Thursday 21 February 2019

A clear picture

For the majority of women, ultrasounds can be the most exciting part of pregnancy but there are genuine medical reasons for them, says Prof John Morrison of the Institute of Obstetricians and Gynaecologists and Galway University Hospital

ULTRASOUND has revolutionised obstetrics over the past three decades, and in particular has changed the practice of high risk obstetrics. It's hard to believe but ultrasound technology was developed as recently as the 1970s and early 1980s. Prior to this it was only possible to get a general idea about the baby in the womb by feeling the mother's abdomen, and even then information was basic. Before ultrasounds, it wasn't uncommon to have a surprise delivery of twins.

Prof John Morrison, consultant obstetrician and gynaecologist with Galway University Hospital, says: "Prior to ultrasound, the mechanisms to examine and make a diagnosis in relation to pregnancy were limited in comparison to what they are today."

In the 21st century, ultrasound is a very safe and non-invasive way of looking at the baby in the womb, according to Morrison.

Best practice suggests that every woman has two ultrasound scans in pregnancy; one in the first trimester by 12 weeks, and the second at 20 weeks. Most hospitals in Ireland provide the early scan at 12 weeks but some are limited by resources and availability of the scanners.

The 12-week scan is used to check that the pregnancy is ongoing, that the foetal heart is beating properly and that the foetus is at the stage it's meant to be. It is also used to determine delivery dates, and to pick up if the woman is having a multiple birth.

On a light note, most hospitals will give the couple a picture of the scan. Hospitals differ in their policies around determining the sex of the baby. Some hospitals won't do it because it takes extra time, and also they don't want to get the diagnosis wrong. Other hospitals have a more liberal policy, and if they are happy to tell the patient what the sex is - if they want to know.

The 20 week scan is quite detailed, examining the baby anatomically.

"Specifically that scan focuses on structure and anatomy, so if a baby has any problem with its heart, spine, brain, limbs or organs, these problems will be detected," says Morrison.

The purpose of the 20-week scan is to rule out any abnormalities. If abnormalities are detected, the medical team will work on possible solutions. Foetal cardiac abnormalities, for example, can be treated with medication.

The team will also start to plan the delivery, ensuring that the right type of paediatric doctor is on hand when the baby is born, and that the baby gets immediate care in many cases.

"The 20-week scan leads to the mother being prepared, and gives her the chance to consider her options. If the foetal malformation is of a very serious nature, the woman may choose not to continue with the pregnancy," says Morrison.

While ultrasound has become a normal part of pregnancy, the scans, especially the latter ones, are very detailed diagnostic examinations.

"Sometimes women get a terrible shock when something arises and they hadn't anticipated it. It's a really traumatic time for a couple so we normally provide information sheets about the 20 week scans, highlighting that a woman should be well prepared for what the 20 week scan entails," says Morrison.

Subsequently, scans are performed on a clinically indicated basis. So, if there is a problem with the pregnancy, if it's a twin pregnancy or if the mum-to-be has high blood pressures, then she will receive more scans.

Women who had small babies, multiple births or stillbirths, and mature mothers, should expect to get more scans after 20 weeks,

"There is a large cohort of high-risk women who will be having regular ultrasound scans for the rest of the pregnancy onwards, but a significant number of our population are healthy in pregnancy, with no complications, and will most likely have a scan just twice throughout pregnancy."

Morrison says that while ultrasounds are very safe, they should only be used when necessary. There are certain types of ultrasound that are higher in exposure than others. While the 3-D ultrasound is a very good development, its use in Irish practice is largely for recreational scans.

"The vast majority of diagnostic or medical ultrasound in pregnancy is absolutely fine on 2-D," say Morrison.

Irish Independent

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