Ultrasound technology in pregnancy

WITH advancements in medicine, expectant mothers can gain a wealth of knowledge about their unborn children with the assistance of ultrasound images. Dr Keisha Buchanan, obstetrician-gynaecologist at ICON Medical Centre, adds that health care professionals can prepare to treat the unborn child or decide on a course of treatment after birth.

“Ultrasounds have revolutionised obstetric care and are now a routine part of obstetric care. Obstetric ultrasounds have been shown to improve pregnancy outcomes in high-risk pregnancies and have no associated risks as they use sound waves and do not expose the foetus to radiation, hence will not cause any birth defects or foetal damage. In some high-risk pregnancies they may be required several times per month/week, and similarly this does not pose a threat to the foetus,” Dr Buchanan said.

In fact, she said the benefits are numerous and expectant mothers should take the time to know these. Some include:

•Ultrasounds encourage and allow bonding between foetus, mother and family. Dr Buchanan said that with the advent of 3D and 4D ultrasounds, the facial features of the baby and baby’s movements can now be visualised well. She said most ultrasound machines will generate a photo for the families to keep, and this will be a precious memento.

• Obstetric ultrasounds allow early localisation of the pregnancy and are essential in ruling out ectopic pregnancy from as early as two to three weeks after conception. It can assess that the foetus is alive as against a missed abortion (presence of the normally located foetus that has demised) and is essential to quantify the number of pregnancies, eg twins.

• The structure of the mother’s pelvic and abdominal organs can be assessed early in the pregnancy to check for defects that can pose increased risk to the pregnancy such as fibroids, ovarian cysts, and a short cervix. “Fibroids are very commonly seen in pregnancy; they are seen in 30-40 per cent of pregnancies. Most cause no complications, but some fibroids can undergo rapid growth and cause pain during pregnancy and can trigger premature labour; some may prevent the foetus from turning and cause abnormal presentation at delivery, requiring Caesarean section,” Dr Buchanan advised.

Most ovarian cysts, however, will resolve spontaneously and require no treatment. But a short cervix may require a cerclage (a stitch that closes the cervix, preventing premature dilatation) in order to prevent miscarriage.

•Pregnancy abnormalities in the embryo can be detected from the first trimester. One example, Dr Buchanan said, is a blighted ovum in which the gestational sac develops but the embryo does not develop, or gestational trophoblastic disease in which there is abnormal development of the placental tissue.

•In the second trimester, Dr Buchanan said spinal abnormalities such as spinal cord tumours and defects such as spina bifida in which the spinal vertebrae is absent, meningoceles in which the meninges is protruding, and intestinal defects such as gastroschisis in which the abdominal wall is absent and the intestines and the stomach protrude from the abdominal cavity, can be detected.

•It can guide procedures such as sampling of the amniotic fluid to assess foetal genetic material such as in Down’s Syndrome screening, sampling the levels of bilirubin produced by the breakdown of red blood cells in Rhesus Isoimmunisation, and to assess for the presence of anaemia. Dr Buchanan explained that in the presence of low levels of amniotic fluid in pregnancy, ultrasounds can be used to guide infusion of fluid to restore normal fluid in the womb.

•It can be used to assess umbilical cord blood flow and to predict the onset of preeclampsia (maternal high blood pressure in the presence of protein in the urine). “In the presence of poor foetal growth, serial ultrasounds can be done at twice-weekly intervals or more to assess the rate of foetal growth and guide when intervention such as early delivery is needed,” Dr Buchanan said.

•It can be used to assess foetal movements, amniotic fluid levels and foetal breathing movements and is an essential tool in high-risk pregnancies such as those complicated by diabetes, high blood pressure and sickle cell anaemia. “Lack of foetal movement is a common complaint in pregnancy and can be a cause of maternal anxiety or at times it can signal the onset of foetal distress. Ultrasounds will reveal the exact cause of decreased movements and ensure that the foetus is not in distress.

•“As the pregnancy progresses towards the due date, there is usually great concern about the foetal weight and mothers worry about their ability to push a large baby. Ultrasound is done to accurately assess foetal weight close to or at term,” Dr Buchanan said. She said if the estimated foetal weight is at or above 4 to 4.5kg, a Caesarian section is usually done to avoid the risk of delivering a large baby vaginally.

• Ultrasounds done at or near term are the most accurate way of assessing what part of the foetus is presenting first and this allows for proper planning of the route of delivery. With abnormal presentations such as breech or cord presentation, these will require Caesarian sections. Cord presentations also require very close monitoring for heartbeat abnormalities that may require an urgent abdominal delivery.