Endometrial cavity thickness 4.3 mm?

Depends: The thickness of the lining of the uterus (endometrium aka em) varies with the menstrual cycle and age (premenopausal or not). We like to make sure it's 'behaving' properly so we report thickness. The lining on both sides of uterus appears on u/s as one 'shade' of grey and is called the em cavity thickness (typically twice as thick as lining). 4.3 mm is typical, but depends on hormone cycle.