A 6-week-old infant is brought to the emergency department by parents who report projectile vomiting after every feeding for the past week. Which assessment finding would be most indicative of hypertrophic pyloric stenosis?
1Bilious vomiting and abdominal distension
2Diarrhea with blood and mucus in the stool
3Palpable olive-shaped mass in the right upper quadrant✓ 정답
4High-pitched bowel sounds and visible peristalsis
해설
The palpable olive-shaped mass in the right upper quadrant is the classic and most definitive physical finding of hypertrophic pyloric stenosis, representing the hypertrophied pyloric muscle. Other options are associated with different gastrointestinal conditions.
Core Nursing ExplanationKey Concept Analysis: This question assesses your ability to identify the classic physical exam finding for Hypertrophic Pyloric Stenosis (HPS). HPS is a common cause of non-bilious, projectile vomiting in infants 2-8 weeks old. The pathophysiology involves hypertrophy and hyperplasia of the circular muscle of the pylorus, creating a narrow, elongated channel that obstructs gastric outflow. This leads to forceful vomiting as the stomach contracts against the obstruction.
Answer Rationale: Key Point! The palpable "olive-shaped" mass in the right upper quadrant is the hallmark physical finding for HPS. This mass represents the hypertrophied pyloric muscle. It is best felt when the infant is relaxed, often after vomiting when the abdominal muscles are less tense. This finding, combined with the history of projectile, non-bilious vomiting, is highly diagnostic.
Distractor Analysis:
Option 1: Bilious vomiting and abdominal distension: Watch out for confusion! Bilious (green) vomiting is a red flag for a more serious, surgical condition like malrotation with midgut volvulus, which is a true emergency. HPS vomiting is typically non-bilious because the obstruction is proximal to the ampulla of Vater.
Option 2: Diarrhea with blood and mucus in the stool: This describes "currant jelly stool," a classic sign of intussusception, which presents with intermittent, colicky abdominal pain, not persistent projectile vomiting after every feed.
Option 4: High-pitched bowel sounds and visible peristalsis: While sometimes present in HPS due to gastric outlet obstruction, these are non-specific signs. Visible peristaltic waves may be seen moving from left to right across the epigastrium, but the "olive" is the most definitive finding. These signs can occur in other obstructive processes.
Related Concepts: The nursing assessment for an infant with suspected HPS includes monitoring for signs of dehydration (e.g., sunken fontanelles, poor skin turgor, decreased urine output) and metabolic alkalosis from the loss of gastric acid (HCl) and potassium. Diagnosis is often confirmed by ultrasound showing a thickened pyloric muscle and a long pyloric channel.
Indicates mucosal ischemia and bleeding from telescoped bowel
Visible peristaltic waves
Any gastric or proximal bowel obstruction (e.g., HPS)
Non-specific sign of obstruction; requires further assessment
Anatomy, Physiology & Pharmacology Points
Anatomy: The pylorus is the muscular valve connecting the stomach to the duodenum. In HPS, the circular muscle layer becomes thickened.
Physiology: Persistent vomiting leads to loss of H+ and Cl- ions, causing a hypochloremic, hypokalemic metabolic alkalosis. The kidney attempts to compensate by excreting bicarbonate, but this requires exchanging for potassium (K+), worsening hypokalemia.
Pharmacology: Pre-operative care focuses on correcting fluid and electrolyte imbalances with IV fluids (e.g., 0.9% NaCl with KCl). The definitive treatment is a pyloromyotomy (surgical splitting of the muscle).
Memory Tips
HPS = Hungry, Projectile, Starving: The infant is hungry (wants to feed), vomits Projectilely, and is Starving (failure to thrive).
The "Rule of 2's" for HPS: Onset at 2 weeks to 2 months, more common in first-born 2 (males), and associated with a 2 (two)-fold increase if mother had it.
Olive in the RUQ: Picture an olive (the mass) stuck in the right upper part of a tiny infant's belly.
High-Frequency NCLEX Topics
The NCLEX loves to test the differentiation of pediatric GI emergencies. You must know:
The classic presentation of HPS (age, vomiting type, physical finding).
That bilious vomiting in an infant is a surgical emergency until proven otherwise (think malrotation/volvulus).
Nursing priorities: Assess for dehydration and electrolyte imbalance first, then prepare for diagnostic confirmation and surgery.
Watch Out for Question Variations!
Shift from Assessment to Intervention: "The nurse palpates an olive-shaped mass in an infant with projectile vomiting. What is the priority nursing action?" (Answer: Prepare for IV fluid resuscitation and electrolyte correction, as the patient is likely dehydrated).
