O.14.2 Chromosomal Abnormalities 2 of 2 PDF

ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 1 2 Chromosomal Abnormalities textbook reference Module O.14 Abnormal Fetal Karyotype • • Rumack 5th Edition Chapter 31 Chromosomal Abnormalities – Part 2 3 4 Chromosomal Abnormalities –...

ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 1 2 Chromosomal Abnormalities textbook reference Module O.14 Abnormal Fetal Karyotype • • Rumack 5th Edition Chapter 31 Chromosomal Abnormalities – Part 2 3 4 Chromosomal Abnormalities – Part 1 • Chromosomes • Congenital anomalies • Aneuploidy • Syndromes • Risk factors • Testing and screening 5 Chromosomal Abnormalities – Part 2 • Ultrasound screening 6 Testing and Screening Tests Testing and Screening • Maternal blood tests • Ultrasound O.14.1 1 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 7 8 Ultrasound Screening Diagnostic medical sonography Ultrasound Screening 9 • General department and/or fetal assessment unit • 1st trimester • 11‐14 weeks GA – nuchal translucency • 2nd trimester • Major abnormalities (structural) • Minor abnormalities (“soft” markers) 10 Nuchal Translucency • • Nuchal Translucency • • 11 Anechoic fluid collection under skin in posterior neck ≥ 2.5 mm AP between 11‐14 weeks GA is abnormal • Rumack: a NT > 95th percentile by CRL is abnormal The greater the NT the higher the risk of aneuploidy and cardiac anomalies • Trisomy 21 Highest risk Adjusted risk determined with maternal age and biochemistry 12 Nuchal translucency – screening ultrasound • Only performed if indicated • Age, risk of anomalies, etc. • Patient counseling done • Prevents fetal loss • Amniocentesis may not be performed if the NT measures normal (1/200 chance of loss with amniocentesis) Nuchal translucency – measurement • Maximum AP diameter • Calipers placed on the inner borders of the lines of the translucency region • Measurement ≥ 2.5 mm is abnormal CORRECT c 2 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 13 14 Nuchal translucency Nuchal translucency • Abnormally thick • Abnormally thick • EVS 9.5 weeks GA • Skin edema • Karyotype: trisomy 21 • Karyotype: trisomy 21 Textbook of Diagnostic Sonography, 7th Edition (Hagen‐Ansert fig 57‐31) 15 16 2nd Trimester Ultrasound “No detectable abnormalities” • 2nd Trimester Ultrasound A normal ultrasound reduces the likelihood of aneuploidy e.g. Likelihood when no abnormalities detected: 17 • Trisomy 21: 0.5 times lower than background risk • Trisomy 13 or 18: 5 times lower than background risk 18 2nd trimester US – markers for Down Marker 2nd trimester US – aneuploidy abnormalities Risk above background Nuchal thickening 10x Hyperechoic bowel 5x Short femur 2x Echogenic cardiac foci 2x controversial Choroid plexus cyst 1.5x Mild ventriculomegaly 1.5x Mild hydronephrosis 2‐3% Soft marker Finding that may indicate increased risk of anomaly but not significant if an isolated finding • Central nervous system • GI tract • Face • Abdominal wall • Neck • GU tract • Thoracic • Skeletal • Cardiac • Other abnormalities 3 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 19 20 Central Nervous System Increased risk of aneuploidy • Alobar holoprosencephaly • Choroid plexus cysts • Mild ventriculomegaly • Dandy‐Walker malformation • Microcephaly • Abnormal head shape • Facial abnormalities Abnormalities Associated with Aneuploidy Central Nervous System 21 – trisomy 13 Highest risk – trisomy 18 & 21 – trisomy 21 – trisomy 18 – trisomy 13 – trisomy 18 & 21 – all trisomies 22 Alobar holoprosencephaly CNS – alobar holoprosencephaly • • Risk of chromosomal abnormality: • Slight – if isolated • Increased – if other abnormalities detected • Trisomy 13 • Coronal fetal head shows monoventricle and fused thalami Most common aneuploidy – trisomy 13 Ultrasonography in Obstetrics and Gynecology, 5th Edition (Callen fig 10‐17) 23 24 CNS – choroid plexus cysts • • • Risk of chromosomal abnormality: • Slight – if isolated • Increased significantly – if one or two additional abnormalities detected Most common aneuploidy – trisomy 18 Slight risk – trisomy 21 Choroid plexus cysts • Risk of trisomy 18 or 21 • Transverse fetal head shows choroid plexus cyst • Check hands and heart • Make sure hands open and close 4 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 25 26 CNS – mild ventriculomegaly • Lateral ventricle atrial diameter measures 10‐15 mm • Risk of chromosomal abnormality: • Slight – if isolated • Mild ventriculomegaly • Trisomy 21 • 18 weeks GA • Lateral ventricles demonstrate mild dilatation (11 mm) Most common aneuploidy – trisomy 21 27 28 CNS – Dandy‐Walker malformation • • Dandy‐Walker malformation Enlarged cisterna magna with a defect in the cerebellar vermis • Trisomy 18 • Fourth ventricle communicates with cisterna magna • Lateral displacement of cerebellar hemispheres Most common aneuploidy – trisomy 18 • Also associated with other aneuploidies Textbook of Diagnostic Sonography, 7th Edition (Hagen‐Ansert fig 48‐20) 29 30 CNS – microcephaly • Most trisomy 13 fetuses with microcephaly also have holoprosencephaly • Most common aneuploidy – trisomy 13 Microcephaly • Trisomy 13 • Fetus presented with microcephaly and holoprosencephaly 5 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 31 32 CNS – abnormal head shape Abnormal head shape Risk of aneuploidy: • Strawberry‐shaped head – trisomy 18 • Brachycephaly – trisomy 21 • 33 • Strawberry‐shaped head • Trisomy 18 • Narrow frontal diameter 34 Abnormal head shape Abnormalities Associated with Aneuploidy Face • Brachycephaly • Trisomy 21 • 32 weeks GA • BPD measures 36 weeks 35 36 Face Increased risk of aneuploidy (if NOT isolated) • Median cleft lip and palate – trisomy 13 • Ocular/nasal abnormalities – trisomy 13 • Micrognathia – trisomy 13/18 • Frontal bossing – trisomy 18 • Shortened/absent nasal bones – trisomy 21 Median cleft lip and palate • Trisomy 13 • Coronal face shows gaping midline cleft lip • Palate was also cleft N: nose L: upper lip 6 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 37 38 P Arrhinia and proboscis • Trisomy 13 (holoprosencephaly) • Other findings may include cleft lip (see previous case), hypotelorism/cyclopia, etc. Micrognathia L L: lips • Trisomy 18 (could have been 13) • 19 weeks GA • Sagittal head showing abnormally small mandible • Abnormal hands and large VSD also present P: proboscis 39 40 Absent nasal bone • Abnormalities Associated with Aneuploidy Neck Trisomy 21 normal NB 41 42 Neck Increased risk of aneuploidy • Cystic hygroma – Turner (45,X0) • Nuchal fold thickening – trisomy 21 Cystic hygroma (CH) • • • Turner syndrome 14 weeks GA Midline nuchal ligament (arrow) 7 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 43 44 Nuchal thickening • Trisomy 21 • Transcerebellar view shows increased nuchal skin Abnormalities Associated with Aneuploidy Thoracic Abnormal nuchal fold thickness: ≥ 5 mm between 15‐18 weeks GA ≥ 6 mm between 19‐24 weeks GA 45 46 Thoracic Increased risk of aneuploidy Congenital diaphragmatic hernia • Congenital diaphragmatic hernia – trisomy 18 • Trisomy 18 • Cardiac anomalies • 4 chamber heart in right chest • Cystic structure (stomach) – all trisomies h: heart st: stomach sp: spine 47 48 Cardiac Abnormalities Associated with Aneuploidy Cardiac Increased risk of aneuploidy • Significantly increased risk for all trisomies and Turner • Strongest association between atrioventricular septal defect (endocardial cushion) and trisomy 21 • Echogenic cardiac foci – trisomy 13 & 21 8 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 49 50 Cardiac abnormalities – echogenic cardiac foci Atrioventricular septal defect • Trisomy 21 • 4 chamber heart view • Enlarged heart with VSD and ASD • Calipers show length of VSD 51 • True echogenic foci located at papillary muscle tip • Majority in the left ventricle • Risk of chromosomal abnormality: Most common • Trisomy 13 • Slight risk of trisomy 21 if advanced maternal age 52 Echogenic intracardiac foci • Risk of trisomy 13 & 21 • 4 chamber heart shows multiple echogenic foci in left and right ventricles 53 Abnormalities Associated