Prenatal diagnosis at 16 weeks of pregnancy

011. Prenatal diagnosis at 16 weeks of pregnancy can be performed using all of the following, except:

1. Amniotic fluid.

2. Maternal blood.

3. Chorionic villi.

4. Fetal blood.

Answer

4. Fetal blood.

Reference

Dutta Obstetrics 4^th Edition Page 113

Nelson 15^th Edition Chapter 96

Quality

Reader

Status

Repeat

QTDF

All books

Discussion

The current protocols for fetal diagnosis include both noninvasive and invasive procedures. The invasive techniques include amniocentesis, cordocentesis (percutaneous umbilical blood sampling) and chorionic villus sampling. A common noninvasive technique is ultrasound.

Explanation

1. Amniocentesis is done during 14 to 16 weeks and early amniocentesis during 10 to 14 weeks.

2. Maternal blood can be used for diagnosis at any time in the pregnancy.

3. Chorionic villi sampling is done by transcervical route from 10 to 12 weeks and transabdominal route from 10 weeks to term.

4. Fetal blood obtained by percutaneous umbilical blood sampling is performed under local anaesthetics usually after 18 weeks of gestation.

Comments

However, Nelson gives that “Cordocentesis is usually performed after 15 wk using high-resolution ultrasound.” Hence if we go by Nelson, prenatal diagnosis at 16 weeks of pregnancy can be performed using ALL of the following with no exceptions

Tips

We arrive at our answer using Dutta as the answer