Obstetric ultrasound: What the radiologist needs to know.

Obstetric ultrasound forms an integral part of modern obstetric care. This includes the use of ultrasound for screening as well as in diagnostic and therapeutic roles. Radiologists involved in this field must have the appropriate training and expertise to match the type of investigation or screening procedure to be undertaken. There should be an explicit understanding of this training and expertise both for the referring obstetrician and expectant mother. All radiologists involved in the care of women should have a thorough understanding of the normal and abnormal appearances of the first trimester as early pregnancy disorders present to the generalist; however, a smaller number of radiologists are involved in anomaly screening and management of growth disorders and still fewer in tertiary referral work. Obstetric medical practice is increasingly litigious and the aims of screening ultrasound and the limitations (false-negative and false-positive rates) should be explicit not only to the referring clinician but also to the expectant parents prior to screening. The diagnostic accuracy of ultrasound should be known in order that the expectant mother can give informed consent.