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Labour

Question
20 out of 23
 

Best timing of transabdominal chorionic villous biopsy (AIIMS May 2009)



A 9 –11 weeks

B 11-13 weeks

C 12 – 14 weeks

D 5 – 7 weeks

Ans. B

11-13 WKS

a. Chorionic villus sampling (CVS) is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus.

b. It entails getting a sample of the chorionic villus (placental tissue) and testing it.

c. CVS can be carried out 10-13 weeks after the last period, earlier than amniocentesis (which is carried out at 16-20 weeks).

d. CVS can be performed via trans abdominal or trans cervical route.

1. Indications

a. Mother's age of 35 years or greater

b. Abnormal first trimester screen results

c. Increased nuchal translucency or other abnormal ultrasound findings

d. Past history of a chromosomal abnormality or other genetic disorder

e. Parents are known carriers for a genetic disorder

2. Risk

a. There is a risk of miscarriage (0.8-1%)

b. There is a risk of infection

c. There is a risk of amniotic fluid leakage.

d. The resulting amniotic fluid leak can cause oligohydramnios .

e. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs).

f. Additionally, there is a risk of CVS causing digit/limb-reduction defects & oro mandibular defects if performed before 11 weeks.

g. Therefore the recommendation to perform CVS is after 10 completed weeks

Summary table of all tests used for screening / Diagnosing congenital anomalies.

Investigation

Period of Gestation

Material of study

Maternal serum

Alpha feto protein

15 – 20 weeks

Maternal serum alfa feto protein

Triple test

15 – 18 wks

MSAFP ()

Unconjugated Estriol ()

Free beta hCG ()

Integrated test

10 wks

14 – 20 wks

Nuchal translucency ()

PAPP – A ()

MSAFP ()

Unconjugated estriol ()

Beta HCG ()

Inhibin ()

USG

10 – 14 wks

16 – 22 wks

Fetal Anatomy to see nuchal translucency

Fetal anatomy

Amniocentesis

Early

Amniocentesis

14 – 16 wks

12 – 14 wks

(can be done at 10 wks)

Fibroblast

Amniotic

Disorders

Chorionic villi sampling

10 – 12 weeks

Trophoblast cells of chorionic villi

Cordocentesis (Percutaneous umbilical blood sampling)

18 – 20 weeks

Blood and fetal white blood cells

Fetoscopy

16 – 20 weeks

Visualization of anatomy

Labour Flashcard List

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