Prevalence and diagnostic dilemma of chromosomal abnormalities in the Niger Delta area of Nigeria; Is prenatal diagnosis worthwhile?

Early detection of increasing numbers of cases of chromosomal abnormalities (aneuploides) at the Rivers State University Teaching Hospital (RSUTH) in the Niger Delta will enhance appropriate counseling of patients and early termination of the affected pregnancies. The study aimed to ascertain the prevalence of aneuploides at the RSUTH and to determine the necessity for early prenatal diagnosis in the Niger Delta. This was a prospective cross-sectional study carried out over a three-year period (01/01/2018 - 01/01/2021) at the RSUTH, Nigeria. Newborn babies delivered at 28 weeks and above were assessed at birth for the phenotypes of aneuploidy and associated birth defects. A convenient sampling method was used to recruit all the babies with chromosomal abnormalities and their mothers. Data including that of socio-demographic, obstetric characteristics, and the fetuses were taken and analyzed using Statistical Package for Social Sciences Version 23 (SPSS version 23). Quantitative variables were summarized using means and standard deviation while qualitative variables were expressed as frequencies and proportions. The total number of babies that were delivered by the 5868 participants in the study was 6078, out of which 10 cases of aneuploides were identified - 3 cases of trisomy 18 and 7 cases of Trisomy 21. The prevalence of chromosomal abnormalities at birth at the RSUTH was 0.165% of the total births, 1:2000 and 1:654 for T18 and T21 respectively. 1:654 mothers had babies with chromosomal abnormalities, 1:2000 and 1:833 for T18 and T21 respectively.

Conclusion: The prevalence of chromosomal abnormalities at birth at the RSUTH of 0.165% represented a gross underestimation because the diagnosis was based on the outward phenotypical appearance of the neonates and it was made not from babies delivered at 20 weeks and above as practiced in Europe and other countries, but from 28 weeks. Prenatal diagnosis was therefore highly recommended in the Niger Delta.