Assessment of the follicular maturity and endometrial receptivity is done by ultrasound follicular testing. We can serially measure the follicle size and endometrium thickness by ultrasound in a menstrual cycle.
Follicular Study
| Day of cycle | Follicular size | Endometrium thickness & structure |
| Day 2 | 3-5mm | Thin or shedding endometrium |
| Day 7 | 5-8mm | 5-7mm, triple line |
| Day 10 | 10-12mm | 6-8mm, triple line |
| Day 14 | 16- 18mm | 8-12mm, triple line changing to secretory |
| Day 18 | collapsed follicle | 8-12mm, secretory |