If you’ve already completed an IVF cycle, you know how much monitoring is involved before an egg retrieval can occur. Monitoring is a crucial part of the IVF process because it allows your healthcare provider to know:

1. If/when you are ready to begin an IVF stimulation
2. What your hormone levels are throughout your IVF stimulation
3. How your body is responding to the IVF medications (and if your dosages need to be adjusted)
4. The size of your follicles as your stimulation progresses
5. How close you are to ovulating

Without this knowledge, the following could occur:

1. You receive the wrong dosage of medication and no follicles (eggs) grow
2. You receive too much medication and run the risk of developing OHSS (more on this later)
3. You ovulate prematurely and no eggs are able to be retrieved

If you haven’t already, I would recommend reading the posts about IVF medications and female reproduction in order to fully understand this blog post. Also, a quick reminder that I’m still not a doctor and never will be, so always discuss any health concerns with your healthcare provider before making any decisions about your health. 

A Quick Review

A woman’s menstrual cycle begins on the day she starts her period. From there, her body goes to work preparing for a pregnancy. Prior to ovulation, a few events occur:

1. The brain releases FSH and LH to help the ovarian follicles grow (the eggs inside of them should be maturing as they grow). Recall that multiple follicles, known as antral follicles, will begin to grow at the beginning of the menstrual cycle through a process known as recruitment, but only one follicle becomes the dominant follicle (which releases its egg at ovulation).
2. As the follicles (eggs) grow, the ovaries release the hormone estrogen (E2).
3. Prior to ovulation, the brain releases a surge of the hormone LH, which triggers ovulation to occur.

During an IVF cycle, medications are given to hyper-stimulate the ovaries (so multiple follicles/eggs grow) and control when ovulation occurs.

IVF Baseline Monitoring

So, you’ve already met with your doctor and determined that you will be completing an IVF cycle. Fast forward past the initial blood tests and ultrasounds, semen analyses, and financial counseling (among other things), and you’re ready to begin your IVF cycle!

Your IVF cycle begins on the day you start your period. Keep in mind, though, that sometimes you may need to take medications, such as birth control pills or Lupron, before your period begins in order to prepare your body for your IVF cycle. Your provider will determine whether or not you need these medications before your IVF cycle is expected to begin.

You should inform your IVF clinical team when your cycle begins. From there, your clinical team will typically schedule you for an appointment 2 days later for baseline testing. Baseline testing normally consists of the following:

1. A transvaginal ultrasound of the pelvis, which shows how many antral follicles are in your ovaries (remember that the eggs are inside of these). This ultrasound also checks for any large ovarian cysts and/or other abnormalities that may interfere with the IVF process, and it confirms that the uterine lining is thin (as it should be when menstruation occurs).
2. Blood tests to confirm that you are not pregnant and to report your FSH, LH, and estrogen (E2) levels. These hormone levels should be low at this point in the menstrual cycle.

If everything looks good on your baseline testing, you will begin taking some of your IVF medications, which will hyper-stimulate your ovaries so multiple follicles (with eggs inside of them) grow. Most clinics will have you return 3-5 days later for your next monitoring appointment.

IVF Stimulation Monitoring

So, you’ve been taking your IVF medications for 3-5 days and are scheduled for your next monitoring appointment. This appointment will consist of the following monitoring:

1. A transvaginal ultrasound of the pelvis, which shows the number and size of the follicles inside the ovaries (see picture). At this point, you should expect to see multiple follicles in each ovary that have grown in size since your baseline scan.
2. A blood test that measures your FSH, E2, and LH levels. At this point, you should expect to see a moderately high level of FSH and E2 (the IVF medications typically contain a synthetic FSH, which causes multiple follicles to mature. The increased number of follicles growing causes the ovaries to release excess E2). The LH level should still be relatively low since the LH surge does not occur until closer to ovulation.

If your hormone levels look appropriate and your follicles seem to be growing, you will typically begin taking a medication to prevent premature ovulation, and you will return to the clinic in 2-5 days (this varies between patients/clinics) for another monitoring appointment.

After 2-5 days, you will return to the clinic for the following monitoring:

1. A transvaginal ultrasound of the pelvis, which shows the number and size of the follicles inside the ovaries. At this point, you should expect to see around the same number of follicles that were seen at your previous ultrasound (sometimes less since not all follicles respond to the medications), but they should be larger than they were at your previous ultrasound.
2. A blood test that measures your FSH, E2, and LH levels. At this point, you should expect to see a higher level of FSH and E2 than what was measured at your previous blood test. The LH level should still be relatively low since the LH surge has not yet occurred.

Your follicle sizes are measured in millimeters. Typically, follicles under ~16mm are too small to be retrieved, while follicles over ~23mm are too large (the eggs inside of them may be “too” mature). Follicles can grow ~1-3mm per day depending on how your body responds to the IVF medications, so the next few days may consist of daily trips to the IVF clinic for monitoring.

The dosage of your IVF medications may be altered to ensure that you have the best stimulation possible. Keep in mind that the quality of the eggs outweighs the number of eggs that are retrieved, so it is important to let them mature at the perfect pace.

Over the next few days, you will continue the same type of monitoring until two events occur:

1. Some or all of your follicles are the “perfect size” (the protocol varies between clinics, but a typical “perfect size” is roughly 18-22mm).
2. Your E2 level is really high (~200pg/mL per mature egg), your FSH level is still high, and your LH level is not high (we don’t want the LH surge to occur yet).

