- Fetal Upturned Nose
- IgA Nephropathy in Pregnancy
- Umbilical vein varix
- Timing of Cranial Markers in Open NTD
- Real world experience Open Neural tube defect and Brain Signs
- Real world experience First Trimester Megacystis – Management
- Real world experience Fetal Megacystis
- Abnormal facial profile
- Azygous Vein & ARSA
- Blakes Pouch Cyst
- Absent nasal bone (ANB)
- Choroid plexus cysts
- Chronic placental abruption
- Fetal Alcohol Syndrome
- Placenta-First Risk Stratification
- AVSD
- Blakes Pouch Cyst
- Confined Placental Mosaicism
- Echogenic Bowel
- Fetal Anemia
- Fetal Club Foot
- Fetal Mild Micromelia
- Hypochondroplasia – Mild Micromelia
- Hypoplastic Nasal Bone
- IgM IgG IgG Avidity
- Increased Nuchal Translucency
- Isotretinoin in Pregnancy
- Partial agenesis of corpus callosum
- PGT A
- PGT-A Mosaicism to CPM
- Placenta First - CPM
- Radiation exposure during pregnancy
- Real world Chorionic bump experience
- Real world Fetal Isotretinoin exposure
- Real world Increased Nuchal Translucency & Genetic RISK
- Real world Renal Pyelectasis
- Real world Transient NT & Cystic Hygroma
- Real world Transient NT
- Renal Pyelectasis or Extra Renal Pelvis
- Right And Double Aortic Arch
- Short Femur Length Foot FL ratio
- Y Microdeletion
- CCAM CPAM
- Coffin–Siris syndrome
- Congenital CMV Infection
- Increased NT and Localized CHAOS
- Indomethacin and Reduction for AFI
- Atrioventricular septal defect (AVSD)
- Choledochal cyst & Cystic biliary atresia
- Duodenal Atresia
- Fetal atrial bigeminy
- Fetal Dilated stomach
- Mutation Types in DMD
- Risk of rubella in nonimmune pregnant woman
- Salt-losing nephropathy
- Syndromic Cystic biliary atresia
- TGA DORV TOF CCTGA
- Unilateral echogenic kidney with polyhydramnios
- Unilateral renal agenesis, Ectopic, Cross fused kidney
Atrioventricular septal defect (AVSD)
Major etiologies of AVSD
1. Chromosomal abnormalities
- Trisomy 21 (Down syndrome)
- Most common etiology overall
- Present in ~40–50% of fetuses with AVSD
- Especially complete AVSD
- Often associated with:
- Duodenal atresia (double bubble)
- Mild ventriculomegaly
- Short long bones
- Echogenic bowel
- Increased NT in first trimester
2. Syndromic and genetic causes
- Ellis–van Creveld Syndrome
- Short limbs
- Postaxial polydactyly
- Narrow thorax
- Noonan Syndrome
- CHARGE Syndrome
- Heterotaxy Syndrome
- Especially left atrial isomerism
- Often with interrupted IVC
- Abnormal cardiac situs
- Smith–Lemli–Opitz Syndrome
3. Sporadic developmental cause
Occurs due to abnormal development of:
- Endocardial cushions
This is the fundamental embryologic basis of AVSD:
- Failure of fusion of superior and inferior endocardial cushions
- Leads to:
- Common AV valve
- Septal defects at atrial and ventricular level
Most isolated AVSDs without syndromes fall into this group.
4. Maternal/environmental factors
These are weaker associations but relevant:
- Maternal diabetes
- Maternal obesity
- Retinoic acid exposure
- Poorly controlled phenylketonuria
Types of AVSD
Complete AVSD
- Strongest association with Trisomy 21
- Often detected prenatally
- More likely syndromic
Partial AVSD
- May be isolated
- Lower chromosomal risk than complete AVSD
Transitional AVSD
- Intermediate features
- Genetic risk depends on associated findings
Important combined associations
When you see AVSD + double bubble, think strongly of:
- Trisomy 21
Prenatal risk estimates to remember
- AVSD → Trisomy 21 risk ~40–50%
- AVSD + additional anomalies → Risk increases significantly
- Isolated AVSD → Still ~30–40% chromosomal risk