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SCREENING |
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DIAGNOSTIC
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| First Trimester Combined Screening(FTS)1 |
Maternal SerumScreening(MSS) |
Routine 2nd trimester Ultrasound |
Chorionic Villus Sampling (CVS) |
Amniocentesis |
| How it is Done |
Blood Test +Ultrasound |
Blood test |
Ultrasound |
Transvaginal or transabdominal procedure. |
Transabdominal procedure |
| Preferred Timing |
11-13 6/7 weeks |
15-19 6/7 weeks |
18-20 weeks |
11-13 weeks |
> 15 weeks (commonly 15-16 wks)
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| Results |
Immediate (2) |
~1 week |
Immediate (2 ) |
~2-3 weeks |
~2-3 weeks |
| Type of Conditions Detected in the Baby |
Risk Assessment for:
Down syndrome, Trisomy 13
Trisomy 18. Some birth defects detectable at this gestation. |
Risk Assessment for:
Down syndrome, Trisomy 18
ONTDs (3) |
Serious birth defects
Soft markers for chromosome conditions. |
Major chromosome conditions.
Genetic molecular testing if indicated. |
Major chromosome conditions.
ONTDs (screen) |
| Detection Rate |
85-90% |
70% for Down syndrome,Trisomy 18
80% for ONTD
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Majority of Major birth defects
90% for ONTDs
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> 99% for
chromosome conditions: (low risk for maternal cell contamination, confined placental mosacisim) |
> 99% for chromosome
conditions |
| Further Testing Available |
CVS or amniocentesis available for women identified at increased risk
(> 1:300 for Down syndrome; > 1: 150 for Trisomy 13 or 18).
18-20 week ultrasound to screen for birth defects.
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Amniocentesis to detect chromosome conditions. Ultrasound to screen for ONTD and other serious birth defects. |
Amniocentesis to detect chromosome conditions.
or
Specific testing as indicated |
18-20 week ultrasound to screen for birth defects |
18-20 week ultrasound to screen for birth defects |
| Miscarriage Risk |
No added risk |
No added risk |
No added risk |
1/100 (1% or less) |
1/200 (0.5% or less) |
| Eligibility |
All pregnant women of any age |
All pregnant women of any age.
Not recommended if FTS has been performed. |
All pregnant women of any age |
Currently within the Calgary Health Region, CVS is limited and eligibility is determined on a case-by-case basis in consultation with MFM and/or Prenatal Genetics
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Positive FTS or NT screen
Optional for women 35 years or older
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