Introduction: Over the last 20 years, first-trimester sonography has become an indispensable step in the monitoring of the pregnancy by assessing nuchal translucency thickness which is a powerful tool for screening for chromosomal abnormalities and fetal malformations. Nuchal translucency is fluid (anechoic) area between the posterior cutaneous covering of the neck and the cervical spine, corresponding to subcutaneous retro-cervical tissue, almost always present between 10 and 14 weeks of gestation in the embryo. This study was aimed at determining the prevalence of abnormal nuchal translucencies (greater than or equal to 3 mm) at 11-14 weeks of gestation in Cameroon and evaluating some associated risks.

Methods: This prospective study was conducted from the 01th of January to the 31th of December 2012 at the Radiology Unit of the Yaounde University Hospital Center, the Yaounde General Hospital, the Yaounde Central Hospital and the Douala General Hospital. Consecutive sampling was used, including 332 Cameroonian women who had undergone first-trimester sonography with fetal crown-rump length between 45 and 84 mm. Nuchal translucency thickness was either measured using transvaginal sonography (for the majority) or transabdominal sonography, as recommended by the Fetal Medicine Foundation. In case of abnormal nuchal translucency, we performed 2nd-trimester maternal serum biochemistry, 2nd-trimester morphological sonography and clinical examination of live born infants by a pediatrician.

Results: 340 fetuses were examined. The median nuchal translucency thickness was 1.5 mm (range: 0-9.7 mm). Nuchal translucency thickness was greater than or equal to 3 mm in 1.5% of cases (5/340). Abnormal nuchal translucencies were significantly predominant in pregnancies with maternal age over 36 years. In 8.8% of cases (30/340), nuchal translucency was absent, including 46.4% (14/30) before 13 weeks of gestation. Pregnancies with the thickest nuchal translucencies (4 mm and 9.7 mm) had unfavorable outcome (miscarriage and intrauterine death), with positive maternal serum markers in one case.

Conclusion: The prevalence of abnormal nuchal translucencies at 11-14 weeks of gestation in our milieu is 1.5% and is significantly higher in pregnancies with maternal age over 36 years. There would be early disappearance of nuchal translucency (before 13 weeks of gestation) in some Cameroonian fetuses. When nuchal translucency thickness is greater than 3.5 mm, there is a risk of unfavorable pregnancy outcome.