Follicular Study: Purpose, Procedure, and Success Rate

IVF, Learning center

by Dr. Firuza Parikh

Follicular monitoring or follicular studies are undertaken to see the progress of growing follicles. This can be done on a natural or hormonal stimulation cycle. The monitoring is preferably done with transvaginal ultrasound, although some women may prefer to have an abdominal ultrasound to monitor the follicles. The procedure is usually started on Day 1 or Day 2 of the period and continues till documentation of ovulation or till the day of oocyte retrieval.

A mature follicle ranges from 16 to 20 mm. The maturity and size depend on the type and amount of medication used and the woman’s age. Moreover, it is noted that couples who have intercourse during the follicular study will have a much higher chance of conceiving. In this blog, we’re going to talk about the purpose, procedure, who needs it and success rate of the follicular study. Let’s dive right in.

Follicular Study: What You Need To Know

Reported first in 1986, Empty Follicle Syndrome is a rather rare condition wherein eggs cannot be retrieved during an IVF. The exact cause of EFS remains unclear, and some experts even question whether the follicles are truly empty. The estimated incidence of EFS in IVF cycles ranges from 0.6% to 7.0%. Now, for couples who plan to undergo in vitro fertilization in the near future, it would be wise to do your due diligence and look into the procedures involved so as to have the ability to make an informed decision. One such step you will go through is a follicular study.

This blog aims to give readers insight into the importance of follicular studies for a successful IVF success journey.

What Are Ovarian Follicles?

Ovarian follicles are small fluid-filled sacs located within a woman’s ovaries. These tiny sacs play quite a huge role in a woman’s menstrual cycle and fertility. Each follicle contains an egg (oocyte) at its early stage of development. The size, quality, and number of follicles become important factors in assessing a woman’s fertility and the success of fertility treatments.

What is a Follicular Study, and Why is it Done?

A woman’s ovaries have multiple sacs filled with eggs called follicles. These tiny sacs play a critical role in ovulation, the process of releasing a mature egg for potential fertilization. But how do we monitor their growth and predict ovulation timing? This is where a follicular study comes in.

A follicular study is a series of painless transvaginal ultrasounds performed during the early part of your menstrual cycle. During these scans, the doctor examines the follicles in your ovaries, tracking their size and development and, ultimately, predicting ovulation. This information is crucial for various reasons:

Find The Right Time For Ovulation: A follicular study helps couples trying to conceive time intercourse naturally to maximize the chances of fertilization, which is why pinpointing ovulation time becomes important.
Understanding Fertility: The size and development of follicles can provide insights into your egg quality and potential fertility concerns (if any).
Planning Fertility Treatments: For procedures like in vitro fertilization (IVF), follicular studies are essential for monitoring follicle growth and determining the ideal time for egg retrieval.

The entire procedure is painless, and it usually takes just a few minutes to complete. There’s no need to fast beforehand, and having a full bladder isn’t a requirement, either.

What Are Follicular Scan Types, and How Many Scans Are Needed?

Follicular scans, also known as follicle tracking, are a series of ultrasounds performed to track the development of tiny sacs within a woman’s ovaries called follicles. These follicles nurture the eggs, and understanding their growth is pivotal when it comes to the subject of fertility. Here’s a look at what you can expect:

Baseline Scan: This initial scan, which is typically done within the first 3 days of your period, is where it begins. It assesses the baseline size and condition of your ovaries, particularly the number of pre-antral follicles (resting follicles with potential). This can help determine the antral follicular count, which is an indicator of your egg reserve. It also provides a snapshot of the uterine lining’s health.
Serial Scans: Now, as your cycle progresses, serial scans are performed every 2-3 days, and they allow the doctor to monitor the growth and development of your follicles.
Rupture Scan: The final scan, sometimes performed near your predicted ovulation time, acts as a confirmation. It checks for two key signs: the disappearance of the dominant follicle (the one most likely to release an egg) and the presence of free fluid in the ovary. These indicate that ovulation has likely occurred.

It’s likely that your doctor will recommend 4-6 follicular scans throughout a single menstrual cycle so as to ensure that the ovulation timing is pinpointed accurately.

Why is follicular Monitoring Done?

For those undergoing or planning to undergo IVF (in-vitro fertilization), follicle scans are particularly vital as the scans help in determining the condition and number of eggs produced during ovulation and assess the levels of involved hormones. If your hormone levels are imbalanced, your doctors can help in adjusting medication dosages to enhance your chances of conception.

As mentioned earlier, follicular monitoring is quite instrumental in pinpointing the exact time of ovulation as it can give you the chance to devise a better plan of intercourse to increase your chances of pregnancy.

