The Utility of the Ultrasound "Superimposed-Line" Sign at the Junction of the Vomer and Maxilla in First-Trimester Screening for Fetal Cleft Palate: A Case-Control Study.

INTRODUCTION

The current retrospective case-control study evaluates the diagnostic value of screening for a fetal cleft palate by using the ultra-sound-based observation of the "superimposed-line" sign appearing at the junction of the vomer and maxilla in the first trimester of pregnancy.

METHODS

Retrospective analyses were performed of ultrasonographic images of nuchal translucency obtained during the first trimester of pregnancy (11-13+6 weeks) from 45 fetuses with a cleft palate later confirmed following parturition or induced labor (cases) and 4,500 normal fetuses confirmed after parturition (controls). Ultrasonographic features of the "superimposed-line" sign were observed and recorded, and between-group comparisons were performed.

RESULTS

The "superimposed-line" sign was absent in 39 cases (86.67%), including 4 (8.89%) with simple secondary hard palate cleft and 35 (77.78%) with secondary hard palate cleft complicated by a primary cleft palate. The "superimposed-line" sign was shown in 6 cases (13.33%), including 2 (4.44%) with a simple secondary soft palate cleft, 1 (2.22%) with a simple secondary bifid uvula, and 3 (6.67%) with a simple primary cleft palate. Among the 4,500 controls, 31 fetuses showed an absence of the "superimposed-line" sign (0.69%) and 4,469 showed the "superimposed-line" sign (99.31%). The between-group difference was significant (p < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive values of the "superimposed-line" sign in the first trimester of pregnancy for predicting fetal cleft palate were 86.67% (39/45), 99.31% (4,469/4,500), 55.71% (39/70), and 99.86% (4,469/4,475), respectively.

CONCLUSION

The "superimposed-line" sign did not appear in fetuses with secondary hard palate cleft and primary cleft palate only when a secondary hard palate cleft is present. The sign appeared in normal fetuses and those with a simple primary cleft palate, simple secondary soft palate cleft, or a simple secondary bifid uvula. Based on these results, we propose that the "superimposed-line" sign in the mid-sagittal plane of the fetal face in the first trimester of pregnancy (11-13+6 weeks) is an important tool in screening for fetal cleft palate, especially secondary hard palate cleft.