The 'equals sign': a novel marker in the diagnosis of fetal isolated cleft palate

Abstract

Objectives: To determine the feasibility of visualization of the uvula and the soft palate during routine two-dimensional (2D) ultrasound examination and to develop a sonographic procedure that facilitates prenatal detection of isolated fetal cleft palate.

Methods: We examined 667 consecutive patients with a singleton pregnancy between 20 and 25 weeks of gestation who were referred to our practice for a detailed fetal anomaly scan. The uvula was visualized either in a frontal section through the neck and pharynx or via a transverse section with subsequent slight tilting of the transducer. The soft palate was visualized in a median sagittal section through the head. To test whether the techniques described are suitable for inclusion in routine examinations, the time allowed for a normal ultrasound scan was not changed from 30 min.

Results: A normal uvula could be visualized with a typical echo pattern (the 'equals sign') in 90.7% of the cases and the soft palate could be completely visualized in a median sagittal section in 85.3% of the cases. Visualization of at least one of the two structures (either the uvula or the soft palate) was successful in 98.4% of the cases. In one case an isolated cleft palate (in an otherwise normal fetus) was diagnosed; in one case with a cleft lip and palate, the cleft palate and the completely split uvula were detected. In 1.2% of the cases the examination did not provide sufficient information on either the uvula or the soft palate.

Conclusions: In a high percentage of cases, relevant soft palate structures can be visualized successfully with 2D ultrasound, permitting cleft palate to be ruled out in routine examinations. Visualization of the equals sign proves an intact palate. Absence of the equals sign indicates cleft palate and should prompt further examination of the soft palate in a median sagittal section. Cleft palate can be confirmed when the soft palate cannot be visualized. This technique also facilitates evaluation of the soft palate in the event of a cleft lip and palate.