Hypertrophic Pyloric Stenosis in Children
Hypertrophic Pyloric Stenosis in Children
Hypertrophic pyloric stenosis (HPS) is a condition affecting infants, typically occurring between 2 and 8 weeks of age. It is characterized by thickening of the pylorus muscle, leading to narrowing of the pyloric canal and obstruction of gastric emptying.
Key Points:
- HPS is the most common cause of gastric outlet obstruction in infants
- It affects approximately 2-5 per 1,000 live births
- More common in male infants and firstborn children
- Surgical intervention (pyloromyotomy) is the definitive treatment
- Excellent prognosis with timely diagnosis and treatment
Pathophysiology
The exact cause of hypertrophic pyloric stenosis remains unclear, but several factors are thought to contribute:
- Genetic predisposition: Higher incidence in certain families and ethnicities
- Environmental factors: Possible link to bottle feeding and maternal smoking
- Hormonal influences: Potential role of gastrin and other growth factors
The pathophysiological process involves:
- Hypertrophy and hyperplasia of the circular muscle fibers of the pylorus
- Elongation and thickening of the pyloric canal
- Narrowing of the pyloric lumen, obstructing gastric emptying
- Resultant forceful contractions of the stomach against the obstruction
This leads to the characteristic projectile vomiting and other symptoms associated with HPS.
Clinical Presentation
The typical presentation of hypertrophic pyloric stenosis includes:
- Projectile, non-bilious vomiting: The hallmark symptom, usually occurring 30-60 minutes after feeding
- Feeding difficulties: Infant may appear hungry and feed eagerly, but then vomit
- Failure to thrive: Weight loss or poor weight gain
- Dehydration: Due to persistent vomiting
- Visible peristaltic waves: May be observed moving across the upper abdomen from left to right
- Palpable olive-shaped mass: In the right upper quadrant (pyloric tumor)
Complications of untreated HPS may include:
- Severe dehydration and electrolyte imbalances
- Metabolic alkalosis: Due to loss of hydrochloric acid from vomiting
- Jaundice: In some cases, possibly due to unconjugated hyperbilirubinemia
- Hematemesis: Rarely, due to gastritis or esophagitis from persistent vomiting
Diagnosis
Diagnosis of hypertrophic pyloric stenosis involves a combination of clinical assessment and imaging studies:
Clinical Evaluation:
- Detailed history: Focusing on feeding patterns and vomiting characteristics
- Physical examination: Looking for signs of dehydration and palpating for pyloric mass
- Assessment of growth parameters
Laboratory Studies:
- Serum electrolytes: To assess for hypochloremic metabolic alkalosis
- Complete blood count: To evaluate for anemia or infection
- Liver function tests: If jaundice is present
Imaging Studies:
- Ultrasound: The gold standard for diagnosis
- Pyloric muscle thickness > 3-4 mm
- Pyloric length > 15-18 mm
- Pyloric diameter > 10-14 mm
- Upper GI series: If ultrasound is inconclusive, may show the "string sign" or "shoulder sign"
Differential diagnosis may include:
- Gastroesophageal reflux disease (GERD)
- Pylorospasm
- Gastroenteritis
- Intracranial pathology
- Metabolic disorders
Treatment
The definitive treatment for hypertrophic pyloric stenosis is surgical intervention. However, initial management focuses on stabilizing the infant:
Preoperative Management:
- Fluid resuscitation: Correct dehydration and electrolyte imbalances
- Nasogastric tube placement: To decompress the stomach
- Monitoring: Close observation of vital signs and urine output
Surgical Treatment:
- Pyloromyotomy (Ramstedt's procedure):
- Longitudinal incision of the pyloric muscle down to the submucosa
- Can be performed open or laparoscopically
- Usually takes about 30 minutes to perform
Postoperative Care:
- Gradual reintroduction of feeding: Usually within 4-6 hours post-surgery
- Pain management: Typically with acetaminophen
- Monitoring for complications: Such as wound infection or incomplete pyloromyotomy
Prognosis after pyloromyotomy is excellent, with most infants recovering quickly and experiencing no long-term effects. Recurrence of pyloric stenosis after surgery is extremely rare.
Hypertrophic Pyloric Stenosis in Children
- QUESTION: What is Hypertrophic Pyloric Stenosis (HPS)?
ANSWER: Hypertrophic Pyloric Stenosis is a condition in infants characterized by thickening of the pylorus muscle, leading to narrowing of the pyloric canal and obstruction of gastric emptying. - QUESTION: At what age do infants typically present with Hypertrophic Pyloric Stenosis?
ANSWER: HPS typically presents between 2 to 8 weeks of age, with a peak incidence around 3 to 5 weeks. - QUESTION: What is the classic presentation of Hypertrophic Pyloric Stenosis?
ANSWER: The classic presentation includes projectile, non-bilious vomiting after feeding, hunger after vomiting, and visible peristaltic waves across the upper abdomen. - QUESTION: What is the gender predilection for Hypertrophic Pyloric Stenosis?
