Hypertrophic pyloric stenosis is characterized by hypertrophy and hyperplasia of the circular muscle of the pylorus, leading to narrowing of the pyloric canal and obstruction of gastric emptying. The condition typically presents between 2-8 weeks of age with a higher incidence in firstborn males and has a genetic predisposition with multifactorial inheritance patterns.
Key Points
Most common in firstborn males (4:1 male to female ratio)
Typically presents between 2-8 weeks of age
Exact cause unknown but has genetic components
Clinical Manifestations
The hallmark symptom is projectile, non-bilious vomiting that progressively worsens after feedings. The infant remains hungry after vomiting and eagerly feeds again. As the condition progresses, the infant may develop signs of dehydration, failure to thrive, and metabolic alkalosis due to loss of gastric acid.
Key Points
Projectile, non-bilious vomiting that progressively worsens
Hungry infant who wants to feed immediately after vomiting
Visible peristaltic waves moving from left to right across the epigastrium
Palpable "olive-shaped" mass in the right upper quadrant
Clinical Scenario
A 4-week-old male infant is brought to the emergency department with a 1-week history of progressively worsening vomiting after feedings. The mother reports the vomiting is forceful and the infant seems hungry afterward. On examination, the nurse observes visible peristaltic waves across the infant's abdomen and palpates a small, firm mass in the right upper quadrant. Laboratory results reveal hypochloremic, hypokalemic metabolic alkalosis.
Diagnostic Evaluation
Diagnosis is confirmed through ultrasound, which shows a thickened pyloric muscle and elongated pyloric channel. Laboratory findings may include hypochloremic, hypokalemic metabolic alkalosis due to loss of hydrochloric acid from persistent vomiting, along with elevated BUN indicating dehydration.
Key Points
Ultrasound is the diagnostic test of choice
Metabolic alkalosis with hypochloremia and hypokalemia
Elevated BUN indicating dehydration
Nursing Management
Preoperative Care
The primary focus of preoperative care is correction of fluid and electrolyte imbalances. IV fluids with appropriate electrolytes are administered to correct dehydration and metabolic alkalosis. Accurate intake and output measurements, daily weights, and monitoring for signs of dehydration are essential nursing interventions.
Key Points
Correct fluid and electrolyte imbalances before surgery
NPO status with IV fluid replacement
Monitor vital signs, intake and output, and daily weights
Assess for signs of dehydration (sunken fontanels, dry mucous membranes, decreased urine output)
Surgical Intervention
The definitive treatment is a pyloromyotomy (Ramstedt procedure), which involves surgically splitting the hypertrophied pyloric muscle down to the submucosa without entering the gastric lumen. This procedure is typically performed laparoscopically, resulting in smaller incisions and faster recovery time.
Key Points
Pyloromyotomy (Ramstedt procedure) is the standard surgical treatment
Surgery involves splitting the pyloric muscle without entering the gastric lumen
Laparoscopic approach is common and preferred
Postoperative Care
Maintain NPO status for several hours after surgery
Begin feeding with small amounts of clear liquids or electrolyte solutions
Gradually advance to formula or breast milk as tolerated
Monitor for vomiting, which may occur initially due to gastric irritation
Assess incision site for signs of infection or dehiscence
Provide pain management as needed
Educate parents on feeding techniques and home care
Some post-operative vomiting is normal but should decrease over time
Most infants resume normal feeding patterns within 24-48 hours
Important Alert
Post-operative vomiting that is persistent, projectile, or bilious may indicate surgical complications and should be reported immediately. Additionally, monitor for signs of infection, including fever, redness or drainage at incision site, and irritability.
Summary of Key Points
Hypertrophic pyloric stenosis is characterized by hypertrophy of the pyloric muscle causing gastric outlet obstruction.
Primary clinical manifestation is projectile, non-bilious vomiting in infants 2-8 weeks of age, predominantly affecting males.
Diagnosis is confirmed by ultrasound showing thickened pyloric muscle.
Metabolic alkalosis with hypochloremia and hypokalemia occurs due to loss of gastric acid.
Preoperative care focuses on correcting fluid and electrolyte imbalances.
Pyloromyotomy (Ramstedt procedure) is the definitive treatment.
Postoperative care involves gradual reintroduction of feedings and monitoring for complications.
Commonly Confused Points
Hypertrophic Pyloric Stenosis
Gastroesophageal Reflux
Projectile, forceful vomiting
Effortless regurgitation or "spitting up"
Progressive worsening of symptoms
May improve with positioning and time
Palpable olive-shaped mass
No palpable mass
Metabolic alkalosis
No significant electrolyte disturbances
Requires surgical intervention
Managed conservatively
Hypertrophic Pyloric Stenosis
Intestinal Obstruction
Non-bilious vomiting
Bilious vomiting (indicates obstruction below ampulla of Vater)
Palpable olive-shaped mass in RUQ
Distended abdomen, may have visible loops of bowel
Normal or decreased bowel sounds
High-pitched, tinkling bowel sounds or absent sounds
No abdominal distention or minimal epigastric distention
Significant abdominal distention
Memory Aid: "PYLORIC"
P - Projectile vomiting
Y - Young infants (2-8 weeks)
L - Loss of weight and fluid
O - Olive-shaped mass
R - Right upper quadrant mass
I - Increased peristaltic waves
C - Chloride depletion (hypochloremic alkalosis)
Study Tips
Focus Areas for NCLEX
Understand the classic presentation: male infant 2-8 weeks old with projectile vomiting
Know the key assessment findings: olive-shaped mass, visible peristaltic waves
Recognize metabolic alkalosis with hypochloremia and hypokalemia as the characteristic laboratory abnormality
Prioritize preoperative fluid and electrolyte correction
Understand the postoperative feeding progression
Memory Aid: "4-2-1"
4:1 male to female ratio
2-8 weeks of age at presentation
1 olive-shaped mass in the RUQ
Memory Aid: Electrolyte Imbalance
"Puke out the Acid, Blood turns Basic"
(Loss of HCl from stomach leads to metabolic alkalosis)
Quick Check
What is the most common electrolyte imbalance in pyloric stenosis?
Hypochloremic, hypokalemic metabolic alkalosis due to loss of gastric acid from persistent vomiting.
Common Pitfalls
Confusing pyloric stenosis (non-bilious vomiting) with intestinal obstruction (bilious vomiting)
Failing to recognize the importance of correcting fluid and electrolyte imbalances before surgery
Not understanding that some vomiting after surgery is normal but should gradually decrease
Forgetting that pyloric stenosis causes metabolic alkalosis (not acidosis)
Parent Education
Discharge Teaching
Educate parents about proper feeding techniques, including smaller, more frequent feedings initially, proper positioning during and after feedings, and burping techniques. Explain that some vomiting may occur post-operatively but should gradually decrease, and provide clear instructions on when to contact healthcare providers.
Key Points
Feed smaller amounts more frequently initially
Position infant with head elevated during and after feedings
Contact healthcare provider if vomiting persists or worsens, fever develops, or signs of dehydration appear