Small gestational sac
A small gestational sac in early first trimester is considered a poor prognostic factor. Some authors use the mean sac diameter to crown rump length difference of 5 mm or greater to be normal .
The smaller than expected sac diameter in pregnancies 36-42 days from the last menstrual period has been reported as a predictor of spontaneous miscarriage.
The difference between the two values should not be used in embryos older than 9 weeks .
See also
