Fetopathological examination and congenital anomalies in the third trimester

The objective of this works to determine the frequency and nature of malformations detected by pathological study of aborted and stillborn third-trimester fetuses. The data were extracted from the files of the fetoplacental unit of Bordeaux University Hospital between January 2000 and December 2003. The study focused on fetuses with a gestational age corresponding to the third trimester (27 weeks to term). Death resulted from either induced abortion (IA) or spontaneous intrauterine death (IUD). A total of 1963 fetopathological examinations were performed during the study period, of which 524 involved third-trimester fetuses (109 IA, 49 IUD). The 109 IA represented nearly 15 % of all abortions performed for medical reasons during the study period. The mean gestational age was 31.2 weeks in the IA group and 34.3 weeks in the IUD group (p < 1 ‰). The abnormalities most frequently observed in the IA group consisted of neurological disorders (34 cases), cardiovascular disorders (26 cases), genetic syndromes (20 cases) and chromosomal aberrations (18 cases). In the IUDm group there were 20 minor malformations and 29 major malformations. The latter included 7 cardiac malformations, 7 central nervous system disorders, and 5 syndromes (Di George, n=3 ; Down's, n=2). The disorders indicating IA were detected during the third trimester in 94 cases, and earlier in the other 15 cases. Despite the retrospective nature of this study, the results show that a significant number of major congenital malformations are only detected in the third trimester, by sonographic examination. This is compatible with the high frequency of major congenital malformations discovered at post mortem examination of third-trimester stillbirths.