Clinical Investigation

Relationship between the follicular distribution pattern of polycystic ovaries and the degree of menstrual disturbance and serum sex steroid levels


  • Ginevra Mills
  • Bernice Goorah
  • Shai E Elizur
  • Weon-Young Son
  • Michael H Dahan

Received Date: 29.05.2022 Accepted Date: 04.08.2022 Turk J Obstet Gynecol 2022;19(3):215-220 PMID: 36149262


This study aimed to examine the associations between follicular distribution pattern (FDP) in polycystic ovaries and menstrual disturbances in women with infertility.

Materials and Methods:

A retrospective review of patients was performed (n=73). Ultrasound images from cycle day 2-5 of a spontaneous or progestin induced menstrual cycle were reviewed. Ovaries were classified as polycystic ovarian morphology (PCOM) if they contained ≥12-follicles measuring 2-9 mm in diameter. Images of PCOM ovaries were classified as having a peripheral cystic pattern (PCP) with follicles arranged at the periphery of the ovary, or general cystic pattern (GCP) if follicles were dispersed heterogeneously throughout the ovarian stroma. Menstrual disturbance was assessed by questionnaire, and oligomenorrhea was defined as cycles >35 days in length.


PCP was more strongly associated with menstrual irregularity that GCP. 94% of subjects with bilateral PCP-experienced oligomenorrhea compared with 65% of women with a unilateral PCP ovary [odds ratio (OR) 9; p<0.05]. 29% of women with bilateral GCP ovaries experienced menstrual disturbances, less than bilateral PCP (OR 36; p=0.002), but similar to unilateral PCP (OR 3; p=0.07). Serum testosterone and luteinizing hormone (LH) levels were significantly correlated with the ovarian FDP.


There is a relationship between menstrual irregularity or certain types of serum steroids and ovarian morphology. It remains unknown if morphology, testosterone or LH causes the menstrual disturbance or if they are co-initiated by an intervening factor.

Keywords: Polycystic ovary syndrome, oligomenorrhea, ovarian follicle

PRECIS: In women with PCOS, there is a relationship between testosterone levels or menstrual irregularity and follicular distribution pattern, particularly when comparing the string of pearls pattern with a multicyclic distribution of follicles, spaced throughout the stroma.


Polycystic ovary syndrome (PCOS) is a common endocrine disorder of unknown, multiple etiologies with a clinical syndrome characterized by hyperandrogenism, oligoamenorrhea, and infertility(1). The clinical findings of PCOS are highly variable, making the diagnostic criteria of the condition controversial(2,3,4). In 1990, the National Institutes of Health (NIH) consensus statement on diagnostic criteria for PCOS excluded ovarian morphology(5). However, the 2003 international consensus on PCOS diagnosis held in Rotterdam proposed the inclusion of ovarian morphology into the diagnostic criteria of PCOS(6). Although the Rotterdam criteria for polycystic ovarian morphology (PCOM) include the presence of ≥12 follicles measuring 2-9 mm in diameter and/or increased ovarian volume (>10 cm3) in a single or both ovaries(2), there remains considerable debate over how to best define the ovarian appearance in PCOS(1). Lujan et al.(7) reported that the follicle number per ovary (FNPO) threshold of 26 follicles resulted in the best sensitivity and specificity to distinguish women with PCOS from healthy controls. Therefore, in 2014, the Androgen Excess Society and Polycystic Ovary Syndrome Society guidelines recommended using FNPO of ≥25 for the definition of PCOM when using newer ultrasound technology with maximal ovarian follicle resolution(8). Most recently, the 2018 international evidence-based guideline for the assessment and management of PCOS recommended using a FNPO of at least 20 follicles(9).