At this point, you should be ready for your ovulation trigger. Administering this medication essentially causes an LH surge to occur, which then triggers ovulation to occur. This medication must be administered exactly when directed (typically 35-36 hours prior to your egg retrieval time), which should be right before ovulation will occur. If ovulation occurs before the egg retrieval, the eggs can become “lost” and unretrievable.

Common Questions About IVF Monitoring

Question 1: Can I have my IVF monitoring done at a different location than where my egg retrieval will be?

Answer: Yes. Outside monitoring, also called satellite monitoring, is possible. However, every clinic has policies/preferences about this, so it’s important to talk with your provider about this before you begin your IVF cycle. For patients who live far from the IVF clinic, outside monitoring provides the advantages of saving time and money. On the flip side, your provider must be able to see your results on the same day that your outside monitoring occurred, so they must be faxed/emailed/etc. ASAP so your stimulation is not delayed.

Question 2: What if I have a large cyst on my ovaries during my baseline scan?

Answer: A cyst is fluid-filled sac in (or on) the ovary that is “left over” from the previous menstrual cycle. The cyst can either be formed by the dominant follicle (ovulation did not occur and the follicle is enlarged), or from the corpus luteum (it was supposed to shrink after ovulation, but it didn’t). Small cysts (<3cm) will usually resolve on their own and won’t cause any issues in an IVF cycle. However, the presence of a large cyst (>3cm) can interfere with your IVF cycle, and your cycle may need to be cancelled until the cyst resolves itself. If you have a cyst and your baseline E2 level is really high, your cycle will likely be cancelled to give the cyst time to shrink/disappear. If the cyst is still present after a few months, it may need to be removed surgically (this isn’t very common). If ovarian cysts are recurring, birth control pills may be prescribed to reduce the number of cysts that develop each menstrual cycle. These prevent a dominant follicle and corpus from developing, so cysts should not occur, either.

Question 3: Why did I originally have 10 follicles growing, but I only have 6 that are growing on the day of my trigger shot?

Answer: Naturally, multiple (antral) follicles will begin to grow at the very beginning of each menstrual cycle. These follicles should be visible on your baseline IVF ultrasound. However, as you begin to take your IVF medications, it’s common to have some follicles that do not grow much or at all. Most likely, these follicles didn’t respond to the IVF medications and therefore did not progress in development. Furthermore, the number of antral follicles is not always predictable (it’s more of an estimate), so try not to focus too much on the antral follicle count (AFC) and focus more on the number of eggs that are actually retrieved (easier said than done, I know).

Question 4: I had 10 “normal” sized follicles on the day of my trigger, so why were only 8 eggs retrieved?

Answer: It’s not uncommon to have less eggs retrieved than expected. Some follicles may grow during an IVF stimulation, but these follicles may not all contain eggs (empty follicles). Thus, the follicular fluid may be aspirated (sucked up) during the egg retrieval, but there will be no egg inside the follicle (the eggs are too small to see on the ultrasound, so it’s up to the embryologist to determine if an egg is present in the follicle). This is common in women with PCOS. It’s also possible that some eggs stuck to the walls of their follicles during the egg retrieval. So, even though the follicular fluid was aspirated, the egg was not removed from the follicle along with the fluid. Finally, if ovulation occurs early, the egg may be released from the follicle before the egg retrieval. In this case, the follicular fluid is still aspirated, but the egg becomes “lost” and unable to be retrieved. Ovulation is timed for an egg retrieval, but some women still ovulate early even with the timed trigger shot.

Question 5: Why did I only get 3 eggs from my IVF cycle, but my friend got 20?

Answer: There are many fluctuations in the number of eggs that can be retrieved in an IVF cycle. Women who have a low ovarian reserve (low egg count) are less likely to have a large number of eggs that mature in an IVF cycle regardless of how much IVF medication they receive. Often, women over 35 tend to have a diminished ovarian reserve, which causes a lower oocyte yield during an egg retrieval. On the flip side, women with PCOS tend to have a higher number of eggs that are retrieved in an IVF cycle, though the quality of these eggs may not always be ideal. A blood test for your AMH (anti-Mullerian hormone) can help determine your ovarian reserve, which can give you an indication of how many eggs you can expect to have retrieved during your IVF cycle. Getting a low number of eggs can be disheartening, but keep in mind that it only takes one healthy embryo to make a baby at the end of the day.

References

1. IVF Monitoring – Medications – Ultrasound – Tennessee Fertility Center (nashvillefertility.com)
2. IVF | In-Vitro Fertilization at San Diego Fertility Center® (sdfertility.com)
3. IVF Cycle Monitoring – Fertility Treatment – Virginia Fertility Center Virginia Center for Reproductive Medicine (vcrmed.com)
4. The Baseline Ultrasound in IVF: What is It & Why Do You Need It – Alex Robles, MD (alexroblesmd.com)
5. Do All Follicles Have Eggs? Why You Got Fewer Eggs Than Expected – Alex Robles, MD (alexroblesmd.com)

About the author

Hi! I’m Jessica. I’m 30 years old and have been an embryologist since 2018. I’ve wanted to be an embryologist since I was in high school because the concept of IVF has always fascinated me. I completed my BS at the University of Pittsburgh, and then my MS at Colorado State University. I love my job and helping people build their families, and I also love educating people about IVF and infertility. In my free time, I love traveling and spending time with my husband, daughter, and dogs!