TERM PREDICTION IN ROUTINE ULTRASOUND PRACTICE

Study objective. Evaluation of the precision of routine ultrasound ter m prediction. Design. Population based follow-up without intervention. Setting. Ultrasound screening in routine clinical practice. Material. 1650 women residing in one Norwegian county giving birth during a 12- month period. All pregnancies were singleton with spontaneous onset of labor, all records contained a term predicted with routine ultrasound in the second trimester. Outcome measure. Difference between actual a nd predicted day of delivery, and difference between ultrasound predic ted term and term calculated from last menstrual period. Main results. More women delivered within two weeks of ultrasound term than two wee ks of term calculated from the last menstrual period (87.5% and 79.3%, p<0.001). Deliveries were significantly closer to the ultrasound pred icted term than the term calculated from the last menstrual period, wi th the exception of deliveries in the 39th week after LMP where no sig nificant difference was found between ultrasound term and LMP-term. No difference was found in the mean performance of 14 different ultrasou nd operators. Conclusions. In a population representative of deliverie s in one county, routine ultrasound term prediction performed in three medium sized hospitals more accurately predicted day of delivery than term calculated from the date of last menstrual period.