When is Ultrasound Neccessary?
- To quickly establish whether or not a fetus is still alive.
- When there is early bleeding, to predict if a miscarriage is happening.
- To confirm a suspected ectopic pregnancy (where the egg has implanted into a fallopian tube rather than the uterus), a blighted ovum (where a sac grows without an embryo inside it), or a molar pregnancy (where a “false” pregnancy grows inside the uterus), when used in conjunction with other tests.
- To determine the position of the baby during procedures such as amniocentesis and Chorionic Villus sampling.
- To establish whether or not levels of amniotic fluid are still adequate in the late weeks of pregnancy.
- To ascertain the position of the placenta at the time of birth if a low-lying placenta is suspected.
When is Ultrasound Unneccessary?
- To try to pin down the baby’s due date. Done prior to 18 weeks it is most accurate (after 18 weeks its only accurate within a week either way).
- To look for unsuspected physical abnormalities. It’s important to keep in mind that many major abnormalities, such as Down Syndrome, cerebral palsy, and heart or kidney problems most likely won’t show up on an ultrasound.
- To confirm multiple fetuses. Ultrasound is only reliable in confirming multiple fetuses when other heartbeats have already been detected with a stethoscope.
- For verification of a breech position: This is where the baby is lying in a feet or buttocks first position near the end of pregnancy, rather than head-down.
- To screen for Intrauterine Growth Retardation (IUGR). IUGR is a condition where the baby is not growing in the womb as it should.
- Location of the placenta during pregnancy. A very low-lying placenta (placenta previa) at birth puts mother and baby at risk of severe bleeding, and usually necessitates a cesarean section. However, placenta previa during the second trimester is not an indication of a problem at birth. In 19 out or 20 pregnancies, the still-growing placenta will move upwards into its correct position as the pregnancy progresses.