More frequent use of ultrasound recommended in twin pregnancies

Featured in the June edition of the Journal of Obstetrics and Gynaecology Canada is a new clinical practice guideline which suggests that carrying twins requires greater monitoring and, therefore, the more frequent use of ultrasound technology to conduct the ongoing assessment of twin pregnancies.

"Ultrasound is the only safe and reliable method for the diagnosis and assessment of twins," said Dr. Lucie Morin, co-principal author of the guideline. "A woman carrying twins cannot simply be treated as one woman with two single pregnancies. Special monitoring and follow-up are required, particularly in the last three months of the pregnancy."

For all pregnancies, ultrasonographic technology is routinely used by health-care providers to assess the size of the baby, how well the baby's organs (such as the heart, spine, brain and kidneys) are growing, and the anticipated date of birth (gestational age). It is also used to diagnose anomalies and complications, to measure cervical length, to monitor amniotic fluid, as well as to determine placental localization and fetal position. However, when it comes to twin pregnancies, there are additional considerations to be factored in.

Early and accurate determination of amnionicity and chorionicity is critical in the management of twins. In other words, it is important to determine whether or not each fetus has its own amniotic sac and its own chorion (which leads to the development of the placenta). Depending on the outcome of the assessment, there are a number of potential complications that can occur and are unique to twins. This is why twin pregnancies are considered to be high-risk.

"There are three key things to remember with twins," emphasized Dr. Kenneth Lim, one of the principal authors of the new guideline. "First, fetuses don't always share. Secondly, there is an increased risk for preterm birth, a major cause of mortality and morbidity in twin pregnancies. And finally, congenital anomalies are 1.2 to 2 times more common in twin gestations."

From the first trimester until delivery of the second fetus, the use of ultrasound in the management of twins is indispensable. The goal of this guideline is to offer health-care professionals recommendations for the best use of ultrasound in twin pregnancies.

"With this guideline, it is hoped that the use of ultrasonographic technology will be optimized, that a more consistent approach will be adopted across the country, and that there will be a reduction in the number of twins who die before birth or must deal with serious complications both inside or outside the womb," said Dr. Ahmed Ezzat, President of the Society of Obstetricians and Gynaecologists of Canada.