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Ultrasound Detection of the Chromosomal Abnormalities

Ultrasound Detection of the Chromosomal Abnormalities. DR. NABEEL BONDAGJI FRCSC, FACOG Associate Prof. Consultant King Abdulaziz University Hospital. Consultant Perinatologist King Faisal Specialist Hospital & Research Center - Jeddah. Introduction. Spontaneous abortions  50%

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Ultrasound Detection of the Chromosomal Abnormalities

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  1. Ultrasound Detection of the Chromosomal Abnormalities DR. NABEEL BONDAGJI FRCSC, FACOG Associate Prof. Consultant King Abdulaziz University Hospital Consultant Perinatologist King Faisal Specialist Hospital & Research Center - Jeddah

  2. Introduction • Spontaneous abortions  50% • 50% trisomy • 25% monosomy • 10-15% mosaic • Others • Stillbirths/neonatal deaths  6-11% • Live births  0.56% • 1/3 autosomal, 1/3 sex xm, 1/3 other • In AMA patients undergoing amnio (2.26%) • 64% trisomy, 17% sex xm, 19% other

  3. Current Screening Methods • Advanced maternal age (AMA) ( 35 yrs) • Maternal serum screening (MSS, triple test. Free BHCG & Alpha HCG and the PAPPA • Family/personal history • Ultrasound

  4. Diagnostic Methods • Amniocentesis  Early  Mid trimester • CVS • Cordocentesis • Fetal cells in the maternal circulation (experimental)

  5. Frequency of aneuploidies vs the number of anomalies PERCENTAGE Number of anomalies

  6. How Good is Ultrasound in Detecting Anomalies? • Chity et al BMJ 1991 8432 2nd trimester U/S 74% detection rate 87% severe anomalies • Lucle et al BMJ 1992 8523 2nd trimester U/S 87.5% detection 92.9% severe anomalies

  7. Accuracy of Ultrasound in Detection of Chromosomal Abnormalities Variables: Trisomy 18 85-90% detection Trisomy 13 85% detection Trisomy 21 60% detection

  8. Specific Chromosomal Abnormalities • Triploidy • Trisomy 13 • Trisomy 18 • Trisomy 21 • Monosomy 45 x 0 Turner S.

  9. Trisomy 21(Down Syndrome) 1:660 M:F 1:1 ULTRASOUND ABNORMALITIES ASSOCIATED WITH DOWN SYNDROME • Nuchal translucency (nuchal edema) 40% of D.S. at 13 weeks • Thickened nucal fold 2nd trimester 5-33% down • Ventriculomegally • Flattened facial profile

  10. Isolated pleural effusion • Congenital heart disease 50% of D.S. comment is endocardial cushion effect • Duodenal atresia 25% of Down (double bubble) 8.Ecogenic focus in the heart

  11. Dilatation of the renal pelvis • Short femure : 0.91 of the expected femur length increase the rate of detection sensitivity 68%, specificity 98%. (Benacerraf)

  12. Short humorous • Short fifth finger • The big toe separated from the rest (sandal sign) • Echogenic bowels • 12.5% of Down babies +ve • 5% folds increase in Down Syndrome

  13. Prognosis • CHD – shorten the life span • GI Defect • I.Q. is limited 25-50 • Hypotonia

  14. First Trimester Nuchal Edema • Nicolaides et al (BMJ ’92) • 827 women undergoing 1st TM karyotyping • Nuchal edema: Subcutaneous translucency between skin and overlying tissue  3mm • 51/827 (6%) cases had nuchal edema (3mm-8mm) • Abnormal chromosomes 18/51 (35%) mainly T21) • Only 10/776 (1%) with no nuchal edema were chromosomally abnormal

  15. First TM Nuchal Edema • Nuchal edema  3mm assoc with 10x risk for Xm abn • Mainly trisomies (T21) as in 2nd TM NF • Sensitivity for T21 is approx 75% • Incidence of nuchal edema in normal is approx 4%

  16. Pondya and Nicalaides Ultrasound in OB/GYN 1995 1015 Amnio for Increasing Nuchal Translucency Thickness 3 mm 3 times higher than expected on basis of age 4 mm 18 times 5 mm 28 times 6 mm 36 times

  17. Echogenic Bowel • Nyberg et al (Obstet Gynecol’91) • 7% of T21 fetuses had echogenic bowel (2nd TM) • Scioscia et al (Am J ’92) • 6/19 (32%) of fetuses with echogenic bowel had Xm abn • 5 T21, 1 T18 HOWEVER, 4/6 had other abnormalities • Crane et al • 1/30 (3.3%) cases with echogenic bowel had T18

