Here is the full GI tract presentation explained simply, condition by condition:
🫁 GI System - Easy Explanation (Dr. Ana Pochkhua, 2026)
🔶 1. Esophageal Atresia + Tracheoesophageal Fistula (TEF)
What is it?
The esophagus (food pipe) ends in a dead end instead of connecting to the stomach. In 90% of cases, it also has an abnormal connection to the trachea (airway) - this connection is called a Tracheoesophageal Fistula (TEF).
Simple image: instead of food going down to the stomach, it can accidentally go into the lungs.
Signs:
- Baby chokes, coughs, or turns blue on the very first feeding
- Recurrent aspiration pneumonia (stomach acid/milk goes into lungs through the fistula)
- Polyhydramnios during pregnancy (baby couldn't swallow amniotic fluid, so it built up)
Diagnosis:
- Chest X-ray shows air in stomach (because air enters GI tract through fistula)
- NG tube coils on X-ray - can't pass tube into the stomach = diagnostic!
- CT scan or esophagogram can also confirm
Treatment:
- Two-step surgery to fix the connection
- Give IV fluids first to prevent dehydration
- Antibiotics for anaerobes (risk of lung abscess from aspiration)
- ⚠️ Always check for VACTERL association:
- Vertebral defects
- Anal atresia
- Cardiac defects
- Tracheoesophageal fistula
- Esophageal atresia
- Renal defects
- Limb defects
🔶 2. Pyloric Stenosis
What is it?
The pylorus (the muscle valve between stomach and small intestine) becomes too thick and tight, blocking food from leaving the stomach.
- Most common in first-born boys
- Symptoms usually appear at 3-5 weeks of age (not at birth)
- Formula feeding may contribute (slower gastric emptying stimulates muscle growth)
Signs:
- Projectile, non-bilious vomiting (vomit is not green - the blockage is above the bile duct)
- Baby is hungry right after vomiting - called "hungry vomiter"
- Feel an "olive-shaped" lump in the upper abdomen (olive sign)
- Succussion splash - sloshing sound when you shake the baby's abdomen
- Blood tests show: low chloride + low potassium + metabolic alkalosis (from losing stomach acid in the vomit)
Why alkalosis? Vomiting = losing HCl (acid) = blood becomes more alkaline. Kidneys then try to compensate but worsen potassium loss.
Diagnosis:
- Abdominal ultrasound - best first test - shows thickened pylorus
- Upper GI series - most accurate test
Treatment:
- IV fluids to rehydrate and replace electrolytes (especially potassium) first
- Then surgery: Pyloromyotomy (cutting the thickened muscle to open the passage)
- Surgery is NOT done until electrolytes are corrected - low potassium raises risk of post-op breathing complications
🔶 3. Gastroesophageal Reflux (GER) in Infants
What is it?
Milk spits back up from the stomach into the esophagus. Very common - affects 50%+ of infants.
Why babies get it more than adults:
- Shorter esophagus
- Incomplete closure of the lower esophageal sphincter (LES)
- Spend most time lying flat
Signs:
- "Spitting up" after feeds - most babies are "happy spitters" - no pain, gain weight well
- Parents are often worried but this is usually normal!
Diagnosis: Just history and physical exam
Treatment (no medication usually needed):
- Small, frequent feeds
- Hold upright 20-30 minutes after feeding
- Place baby prone (on tummy) when awake and supervised
- Avoid tight diapers, bringing knees up to stomach (increases abdominal pressure)
- Usually resolves at 6 months (when baby can sit up) and gone by 1 year
🔶 4. Hirschsprung Disease
What is it?
The large intestine (colon) is missing nerve cells (ganglion cells) in a section of it - specifically the Auerbach (myenteric) plexus. Without nerves, that section stays permanently contracted and blocked.
- Nerve cells (neural crest cells) travel from the top of the intestine downward during development. If they stop too early, the bottom part of the colon has no nerves.
