Abnormalities of fetal rib number and associated fetal anomalies using three dimensional ultrasonography

AimTo determine incidence of abnormal number of fetal ribs and its association with other fetal anomalies using 3D ultrasonography.Materials and methodsA prospective study conducted on 188 singleton pregnant women searching for fetal anomalies including the incidence of abnormal number of fetal ribs and other anomalies. Static 3D volumes with volume contrast imaging using spine map were used. Rendered images were displayed and the ribs were counted.Results173 fetuses (92%) were having normal number of ribs. Fifteen fetuses (8%) were found to have abnormal number of ribs; ten fetuses (5.3%) had 11 ribs. On the other hand five fetuses (2.7%) had supernumerary 13 ribs. Eight fetuses (4.2%) were having abnormal number of ribs with no associated anomalies (isolated abnormal number). Seven fetuses (3.7%) in this study had associated anomalies.ConclusionAbnormal number of fetal ribs more to be an isolated finding (4.3%) but it may also be seen with other anomalies (3.7% in this study). 3DUS is useful for scanning the fetal ribs in the mid trimester of the pregnancy for early detection of associated genetic aberrations.