Abstract
Intra‐abdominal masses and cystic lesions are not commonly identified during the routine 20‐week anomaly scan but are not infrequently seen as incidental findings during a third trimester scan assessing fetal growth and well being. This review looks at the potential differential diagnosis of masses and cysts seen prenatally and aims to define a method of assessment that will help limit the differential diagnosis before delivery. Copyright © 2008 John Wiley & Sons, Ltd.