- Rectum is ALWAYS involved (because it's the furthest from where the cells start)
- More common in boys (4:1 ratio) and associated with Down syndrome
Signs:
- Failure to pass meconium (first stool) within 48 hours of birth (normal is <24 hours)
- Severe constipation, abdominal bloating
- "Squirt sign" - when doctor does a rectal exam, gas and stool explode out because the blockage is temporarily relieved
Diagnosis:
- X-ray: dilated bowel loops, no air in rectum
- Contrast enema: shows a "transition zone" between the narrow, blocked segment and the dilated normal bowel
- Gold standard: rectal biopsy showing NO ganglion cells
Treatment:
- 3-stage surgery - curative
🔶 5. Meconium Ileus (vs. Hirschsprung)
What is it?
Meconium (baby's first stool) is so thick and sticky it blocks the small intestine (ileum). This is almost always a sign of Cystic Fibrosis (CF).
Key fact: Almost all newborns with meconium ileus have CF. CF causes thick, viscous secretions in all organs, including the gut.
How is it different from Hirschsprung?
| Feature | Hirschsprung | Meconium Ileus |
|---|
| Location of block | Rectosigmoid (large bowel) | Ileum (small bowel) |
| Rectal exam | Relieves blockage (squirt sign) | Does NOT relieve blockage |
| Associated condition | Down syndrome | Cystic Fibrosis |
| Meconium texture | Normal | Thick, sticky (inspissated) |
Treatment:
- Gastrografin enema (hyperosmolar) can break up the thick meconium
- Surgery if enema fails
🔶 6. Imperforate Anus
What is it?
The baby is born without an anal opening - the rectum ends in a blind pouch. The sphincter muscles are still intact.
- Associated with Down syndrome and VACTERL syndrome
Signs:
- Baby completely fails to pass meconium
- Physical exam: no anus visible
Treatment:
- Surgery is curative
- Diagnosis is made by physical exam - NOT by barium study or manometry (common wrong answers!)
🔶 7. Duodenal Atresia
What is it?
The duodenum (first part of small intestine, just after the stomach) did not form a proper tube - the lumen is blocked or absent.
- Associated with Down syndrome and annular pancreas (pancreas wraps around and squeezes the duodenum)
- Prenatal ultrasound: polyhydramnios (baby can't swallow amniotic fluid)
Signs:
- Bilious (green) vomiting within 12 hours of birth (blockage is below the bile duct, so bile is in the vomit)
Diagnosis:
- "Double bubble sign" on X-ray = air trapped in stomach + first part of duodenum; no gas below
Treatment:
- IV fluids + replace potassium
- NG tube to decompress the bowel
- Surgery: duodenostomy
🔶 8. Jejunal Atresia
What is it?
The jejunum or ileum (middle part of small intestine) is blocked - caused by a vascular accident in the womb (blood supply cut off to part of the gut, which then died and sealed shut).
- Risk factors: mother used cocaine, tobacco, or vasoconstrictive drugs
- NOT associated with chromosomal abnormalities (unlike duodenal atresia)
Diagnosis:
- "Triple bubble sign" or "apple peel" appearance on X-ray - air trapped in stomach + duodenum + jejunum; colon is empty/gasless
Treatment:
- Resuscitate first, then surgery
🔶 9. Volvulus (Midgut Volvulus)
What is it?
A loop of bowel twists on itself, cutting off its own blood supply. This is a surgical emergency - the bowel can die (necrose) within hours.
- In children, caused by malrotation (the intestines didn't rotate into the correct position during fetal development)
- Most common in the ileum
Signs:
- Severe abdominal pain, bloating, bilious vomiting
- Bloody stools when blood supply is cut (late, serious sign)
- Initially soft abdomen - gets distended as it worsens
Diagnosis:
- X-ray first - rules out perforation (free air under the diaphragm = emergency surgery now)
- If no free air: Upper GI series (barium swallow) - fastest and most accurate
- Ligament of Treitz on the RIGHT side = malrotation
- "Corkscrew" pattern of contrast = volvulus
Ligament of Treitz = a ligament that holds the junction of duodenum and jejunum in the upper LEFT abdomen normally. If it's on the right, the bowel is malrotated.
