First-trimester pregnancy scanning as a screening tool for high-risk and abnormal pregnancies in a district general hospital setting

Abstract

This study set out to evaluate the feasibility and acceptability of routine early ultrasound (12-14 weeks) within a district general hospital (DGH) for identifying high-risk and abnormal pregnancies. This was a pilot study for screening by ultrasound examination all women who presented to their community midwife before 12 weeks' gestation. The study involved 991 women who presented clinically pregnant before 12 weeks' gestation between May 1998 and May 1999. Women were offered routinely two ultrasound examinations during their pregnancy, the first at 12-14 weeks' gestation and the second at 20-21 weeks' gestation. The main outcome measures were: range and number of abnormal/high-risk pregnancies identified during an ultrasound scan at 12-14 weeks' gestation; range and number of abnormalities diagnosed during scans at later gestations; outcomes of the pregnancies; questionnaires assessing how the women viewed early pregnancy ultrasound as a method of screening. Nine hundred and eighty-four (99%) women accepted the offer of an early ultrasound scan at 12-14 weeks' gestation; of these 840(85%) women accepted screening for trisomy 21 (T21) by fetal nuchal translucency thickness (NT) and maternal age (fetal medicine foundation risk assessment programme) and this was completed successfully in 797(80%) of cases. Twenty-four women (2%) had a failed pregnancy and where necessary an ERPC was performed following a planned admission. Thirty pregnancies (3%) were diagnosed as abnormal or having high risk of abnormality at the early scan. A major abnormality was confirmed before the expected anomaly scan at 20 weeks in five (17%) pregnancies; all of these patients opted for an elective termination. Twenty-six (3%) pregnancies had a diagnosis of abnormality at their anomaly scan. Of these, three pregnancies were diagnosed as major abnormalities with two resulting in termination of the affected pregnancy before 24 weeks' gestation. Eight hundred and thirty-seven women (85%) completed questionnaires, 833 women (84·5%) were satisfied with the counselling they received before the ultrasound scan and 827 women (84%) answered that they would accept an early pregnancy scan if offered during their next pregnancy. Early pregnancy ultrasound at 12-14 weeks' gestation can be used as an effective method of identifying and screening for major abnormalities of pregnancy within a DGH setting, but it is appropriate to use this in conjunction with an anomaly scan at around 20 weeks' gestation. Women found this method of screening acceptable.