However, it is important to note that follicular monitoring does not guarantee the fertilization of the egg by the sperm or the implantation of the fertilized egg in the uterine wall. Some problems preventing conception post-ovulation cannot be addressed by these scans alone.

For more accurate predictions of trigger timing and to assess the risk of over-response, data from follicular tracking scans on Days 5, 6, or 7 of stimulation are the most valuable.

Role of follicular study during IVF assessment and timing

It is a very important part of the IVF cycle. Based on the daily findings, the fertility expert will suggest,

The dose and type of hormonal stimulation,
What dose to continue as the follicles develop and
When to stop the medication in preparation for ovulation or oocyte retrieval.

The procedure is not painful. In some women, there may be a feeling of discomfort when the probe is inserted into the vagina.

When is follicular monitoring necessary?

It is necessary for many procedures like planned intercourse, IUI and, IVF, ICSI. Here are some of the top reasons justifying the necessity of follicular monitoring:

There can be quite a few reasons why your doctor may recommend follicular monitoring:

Unexplained Infertility: If you’ve been trying to conceive for a year (or 6 months if you’re over 35) without success, follicular monitoring can be a first step, as it can help to identify potential ovulation issues that might be hindering pregnancy.
Age Concerns: As a woman’s age increases, so does the likelihood of irregular ovulation. If you’re over 35 and haven’t conceived within the recommended timeframe, follicular monitoring can provide valuable insights into your ovulation patterns.
PCOS (Polycystic Ovary Syndrome): Women with PCOS often have irregular cycles and ovulation. Follicular scans can help assess your ovulation patterns and guide treatment plans if needed.
Fertility Medications: If you’re using fertility drugs to stimulate ovulation or produce multiple eggs for procedures like IUI (intrauterine insemination) or IVF (in-vitro fertilization), follicular monitoring could become necessary. It allows your doctors to monitor follicle growth and adjust medication dosages as needed.

The fertility doctor suggests the Follicular scan. The follicular scan starts on Day 1 or Day 2 and may be repeated on Day 6 onwards until ovulation. The treating doctor decides the frequency of the scans.

How does follicle tracking work?

Follicle tracking involves a series of painless transvaginal ultrasounds. These quick scans, typically lasting 5-10 minutes each, are performed during the early part of your menstrual cycle, usually starting around day 9. Monitoring the follicles in your ovaries with these scans allows doctors to track their development and growth.

Couples are then suggested to have intercourse. This becomes quite helpful in assisting conception as it optimizes the timing of the sperm and egg to meet.

Who needs follicle tracking?

Among the few reasons you may need to undergo follicle tracking, here are some of the most common ones:

If You Are Unsure About Your Ovulation Timing: Even if you have been using ovulation prediction kits, follicle tracking can provide a more accurate assessment of when you are ovulating.
If You Have Experienced Miscarriages in Early Pregnancy: Follicle tracking can help identify potential issues that might be causing early pregnancy loss.
If You Are Taking Medication to Induce Ovulation: If you are on fertility drugs to stimulate ovulation or to address other conception-related problems, follicle tracking can help monitor the effectiveness of these treatments.

What Information Do Follicular Scans Provide?

Follicular scans provide several key pieces of information about your reproductive health, including:

Antral Follicle Count: This refers to the total number of small follicles (antral follicles) present in each of your ovaries. A higher count generally indicates a larger egg reserve.
Follicular Size: The size of each developing follicle is measured in millimeters, and this can help doctors track the growth and identify the dominant follicle, which is the one most likely to release an egg.
Endometrial Thickness: Your uterine lining’s thickness is important for successful embryo implantation. Follicular scans measure this thickness to make a healthy environment for a potential pregnancy.
Endometrial Pattern: Beyond thickness, the scan also assesses the pattern of your endometrium. A healthy lining typically exhibits a tri-layered pattern and this indicates proper development.
Dominant Follicle: The scan identifies the lead follicle, which is usually the one that will release an egg during ovulation.

The success rate of follicular study

Although many researchers suggest that the success rate of follicular study is just 10%, it can vary depending on the patient’s age, hormone levels, and other factors. For example, a woman in her 20s may have a higher success rate than a woman in her 60s. Moreover, the medical history of a woman also affects this rate.
There are alternatives like LH kits to measure the LH surge and calendar apps, but those are not very reliable. It is more efficient to do more follicular monitoring as that increases the chances of Pregnancy and decreases TTP (Time to pregnancy).

What are the advantages of folliculometry?