While the number of follicles required for the definition of PCOM has been debated and updated, there has been less discussion about the patterns of follicle distribution (FDP) within a PCOM ovary. The Adam’s criteria of PCOM on ultrasound initially described 10 or more follicles arranged in a peripheral pattern around a dense core of stroma, called the “string of pearls” pattern(10). This pattern became known as one of two classes of PCOM ovaries based on the distribution of follicles in the ovary: A peripheral cystic pattern (PCP). The second class, called a general cystic pattern (GCP), describes ovaries with multiple small follicles occupying the entire parenchyma of the ovary(11). Takahashi et al.(12) examined differences between women with PCP and GCP ovaries and reported that serum androstenedione and the luteinizing hormone (LH)/Follicle stimulating hormone (FSH) ratio was significantly higher in women with PCP rather than GCP ovaries. This finding suggests an endocrinological difference between PCP and GCP ovaries. Furthermore, different underlying pathophysiological processes of disturbed folliculogenesis may result in different patterns of FDP in PCOM ovaries(13,14). Earlier studies investigating the ultrasound characteristics of PCOM revealed that a peripheral distribution of ≥10 follicles around the midpoint of the ovary was a highly sensitive criterion for the diagnosis of PCOS(15).

Therefore, this study aimed to evaluate whether, in women with infertility and PCOM, the PCP FDP when measured at the ovarian midpoint is more strongly associated with menstrual irregularity compared with women GCP FDP and the relationship between FDP and serum hormone levels.

Materials and Methods

A retrospective chart review was conducted of 123 cycles of in vitro maturation (IVM) during a two-year period at the McGill University Reproductive Centre. After excluding additional cycles in patients with multiple cycles and incomplete records, 73 subjects remained for analysis. Subjects were required to have ≥12 follicles measuring 2-9 mm in diameter in at least one ovary (per the Rotterdam Criteria)(6). Subjects with a dominant follicle ≥10 mm or an ovarian cyst on either ovary were excluded from the study. Furthermore, subjects were required to have no: Clinical or biochemical evidence of thyroid abnormalities (0.39< serum thyroid-stimulating hormone <3.0 µIU/mL); hyperprolactinemia (am fasting serum prolactin <26 ng/mL); hypothalamic pituitary dysfunction or ovarian failure (1.4< FSH >20 IU/L and estradiol >20 pg/mL); ovarian and adrenal androgen-secreting tumors (total testosterone <200 ng/mL and DHEAS <800 µg/dL); and non-classical congenital adrenal hyperplasia (am fasting 17-hydroxy-progesterone <2 ng/mL). Finally, subjects were excluded from analysis if they used hormones, clomiphene citrate, aromatase inhibitors, or other medications (including insulin sensitizing medications), which could have affected the follicle count or distribution in the previous 90 days.

All patients who underwent IVM had a baseline pelvic ultrasound by a certified technician (Quebec diplomat in Radiology techniques), and serum blood tests (total testosterone, free testosterone, LH, and FSH) on day 2-5 of a natural or progesterone provoked cycle (medroxyprogesterone, 10 mg daily taken orally for 5-14 days). The number of follicles was documented and a copy of the ultrasound images was included in the chart. Follicle count and distribution was assessed by subjective evaluation of ultrasound images by two physician investigators and images were categorized into three groups based on ovarian morphology:

1) Normal morphology: (<12 follicles) without a predominantly peripheral distribution,

2) PCP: ≥12 follicles peripherally distributed around a dense stromal core for at least 50% of the ovarian diameter.

3) GCP: ≥12 follicles located throughout the ovary and not more than 49% in a peripheral distribution.

Each physician was blinded to the other’s diagnoses. If the diagnoses of the two physicians differed, a third physician was consulted and then agreement of the diagnosis of two of three physicians was then accepted. All physicians were gynecologists with extensive experience in trans-vaginal ultrasonography. The third physician was consulted only for two cases.

Menstrual regularity was determined by questioning the patient on the duration of most menstrual cycles at the time of initial presentation to the fertility clinic. Subjects with cycles less frequent than 35 days, for 75% of cycles, were considered oligomenorrheic.

