OC23.04: The “superimposed line sign”: a novel marker in early diagnosis of secondary cleft palate

The objective of the study is to describe a novel diagnostic marker “the superimposed line sign” which is visible in mid sagittal view of face and it serves as the clue to identify secondary palatine clefts. The mid sagittal view was examined in 9576 cases between 12 to 20 weeks of gestation and the superimposed line sign was evaluated in 2D. In mid sagittal view, the vomer bone appears as a superimposed line at the distal two thirds of the palate as the secondary palate merges with the vomer bone in the midline. In midline cleft of the secondary palate, the line formed by the palate is absent and hence only the vomer bone is visualised creating a single line instead of the normal superimposed double line. Failure to demonstrate this sign prompted further 3D evaluation and the palate was examined in stored volumes of the fetal face. Based on this observation the superimposed line was absent in 17 fetuses with cleft of secondary palate which was confirmed by 3D evaluation and also postnatally. Out of 17, thirteen had defects involving the premaxilla and four had isolated median cleft of the secondary palate. The appearance of the superimposed line was useful in ruling out median cleft palate in 32 high risk cases with a previous history of cleft palate. None of the cases with the normal appearance of the superimposed line had median palatine cleft when evaluated postnatally. The superimposed line sign is a new sonographic marker in evaluation of midline defects of secondary palate and documentation of this sign proves the presence of both palate and vomer in midline. This marker can be better demonstrated in the late first trimester leading to early diagnosis of palatine clefts and this sign could also increase the detection rate of isolated cleft palate. Early diagnosis of median cleft palate can lead to better counselling options at the time of first trimester aneuploidy screening.