Preeclampsia, which is high blood pressure in pregnancy, is one the most common health complications in pregnancy and can result in a life-threatening condition for women and their baby. This is of particular importance when preeclampsia results in the need for preterm delivery (less than 37 weeks gestation) of your baby.
This 13-week anatomy scan provides an ideal opportunity to screen for preeclampsia at the same time when assessing anatomy of the baby. The scan is performed between 12 weeks 2 days and up to 13 weeks + 6 days.
Individual maternal risk factors have been shown to be overall poor predictors of preterm preeclampsia. Recently, studies using multiple factors such as maternal risk factors, maternal uterine artery Dopplers, and blood tests in a screening calculation at 11-13 weeks using a cut of > 1:100 demonstrated a 75% detection rate of preterm preeclampsia < 37 weeks gestation with a 10% false positive rate. This means, we will be able to predict preterm preeclampsia in a majority of women (but not all). Not all women, who screen positive for preterm preeclampsia will actually develop preterm preeclampsia and of every 10 women screened, 1 will screen positive. Those women screened high can be offered low dose aspirin started prior to 16 weeks of pregnancy to significantly reduce the risk of developing preterm preeclampsia and improve the chances for healthy pregnancy and baby.
Before, during or after your scan, the staff will ask you some basic health questions that will assess maternal risks for the development of preeclampsia. We will then have you sit rested and take your blood pressure in each arm with an automated blood pressure cuff.
During the anatomy scan, we will perform measurement of your uterine arteries which demonstrates blood flow from you to the placenta.
In most cases the scan will be performed transabdominally, but there are some situations where a transvaginal (internal) ultrasound may be necessary. Transvaginal ultrasound involves inserting a thin transducer (ultrasound probe slightly thicker than a tampon) into the vagina to get more detailed images as the transducer is closer to the pelvic organs. This improves the accuracy of diagnosis.
Transabdominal and transvaginal ultrasound examinations are safe at all stages of pregnancy.
After the scan is completed, you will then be asked to wait in our counselling room while our staff perform the computer-generated preterm preeclampsia risk calculation. The AWI Doctor will discuss the risk results with you. A detailed report will also be sent to your referring Doctor.
Before your scan
Ideally, please call to book your appointment as early in the pregnancy as possible, so that the procedure can be done during the suggested period.
Your doctor’s referral must include their wish to perform preeclampsia screening. This is commonly stated on the request, Fetal anatomy and Pre-eclampsia Screening.
As part of the test involves combining the ultrasound findings with the maternal blood biochemistry, please take your maternal serum screening blood test form to any pathology company at least 4-7 days before your ultrasound appointment. We can then access these results at the time of your ultrasound. Blood test for preeclampsia screening be done over 10 weeks of pregnancy, but higher accuracy is obtained if blood tests are done from 11 weeks + 0 days.
If possible, please wear comfortable, loose-fitting clothing that allows easy access to the area that is being imaged. Two-piece clothing is ideal (separate upper/lower garments).
Please empty your bladder 2 hours before the examination time. Then slowly drink 600ml of water to fill your bladder and keep it full for your examination.
About the Preeclampsia screening at time of the 13 Week Anatomy Scan procedure
When you visit Adelaide Women’s Imaging for a 13 week anatomy scan you will be greeted by one of our friendly reception staff. A sonographer will then collect you from the waiting room and take you to the ultrasound room. The sonographer will perform an ultrasound of the abdomen (transabdominal ultrasound) detailing the fetal anatomy and maternal pelvic anatomy.
Occasionally, the scan may need to be performed through the vagina (transvaginal imaging). Transvaginal ultrasound involves inserting a thin transducer (ultrasound probe slightly thicker than a tampon) into the vagina to get more detailed images as the transducer is closer to the pelvic organs. The transducer is lubricated with gel before insertion into the vagina. It is disinfected, and a protective cover is placed over the transducer each time it is used, so there is no risk of infection. This improves the accuracy of diagnosis and greater detail may be obtained of the fetal anatomy.
The Adelaide Women’s Imaging doctor will discuss the results of the scan with you on the day in the ultrasound room. A detailed report will be sent to your referring doctor.
Duration of Scan and Counselling
Approximately 45 minutes.