Statistical Analysis

Statistical analysis was performed using Stats Direct. Chi-square tests with Yates correction and odds ratios with Fisher’s exact tests were also used. ANOVA was used to compare group continuous data, while chi-squared tests were used to compare the categorical data. Tukey’s Post-hoc testing was used for post ANOVA comparisons. For the case of the chi-square test, if a number was zero in one category a one was substituted. Spearman’s correlation coefficient was used to compare relationships in different groupings with the continuous demographic data. Data were compared with odds ratios and confidence intervals. Data are presented as N and percentage or mean ± standard deviation.

Committee for the Protection of Human Subjects approval of the study was obtained. None of the authors have any conflicts of interest.


The demographic, data, rates of menstrual disturbance and serum steroid levels, stratified for follicular distribution pattern are reported in Table 1. When considering the demographics, the groups were similar for age and BMI. The oldest woman in this study was 36 years of age. However, the group with one GCP was more likely to have conceived previously, suggesting a relationship between follicular distribution pattern and fertility potential. All subjects had follicle counts of at least twelve in one ovary.

When considering serum hormone levels (Table 1) patterns were discernable based on the follicular distribution pattern and whether that distribution pattern occurred in one or both ovaries. The serum total and free testosterone levels decreased in a linear fashion from women with two PCP, to one PCP ovary, to two GCP ovaries, then to one GCP ovaries. A similar decrease in serum LH and the LH to FSH ratio was noted in the relationship with follicular distribution patterns. These findings demonstrated statistically significant correlations between ovarian morphology and serum total testosterone (r=-0.63, p<0.01), serum free testosterone (r=-0.58, p=0.01), serum LH levels (r=-0.66, p<0.01), and the LH/FSH ratio (r=-0.45, p<0.05). (For this analysis groupings were performed in the following order two PCP, one PCP, two GCP, one GCP).

Fifty-three percent of women were oligomenorrheic (39/73), defined as having menstrual cycles longer than thirty-five days, at least 75% of the time. Sixteen subjects had PCP morphology in both ovaries, 94% (15/16) of which were oligomenorrheic. Twenty-one subjects had one ovary with PCP morphology with the second ovary having <12 follicles and 62% (13/21) of these patients were oligomenorrheic. Seventeen subjects had GCP morphology in both ovaries, 29% (5/17) of which were oligomenorrheic. Thirty-six subjects had one ovary with GCP morphology with the second ovary having <12 follicles and 17% (6/36) of them were oligomenorheic. Interestingly, none of the subjects had a PCP on one ovary and a GCP on the other ovary.

The odds ratio of menstrual disturbance comparing either of the FDPs to the other three types is presented in Table 2. PCP ovaries were more strongly associated with menstrual disturbances than were GCP ovaries. Compared to having bilateral GCP ovaries (29% oligomenorrheic), having bilateral PCP ovaries conferred 36 times increased odds of experiencing menstrual disturbance compared to women with a unilateral PCP ovary (62% oligomenorrheic), women with bilateral PCP ovaries (94% oligomenorrheic) were 9 times more likely to experience menstrual irregularities. Women with a unilateral PCP were more likely to experience menstrual irregularity (62%) than women with bilateral GCP (29%), although this was not statistically significant (p=0.07). There was no statistical difference in the rates of menstrual disturbances in women with bilateral GCP ovaries (29% oligomenorrheic) compared to women with a unilateral GCP ovary (17% oligomenorrheic). Women with a unilateral PCP ovary (62% oligomenorrheic) were 8 times more likely to experience menstrual disturbances than women with a unilateral GCP ovary (17% oligomenorrheic).


The main objective of the current study was to evaluate whether the FDP in PCOM ovaries of women with infertility can be useful in predicting the severity of menstrual irregularities, specifically oligo and anovulation. From a clinical standpoint, it is important to understand how different PCOM morphologies are related to the severity of the disease itself. Using a subset of women undergoing IVM at the McGill University Reproductive Centre who were known to have PCOM and infertility, we evaluated whether the FDP of their ovaries correlated with the degree of menstrual irregularity experienced by the patient. We noted a significantly higher correlation between PCP ovaries and oligomenorrhea than with GCP ovaries and oligomenorrhea. Furthermore, none of the subjects in the study were found to have one ovary with each type of distribution pattern; they either had only PCP or GCP ovaries, not both.