Lab Value Interpretation: "An infant with HPS has the following ABG: pH 7.48, PaCO2 48, HCO3- 36. What acid-base imbalance is present?" (Answer: Compensated metabolic alkalosis).
Post-operative Care: "Following a pyloromyotomy, the nurse should initially feed the infant..." (Answer: Small, frequent feeds of clear liquids or formula as ordered, observing for vomiting).
Nursing Clinical Practice GuideClinical Scenario: You are a nurse in the Pediatric ED. Parents bring in their 6-week-old son, Liam. They report that for the past 5 days, Liam has been vomiting "with great force" about 20-30 minutes after every feeding. He seems hungry again immediately after vomiting. They are worried because he has had fewer wet diapers today.
Nursing Intervention Strategy:
Assessment:
History: Focus on the pattern of vomiting (projectile? non-bilious?), feeding habits, weight trends, and urine/output.
Physical Exam:
Inspect: Look for visible peristaltic waves moving left to right across the epigastrium. Check for signs of dehydration (sunken fontanelles, dry mucous membranes).
Palpate: This is key! With the infant calm and supine, flex the hips and knees to relax the abdomen. Use your fingertips to gently palpate the right upper quadrant, just lateral to the midline and above the umbilicus. Feel for a small, firm, movable mass about the size of an olive. It is often easiest to feel after the infant has vomited and the stomach is empty.
Auscultate: Listen for hyperactive bowel sounds.
Diagnostics: Anticipate orders for an abdominal ultrasound (gold standard) and basic metabolic panel (BMP) to check for alkalosis and hypokalemia.
Nursing Diagnosis: Risk for Deficient Fluid Volume, Imbalanced Nutrition: Less Than Body Requirements, Anxiety (parental).
Planning & Implementation:
Immediate: Establish IV access. Administer IV fluids (typically 0.9% NaCl with potassium chloride (KCl) added once urine output is confirmed) to correct dehydration and electrolyte imbalances before surgery.
Pre-operative: Keep NPO (Nothing by mouth). Provide parental education and emotional support. The surgery (pyloromyotomy) is not an emergency but is done urgently after stabilization.
Post-operative: Monitor for surgical site infection. Feeding usually begins 4-6 hours post-op with small, frequent amounts (e.g., 15-30 mL of Pedialyte or formula) advancing as tolerated. Vomiting may persist for a day or two but should not be projectile.
Patient Safety and Precautions:
Critical: Do NOT mistake bilious vomiting for HPS. Bilious vomiting requires immediate notification of the provider and rapid workup for malrotation/volvulus.
Medication: When adding KCl to IV fluids, always use an infusion pump and follow hospital policy for maximum concentration and infusion rate to prevent life-threatening hyperkalemia.
Monitoring: Strict I&O (Intake and Output), daily weights, and frequent assessment of hydration status (skin turgor, fontanelle, mucous membranes).
Initiate IV fluids: 1.5-2x maintenance rate with 0.9% NaCl to correct dehydration.
Once labs are back and urine output is adequate (>1 mL/kg/hr), add KCl to fluids per order (e.g., 20 mEq KCl per 500 mL bag).
Keep patient NPO.
Prepare parents for the surgery and post-op care.
A Word from Your Senior Nurse
"Mastering these pediatric GI distinctions is a game-changer. In practice, the parents of an infant with HPS are often exhausted and terrified. Your calm, knowledgeable assessment—especially that skillful palpation for the 'olive'—not only guides the medical team but also builds immense trust with the family. Remember, your priority is always the ABCs: Is the airway clear? Is the baby breathing adequately? Is there circulatory compromise from dehydration? Get those IV fluids going, correct the electrolytes, and then you've set the stage for a safe and successful surgery. This holistic thinking is what makes a great nurse!"
Hypertrophic Pyloric Stenosis — A condition in infants characterized by hypertrophy of the pyloric muscle, causing gastric outlet obstruction and projectile, non-bilious vomiting.
Pyloromyotomy — The surgical procedure to treat HPS, involving a longitudinal incision through the hypertrophied pyloric muscle to relieve the obstruction.
Hypochloremic Hypokalemic Metabolic Alkalosis — The classic electrolyte and acid-base imbalance in HPS, resulting from the loss of gastric acid (HCl) and potassium through persistent vomiting.
Olive-Shaped Mass — The palpable, firm, movable mass in the right upper quadrant representing the hypertrophied pylorus; the pathognomonic physical finding of HPS.
Projectile Vomiting — Forceful vomiting where stomach contents are ejected several feet away; a hallmark symptom of gastric outlet obstruction like HPS.