NOTES FOR UNDERGRADUATES AND POSTGRADUATES IN GYNE

1. SCREENING FOR DOWN
SYNDROME
DR.PRIYA SAXENA

2. SCREENING FOR DOWN SYNDROME
 First trimester screening
 Second trimester screening

3. FIRST TRIMESTER SCREENING
 Routinely used for screening for Down’s syndrome
 Most commonly used protocol:
 Maternal age
 Ultrasound for nuchal translucency
 Measurement of 2 serum analytes
o HCG
o PAPP-A
 HCG is higher and PAPP-A is lower in Down’s syndrome. This is called
combined first trimester screening.
 Performed between 11-14 weeks of gestation

4.  Other ultrasound markers which are helpful in first trimester aneuploidy
screening are:
o Absence of fetal nasal bone
o Assessment of flow of blood across the tricuspid valve of fetal heart and
ductus venosus.

5. SECOND TRIMESTER SCREENING
 Carried out between 15-20 weeks of pregnancy
 Two components double test: MSAFP+HCG
 MSAFP- lower
 HCG-raised in down’s syndrome
 Triple test-MSAFP+HCG+UE3
 UE3 and MSAFP-lower
 HCG-higher in down syndrome
 Quadruple test-MSAFP+HCG+UE3+Inhibin A
 Inhibin A- raised in Down syndrome

6.  Penta screen-AFP+HCG+UE3+Inhibin A+HHCG(hyperglycosylated HCG)
 Values of HHCG-higher in down syndrome

7. PROTOCOL FOR MEASUREMENT OF
NUCHAL TRANSLUCENCY
 Gestational period-must be 11-13 weeks and 6 days
 Fetal crown rump length- should be between 45 and 84mm
 Magnification of the image-should be such that the fetal head and thorax
occupy the whole screen
 Mid saggital view of the face should be obtained
 Fetus should be in neutral position with head in line with spine
 Care must be taken to distinguish between fetal skin and amnion
 Widest part of translucency must always be measured
 Umbilical cord may be round the fetal neck in about 5% cases as it is more
appropriate to use the average of two measurements.

8. THANK YOU