Invasive Procedures

Amniocentesis a procedure where a small quantity of fluid is taken from the amniotic sac and is tested for the cells in it. Amniocentesis is usually done after 16 weeks of pregnancy. The amniotic sac is the bag of fluid in which the baby floats in the womb. The cells in the amniotic fluid originate from the baby and so the chromosomes present in these cells are the same as those of the baby.

This is a diagnostic test for the chromosomal abnormalities and certain genetic defects in the fetus. It is required if any screening tests for chromosomal abnormalities – NT scan and/or serum screening tests, or anomaly scan with genetic sonogram suggest that there is an increased risk of fetal chromosomal / genetic problems.

While preparing for an amniocentesis, an ultrasound scan is done to check the position of the baby and the placenta (or after-birth). The skin over the womb area is then cleaned with antiseptic solution. Next, a thin needle is passed through the skin and the abdomen (the tummy or belly) into the womb, and a syringe is used to remove a sample (about 20ml) of the fluid that surrounds the baby. The needle is carefully observed using ultrasound scan. The fluid is fetal urine and the amount removed by amniocentesis reaccumulates within a few hours.

The procedure lasts for 1 minute and afterwards we check that the fetal heart beat is normal. It does not require anaesthesia and it is as painful as an injection. There is no direct contact with the fetus since the needle is always carefully observed using ultrasound scan.

There is no need for fasting before the procedure and we suggest that you have your meal. You will be asked to rest for 1hour after the procedure and then you can go home (No need for admission).

It is safe to avoid physical stress for a couple of days after the procedure. Rh immunoprophylaxis is given to the susceptible women prior to the procedure.

Chorionic villus sampling (CVS) is a prenatal test that is used to detect birth defects, genetic diseases, and other problems during pregnancy. During the test, a small sample of cells (called chorionic villi) is taken from the placenta where it attaches to the wall of the uterus. Chorionic villi are tiny parts of the placenta that are formed from the fertilized egg, so they have the same genes as the baby. You may be offered CVS if you have certain risk factors for having a baby with a birth defect or genetic disease, so that problems can be found early in pregnancy. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.

CVS can help identify such chromosomal problems as Down syndrome or other genetic diseases such as cystic fibrosis, Tay-Sachs disease, and sickle cell anaemia. CVS is considered to be 98% accurate in the diagnosis of chromosomal defects.

CVS can be done early in pregnancy (earlier than amniocentesis), and results are usually obtained within 10 days. Getting this kind of information early allows a woman to make choices in the beginning stage of her pregnancy. If a woman chooses to terminate the pregnancy after receiving abnormal test results, the termination will be safer than if she waits until later for amniocentesis results.

Selective fetal reduction is a procedure which allows reduction of viability of a multifetal pregnancy to a lower order pregnancy. For example, triplets could be reduced to twins. Multiple gestations of triplets or more have a significant increase in perinatal morbidity and mortality compared with twins. On average, triplet gestations deliver at approximately 33.5 weeks. Approximately 25% deliver at < 32 weeks and 10% deliver < 28 weeks. Maternal complications are also significantly increased. Multifetal pregnancy reduction involves the ultrasonically guided injection of KCl into the fetal thorax to induce asystole. It is performed to reduce the potential for early preterm delivery associated with higher-order multiple gestations. Multifetal pregnancy reduction to twins increases gestational age at delivery by 4 weeks and significantly improves maternal and fetal outcomes.

In some cases, there may be twins with one fetus having a serious anomaly which can affect the other healthy co -twin. In these cases, an appropriately timed and executed fetal reduction procedure can optimise the prospects for the healthy co twin

These procedures require precision and judgement of risk factors and are associated with possible adverse outcomes in few cases like complete miscarriage of the pregnancy. It is thus imperative that these procedures are undertaken with all precautions, by an experienced operator and with due consideration of all other alternatives.