How is follicular monitoring performed?
Sep 29, 2021
Source: Cainiu Health
Dr. Liu Xiuyan
Introduction
In general, follicular monitoring is calculated according to the menstrual cycle. For women with regular menstrual cycles, the ovulation period typically begins around day 10 of the menstrual cycle. The duration of menstruation is related to the length of the follicular phase. Ovulation can be assessed by tracking basal body temperature (BBT): measure your temperature once each morning—preferably under the armpit or orally—before getting out of bed. A rise in temperature typically occurs approximately 10 days after the onset of menstruation.
Follicular monitoring is a diagnostic procedure used for patients experiencing infertility. It involves serial transvaginal ultrasound examinations to track the development of ovarian follicles and assess whether ovulation occurs. Clinical data show that many women with infertility or menstrual irregularities are found—through follicular monitoring—to have impaired follicular development or ovulatory dysfunction. So, how is follicular monitoring performed? Below, we address this question.
How Is Follicular Monitoring Performed?
Generally, follicular monitoring is scheduled according to the menstrual cycle. In women with regular cycles, the ovulatory phase typically begins around day 10 of the cycle. The duration of menstruation and the length of the follicular phase are interrelated. One common method for identifying ovulation is basal body temperature (BBT) charting: measuring oral or axillary temperature each morning upon waking. A sustained rise in temperature—occurring approximately 10 days after the onset of menses and persisting for at least 12–14 days—indicates a biphasic thermal pattern and confirms ovulation. Another approach involves detecting luteinizing hormone (LH) in urine using ovulation predictor kits (OPKs). During a normal ovulatory cycle, LH surges in the urine; a positive test result suggests that ovulation will occur within 36–48 hours. However, this method may be affected by lifestyle factors and individual physiological variations, making it unsuitable for all women. Alternatively, transvaginal ultrasound can directly visualize ovarian follicles and dynamically assess their maturation. A mature follicle typically measures 1.8–2.0 cm in diameter. A follicle smaller than 1.8 cm indicates abnormal follicular development.
Additional Information: Causes of Poor Follicular Development
1. Polycystic Ovary Syndrome (PCOS)
PCOS is one of the most common causes of impaired follicular development and anovulation in women. Characteristic features include enlarged ovaries containing multiple small, immature follicles that fail to develop to maturity. Consequently, pharmacological intervention—such as ovulation induction—is often required.
2. Premature Ovarian Insufficiency (POI)
Some women experience poor follicular development due to premature ovarian insufficiency. Initially, menstrual cycles may appear normal, but over time they become increasingly infrequent and may eventually cease entirely (amenorrhea). In such cases, the ovarian reserve is severely depleted, rendering ovulation-inducing medications ineffective.
3. Endocrine Disorders
Dysregulation of hypothalamic-pituitary-ovarian axis function—or abnormal ovarian hormone secretion—can impair follicular development. Examples include adrenal cortical hyperfunction and hypothyroidism. Pituitary disorders—such as prolactinoma or hyperprolactinemia—are also frequent causes of ovulatory dysfunction; elevated prolactin levels suppress gonadotropin secretion and inhibit ovulation.
The above outlines how follicular monitoring is performed. We hope this information is helpful to you.
