Measurement of the Cobb angle by 3D ultrasound: a valuable additional method for the prenatal evaluation of congenital scoliosis.

BACKGROUND

This study aimed to measure the Cobb angle of the fetal spine using three-dimensional ultrasound (3D-US) and to assess the relationship between the Cobb angle and the prognosis of congenital scoliosis.

METHODS

From March 2015 to June 2019, 77 pregnant women whose fetuses had suspected spinal skeletal dysplasia consented to undergo 3D-US examinations, and 54 fetuses were selected for the analysis group. The study protocol was approved by the review board of the Institutional Ethics Committee for Fetal Medicine. 3D-US was used to show the structure of the fetal spine in 3 planes, and the Cobb angle was measured on the coronal plane. The diagnostic efficacy of 3D-US was compared to that of X-ray for 33 fetuses.

RESULTS

In the diagnosis of congenital scoliosis, the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of 3D-US were 91.7%, 90.0%, 90.7%, 88.0%, and 93.1%, respectively. The area under the receiver operating characteristic (ROC) curve with 3D-US was 0.908. The Spearman correlation coefficient between the Cobb angle measurement on an X-ray image and on the coronal plane image acquired by 3D-US was 0.84, which showed a significant correlation (P<0.05).

CONCLUSIONS

3D-US was successful in the diagnosis of congenital scoliosis. It is feasible to measure the Cobb angle on the coronal plane of the fetal spine by using 3D-US. The Cobb angle has the potential to become an auxiliary index for evaluating the prognosis of congenital scoliosis.