🍽️ Pediatric GI — Pyloric Stenosis, Intussusception & Hirschsprung
Three conditions defined by how the baby vomits and what the stool looks like.
⚖️ Telling them apart
| Pyloric stenosis | Intussusception | Hirschsprung | |
|---|---|---|---|
| Age | 3–6 weeks | 6 months–3 years | Newborn |
| Vomit | Projectile, non-bilious | Bile-stained | Bile-stained |
| Stool | Constipated, small | Currant-jelly — blood and mucus | Ribbon-like; no meconium in 48 h |
| Abdomen | Olive-shaped mass RUQ; visible peristaltic waves | Sausage-shaped mass; child draws knees up | Distended |
| Hungry after vomiting? | YES — ravenous | No | No |
"Projectile vomiting, then immediately hungry again, in a 4-week-old" is pyloric stenosis every time. The stomach empties forcefully but nothing gets through, so the baby is genuinely starving.
🚨 What matters in each
Pyloric stenosis
The pyloric muscle thickens and blocks the stomach outlet.
- Metabolic alkalosis with hypokalemia and hypochloremia — from losing gastric acid
- Dehydration, weight loss, fewer wet diapers
- Treated surgically (pyloromyotomy); feeds resume within hours
The acid-base picture is the exam point: vomiting stomach contents means losing hydrogen and chloride, so the blood turns alkalotic.
🚨 Intussusception
One segment of bowel telescopes into the next, cutting off its blood supply.
- Sudden severe intermittent pain — the child draws the knees to the chest and screams, then is calm between episodes
- Currant-jelly stool — blood and mucus
- Palpable sausage-shaped mass
A normal brown stool before surgery may mean the bowel has reduced itself. Report it immediately - the operation may be canceled.
Treated by air or contrast enema, which often reduces it; surgery if that fails or the bowel is necrotic.
Hirschsprung disease
A segment of colon has no ganglion cells, so it cannot relax and propel stool.
- No meconium within 48 hours — the classic newborn clue
- Ribbon-like, foul stools; distension; poor feeding
- Diagnosed by rectal biopsy; treated surgically
Watch for enterocolitis - explosive diarrhea, fever and a rapidly worsening child. It is the life-threatening complication.
🩺 Dehydration — the thread through all of them
Weight change is the most accurate measure of fluid loss in a child. Children have proportionally more body water and lose it faster than adults.
| Sign | Mild | Moderate | Severe |
|---|---|---|---|
| Weight loss | 3–5% | 6–9% | ≥10% |
| Capillary refill | <2 s | 2–3 s | >3 s |
| Mucous membranes | Slightly dry | Dry | Parched, no tears |
| Urine | Slightly reduced | Reduced, dark | Minimal or none |
| Behavior | Normal, thirsty | Irritable | Lethargic, sunken fontanelle |
In an infant, the earliest reliable signs are fewer wet diapers and no tears when crying. Ask about both, every time.
First-line treatment for mild to moderate dehydration is oral rehydration solution, in small frequent amounts.
Not plain water, not juice, not sports drinks. The sugar load worsens diarrhea and the electrolytes are wrong.
🎯 NCLEX traps
- Projectile vomiting + still hungry + olive mass = pyloric stenosis, with metabolic alkalosis
- Currant-jelly stool = intussusception; a normal stool before surgery must be reported
- No meconium in 48 hours = Hirschsprung
- Daily weight is the best measure of dehydration
- ORS, not water or juice