Pediatric Abdominal Imaging

Neonatal Obstruction - Blocked Pipes & Twisted Guts

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Inflammation/Invagination - Fiery Bellies & Telescopes

Necrotizing Enterocolitis (NEC)

• Acute bowel inflammation/necrosis, mainly in premature infants. Risk factors: prematurity, formula feeding.
• Key X-ray findings:
  • Pneumatosis intestinalis (intramural air) - hallmark.
  • Portal venous gas (severe sign).
  • Pneumoperitoneum (indicates perforation).
• Bell's Staging guides management. Complications: strictures, short bowel syndrome.

Intussusception

• Telescoping of bowel segment; commonest cause of obstruction in children < 2 years (peak 6-36 months).

• Typically ileocolic & idiopathic. Lead point (e.g., Meckel's diverticulum, polyp) more common in older children or recurrent cases.

• Clinical: Sudden, severe, colicky abdominal pain; vomiting; red currant jelly stool (late sign). Palpable sausage-shaped mass.

• Diagnosis & Management Flow:

  ⭐ "Target sign" (concentric rings) on ultrasound is pathognomonic for intussusception.

Pediatric Abdominal Masses - Lumpy Tummy Terrors

• Wilms' Tumor (Nephroblastoma):
  • Most common renal tumor (peak 3-4 yrs).
  • Intrarenal, well-circumscribed, "claw sign".
  • Assoc: WAGR, Denys-Drash, Beckwith-Wiedemann.
• Neuroblastoma:
  • Most common extracranial solid tumor (median age <2 yrs).
  • Adrenal/sympathetic chain; crosses midline; calcifications.
  • ↑ VMA/HVA; N-myc. 📌 "N"euroblastoma: N-myc, Near midline, Nerve origin.
• Hepatoblastoma:
  • Most common primary malignant liver tumor (peak 1-2 yrs).
  • Solitary, large, ↑ AFP.
  • Assoc: Beckwith-Wiedemann, FAP.
• Teratoma:
  • Germ cell tumor; sacrococcygeal common.
  • Mixed: solid, cystic, fat, calcification.

⭐ Neuroblastoma often presents with calcifications (seen in up to 85% on CT) and commonly crosses the midline, distinguishing it from Wilms' tumor which is typically intrarenal and does not cross the midline as frequently or extensively.

Hepatobiliary & Bowel - Yellow Babies & Lazy Bowels

• Biliary Atresia (BA):
  • Conjugated hyperbilirubinemia (onset 2-8 wks).
  • USG: Triangular Cord Sign (TCS) >4mm, small/absent GB, no post-feed contraction.
  • HIDA (post-phenobarb): No bowel excretion at 24 hrs.
  • Kasai <60-90 days.
• Choledochal Cyst:
  • Todani Type I (most common). Cystic biliary dilatation.
  • USG/MRCP diagnosis.
  • Risks: Cholangitis, cholangiocarcinoma.
• Neonatal Hepatitis:
  • Dx of exclusion. HIDA: Normal uptake, ↓/delayed excretion.
• Hirschsprung Disease (HD):
  • Aganglionosis (distal bowel, rectosigmoid).
  • Delayed meconium (>48 hrs).
  • Contrast Enema: Transition zone, rectosigmoid ratio <1.
  • Biopsy: Gold std (absent ganglion cells).

  ⭐ Triangular Cord Sign (TCS) on USG: >4mm echogenic density anterior to portal vein, highly specific for Biliary Atresia.

High‑Yield Points - ⚡ Biggest Takeaways

• Necrotizing Enterocolitis (NEC): Pneumatosis intestinalis is key; portal venous gas signifies severity.
• Intussusception: Target sign or doughnut sign on USG; air/contrast enema for diagnosis & therapy.
• Hypertrophic Pyloric Stenosis (HPS): USG shows pyloric muscle >3 mm thick, canal >14 mm long.
• Malrotation with Volvulus: Upper GI series shows corkscrew sign; USG may show whirlpool sign.
• Hirschsprung's Disease: Contrast enema reveals transition zone; rectal biopsy confirms.
• Wilms' Tumor: Most common childhood renal malignancy; claw sign on imaging.
• Neuroblastoma: Common extracranial solid tumor, often adrenal; may show calcifications on imaging.