Follicular

The start day for follicular tracking depends on whether the woman has regular cycles and whether fertility medications are used:

​

• Natural Cycles - Ultrasounds generally begin by cycle day 10 in ovulatory women with regular cycles. Earlier if cycles are shorter.

• Ovulation Induction - With medications like clomiphene or letrozole, ultrasounds often start on cycle day 3 to establish a baseline. Continue until ovulation.

• IVF Cycles - Tracking begins with the onset of menstrual bleeding. Frequent ultrasounds monitor follicle response to fertility drugs.

•  Irregular Cycles - Unpredictable cycles may require ultrasounds from the start of menstruation to identify follicle growth whenever it occurs.

​

The goal is always to pinpoint the optimal ovulation day based on follicle maturity. Starting scans early enough to detect the beginning of follicle growth is important.

​

How Often are Follicular Tracking Scans Needed?

​

The frequency of follicular tracking depends on the stage of follicle development:

​

• Early Follicular Phase - Every 2-3 days

• Around Selection of Dominant Follicle - Every 1-2 days

• Approaching Ovulation - Daily

 

At critical decision points closer to ovulation, daily ultrasounds are often needed to time procedures precisely and avoid premature ovulation. The frequency balances monitoring needs with reducing visits and costs.

​

Some key factors that may warrant more intensive follicular tracking include:

​

• Use of injectable fertility medications

• History of rapid ovulation

• Irregular or unpredictable cycles

• Undergoing IUI or IVF treatment

​

Otherwise, every 2-3 days is typically adequate to effectively track follicle growth.

​

What is Monitored During Follicular Tracking Ultrasounds?

​

Several parameters are assessed during each follicular tracking ultrasound:

​

• Number of Follicles - The total number of follicles visible in each ovary.

• Size of Follicles - The diameter of each follicle is measured. Mature follicles ovulate around 18-24 mm.

• Dominant Follicle - The largest, most mature follicle that will likely ovulate.

• Endometrial Lining - The thickness of the uterine lining should reach around 8 mm for implantation.

• Ovulation - Follicles may show collapse, fluid or blood when the egg releases.

• Ovaries & Uterus - Screen for abnormalities in anatomy, fibroids, cysts etc.

​

Monitoring all of these parameters provides an overall picture of menstrual cycle health and how follicles are progressing each day.

​

Follicular Tracking Results and Interpretation

​

The follicular tracking results will be interpreted by a fertility specialist based on:

​

• Number of Follicles - Typically see less than 10 growing together initially. Too many could mean overresponse risk.

• Follicle Growth Rate - Ideal is 1-3 mm increase in size per day after reaching 10 mm. Slower growth may need medication changes.

• Dominant Follicle Size - Looking for the lead follicle to reach 18-24 mm before ovulating.

• Endometrial Lining - Should reach 8 mm thickness to be ready for implantation after ovulation.

• Ovulation Timing - Want to see ovulation around cycle day 14 if regular cycles. Later in polycystic ovary syndrome.

• Cycle Cancelation - Overresponse or underresponse to medications may result in canceling the cycle.

​

The follicular phase results will guide medication dose adjustments and optimal timing of procedures like IUI or egg retrieval in IVF.