Pyloric Stenosis: A Must-Know Topic for all Aspirants
Introduction
If you're preparing for the AIIMS PG entrance or any medical competitive exam, pyloric stenosis is a high-yield topic you can’t afford to skip. It’s one of the most common causes of non-bilious projectile vomiting in infants—and a favorite of examiners!
In this blog post, we’ll break down everything you need to know about pyloric stenosis in an easy, concept-based format that sticks, while keeping it SEO-rich for medical readers like you.
What is Pyloric Stenosis?
Pyloric stenosis (also called infantile hypertrophic pyloric stenosis) is a congenital condition where the pyloric muscle (the muscle between the stomach and duodenum) becomes abnormally thickened, leading to gastric outlet obstruction.
🧠 Exam Tip: It usually presents between 2 to 6 weeks of age, more commonly in first-born male infants.
Why Does It Happen?
The exact cause of pyloric stenosis is not fully understood, but here are some contributing factors:
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Genetic predisposition
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Macrolide antibiotic exposure (e.g., erythromycin)
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Male sex predominance (4:1 male to female ratio)
Key Clinical Features (Easy Mnemonics & Points)
🔑 Remember the “3 Ps” of pyloric stenosis:
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Projectile vomiting (non-bilious)
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Palpable olive mass in the epigastric region
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Peristaltic waves visible after feeding
👶 Classic Scenario: A 4-week-old baby, vomiting forcefully after feeds, still hungry after vomiting, and losing weight.
Diagnosis: How is it Confirmed?
1. Clinical Examination
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Olive-shaped mass in the right upper abdomen
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Visible gastric peristalsis (left to right)
2. Investigations
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Ultrasound is the gold standard:
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Pyloric muscle thickness > 3 mm
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Pyloric channel length > 15–18 mm
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Lab findings (due to vomiting):
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Hypochloremic, hypokalemic metabolic alkalosis
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🎯 Exam Focus: Remember the "metabolic alkalosis" with paradoxical aciduria due to volume depletion.
Management of Pyloric Stenosis
Step 1: Stabilization
Correct dehydration and electrolyte imbalances before surgery.
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IV fluids: Normal saline + potassium
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Monitor electrolytes and urine output
Step 2: Surgery
✅ Ramstedt’s Pyloromyotomy – A longitudinal incision through the hypertrophied muscle to relieve obstruction.
🩺 Prognosis is excellent after surgery, with most infants recovering completely.
Differential Diagnosis (Don’t Confuse in Exams!)
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Gastroesophageal reflux
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Intestinal atresia (bilious vomiting)
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Malrotation with volvulus (urgent!)
🔍 Key point: Pyloric stenosis = non-bilious vomiting
Malrotation = bilious vomiting
Radiological Clues (Image-Based Questions)
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Ultrasound – elongation & thickening of pyloric muscle
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Barium study (if USG unavailable):
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“String sign” or “Double tract sign”
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“Shoulder sign” – bulging pylorus
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📸 These signs are popular in AIIMS/INI-CET image-based MCQs!
Your’s Role in Pyloric Stenosis
Monitor for dehydration signs (sunken fontanelle, dry mucosa)
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Ensure NPO (nil per os) status pre-surgery
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Maintain IV fluid and electrolyte balance
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Post-op care: monitor for vomiting, pain, and wound infection
Key Facts to Revise Before Exam
Feature | Pyloric Stenosis |
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Age of Onset | 2–8 weeks |
Vomiting | Projectile, non-bilious |
Mass | Olive-like, epigastric |
Electrolyte Disturbance | Hypokalemic, hypochloremic alkalosis |
Treatment | Ramstedt's pyloromyotomy |
Imaging | USG: muscle >3 mm, length >15 mm |
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