This document discusses screening methods for Down syndrome during pregnancy. It describes first trimester screening, which uses maternal age, ultrasound measurement of nuchal translucency, and levels of HCG and PAPP-A to assess risk. It also discusses second trimester screening, including the double, triple, quadruple, and penta tests, which measure various serum markers like AFP, HCG, UE3, Inhibin A, and HHCG to determine risk. The document provides detailed guidelines for properly measuring nuchal translucency between 11-13 weeks gestation, including fetal positioning and magnification.

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