with Aneuploidy GI Tract 54 GI Tract Increased risk of aneuploidy Duodenal atresia • Duodenal atresia – trisomy 21 • Trisomy 21 • Echogenic bowel – trisomy 21 • 22 weeks GA • “Double bubble” sign (should connect) 9 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 55 56 GI Tract GI tract – echogenic bowel • • Echogenic bowel Risk of chromosomal abnormality: • Slight risk – if isolated • Increased significantly – if other abnormalities found Most common aneuploidy – trisomy 21 57 • Trisomy 21 • 20 weeks GA • Bowel isoechoic to fetal bone (arrow) 58 Abdominal Wall Increased risk of aneuploidy Abnormalities Associated with Aneuploidy Abdominal Wall 59 • Omphalocele – trisomy 18 • Gastroschisis – slight risk 60 Abdominal wall – omphalocele • Risk of chromosomal abnormality: • Increased – if omphalocele contains only bowel • Most common aneuploidy – trisomy 18 Omphalocele • Trisomy 18 • Transverse fetal abdomen at cord insertion • Loop of bowel (arrow) herniated into base of umbilical cord (arrowheads) 10 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 61 62 GU Tract Risk of aneuploidy Abnormalities Associated with Aneuploidy GU Tract 63 • Low incidence, but can occur in all aneuploidies • Most common aneuploidy is trisomy 13 • MCDK • Renal pyelectasis / hydronephrosis – trisomy 21 • Slight increase in risk – trisomy 18 64 Renal pyelectasis / hydronephrosis MCDK • Trisomy 18 • Fetus with multicystic dysplastic kidney 65 • Most common aneuploidy – trisomy 21 66 Renal pyelectasis • Trisomy 21 • Transverse fetal kidneys • Bilateral renal pyelectasis • Renal pelvis measures 7 mm AP diameter Abnormalities Associated with Aneuploidy Skeletal 11 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 67 68 Skeletal Increased risk of aneuploidy Skeletal – short femur • Short femur – trisomy 21 • Most common – trisomy 21 • Widened iliac angle – trisomy 21 • • Hand/foot abnormalities – all trisomies If femur measures short, assess other long bones and consider follow‐up 69 70 Iliac widening • Trisomy 21 • Skeletal – hand and foot abnormalities normal Transverse fetal pelvis 110° 71 • Clenched hand with overlapping fingers – trisomy 18 • Rocker bottom feet • Club foot – trisomy 18 • Clinodactyly (5th finger) – trisomy 21 • Sandal gap toes – trisomy 21 • Polydactyly – trisomy 13 – trisomy 18 72 Clenched hand • Trisomy 18 Rocker bottom foot • Trisomy 18 12 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 73 74 Club foot Clinodactyly Trisomy 18 • 75 • Trisomy 21 • Small middle phalanx of 5th digit • Inward curvature of digit 76 Sandal gap toes • Trisomy 21 Polydactyly • Trisomy 13 postnatal 77 78 Fetal hand • Normal! • No “sandal gap” sign exists for the hand Abnormalities Associated with Aneuploidy Other Sonographic Abnormalities 13 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 79 80 Other Sonographic Abnormalities Increased risk of aneuploidy Single umbilical artery • Single umbilical artery • Risk of aneuploidy is not significant if an isolated finding • Polyhydramnios & IUGR – trisomy 18 • Seen with more than one aneuploidy • IUGR • Severe assymetric IUGR – triploidy • Thick, cystic placenta – trisomy 13, 18, & triploidy – triploidy 81 82 Single umbilical artery (2VC) 3VC Polyhydramnios & IUGR • Trisomy 18 2VC NORMAL ABNORMAL 83 • Axial fetal abdomen (F) measures small • Severe polyhydramnios (AF) 84 Intrauterine growth restriction (IUGR) • Risk of trisomy 18, 13, and triploidy • Aneuploidy with IUGR often presents with multiple structural abnormalities Severe IUGR – head is normal size for GA, AC is small • Triploidy 14 ULTR‐3014 OBGYN Sonography 3 Module O.14: Abnormal Fetal Karyotype 2 Chromosomal Abnormalities – Part 2 85 86 Thick placenta with cystic areas • Triploidy • Seeing a molar placenta before 20 weeks is the most common sign of triploidy Module O.14 Abnormal Fetal Karyotype Chromosomal Abnormalities – Part 2 87 References WRHA guidelines for prenatal screening bit.ly/3vr2VHO Calculating NT percentile by CRL (>95th percentile is abnormal as per Rumack) bit.ly/3vz0ZNT 15