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If there is no increase in follicle size on three studies on alternate days from day 11, then there is little chance of follicle maturing.
Follicle study should commence on 7th day of cycle, to assess the base line state of uterus
and adnexa. There after the study should be done on 10th or 11th day, taking into consideration the holiday of the sonography
Most likely you will need drugs to stimulate follicle to mature and may be injection to induce ovulation.