Folliculometry, a term used for a series of ultrasound scans, can give you and your doctors valuable insights into your reproductive health. Here are some of the advantages it brings:

Detecting Premature Rupture of Follicles: Folliculometry has the chance to help you identify if any follicles rupture before reaching the optimal size.
Identifying Non-Growing Follicles: Some follicles may not grow at all, and this can be detected through regular monitoring.
Recognizing Luteinized Unruptured Follicles: In some cases, dominant follicles may not rupture as expected. This condition, known as luteinized unruptured follicle syndrome, can be diagnosed with folliculometry.
Assessing Endometrial Lining: The thickness and quality of your endometrial lining can be evaluated, and this will help in making sure that it is adequate for embryo implantation.
Timing Ovulation: Folliculometry is quite necessary for predicting the exact time of ovulation, especially in IVF.
Guiding Treatment: If you are undergoing treatment with ovulation-inducing drugs or injections, folliculometry can help with these treatments.
Early Detection of Complications: Conditions like ovarian hyperstimulation syndrome (OHSS) can be detected early. This way, you will get the chance to seek treatment immediately.
Identifying Luteal Phase Deficiency: Folliculometry can help detect deficiencies in the luteal phase, which is essential for maintaining pregnancy.

How Much Time Does It Take To Undergo A Follicle Scan?

Each scan itself typically takes only 15-20 minutes, making it a quick and painless procedure. To accurately predict ovulation, a series of 4-6 scans are usually performed throughout a single menstrual cycle. These scans track the growth of follicles in your ovaries and the development of the uterine lining. With all the necessary information gathered through these scans, your doctor can pinpoint your ovulation window with greater precision.

Side effects of follicular ultrasound scan

Follicular ultrasound scans are a safe and routine procedure used to monitor egg development during your menstrual cycle. Unlike some fertility procedures, they are non-invasive and generally involve minimal to no side effects. But do bear in mind that every walk through an IVF procedure can be taxing and stressful for many couples.

Frequently Asked Questions (FAQs)

Q: When does a follicular scan have to be done?

Ans – Women undergo several follicle scans during their menstrual cycle, usually between days 9 and 20.

Q: What should be the size of the follicle to get pregnant?

Ans – A mature follicle to get pregnant is between 16 to 20 mm. Also, remember that the medication type, dosage, and the woman’s age determine the maturity and size of the follicle.

Q: How does a Follicular Study Work?

Ans – Follicle Study involves a series of ultrasound scans of the vagina that take approximately 5-10 minutes.

Q: Can follicular monitoring help me conceive?

Ans – It is possible to identify the exact time of ovulation using follicular monitoring. Thus, there is a much greater chance of getting pregnant if intercourse is planned during that period.

Q: Is follicular monitoring painful?

Ans – This procedure does not cause any pain. Inserting the probe into the vagina may cause discomfort in some women.

Q: Can follicular studies confirm pregnancy?

Ans – If the scan is continued in case the woman misses her period and the bHCG goes above 1000 units, then the ultrasound scan can confirm a pregnancy. At that time, it is no longer called a follicular scan.

Q: What is ET in the follicular study?

Ans – ET stands for Endometrial thickness.

Q: What is MSF in the fallopian study?

Ans – MSF stands for Multiple small follicles, usually seen in women with PCOS.

Q: Can follicular studies detect fallopian tube blockage?

Ans – If there are distinct hydrosalpinges, follicular studies may be able to pick up hydrosalpinges but not other types of tubal blockages.

Q: Which injection is given after a follicular study?

Ans – HCG injection, which will increase your chances of pregnancy, will be given to you after your follicular study is complete.

Q: Can follicular study detect egg release accurately?

Ans – Follicular studies can be very helpful in predicting ovulation.

Q: Is follicular study done during periods?

Ans – For the ideal ovulation prediction, women usually have several follicle scans during a specific window – days 9 to 20 of their menstrual cycle.

Q: What is the Procedure?

Ans – Here’s what to expect during the procedure:

While some doctors might consider an abdominal ultrasound, the preferred and most accurate method for follicular studies is a transvaginal ultrasound.
For the transvaginal ultrasound, you’ll comfortably lie on your back with your legs bent and knees up. This position allows for optimal probe placement.
The sonographer or doctor will gently insert a smooth, flexible probe into your vagina. This probe emits sound waves that bounce off your internal organs, creating detailed images of your ovaries on a screen.
The doctor will use the ultrasound images to examine your ovaries, focusing on the follicles – tiny sacs where your eggs mature. They’ll assess the size, number, and growth of these follicles, particularly the dominant follicle (the one most likely to release an egg).
The scan might also evaluate the thickness and health of your uterine lining, which plays a vital role in implantation if pregnancy occurs.
The entire procedure typically takes only 15-20 minutes and is generally painless. You might feel slight pressure during probe insertion, but it shouldn’t cause any discomfort.

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