Women with a unilateral PCOM ovary showing a PCP FDP were more likely to experience menstrual irregularity than women with bilateral GCP FDP. This finding suggests that the FDP seen in the ovary is a more significant prognostic factor for the severity of clinical presentation than is the bilaterality of PCOM ovaries. Furthermore, PCP FDP was more likely to be associated with increased total and free testosterone levels, as well as increased LH/FSH ratio. These findings are in agreement with previous studies illustrating a relationship between FDP and hyperandrogenism, supporting the assertion that PCP and GCP ovarian morphologies may differ in their endocrine and pathophysiological processes(12,13,14).

Christ et al.(16) previously studied the FDP and compared it with reproductive and metabolic features of PCOS to assess the use of sonographic features to predict the severity of PCOS. In contrast to the results presented in this study, Christ et al.(16) concluded that FDP was not associated with any reproductive marker or metabolic parameter associated with PCOS. A potential explanation for this discrepancy may be due to the cohort of subjects used for each study. Our study population was that of infertile patients undergoing IVM cycles for known PCOM. Unlike in Christ et al.’s study,(16) which used the NIH definition of PCOS, evidence of hyperandrogenism was not used as an inclusion criterion in our study(4,16).

When compared to women with a unilateral PCP ovary, women with bilateral PCP were nine times more likely to experience menstrual irregularities. While there was no difference seen in the rates of menstrual irregularity in women with bilateral GCP ovaries compared to women with a unilateral GCP ovary, a trend was present, which may become statistically significant in a larger study. The presence of a PCP FDP is suspected to occur secondary to a stromal core with increased density and vascular blood flow, which could push the ovarian follicle peripherally. Stromal density and vascular flow have previously been shown to predict the severity of PCOS as they are correlated with levels of ovarian hyperandrogenism(1,17,18,19,20). Unlike PCP ovaries, GCP ovaries do not display increased stromal density and may suggest less androgenic disturbance in the patient, even when both ovaries are found to be multicystic. This would provide a plausible explanation for the difference in menstrual disturbances seen in women with two PCP ovaries, verses one PCP ovary, verses any GCP ovaries.

Study Limitations

Our study has limitations. First, this study is based on the retrospective and subjective assessment of FDP by static, baseline ultrasound images. Although the investigators reviewing the images did not have information regarding the cycle lengths of the subjects and any disagreement between investigators was resolved with a third assessor, we cannot completely rule out the low possibility of a classification bias. Second, our analysis was restricted to a relatively homogenous population of women undergoing infertility assessment and treatment. We cannot determine whether the difference in ovarian morphology represents different, similar syndromes grouped into PCOS or a continuum determined by increased severity of the disease in one population. Anti-Müllerian hormone levels would have been interesting to have; however, they were unavailable as they were not being routinely performed in our clinic at the time the patients were evaluated.


This study affirms the importance of assessing FDP in a population of women with known PCOM and undergoing infertility treatment. A PCP FDP may be useful in identifying a subset of women who are more likely to have worse menstrual disturbances. The mechanism of the relationship between menstrual irregularity and ovarian morphology requires further study to better understand the pathophysiology of this disease.


Ethics Committee Approval: Committee for the Protection of Human Subjects approval of the study was obtained.

Informed Consent: Retrospective study.

Peer-review: Internally peer-reviewed.

Authorship Contributions

Concept: G.M., B.G., S.E.E., W.Y.S., M.H.D., Design: G.M., B.G., S.E.E., W.Y.S., M.H.D., Data Collection or Processing: B.G., S.E.E., Analysis or Interpretation: M.H.D., W.Y.S., Literature Search: G.M., B.G., S.E.E., W.Y.S., M.H.D., Writing: G.M.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.


