Donetsk`s regional specialized center of medical genetic and prenatal diagnosis, Ukraine.

Case report
 
A 32-year-old woman (G3P2) was referred to our center at 13 weeks + 5 days of her pregnancy.  Her first child had patent foramen ovale and prolapse of the mitral and tricuspid valves. She took some antiallergic drugs in early stage of the pregnancy. Her husband and his brother and uncle have congenital colobomas of iris.

The first trimester screening was normal (risk of trisomy 21 – 1:321, risk of trisomy 18 – 1:10 000, HCG 0,82 MoM, PAPP-A 0,92).

During the first scan (13 weeks + 5 days) the absence of the parietal bones was considered to be a problem of bone mineralization. Subsequent amniocentesis was done, revealing normal karyotype (46, XX).

At 19 weeks the absence of the parietal bones became more evident and additionally choroid plexus cyst and renal pyelectasis were found.

At 21 weeks a hyperechoic bowel and gastromegaly were also suspected.

The neonate (girl) was born at term. The diagnosis of the absence of the parietal bones was confirmed and the baby is doing fine.

Images 1, 2: Oblique coronal planes showing lack of ossification of the parietal part of the skull representing the absence of the parietal bones.

Images 5, 6: The image 5 shows a transverse scan of the fetal head positioned more caudally (closer to the base of the skull – the echogenic lining of the skull originate from occipital, temporal and frontal bones. The image 6 represents a transverse scan of the skull which was taken more cranially than in the image 5. Missing parietal bones cause the lack of hyperechoic lining around the skull at this level.