Evaluation of the fetal secondary palate by 3-dimensional ultrasonography

Diagnosis of cleft lip and palate remains a challenge with 2-dimensional ultrasonography, particularly when clefting involves only the secondary palate. The utility of 3-dimensional ultrasonography (3DUS) has enhanced our ability to detect clefts. We report our experience with a modification of the flipped face technique to aid in the diagnosis of clefting of the secondary palate.

Ninety-two volumes of 92 fetal faces were evaluated. Thirty-six volumes were acquired prospectively. Fifty-six volumes had previously been acquired and included 8 with clefting of the secondary palate. Volumes were obtained on 3DUS systems and reviewed by 4 blinded readers on personal computer workstations. Volumes were manipulated so that an upright profile was visualized. The palate was then rendered using a thin, curved render box. Statistical analysis was performed using the Fisher exact test for categorical data. Intraclass correlations were computed to assess inter-rater agreement.

The mean gestational age at image acquisition +/- SD was 22 +/- 5 weeks. Image quality of the secondary palate was obtained and rated as adequate by at least 2 reviewers in 34% (31 of 92) of volumes. The sensitivity of cleft detection ranged from 33% to 63%, and the specificity ranged from 84% to 95%. The low sensitivity was mainly due to artifacts/shadowing. The inter-rater reliability was 0.62 (95% confidence interval, 0.47-0.76).

Three-dimensional ultrasonography can be used to diagnose clefts of the secondary palate. This evaluation is limited by the fetal position and artifacts from shadowing of adjoining structures. Pseudoclefts can be created, and optimal imaging cannot be obtained in all fetuses.