  1. Zhu RY, Wong YC, Yong EL. Sonographic evaluation of polycystic ovaries. Best Pract Res Clin Obstet Gynaecol 2016;37:25-37.
  2. Balen AH, Laven JS, Tan SL, Dewailly D. Ultrasound assessment of the polycystic ovary: international consensus definitions. Hum Reprod Update 2003;9:505-14.
  3. Lujan ME, Chizen DR, Pierson RA. Diagnostic criteria for polycystic ovary syndrome: pitfalls and controversies. J Obstet Gynaecol Can 2008;30:671-9.
  4. Azziz R. Diagnostic criteria for polycystic ovary syndrome: a reappraisal. Fertil Steril 2005;83:1343-6.
  5. Zawadzki JK, Dunaif A. Diagnostic Criteria for Polycystic Ovary Syndrome: Towards a Rational Approach. In: Dunaif, A., Givens, J.R. and Haseltine, F., Eds., Polycystic Ovary Syndrome, Blackwell Scientific, Boston 1992;377-84.
  6. Group RE-SP consensus workshop. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (PCOS). Hum Reprod 2004;19:41-7.
  7. Lujan ME, Jarrett BY, Brooks ED, Reines JK, Peppin AK, Muhn N, et al. Updated ultrasound criteria for polycystic ovary syndrome: reliable thresholds for elevated follicle population and ovarian volume. Hum Reprod 2013;28:1361-8.
  8. Dewailly D, Lujan ME, Carmina E, Cedars MI, Laven J, Norman RJ, et al. Definition and significance of polycystic ovarian morphology: a task force report from the Androgen Excess and Polycystic Ovary Syndrome Society. Hum Reprod Update 2013;20:334-52.
  9. Teede HJ, Misso ML, Costello MF, Dokras A, Laven J, Moran L, et al. Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Hum Reprod 2018;33:1602-18.
  10. Adams J, Franks S, Polson DW, Mason HD, Abdulwahid N, Tucker M, et al. Multifollicular ovaries: clinical and endocrine features and response to pulsatile gonadotropin releasing hormone. Lancet 1985;2:1375-9.
  11. Matsunaga I, Hata T, Kitao M. Ultrasonographic identification of polycystic ovary. Asia Oceania J Obstet Gynaecol 1985;11:227-32.
  12. Takahashi K, Ozaki T, Okada M, Uchida A, Kitao M. Relationship between ultrasonography and histopathological changes in polycystic ovarian syndrome. Hum Reprod 1994;9:2255-8.
  13. Battaglia C. The role of ultrasound and Doppler analysis in the diagnosis of polycystic ovary syndrome. Ultrasound Obs Gynecol 2003;22:225-32.
  14. Raine-Fenning N. Editorial commentary: What’s in a number? The polycystic ovary revisited. Hum Reprod 2011;26:3118-22.
  15. Atiomo WU, Pearson S, Shaw S, Prentice A, Dubbins P. Ultrasound criteria in the diagnosis of polycystic ovary syndrome (PCOS). Ultrasound Med Biol 2000;26:977-80.
  16. Christ JP, Vanden Brink H, Brooks ED, Pierson RA, Chizen DR, Lujan ME. Ultrasound features of polycystic ovaries relate to degree of reproductive and metabolic disturbance in polycystic ovary syndrome. Fertil Steril 2015;103:787-94.
  17. Pache TD, Wladimiroff JW, Hop WC, Fauser BC. How to discriminate between normal and polycystic ovaries: transvaginal US study. Radiology 1992;183:421-3.
  18. Buckett WM, Bouzayen R, Watkin KL, Tulandi T, Tan SL. Ovarian stromal echogenicity in women with normal and polycystic ovaries. Hum Reprod 1999;14:618-21.
  19. Battaglia C, Battaglia B, Morotti E, Paradisi R, Zanetti I, Meriggiola MC, et al. Two- and three-dimensional sonographic and color doppler techniques for diagnosis of polycystic ovary syndrome. The stromal/ovarian volume ratio as a new diagnostic criterion. J Ultrasound Med 2012;31:1015-24.
  20. Fulghesu AM, Angioni S, Frau E, Belosi C, Apa R, Mioni R, et al. Ultrasound in polycystic ovary syndrome—the measuring of ovarian stroma and relationship with circulating androgens: results of a multicentric study. Hum Reprod 2007;22:2501-8.