Your pregnancy: the ultrasound
GETTING an early peek at your baby’s development is one of the most incredible experiences that new parents will have. Ultrasounds during pregnancy can also prepare doctors 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. The benefits are numerous and include:
FIRST TRIMESTER
• 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.
•Pregnancy abnormalities in the embryo can be detected from the first trimester. One example 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.
SECOND TRIMESTER
•The second ultrasound occurs between 18 and 22 weeks. In the second trimester, 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.
•With the advent of 3D and 4D ultrasounds, the facial features of the baby and baby’s movements can now be visualised well.
•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. 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.
THIRD TRIMESTER
•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).
•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. An ultrasound is done to accurately assess foetal weight close to or at term.
• 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.