  18. Fetal Cerebral Ventriculomegaly • Filly et al (’91): Posterior horns of lateral ventricles • GA independent (15-40 weeks) • Normal < 10mm (mean 6-7 mm) • Borderline 10-12 mm (or 10-15 mm) • Abnormal  15mm • Should be routinely measured at 18 week scan

  19. Isolated Mild Ventriculomegaly • Summary of published cases (Achiron ’89-92) • Incidence of fetal trisomy: 11/92 (12%) • Spontaneous resolution in utero: 17 (18%)

  20. Benacerraf and Group Scoring System • Nucal Fold =2 • Major structural defect =2 e.g. endocardial cushion, ompholocele, etc. Short femur & S = 1 Echogenic focus = 1 Pylactasis = 1 Echogenic Bowel = 1 Assoc with 2 or more will detect 81% of Down fetuses

  21. TRISOMY 18 Incidence: 1:3000 1:5000 M:F 1:3

  22. Ultrasound Abnormalities • Limb abnormalities clenched hand and overlapping of the fingers Rocker-Bottom feet • Micrognethia • Congenital Heart Disease in 80% • VSD comment • TGV Fallot Tetralogy

  23. choroid plexus cyst 25% • 2-9% of CPC associated with trisomy 18 • Omphalocele 25% • Enlarged cisterna magna 15% • Echogenic chordae tendaneai 35% • Diaphragmatic hernia 30% associated of aneuploidy and the majority are 18%

  24. The Posterior Fossa • Includes cerebellum and cisterna magna • Measures 1-10 mm (>10mm abnormal) • Abnormalities: • Dandy Walker malformation • Dandy Walker variant • Large cisterna magna (“Mega-cisterna magna”)

  25. Large Cisterna Magna • Cisterna magna  10mm • Vermis intact, hydrocephalus usually absent • Nyberg et al (Obstet Gynecol\91) • 33 fetuses cisterna magna > 10mm • Assoc anomalies 30/33 (90%) • Chromosome abnormalities 8/33 (55%) • T18 (12), T13 (3), other (3) • Correlated with absence of ventriculomegaly and presence of other anomalies

  26. Prognosis: lethal poor prognosis 70% antenatal still birth 85% die in 1st year all senses profound mental retardation - failure to thrive - hearing defect - visual difficulties - seizures

  27. Ultrasound AbnormalitiesAssociated with Trisomy 13 • Single umbilical artery • Midline cleft, Cyclops (45%) • Microcephaly (12%) Incidence 1:5000 1:10000 Births

  28. Holoprosencephaly (40%) • polydactly and syndactaly • Scalp defect • A S D, VSD and hypoplastic left heart • .agenesis of the corpus collosum

  29. Holoprosencephaly • Failure of cleavage of pros encephalon • Alobar, semilobar and lobar • Assoc with facial defects (cyclope, proboscis, clefts) • Incidence of chromosome abnormalities: 40-60% • Usually Trisomy 13 • Also trisomy 18, triploidy, 5p+, 13 q-,18p-.

  30. Agenesis of Corpus Callosum • Associated with variety of Xm abnormalities • Trisomy 13, 18, 8, triploidy and translocations • Bertino et al (J U/S Med’87) • 1/8 (14%) with fetus with agenesis CC: Trisomy 8

  31. Prognosis Lethal Poor Prognosis • 50% dies 1st two months • 90% dies 1st year • Survivors will develop profound mental retardation

  32. Ultrasound AbnormalitiesAssociated with Triploidy • Severe IUGR (early onset) • Oligohydramnios • Molar degeneration of the placenta • Holoprosencephaly & agenesis CC Prognosis: lethal antenatally mosaic M.R.

  33. Turner Syndrome 1:5000 1:1000 Ultrasound Abnormalities • Cystic hygroma 90% of Turner • CHD aortic coarctation • Renal agenesis & pelvic kidney and horse shoe kidney • Hydrops fetalis

  34. Prognosis:With hydrops mortality approaches 100% survivor: • Degree of CHD • Hearing defect 50% • Absence of 2nd sexual character and infertility • Skeletal growth retardation • Normal intelligence

  35. Nuchal Cystic Hygroma • Azar et al (Fetal Diag Ther ’91) • Abnormal chromosomes: 75% • Turner’s syndrome (45 x0): 94% • Assoc CHD 48%, renal 20%, abn biometry 90% • Normal chromosomes: 25% • Associated abnormalities: 75% • Live born healthy: 2-3%

  36. ThankYou

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