Enlargement of cisterna magna as an indicator of chromosomal abnormalities in a low-risk Asian population.

AIMS

The aims of this study was to invent the prevalence of cisterna magna (CM) enlargement in a low-risk population and relate this to chromosomal abnormalities and initial delivery outcome.

STUDY DESIGN

11,145 patients having routine ultrasound scan at 21st week of pregnancy were screened for abnormalities. Cases with CM enlargement were traced and outcome retrieved either from case notes or from the patients.

RESULTS

In our low-risk population six fetuses were found to have CM enlargement. Only one had a chromosomal abnormality, 47XY + 18, and this fetus also presented with other malformations. Four were healthy at birth and one, also with other malformations, is showing signs of mental retardation. All cases were male.

CONCLUSION

Isolated CM enlargement does not seems to be an indicator for chromosomal abnormalities, especially if the fetus is a male. Still, it should alert the examiner of the possibility of other malformations, which may be of importance.