Gestational Age Assessment

Excerpt

Gestational age is a key piece of data used by healthcare providers to determine the timing of various screening tests and assessments of the fetus and mother throughout pregnancy. Gestational age may be assessed at any time during pregnancy, and several modes of assessment exist, each requiring different equipment or skills and with varying degrees of accuracy. Obtaining more accurate estimates of gestational age through better diagnostic approaches may initiate more prompt medical management of a pregnant patient.

There are numerous approaches to assess gestational age. Before sonography, practitioners had to rely on detailed histories and physical exam findings. In particular, determining the date of the last known menstrual period was of significance. Inputting the date of the last menstrual period into various formulas can give both an estimated gestational age and an estimated delivery date. Physical exam findings such as determining uterine fundal height is also a method for estimating gestational age.

Ultrasound has emerged as the more accurate method of assessing fetal gestational age, especially in the first trimester. Both transvaginal and transabdominal probe assessments are used to obtain a more accurate measurement of gestational age. Transvaginal is more helpful in first trimester pregnancies. Multiple parameters have been described using ultrasound to aid in calculating gestational age and will be described here. Additionally, postnatal scoring systems involving focused physical and neurologic exams may also provide insight into gestational age.