A 3-week-old baby is brought to the Emergency Department with a 36-hour history of progressive vomiting. The birth weight was 3.1 kg. On physical examination, his weight is 2.8 kg; he is 5% dehydrated and is very irritable but not toxic. There's a small and firm movable mass palpated deep in epigastrium. His blood work reveals:
Which one of the following diagnoses is the most likely?
Correct Answer D: Hypertrophic pyloric stenosis (choice D) may cause almost complete gastric outlet obstruction. It is more common in males by a 4:1 ratio. The exact etiology is uncertain, but a genetic component is likely because siblings and offspring of affected people are at increased risk.
Symptoms develop between 2 and 6 weeks of life. Projectile vomiting (without bile) occurs shortly after eating. Until dehydration sets in, the child feeds avidly and otherwise appears well, unlike many of those with vomiting due to systemic illness. Gastric peristaltic waves may be visible, crossing the epigastrium from left to right. A discrete, 2- to 3-cm, firm, movable olive-like pyloric mass is sometimes palpable deep in the right side of the epigastrium. With progression of illness, the child fails to gain weight, and signs of dehydration appear.
Diagnosis is by abdominal ultrasonography showing increased thickness of the pylorus (typically to ≥ 4 mm; normal, < 2 mm). Hypochloremic, hypokalemic metabolic alkalosis is the classic electrolyte and acid-base imbalance of pyloric stenosis. Persistent emesis causes progressive loss of fluids rich in hydrochloric acid, which causes the kidneys to retain hydrogen ions in favor of potassium.
> Congenital adrenal hyperplasia-CAH (choice A) encompasses a group of autosomal recessive disorders, each of which involves a deficiency of an enzyme involved in the synthesis of cortisol, aldosterone, or both.Deficiency of 21-hydroxylase accounts for 90% of all CAH. In 21-hydroxylase deficiency most severe form, it is a salt-wasting disease characterized by ambiguous genitalia and aldosterone and cortisol levels are both reduced, which leads to hyperkalemia.
> Cystic fibrosis (choice B) is a genetic disease with manifestations that could be noted in the first 48 hours with delayed passage of meconium. The clinical picture of this child suggests pyloric stenosis.
> Gastroenteritis (choice C) is commonly caused viruses in western countries and is associated with osmotic and secretory diarrhea. This child has a firm movable mass palpated deep in epigastrium, which is a characteristic physical finding in pyloric stenosis.
> Obstructive uropathy (choice E) impedes urine flow and causes distention of the urinary tract proximal to the point of obstruction.Symptoms and signs of obstruction are often mild, occurring over long periods of time and requiring a high index of suspicion for diagnosis. Presentation varies with the location, duration, and degree of obstruction. This child's clinical picture suggests an upper gastrointestinal pathology and the findings on physical examination and initial laboratory studies are suggestive of pyloric stenosis.
A 6-week-old male infant develops recurrent episodes of vomiting with dehydration. Each of the following would be consistent with a diagnosis of congenital hypertrophic pyloric stenosis, except:
Correct Answer B: Hypertrophic pyloric stenosis can cause almost complete gastric outlet obstruction. Symptoms develop between 2 and 6 weeks of life. Projectile vomiting (without bile) occurs shortly after eating. Until dehydration sets in, the child feeds avidly and otherwise appears well, unlike many of those with vomiting due to systemic illness.
Diagnosis is by abdominal ultrasonography showing increased thickness of the pylorus (typically to = 4 mm; normal, < 2 mm). The classic electrolyte pattern of an infant with pyloric stenosis is that of hypochloremic, hypokalemic, metabolic alkalosis.
Initial treatment is directed at hydration and correcting electrolyte abnormalities. Definitive treatment is a longitudinal pyloromyotomy, which leaves the mucosa intact and separates the incised muscle fibers.
A 3-week-old white male presents with a history of several days of projectile vomiting after feeding, and documented weight loss despite a good appetite. There is a questionable history of a paternal uncle having surgery for a similar problem when he was an infant.
Which one of the following findings is a characteristic sign of this disease?
Correct Answer A: Hypertrophic pyloric stenosis is the most likely diagnosis in this case. If it is allowed to progress untreated, there may be signs of malnutrition, constipation, oliguria, and profound hypochloremic metabolic alkalosis (choice A). The latter is a characteristic sign of pyloric obstruction. As the child vomits chloride and hydrogen-rich gastric contents, hypochloremic alkalosis sets in.
→ Pneumonia (choice B) is not a common problem with pylori stenosis, as it can be with congenital tracheoesophageal fistulae for example.
→ After feeding, there may be a visible peristaltic wave that progresses across the abdomen. However, since the point of obstruction is proximal to the small and large intestines and affected infants lose weight, the abdomen is usually flat rather than distended (choice C), especially in the malnourished infant.
→ Currant jelly stool (choice D) is a common clinical manifestation of intussusception.
→ Mild jaundice with elevated indirect bilirubin (not direct, as stated in choice E) is seen in about 5% of infants with pyloric stenosis, but is not a characteristic sign.
A 4-week-old full-term male is brought to your office by his parents. They report that their child started vomiting just after his 1-week visit. The parents are concerned because they think the vomiting is worsening, occurring after every feeding, and “shooting across the room”. You note that the baby is afebrile, but has not gained any weight since birth.
Based on this information, the most likely diagnosis is:
Correct Answer D: Pyloric stenosis fits the described scenario; it is characterized by the early onset of worsening projectile vomiting and poor weight gain, and occurs most often in full-term male infants who are otherwise healthy. Formula intolerance causes regurgitation, as would inappropriate feeding. Meningitis, whether viral or bacterial, would be associated with fever. Viral gastroenteritis is a common cause of vomiting in older children, and is usually associated with fever and diarrhea.
A 6-week-old male infant presents with a history of projectile vomiting for the past five days. Physical exam reveals a dehydrated, irritable, afebrile infant. Laboratory evaluation reveals hypochloremic, hypokalemic metabolic alkalosis.
The likely diagnosis is:
Correct Answer B: This is the classic presentation of pyloric stenosis. It presents most commonly in a 6-week to 3-month-old first-born male infant. Hypochloremic, hypokalemic metabolic alkalosis is seen secondary to the loss of HCI and a compensatory H+/K+ exchange in the kidneys.
A. Gastroesophageal reflux disease is common, although it generally does not cause dehydration.
C. In the setting of a viral infection, the infant would likely have fever and diarrhea.
D. Duodenal atresia presents with vomiting (usually bilious) in the first few days of life.
E. Hirschsprung’s disease is characterized by constipation.
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