Every pregnant woman wants to know her due date , and a due date that is calculated from her last menstrual period with a due date calculator often doesn't match the due date that is estimated by her first ultrasound also known as a sonogram. During an ultrasound, a technician will spread a warm gel over the lower part of your abdomen and then press a tool called a transducer against your belly to examine your fetus using sound waves. An image of your fetus will appear on an accompanying computer screen and while looking at this image, the technician will take some standard measurements from different angles and listen for a heartbeat. Don't worry: This type of exam is painless and risk-free, and seeing your baby for the first time will likely be an enjoyable experience.
A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Most dating scans are done with a trans-abdominal transducer and a fullish bladder. If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures.
Pettker, MD; James D. Goldberg, MD; and Yasser Y. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed.