Infertility/Fertility/Shrinking Follicle


I am going through my first round of natural fertility treatment. I take progesterone during ovulation until 14 days past. My RE was monitoring my growing follicle and blood levels every other day from day 2 of my period.  During my last appointment, my follicle shrunk from 23 to 21, but my blood levels were conclusive with ovulation.  They said they like to see follicles shrink at least 5mm to be sure an egg was released.  Is there still a chance I could have released an egg even though my follicle shrunk just 2mm when they last measured? Or did they check too soon? How long does it take for a follicle to shrink after it releases an egg?

Hello Jacquie from the U.S. (Pennsylvania),

In general, if a patient is being followed for ovulation, ultrasound is done each day after the trigger date (HCG or positive OPK).  Then if you continue to follow on a daily basis, the ovulated follicle will disappear.  The difference in sizes that you noted could be just the variance that can be found on ultrasound (there is a margin of error).

Hope that helps.

Good Luck,

Dr. Edward J. Ramirez, M.D., FACOG
Executive Medical Director
The Fertility and Gynecology Center
Monterey Bay IVF Program

Monterey, California, U.S.A.

for additional information check out my blog at check me out on twitter with me at @montereybayivf and facebook @montereybayivf.  Skype and internet comprehensive consultations now available via my website for those who want a more extensive evaluation that this site can accommodate  


All Answers

Answers by Expert:

Ask Experts


Edward Joseph Ramirez, MD, FACOG


I am a specialist in infertility and advanced gynecological care. I can answer questions about infertility, gynecology related ills, menopause...virtually anything that affects women's health. PLEASE tell me where you are writing from as I am always interested.


I have been practicing as an Ob/Gyn and Infertility Specialist for over 23 years. Gynecology, advanced laparoscopic surgery, basic infertility, IUI's, IVF, reproductive surgery, and ovulation induction are all areas of my expertise. I am Board Certified. I have been doing In Vitro Fertilization in my clinic for 19 years.

American College of OB/GYN, American Board of Obstetrics and Gynecology, American Society of Reproductive Medicine, California Medical Association, American Association of Gynecologic Laparoscopists, Fellow of The American College of Obstetricians & Gynecologists

American Journal of Obstetrics and Gynecology, Wall Street Journal, Monterey Herald, SERMO, Women's Health and Fertility Blog

Medical Degree from Stanford University, Residency at Tripler Army Medical Center, Reproductive Training at Pacific Fertility Center, San Francisco

©2017 All rights reserved.