Ultrasound accuracy for dating
Optimal management of pregnancy relies on accurate assessment of the gestational age (GA) of the fetus; which can be determined by the history of the last menstrual period (LMP), clinical estimation of the 1st symphysis-to-fundal height measurement (FH) or ultrasonographic fetal biometry.
However, many women fail to recall their LMP accurately.1 Moreover, pregnancy duration and fertile period are highly variable, even for women with regular cycles.1 FH suffers from poor reproducibility and high variability due to maternal and fetal factors;2-4 its accuracy for dating has not been extensively studied5-7 and requires FH dating charts (rather than growth charts).
Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.
We ask that you to fill your bladder by drinking a pint of water before the scan.
This makes it easier to see the uterus and ovaries as the full bladder pushes away the overlying bowel area.
Values: The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).
Benefits, harms, and costs: Accurate assignment of gestational age may reduce post-dates labour induction and may improve obstetric care through allowing the optimal timing of necessary interventions and the avoidance of unnecessary ones.