Differences between proximal and distal endometrial monolayer thickness in women aged over 50 years undergoing saline infusion sonohysterography.

Distal endometrium measures thicker than the proximal endometrium in most SIS cases and in one out of six women, the difference is >1 mm. The distal layer is three times more likely to contain focal thickening. Sonologists should be conscious of possible enhancement artifact when measuring the EE during SIS.