ANSWER: HPS is more common in males, with a male to female ratio of approximately 4:1 to 5:1. - QUESTION: What is the "olive" sign in Hypertrophic Pyloric Stenosis?
ANSWER: The "olive" sign refers to the palpable, firm, olive-shaped mass in the right upper quadrant of the abdomen, representing the hypertrophied pylorus. - QUESTION: How is Hypertrophic Pyloric Stenosis diagnosed?
ANSWER: Diagnosis is typically made through a combination of clinical presentation, physical examination, and imaging studies, with ultrasound being the gold standard for confirmation. - QUESTION: What are the typical ultrasound findings in Hypertrophic Pyloric Stenosis?
ANSWER: Typical ultrasound findings include pyloric muscle thickness >3-4 mm, pyloric channel length >14-16 mm, and overall pyloric diameter >13-14 mm. - QUESTION: What electrolyte abnormalities are commonly seen in infants with Hypertrophic Pyloric Stenosis?
ANSWER: Common electrolyte abnormalities include hypochloremic, hypokalemic metabolic alkalosis due to loss of hydrochloric acid through vomiting. - QUESTION: What is the standard treatment for Hypertrophic Pyloric Stenosis?
ANSWER: The standard treatment is surgical pyloromyotomy, typically performed laparoscopically, after correction of fluid and electrolyte imbalances. - QUESTION: What is the Ramstedt procedure?
ANSWER: The Ramstedt procedure is the surgical technique used for pyloromyotomy, involving longitudinal incision of the pyloric muscle down to the submucosa without closing the muscle layer. - QUESTION: How quickly do infants typically recover after pyloromyotomy?
ANSWER: Most infants recover quickly, with feeding often resumed within 4-6 hours after surgery and discharge typically possible within 24-48 hours. - QUESTION: What are the potential complications of pyloromyotomy?
ANSWER: Potential complications include incomplete myotomy, mucosal perforation, wound infection, and rarely, dumping syndrome. - QUESTION: Is there a genetic component to Hypertrophic Pyloric Stenosis?
ANSWER: Yes, there appears to be a genetic component, with a higher incidence in first-degree relatives of affected individuals and in certain ethnic groups. - QUESTION: How does Hypertrophic Pyloric Stenosis affect an infant's growth and development?
ANSWER: If left untreated, HPS can lead to failure to thrive due to inadequate nutrient intake. However, with prompt treatment, most infants quickly catch up on growth and development. - QUESTION: What is the role of medical management in Hypertrophic Pyloric Stenosis?
ANSWER: Medical management focuses on correcting fluid and electrolyte imbalances preoperatively. Atropine therapy has been used in some cases but is generally not considered a substitute for surgery. - QUESTION: How does Hypertrophic Pyloric Stenosis differ from gastroesophageal reflux in infants?
ANSWER: HPS typically presents with forceful, projectile vomiting after feeds, while reflux is usually characterized by effortless regurgitation. HPS vomiting tends to worsen over time, unlike reflux which often improves. - QUESTION: What is the long-term prognosis for infants who undergo pyloromyotomy for HPS?
ANSWER: The long-term prognosis is excellent, with most infants experiencing no long-term sequelae and normal gastric function. - QUESTION: Are there any known environmental risk factors for Hypertrophic Pyloric Stenosis?
ANSWER: Some studies suggest associations with bottle feeding, early antibiotic use (particularly erythromycin), and maternal smoking during pregnancy, although causality is not firmly established. - QUESTION: How does the thickness of the pyloric muscle change after pyloromyotomy?
ANSWER: The pyloric muscle gradually returns to normal thickness over several months following pyloromyotomy, with gastric emptying typically normalizing within weeks. - QUESTION: What is the significance of jaundice in some infants with Hypertrophic Pyloric Stenosis?
ANSWER: Jaundice can occur in some infants with HPS, possibly due to caloric deprivation and altered enterohepatic circulation. It typically resolves quickly after successful treatment. - QUESTION: How does Hypertrophic Pyloric Stenosis affect the stomach's function and anatomy?
ANSWER: HPS can lead to gastric dilatation due to outflow obstruction. The stomach typically returns to normal size and function after successful treatment. - QUESTION: What is the role of serum gastrin levels in Hypertrophic Pyloric Stenosis?
ANSWER: Some studies have found elevated serum gastrin levels in infants with HPS, potentially contributing to pyloric muscle hypertrophy, although the exact relationship is not fully understood. - QUESTION: How does the management of Hypertrophic Pyloric Stenosis differ in premature infants?
ANSWER: Management in premature infants may be more challenging due to their smaller size and potential comorbidities. Extra care is needed in fluid management and surgical technique. - QUESTION: What is the importance of follow-up care after pyloromyotomy for HPS?
ANSWER: Follow-up care is important to ensure proper wound healing, adequate weight gain, and to address any feeding issues or parental concerns. Most infants require only short-term follow-up.
