Page modified at: 28/08/2011
Early Viability Pregnancy Scan
Why have an early pregnancy scan?
Early pregnancy Scans are usually only offered once around 10-12 weeks in most NHS hospitals and clinics.
Their main purposes are to:
Early pregnancy Scans are usually only offered once around 10-12 weeks in most NHS hospitals and clinics.Their main purposes are to:
- exclude ectopic pregnancy (6-7w)
- confirm the pregnancy is viable (7+w)
- identify twins and triplets etc.
- date the pregnancy (work out the Estimated Due Date or EDD)
- identify some major abnormalities
- identify pregnancies at increased risk of chromosomal abnormalities and cardiac defects (Nuchal Tranlucency Scan)
Types of Early Pregnancy Scan
Although most pregnancy scans are carried out transabdominally, it is sometimes necessary in early pregnancy to perform transvaginal scans as they image quality is much better.
Transvaginal ultrasound scans are safe and painless. A hand held probe is inserted directly into the vagina. The probe is moved within the vaginal cavity to scan the pelvic structures, while ultrasound pictures are viewed on a monitor.
Ectopic Pregnancy
Sometimes the pregnancy does not implant properly inside the cavity of the uterus and may instead implant in the fallopian tube or elsewhere in the pelvis. This may be a life-threatening condition as the ectopic pregnancy can rupture causing massive bleeding, collapse and shock in the pregnnat woman.
Early diagnosis allows early treatment and may avoid the need for surgery and the removal of the tube which may reduce the chance of another successful pregnancy.
Viability 
Although modern pregnancy tests are relaible indicators of a pregnancy from a few days before the time of the missed period, they cannot tell if the pregnancy is in the right place or if the baby is viable.
Pregnancy symptoms are often present even in case where a silent miscarriage has occurred or the baby has not even developed at all and the pregnancy gestation sac is empty (blighted ovum).
Early pregnancy scans can confirm the baby is viable with a visible heart beat seen from about 7 weeks.
This picture shows the signal from the blood flow in the baby's heart at around 7 weeks.
By measuring the time interval between the pulses on the lower part of the image it is possible to determine the baby's heart rate.
Dating the Pregnancy
Ultrasound dating of the pregnancy based on measuring the Crown Rump LEngth (CRL) of the baby with ultrasound can date the pregnancy with an accuracy of about +/- 5 days and calculate the Estimated Due Date.
Multiple Pregnancy
It is important to identify multiple pregnancies and also whether or not any of the babis are sharing the same placenta (afterbirth).
In Monochorionic twin pregnancies where there is a shared placenta, closer monitoring will be required because of the risk of Twin to Twin Transfusion Syndrome wheer the blood supply is unequally distributed between them.These pregnancies should be scanned every 2 weeks.
Fortunately most twin pregnancies are Dichorionic and each baby has it's own placenta and they are not at risk of TTTS. These pregnancies should be scanned every 4 weeks.
Early Pregnancy Support Package
We have developed an Early Pregnancy Support Package which offers weekly scans from 7 to 13 weeks for women who are anxious about the possibility of a silent miscarriage and who want the additional reassurance of checking their baby is alive and developing normally during the time period when most miscarriages occur.This is especially important for those with a previous miscarriage. If you are having a Nuchal Translucency Scan this will also inlcude your early viability scan for that week.
This picture shows a typical fetus at 5w, 8w and 13w.