The later the pregnancy, the larger the standard deviation of the estimated gestational age and thus estimated date of delivery EDD is. Mean sac diameter MSD before a fetal pole is identified and biparietal diameter BPD after 11 weeks can also be used to support the calculation of the gestational age. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait.
Estimating Fetal Gestational Age | Radiology Key
Gestational age is a measure of the age of a pregnancy which is taken from the beginning of the woman's last menstrual period LMP , or the corresponding age of the gestation as estimated by a more accurate method if available. Such methods include adding 14 days to a known duration since fertilization as is possible in in vitro fertilization , or by obstetric ultrasonography. The popularity of using such a definition of gestational age is that menstrual periods are essentially always noticed, while there is usually a lack of a convenient way to discern when fertilization occurred. The initiation of pregnancy for the calculation of gestational age can be different from definitions of initiation of pregnancy in context of the abortion debate or beginning of human personhood. According to American College of Obstetricians and Gynecologists , the main methods to calculate gestational age are: . Gestational age can also be estimated by calculating days from ovulation if it was estimated from related signs or ovulation tests , and adding 14 days by convention. A more complete listing of methods is given in following table: .
Estimating Fetal Gestational Age
Read terms. Miller, MD, and R. Phillips Heine, MD. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change.
Gestational age, synonymous with menstrual age, is defined in weeks beginning from the first day of the last menstrual period LMP prior to conception. Accurate determination of gestational age is fundamental to obstetric care and is important in a variety of situations. For example, antenatal test interpretation may be dependent on gestational age.