Treatment:
- Emergency surgery to untwist the bowel
- If caught early, endoscopic decompression can be tried first
- Delay = bowel necrosis = life-threatening sepsis
🔶 10. Intussusception
What is it?
One part of the bowel telescopes/slides into the next segment, like a sock folding inside itself. This blocks blood flow and causes obstruction.
- Most common intestinal obstruction in children age 6-36 months
- Most common location: ileocolic junction (ileum slides into colon)
- Causes: viral infections (Peyer's patch hypertrophy), polyps, Henoch-Schönlein Purpura hematomas, lymphoma
Signs:
- Colicky abdominal pain (comes and goes, baby screams and then goes quiet)
- Bilious vomiting
- Currant jelly stool - bloody, mucusy stool (classic!)
- Palpable "sausage-shaped" mass in the right upper abdomen
Diagnosis:
- Ultrasound first - shows "doughnut sign" or "target sign" (concentric rings of bowel layers)
Treatment:
- IV fluids + electrolyte correction
- NG tube decompression
- Air or saline enema under ultrasound guidance - this both diagnoses AND treats
- If enema fails: emergency surgery (to prevent bowel necrosis)
🔶 11. Meckel's Diverticulum
What is it?
A small pouch left over from fetal development (remnant of the vitelline duct connecting the gut to the yolk sac). It sticks out from the small intestine.
- 85% contain ectopic gastric tissue (stomach cells in the wrong place!) - these cells secrete acid and can ulcerate the surrounding bowel
The Rule of 2s (easy to remember!):
| Rule | Detail |
|---|
| 2% of population | Very common finding |
| Under age 2 | Usually presents in children |
| 2x more in males | Boys affected more |
| 2% become symptomatic | Most never cause problems |
| 2 types of ectopic tissue | Gastric + pancreatic |
| 2 feet from ileocecal valve | Specific location |
| ~2 inches long | Size |
Signs:
- Usually no symptoms (found incidentally)
- Most common symptom: painless rectal bleeding (ectopic gastric acid ulcerates the bowel)
- Can mimic appendicitis if it gets inflamed
Diagnosis:
- Technetium-99m scan (Meckel's scan) - radioactive tracer lights up gastric mucosa including ectopic tissue
Treatment:
- Surgical removal (resection) to prevent bleeding or complications like intussusception
🔶 12. Necrotizing Enterocolitis (NEC)
What is it?
The bowel wall starts dying (necrosing) and bacteria invade it. This is the most common GI emergency in the neonatal ICU - mortality up to 30%.
- Affects mainly premature babies with very low birth weight
- The premature gut is too leaky, has poor defenses, poor motility - bacteria overgrow and destroy the bowel wall
- Also occurs in term babies with poor gut blood flow (heart defects, hypotension)
- Breast milk reduces NEC risk - give breast milk instead of formula whenever possible
Signs:
- Premature baby with: vomiting + abdominal distension + fever
- Blood in stool
Diagnosis:
- X-ray shows "pneumatosis intestinalis" - air INSIDE the bowel wall (pathognomonic/classic)
- CT shows air in the portal vein, dilated bowel loops
- If perforation occurs: pneumoperitoneum (air in the abdomen)
Treatment:
- Stop all feeds - bowel rest
- IV fluids immediately
- NG tube decompression
- Broad-spectrum IV antibiotics
- If no improvement: surgery to remove dead bowel
🔶 13. Congenital Diaphragmatic Hernia (CDH)
What is it?
The diaphragm (muscle separating chest from abdomen) has a hole - so abdominal organs (stomach, intestines, sometimes liver) push up into the chest. This prevents the lungs from growing properly.
Problems:
- Breathing difficulty at birth
- Pulmonary hypertension (high blood pressure in the lungs)
- ⚠️ Respiratory distress within 6 hours of birth = poor prognosis sign
Treatment:
- Surgery to push organs back and close the diaphragm
- Ventilator support for the underdeveloped lungs
🔶 14. Appendicitis
What is it?
Inflammation of the appendix (a small finger-like pouch attached to the large intestine in the lower right abdomen). If it bursts, bacteria spill into the abdomen = life-threatening emergency.
Classic Symptoms:
- Pain that starts around the belly button, then moves to the lower right abdomen (McBurney's point)
- Pain worsens with walking, coughing, pressing on the area
- Nausea, vomiting
- Loss of appetite
- Low-grade fever
- Constipation or diarrhea
Physical Exam Signs:
| Sign | What It Means |
|---|
| McBurney's Point tenderness | Press lower right abdomen - tenderness there |
| Rebound tenderness | Pain increases when pressure suddenly released |
| Rovsing's sign | Press LEFT side - pain felt on RIGHT side |
| Psoas sign | Pain when extending right leg - inflamed appendix touching psoas muscle |
| Obturator sign | Pain when rotating right leg internally |
Lab Tests:
- CBC: High white blood cells (leukocytosis) = infection
- CRP: Elevated = inflammation
- Urinalysis: Rules out UTI or kidney stones
- Pregnancy test in females: Rules out ectopic pregnancy
Pediatric Appendicitis Score (PAS):
| Score | Risk | Action |
|---|
| 0-2 | Low risk | Safe to discharge with monitoring |
| 3-6 | Moderate | Get ultrasound |
| 7+ | High risk | Surgery likely needed |
Imaging:
- CT scan - most accurate in adults
- Ultrasound - preferred for children and pregnant patients (no radiation)
- MRI - for pregnant patients if ultrasound is unclear
Treatment:
- Surgery (laparoscopic or open appendectomy) - definitive
- Antibiotics (Ceftriaxone + Metronidazole) - for mild cases or as bridge to surgery
✅ Quick Summary Table - All GI Conditions
| Condition | Key Feature | Vomiting Color | Key Test | Treatment |
|---|
| Esophageal Atresia + TEF | Chokes on 1st feed | N/A | NG tube coils on X-ray | Surgery (2-step) |
| Pyloric Stenosis | Projectile vomiting, hungry baby | Non-bilious (white) | Ultrasound | Pyloromyotomy |
| GER | Spitting up, happy baby | N/A | Clinical | Small feeds, upright position |
| Hirschsprung | No meconium >48h, squirt sign | N/A | Rectal biopsy | 3-stage surgery |
| Meconium Ileus | Thick meconium, CF | N/A | Gastrografin enema | Enema ± surgery |
| Imperforate Anus | No anus on exam | N/A | Physical exam | Surgery |
| Duodenal Atresia | Vomiting at 12h, Down syndrome | Bilious (green) | Double bubble sign | Duodenostomy |
| Jejunal Atresia | Drug/cocaine exposure | Bilious | Triple bubble/apple peel | Surgery |
| Volvulus | Severe pain, twisting | Bilious | Upper GI series (corkscrew) | Emergency surgery |
| Intussusception | Currant jelly stool, sausage mass | Bilious | Ultrasound (doughnut sign) | Air enema ± surgery |
| Meckel's Diverticulum | Painless rectal bleed, rule of 2s | N/A | Technetium-99m scan | Surgical resection |
| NEC | Premature baby, pneumatosis | N/A | X-ray (air in bowel wall) | Stop feeds + antibiotics ± surgery |
| CDH | Breathing difficulty at birth | N/A | X-ray (bowel in chest) | Surgery + ventilator |
| Appendicitis | RLQ pain moves from umbilicus | N/A | CT/Ultrasound | Appendectomy ± antibiotics |