Are first trimester ultrsounds accurate dating
However, the accuracy of the ultrasound examination is always dependent on the skill of the sonographer and the quality of the equipment.
Usually the expected date of delivery (EDD or EDC) is calculated from your last menstrual period - if the early dating scan calculates the EDD to be within 5 days of the EDD from your last menstrual period.
This is because the fetus is growing so quickly that there is a big difference in size from week to week.
Also the fetus cannot bend and twist too much yet, so the length of the body is fairly constant.
Perkins also has extensive experience working in home health with medically fragile pediatric patients.
Before the advent of routine ultrasound in pregnancy, medical personnel estimated a baby’s due date by the date of the last menstrual period and by feeling the uterus and determining the size to see if it matched the given due date.
Ultrasounds performed during the first 12 weeks of pregnancy are generally within 3 - 5 days of accuracy.
D., explains in "Obstetric Ultrasound: A Comprehensive Guide".the baby and its heart beat can be detected relatively easily with trans-abdominal and trans-vaginal examination.