Prenatal Screening and Diagnosis

Question 1

All pregnant women should be offered a routine second trimester ultrasound between _____week gestation. The second trimester ultrasound should screen for fetal anomalies.

Answer 1

All pregnant women should be offered a routine second trimester ultrasound between 18 -22 week gestation. The second trimester ultrasound should screen for fetal anomalies.

(the first US was a dating US)

Question 2

t/f . Amniocentesis and chorionic villus sampling are screening tools

Answer 2

false. they are diagnostic.

Question 3

Cell Free DNA– screening or diagnostic?

Answer 3

Cell Free DNA:Baby DNA within the maternal circulation that comes from apoptotic cells. Acts as a SCREENING TEST for common aneuploidies (21, 18, 13). Can also determine chromosome anomalies, fetal sex determination, rhesus typing, and single gene disorders (cystic fibrosis, FGF2/3 related conditions)

SCREENING TEST

Question 4

is NIPS a screening or diagnostic test?

Answer 4

NIPS: noninvasive prenatal screening/testing. Also detects aneuploidies. Most results are reported as positive or negative, or high (>99% or low<1/10,000) risk. Positive NIPS is seen more often in advanced maternal age.

High risk NIPS result requires confirmatory diagnostic testing. Management decisions should be made based on diagnostic testing and not on NIPS alone.

False positive NIPS (normal fetal karyotype) can be due to a confined placental mosaicism, vanishing twin/demise, maternal malignancy (apoptosis of cancer cells often show chromosome aneuploidy), maternal unbalanced chromosome abnormality/ copy number variant, maternal organ transplant. If male donor, may have Y chromosome fragments in DNA.

Question 5

I. First Trimester Screening

Answer 5

• ultrasound markers for trisomy

Nuchal translucency, nasal bone hypoplasa and maternal serum biochem (PAPPA, betaHCG)

Question 6

what is the quad test?

Answer 6

a SCREENING TEST IN SECOND TRIMESTER

Multimarker maternal serum screen for trisomies 21, 18, 13 offered between 15-22 weeks of pregnancy.

Performance: DR 77%, FPR 5%

Question 7

T/f if you see soft markers for trisomy 21 (no nose bridge) at the 18-22 anatomic scan, but the patient is with low risk of aneuploidy based on prior screening, these markers warrant fruther testing

Answer 7

false. In a patient with low risk of aneuploidy based on prior screening, soft markers are not considered clinically relevant and do not warrant further testing (SOGC).

Question 8

features assessed on prenatal ultrasond/the nuchal scan at first trimester

Answer 8

Number of fetuses:

• If >1 : Chorionicity
• Fetal heart beating: yes/no
• FHR: beats per minute
• Crown rump length (CRL)
• Biparietal diameter (BPD)
• Nuchal translucency
• Nasal bone
• Fetal anatomy:

Approximately 50% of major anomalies can be detected at the first trimester scan (11-13+6 weeks)