Antenatal ultrasound is widely used to detect major fetal abnormalities such as anencephaly. However, a recent editorial (BMJ,1997; 314: 918) questions its use in detecting less straightforward problems, sometimes called "soft markers".
Soft markers are minor, sometimes transient, anomalies which may indicate more severe fetal problems, especially in older mothers. Unfortunately, many of these markers reveal problems which we know very little about, can do nothing to treat and which may even resolve themselves during the course of the pregnancy. As such, no one can claim to fully understand their significance.
Detecting these markers raises difficult ethical questions and does not benefit mothers, the authors conclude.
For more information see WDDTY vol 1 no 6 and vol 4, nos 5 and 10.