Accuracy of prenatal diagnosis in a tertiary fetal medicine unit

To establish the accuracy of prenatal diagnosis in a tertiary referral fetal medicine unit by comparing those diagnoses made prenatally with diagnoses made at birth until discharge, and with postmortem information from cases that resulted in termination, intrauterine, or neonatal death.

All cases seen in the Fetal Medicine Unit between 1 June 2004 and 30 November 2005 were collected prospectively and sorted according to diagnosis. Relevant outcome data for these pregnancies were collected including postmortem information.

681 cases seen which accounted for 1219 visits. 198 were classified prenatally as a major abnormality, 46 cases minor, 56 with raised nuchal translucency, and 381 no abnormality. Outcome details were not available for analysis in two cases. Therefore 679 (99.7%) cases were available (711 out of 713 fetuses). Of the liveborns, 93.6% of the prenatal diagnoses were confirmed, 5.1% were resolved (predominantly soft markers), and 1.3% resulted in an additional major abnormality that had a significant clinical effect. Postmortem examinations were performed on 52% fetal or neonatal deaths with a normal or unknown karyotype. There was one new finding at postmortem that changed the fetal medicine diagnosis significantly.

Accuracy of prenatal diagnosis in a tertiary fetal medicine unit is high. Parents and staff need to be aware that not all abnormalities will be detected prenatally, but inaccurate diagnosis is uncommon. Clinical indicators for benchmarking need to be developed.