylorus (Choice A) Abdominal radiograph detects intestinal obstruction, which would cause bilious emesis and abdominal distension and tenderness, which are not present in this patient. (Choice C) A head CT scan is performed when increased intracranial pressure (ICP) is the suspected cause of vomiting. However, an infant with increased ICP would normally exhibit lethargy, a bulging anterior fontanelle, and poor appetite. (Choice D) Serum 17-hydroxyprogresterone level is elevated in congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Mineralocorticoid deficiency causes vomiting, weight loss, and dehydration. However, affected male infants typically present by age 1-2 weeks and are critically ill due to inability to maintain blood pressure. (Choice E) Stool guaiac testing is helpful in detecting milk protein-induced allergic proctocolitis (milk protein intolerance), which can present with vomiting, poor weight gain, and bloody stools. The dehydration and projectile nature of the vomiting in this patient are more consistent with pyloric stenosis. (Choice F) Physiologic gastroesophageal reflux occurs in most infants due to incomplete closure of the lower esophageal sphincter, short esophagus, and decreased angle between the esophagus and stomach. Reflux is not typically projectile and rarely results in weight loss or dehydration. Educational objective: Infantile hypertrophic pyloric stenosis is most common in first-born boys age 3-5 weeks who are fed formula. Nonbilious, projectile vomiting causes dehydration and weight loss. Abdominal ultrasonography confirms the diagnosis. References: The changing clinical presentation of hypertrophic pyloric stenosis: the experience of a large, tertiary care pediatric hospital. (http://www.ncbi.nlm.nih.gov/pubmed/21098534) Role of bottle feeding in the etiology of hypertrophic pyloric stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/24146084) Bottle-feeding and the risk of pyloric stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/22945411) Pre- and perinatal risk factors for pyloric stenosis and their influence on the male predominance. (http://www.ncbi.nlm.nih.gov/pubmed/22553083)

A 4-Week-Old, Full-Term Boy Is Brought to the Office Due