Congenital Anomalies

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Congenital Anomalies: General Principles - Tiny Troublemakers

  • Structural/functional defects at birth; major cause of infant mortality.
  • Classification:
    • Malformation: Intrinsic error in morphogenesis (e.g., cleft palate).
    • Deformation: Extrinsic mechanical forces (e.g., positional talipes).
    • Disruption: Breakdown of normal tissue (e.g., amniotic bands).
    • Dysplasia: Abnormal cell organization in tissue (e.g., skeletal dysplasias).
    • Sequence: Anomalies from single defect (e.g., Potter sequence).
    • Syndrome: Multiple anomalies, common cause (e.g., Down syndrome).
  • Teratogens: Agents causing birth defects.
    • Critical period: Organogenesis (3-8 weeks).
    • 📌 TORCH (Toxo, Other, Rubella, CMV, Herpes).
    • Drugs: Thalidomide, Valproate (NTDs), Warfarin, ACEi.
    • Maternal: Diabetes (caudal regression, VSD), PKU.
  • Prevention: Folic acid (0.4 mg/day).

⭐ The most common major congenital anomaly is congenital heart disease.

Congenital Anomalies: CNS - Brainy Birth Bumps

  • Neural Tube Defects (NTDs)
    • Prevention: Folic acid (0.4 mg/day; 4 mg/day high risk).
    • Dx: ↑AFP, ↑Amniotic AChE.
    • Types:
      TypeKey Feature
      AnencephalyAbsent brain/skull; "frog-like"
      EncephaloceleBrain/meninges herniation via skull
      Spina Bifida OccultaVertebral defect, hair tuft
      Spina Bifida CysticaMeningocele, Myelomeningocele (+neural tissue)
    Types of Neural Tube Defects
  • Hydrocephalus: ↑CSF; Signs: ↑HC, bulging fontanelle, sunset eyes.
    • Types: Communicating (↓absorption), Non-communicating (obstruction, e.g., aqueductal stenosis).
  • Holoprosencephaly: Forebrain cleavage failure. Facial anomalies. Trisomy 13.
  • Dandy-Walker Malformation: 4th vent. cystic dilation, cerebellar vermis agenesis.
  • Arnold-Chiari Malformation Type II: Cerebellar, brainstem herniation.

    ⭐ Arnold-Chiari Type II: strong assoc. with myelomeningocele.

  • Microcephaly: HC < -2 SD. Causes: TORCH, genetic, FAS.
  • Lissencephaly: Smooth brain (agyria). Severe neuro deficit.

Congenital Anomalies: CVS - Heart's Hiccups

  • CHD Types:
    Shunt TypeExamplesClinical CluesO2 Test (PaO2)
    Acyanotic (L→R)VSD, ASD, PDACHF, ↑Pulm. flowResponds
    Cyanotic (R→L)TOF, TGACyanosis, ↓Syst. O2No response
  • VSD (Ventricular Septal Defect): Most common CHD. Harsh pansystolic murmur (L lower sternal border).
    • Ventricular Septal Defect (VSD) Illustration
  • ASD (Atrial Septal Defect): Wide, fixed split S2. Ostium secundum commonest.
  • PDA (Patent Ductus Arteriosus): Continuous machinery murmur (L infraclavicular). Close: Indomethacin. Open: Prostaglandin E1 (PGE1) (0.05-0.1 mcg/kg/min).
  • TOF (Tetralogy of Fallot): 📌 PROVe (Pulmonary Stenosis, RVH, Overriding aorta, VSD). Boot-shaped heart (CXR). Tet spells (knee-chest position).
    • Tetralogy of Fallot: X-ray and diagram
  • TGA (Transposition of Great Arteries): Severe cyanosis at birth. "Egg-on-string" (CXR). PGE1 vital for mixing.

⭐ VSD is the most common congenital heart defect; Bicuspid Aortic Valve is the most common congenital cardiovascular malformation overall.

Congenital Anomalies: GIT & Abdomen - Gut Gaffes & Outies

  • Tracheoesophageal Fistula (TEF) & Esophageal Atresia (EA):

    • Most common: Type C (EA + distal TEF, 85%). Polyhydramnios.
    • 📌 VACTERL: Vertebral, Anal, Cardiac, TEF, Renal, Limb.
    • Dx: NG tube coils in esophageal pouch. Types of Esophageal Atresia and Tracheoesophageal Fistula
  • Duodenal Atresia:

    • "Double bubble" sign on X-ray. Bilious vomiting.
    • Associated with Down syndrome (30%).
  • Malrotation with Volvulus:

    • Bilious vomiting in neonate = surgical emergency!
    • "Corkscrew" sign on upper GI contrast study.
  • Omphalocele vs. Gastroschisis:

    FeatureOmphaloceleGastroschisis
    SacPresent (amnion, peritoneum)Absent
    LocationMidline, umbilical cord inserts into sacRight of umbilicus, cord insertion normal
    BowelUsually normalEdematous, matted, inflamed
    Liver in sacCommonRare
    Associated anom.Common (50-70%, cardiac, chromosomal)Less common (10-15%, e.g., gut atresia)
    Maternal AFP↑↑

    Differential Diagnosis: Anterior Abdomen Defects

⭐ Gastroschisis: No sac means bowel is exposed to amniotic fluid, leading to chemical peritonitis; often an isolated defect compared to omphalocele which has higher rates of associated anomalies.

High‑Yield Points - ⚡ Biggest Takeaways

  • Neural Tube Defects: Folic acid prevents; anencephaly & spina bifida are key types.
  • Congenital Heart Defects: Most common; VSD most frequent. Differentiate cyanotic (e.g., TOF) vs. acyanotic (e.g., ASD).
  • Down Syndrome (Trisomy 21): Linked to duodenal atresia ("double bubble") and AV canal defects.
  • Diaphragmatic Hernia: Usually left-sided (Bochdalek), causes severe pulmonary hypoplasia.
  • Esophageal Atresia/TEF: Polyhydramnios, choking with feeds; Type C (distal TEF) is most common.
  • Gastroschisis vs. Omphalocele: Gastroschisis (no sac, bowel exposed); Omphalocele (sac present, other anomalies common).

Practice Questions: Congenital Anomalies

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Which of the following statements about encephalocoele is false?

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Flashcards: Congenital Anomalies

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Type _____ of trachoesophageal fistula consists of fistula without atresia

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Type _____ of trachoesophageal fistula consists of fistula without atresia

E (or H)

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