Repeatability of Ovarian Antral Follicular Wave Dynamics during the Human Menstrual Cycle
Date
2023-10-20
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0001-6508-2954
Type
Thesis
Degree Level
Masters
Abstract
Context: Ovarian follicles are fluid-filled sacs which contain oocytes (‘egg’ cells). The number of ovarian follicles depletes with age and thus, is indicative of reproductive potential. Two or three waves of follicular development have been identified in the human menstrual cycle, consistent with domestic farm animals. In the bovine species, the number of follicular waves has been documented to be repeatable in 70% of estrous cycles. However, repeatability of the numbers and patterns of follicular waves have not been evaluated in humans.
Overall Objective: To test the hypotheses that the numbers and patterns of follicular waves are repeatable across multiple menstrual cycles.
Materials and Methods: Transvaginal ultrasonography (TVUS) was conducted every 1-3 days over 2 Inter Ovulatory Intervals (IOIs) for 22 ovulatory participants. Participants of reproductive age (RA, age 18-35, n=14) and advanced reproductive age (ARA, age 36-55, n=8) were evaluated. The number of follicles on each day across the IOI were tabulated for the following diameter categories: 2-5 mm, 2-10 mm, ≥5 mm, ≥4 mm and 4-6 mm. The size and location of follicles ≥4 mm within each ovary were sketched each day during the IOI. The growth profiles of individually identified follicles that attained a diameter of ≥6 mm were retrospectively determined and graphed. A wave was defined as an increase and subsequent decrease in the number of follicles ≥5 mm, associated with the growth of 1 or more follicles to ≥6 mm.
Results: Across 2 IOIs, the mean number of waves was 2.1 for both the RA and ARA groups (p=0.16). In the RA group, 27/28 (96%) of cycles were comprised of 2 waves while 1/28 (4%) had 3 waves. Similarly, 15/16 (94%) of cycles in ARA participants had 2 waves while only 1/16 (6%) had 3 waves. The patterns of waves documented included 1) minor-major, 2) major-major, 3) major- minor-major and 4) minor-minor-major. The majority of RA (21/28; 75%) and ARA (12/16; 75%) participants developed a minor-major pattern of development. Furthermore, 6/28 (21%) and 3/16 (19%) of cycles from the RA and ARA groups, respectively revealed a major-major pattern. One RA participant (1/28; 4%) demonstrated a major-minor-major pattern, and one ARA participant (1/16; 6%) demonstrated a minor-minor-major pattern. The number of waves (2 or 3) across 2 IOIs was repeatable in 20/22 (91%) of participants. Similarly, the pattern of waves across 2 IOIs was repeatable in 13/22 (59%) of participants. No differences in the numbers or patterns of waves were detected among age groups nor continuous versus discontinuous cycles (p>0.1).
Conclusions: The numbers and patterns of ovarian follicular wave dynamics were repeatable across 2 cycles in the majority of participants. Elucidating the repeatability of antral follicular wave dynamics may enable the individualization of hormonal contraceptive and ovarian stimulation protocols.
Description
Keywords
Follicular waves, transvaginal ultrasonography, menstrual cycle
Citation
Degree
Master of Science (M.Sc.)
Department
Medicine
Program
Health Sciences