PREGNANCY TESTS For most pregnant women, carrying a baby to term is largely a mysterious process. This section helps new parents answer some of the most important questions about pregnancy and childbirth.

The Second Trimester Scan

This is the scan done to assess the physical abnormalities or congenital malformations of the child. The liquor in the amniotic fluid, placenta and the lie of the fetus is also assessed.

What are the chromosomal disorders that can be picked up?

1. Trisomy 18 (Edward's syndrome):

90% have an abnormal early second trimester morphology like choroid plexus cysts, enlargement of ventricles, strawberry shaped skulls, agenesis of corpus callosum, meningomyelocele, microophthalmos, thickened nuchal skin fold, cardiac defects, renal anomalies, clenched hands with overlapping fingers, club foot, rocker bottom foot, polyhydramnios, intrauterine growth retardation, single umbilical ,umbilical cord cysts, low set ears, cystic hygromas.

2. Trisomy 13 (patau’s syndrome):

In this syndrome abnormalities are evident from 10 weeks onwards and the sensitivity is 90-100%. Features include holoprosencephaly, agenesis of corpus callosum, enlarged ventricles, small head and small eyes, cleft lip and cleft palate, nuchal thickening, cardiac defects, neural tube defects, enlarged kidneys, polydactyly, single umbilical artery etc.

3. Turners syndrome (XO):

In this syndrome, there is a loss of one X chromosome. Most of the fetuses are    spontaneously aborted. Ultrasound will show left heart defects, short femur horseshoe kidney.

4. Trisomy 21:

Most common chromosomal abnormality features in ultrasound would include -

a. A thickened nuchal skin fold
b. Brachycephaly
c. Choroids plexes cysts
d. Ventriculomeghaly
e. Low set ears
f. Hypoplasia of middle phalanx of the fifth digit
g. Incurving of fifth digit
h. Wide separation of the ring and middle finger
i. Simian palmer crease
j. Cardiac defects
k. Sandal gap foot duedenal atresia and omphalocele