thank you for your query.
A follicular study
is done to review the serial growth of the ovarian follicles, and to document ovulation.
It also helps to study the serial growth and development of the endometrium ( lining ) of the uterus
Please remember that in order to visualize the uterus and ovaries, the best modality is the internal or transvaginal ultrasound
Many doctors do perform follicular monitoring by abdominal ( or what I assume you are calling an outside, or normal , method ) - however, the more reliable way is to perform a serial transvaginal ultrasound.
Take care, and please ensure that you are under proper treatment by a reputed gynecologist, else the entire procedure is meaningless.