Prenatal Diagnosis and Aneuploidy Screening Diagnostico prenatal y screening de aneuploidias

1. Prenatal Diagnosis and Aneuploidy Screening Diagnostico prenatal y screening de aneuploidias Leonardo Pereira MD Assistant Professor Maternal-Fetal Medicine Oregon Health & Science University

2. Screening for aneuploidy

3. Screening for aneuploidy Test When What Performance* Diagnostic test Maternal Age > 35 y.o. Age alone T21 30-40% T18 30-40% NTD no relation 1.CVS or amniocentesis 2. higher miscarriage rate with T18 Ultrasound 10-12 Age + NT T21 75-80% CVS or amniocentesis Ultrasound 18-20 Age + sonogram T21 60% T18 85% NTD 70-98% Amniocentesis Triple Screen 16-20 (15-21) E3 msAFP BHCG T21 60-70% T18 60% NTD 75-80% Amniocentesis Quad Screen 16-20 (15-21) E3 msAFP BHCG Inhibin-A T21 75-80% T18 60% NTD 75-80% Amniocentesis FTS: First Trimester Screen, Ultrascreen 11-12 (10-14) PAPP-A Free BHCG NT T21 83-90% T18 80% NTD ----- 1.CVS or amniocentesis 2.Need msAFP 3. detection of miscarriages Integrated Screen 10-14 16-20 (15-21) PAPP-A NT Quad Screen T21 92% T18 90% NTD 80% Amniocentesis First trimester serum, stepwise sequential screen, contingency sequential screen *SPR 5%

4. Contingency Screening Very high risk 1:60 – refer for CVS Intermediate Risk – Go to second step Very low risk 1:1000 – done First Step Second step % Pop First trimester serum: have NT measured 40% (PAPP-A, Free BHCG) First trimester screen: have second trimester 20-25% (PAPP-A, Free BHCG, NT) serum screening First trimester screen: have first trimester 19% (PAPP-A, Free BHCG, NT) targeted US (DV, TV, Nasal Bone)

5. Future Directions First trimester US alone 3D/4D US Noninvasive Isolation of fetal DNA

6. First trimester screening for trisomy 21 by ultrasound and age* Test Performance NT T21 70-80% NT + nasal bone T21 85-90% Abnormal Ductus Venosus waveform T21 78% (at a SP rate of 1.7% in a high risk population)8 NT + nasal bone + abnormal DV T21 >90% at a lower SP rate 2-3% *SP = screen positive rate 5%

7. First Trimester US OSCAR study: One stop clinic for first trimester assessment of risk 30,564 pregnancies: age, NT, free-B HCG, PAPP-A median maternal age 34 196 cases of T21 – median maternal age 38 (0.64%) SP rate of 5%, detection of T21 using age + NT = 81% using age, NT, free-B HCG, PAPP-A = 90% FASTER study: First-Trimester or Second Trimester Screening, or both 33,546 pregnancies first and second trimester screening 29,834 (78%) < maternal age 35 87 cases of T21 (0.29%) detection rate using maternal age + NT not reported Estimated detection rates using 1999 U.S. pop distribution: SP rate of 5%, detection of T21 using age + NT = 64-70% using age, NT, free-B HCG, PAPP-A = 82-87% detection rates estimated to decrease with advancing weeks gestation 11-13

8. First Trimester US NT and other first-trimester sonographic markers of chromosomal abnormalities: analysis of 19 trials 200,868 pregnancies, 871 fetuses with T21 (0.43%) Age + NT = detects 77% of T21 at a SP rate of 4.6% Absent nasal bone detects 69% of T21 at a SP rate of 1.4% mid-sagittal view of the fetal profile with the US transducer held parallel to the longitudinal axis of the nasal bone Nicolaides 2004

9. First Trimester US – Nasal Bone Nasal bone present in a euploid fetus in the first trimester Nasal bone absent in a fetus with T21in the first trimester

10. Second Trimester US – Nasal Bone 3D US coronal view in the second trimester bilateral nasal bones present

11. First Trimester US How does the addition of nasal bone screening affect the detection rate for T21? Probably adds 5-10% to sensitivity at the same SP rate, or maintains the same detection rate at a lower SP rate FTS using simplified method to assess the nasal bone 2411 fetuses, 15 cases of T21 (0.62%) Nasal bone alone, sensitivity 53% (8/15); PPV 47% Standard FTS (age+NT+PAPP-A+free B-HCG): 87% at 4.3% SPR Standard FTS + nasal bone: 90% at 2.5% SPR 60 screen positives instead of 104 screen positives Orlandi 2005

12. First Trimester US Possible role for measurement of the ductus venosus

13. First Trimester US Screening for aneuploidy using first trimester DV abstract Murta 2005 934 fetuses, 49 aneuploid fetuses (5.2%) 38/49 aneuploid fetuses had absent or reversed DV flow during atrial contraction (sens 78%, spec 98%, PPV 72%); SP rate 1.8% Combination of FTS + nasal bone + DV screen: may allow for detection of > 90% of aneuploidy at a SP rate ~2% Other first trimester markers being investigated: maxillary bone length umbilical cord diameter omphalocele single umbilical artery megacystis fetal growth restriction abnormal heart rate

14. 3D/4D US Can 3D/4D US improve screening for aneuploidy and fetal anomalies? Ensure midsagittal views Easier to look for bilateral structures – vertebrae, nasal bones Cardiac imaging Technological improvements – “real time” transducers faster imaging Training/Experience of sonographers/sonologists Rendering Packages becoming easier to use; automation

15. 3D/4D US

16. 3D/4D US Use of 3D US to improve the detection of absent nasal bone Benoit, 2005

17. 3D/4D US Benoit, 2005

18. 3D/4D US Cardiac screening Automated image acquisition

20. Noninvasive Isolation of fetal DNA Potential sources of fetal DNA Maternal blood Cervical-vaginal secretions

21. Invasive Prenatal Diagnosis Complications associated with invasive prenatal diagnostic tests: Pregnancy loss (0.15%-1.0%) PPROM Vaginal bleeding Worsening sensitization of alloimmunization Infection Placental mosaicism

22. Invasive Prenatal Diagnosis Pregnancy loss after invasive testing: (0.15%-1.0%) Loss rates after CVS? TA vs. TC CVS? Loss rates after amniocentesis? FASTER trial: loss rate after amniocentesis 0.15% - abstract SMFM 2006

23. Invasive Prenatal Diagnosis Loss rate following amniocentesis Danish RCT*: 4606 women 25-34 y.o.; followed for 6 weeks spontaneous 0.7% vs. amniocentesis 1.7% RR 2.5, attributable loss rate due to amniocentesis: 1% *Tabor A, et al. RCT of amniocentesis in 4606 low risk women. Lancet 1986;1:1287-93

24. Invasive Prenatal Diagnosis

25. Invasive Prenatal Diagnosis Miscarriage rate for TC CVS vs. amniocentesis: favors amniocentesis

26. Invasive Prenatal Diagnosis Prospective 7 year trial in Denmark (21,723 CVS procedures, and 26,952 amniocentesis procedures) Main outcome measure was loss rate at 22 weeks gestation Pregnancy loss rate following CVS: 0.9% (210) Pregnancy loss rate following Amniocentesis: 0.8% (228) Conclusion: loss rate due to invasive procedures < 0.5% CVS may be the safest option; predominantly TA CVS

27. Invasive Prenatal Diagnosis Miscarriage rate for TA vs. TC CVS: trend to favor TA CVS But studies done in the 80’s Modest difference if any: 3.8% compared to 4.8% 18 gauge catheter vs. 20 gauge needle

28. Invasive Prenatal Diagnosis Single center comparison of loss rates following invasive diagnostic procedures* Miscarriage rate for amniocentesis vs. CVS >9,000 CVS and >20,000 amniocenteses Over time complication rates of both fell From 1998-2003: amnio and CVS had the same loss rate (OR 1.03) Both had loss rate 1: 360-370 over last 5 years Limitations: retrospective review, did not specify TA vs. TC CVS *Obstet Gynecol Sep 2006

29. Invasive Prenatal Diagnosis Complication rate from CVS or amniocentesis probably both <1%: TA CVS in experienced hands may be safest option CVS is safer than early amniocentesis: risk of talipes 2Δ amniocentesis slightly safer than TC CVS, same as TA CVS In U.S., 2Δ amniocentesis may be safest option because of less experience with CVS, especially TA CVS But maximizing the approach to get sufficient villi with a single pass is critical with CVS Avoiding the placenta, using a 22 gauge needle, and decreasing procedure time are critical with amniocentesis

30. Noninvasive diagnosis of fetal aneuploidy Safest option, without question Once validated, this will make screening for aneuploidy obsolete Still will need targeted US to exclude fetal malformations 2 potential sources of fetal DNA Maternal serum Cervical-vaginal secretions

31. Noninvasive diagnosis of fetal aneuploidy Proteomic analysis of maternal serum to diagnose Down Syndrome Profiling of 6 proteins was able to differentiate Down Syndrome from euploid pregnancies in 20 cases and 20 controls Half of the samples were 1st trimester, remainder were second trimester

32. Noninvasive diagnosis of fetal aneuploidy Maternal Serum – manuscript in press CONTROL vs. TRISOMY 21

33. Differential Expression of Proteins in 2nd Trimester Maternal Sera CONTROL vs. TRISOMY 21

34. Differential Expression of Proteins in 1st Trimester Maternal Sera CONTROL vs. TRISOMY 21

35. Noninvasive diagnosis of fetal aneuploidy Diagnostic testing on maternal plasma Fetal sex determination Fetal RhD status

36. Conclusions In the U.S., screening for aneuploidy is moving from the second trimester to the first trimester Diagnostic tests should be done in experienced centers to minimize loss rates Proteomics may identify biomarkers in the first trimester which may replace current screening strategies A noninvasive diagnostic test for aneuploidy remains elusive, may rely on isolation of fetal DNA in maternal serum

37. Thank you