Ovarian Reserve and Hormone Alteration Following Laparoscopic Ovarian Drilling for Polycystic Ovarian Syndrome: A Systematic Review

We aimed to conduct a systematic review of the data in the literature on ovarian reserve and ovarian hormone following laparoscopic ovarian drilling (LOD). The PubMed, ScienceDirect, and ProQuest databases were comprehensively searched using a combination of keywords such as “ovarian reserve”, “laparoscopic ovarian drilling”, “luteinizing hormone”, “follicle-stimulating hormone”, “inhibin”, “LH/FSH ratio”, “ovulation”, and “testosterone”. All studies involving females of reproductive age who were officially diagnosed with polycystic ovarian syndrome (PCOS) and had undergone LOD with reported data concerning at least one of the following parameters were considered for inclusion: ovarian reserve, anti-Mullerian hormone (AMH), inhibin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), LH/FSH ratio, and testosterone. All the included studies were evaluated by the GRADE scale for bias and their findings were synthesized by four independent coauthors. A total of 38 studies involving 3118 female patients were included. Based on our findings, a significant number of participants experienced spontaneous ovulation along with a significant decrease in ovarian reserve, and a significant decrease in AMH, LH, and testosterone, with no significant changes in FSH and inhibin B. With the end goal of LOD being to improve fertility and pregnancy rates among females with PCOS, it is important to look at the first few steps that enable this. As expected, there was a significant improvement in ovulation while the ovarian reserve decreased. Along with the decrease in ovarian reserve, there was a significant normalization in AMH, LH, and testosterone levels. LOD may exert its main effects through the manipulation of the ovarian reserves.


Introduction And Background
Polycystic ovarian syndrome (PCOS) affects up to 15% of females and is considered one of the most common endocrine pathologies in females of reproductive age [1].While PCOS is generally a diagnosis of exclusion, the definitive diagnosis is made based on the Rotterdam criteria, consisting of at least two of the following: hyperandrogenism (clinical or biological), polycystic ovary morphology, and anovulation [2].PCOS is defined as a hyperandrogenic state, typically stemming from the ovaries, due to an exaggerated response of 17-hydroxyprogesterone to gonadotropin stimulation [1].This dysregulation has been posited to be due to excess insulin, which sensitizes the ovary to luteinizing hormone (LH), thereby leading to the overproduction of downstream steroid hormones such as testosterone [2].
The androgens ultimately lead to the formation of polycystic ovaries as they recruit primordial follicles and initiate premature luteinizations, impairing the dominant follicle selection [1].The dysregulation also alters the pulsatile release of gonadotropin-releasing hormone, decreasing follicle-stimulating hormone (FSH) simultaneously and increasing the LH/FSH ratio [2].The first-line intervention for PCOS involves lifestyle modifications with the goal of weight loss and glucose control [1].When this fails, pharmacological treatments such as hormonal contraceptives, metformin, and infertility treatment with clomiphene citrate are used [1].In some cases, however, more aggressive treatment needs to be employed, such as laparoscopic ovarian drilling (LOD).
LOD is primarily based on the laparotomic "wedge resection" procedure of the ovaries to aid in treating ovulation to improve the chances of pregnancy [3].While this surgery is no longer routinely performed due to drastic improvements in pharmacological management, medications may prove to be refractory in some cases.The mechanism of LOD is through the mechanical manipulation of the ovary and its follicles, either by heat or laser, but the reason for subsequent follicular growth followed by ovulation has not been elucidated [3].The proposed pathophysiology centers around this mechanical manipulation of the ovarian follicle via thermal destruction, leading to a significant decrease in most local ovarian hormones and androgens [3].At the same time, this normalizes the intrafollicular environment to allow for follicular maturation and ovulation due to the rise in FSH [3,4].The thermal injury also causes an increase in ovarian blood supply, which allows for the cascade of local growth factors to grow the follicle and, therefore, ovulation [3].Also, another possible mechanism behind LOD's success is the supposed reduction in anti-Mullerian hormone (AMH) concentrations and disruption of the polycystic ovary walls [3].Some studies have found no significant difference between LOD and clomiphene citrate in terms of restoring ovulation [3].LOD has been shown to improve fertility in up to 64% of females who have refractory PCOS despite being on clomiphene citrate, mainly because of the regulation of abnormal menstrual cycles due to hormonal alteration [3].One or two punctures are insufficient to evoke ovulation; studies have reported that four or more are necessary to lead to success regarding ovulation and even fertility rate; essentially, the success rate is positively correlated with the energy used [3].Among specific concerns associated with LOD is the iatrogenic creation of adnexal adhesions, which can lead to complications in pregnancy, such as ectopic pregnancy and reduction in the ovarian reserve, affecting future fertility [3].New techniques have emerged to improve the LOD, such as unilateral ovarian drilling (ULOD), as it still induces activity in both ovaries while minimizing procedure time [3].One thing is absolutely evident: LOD is not a permanent solution, as its effects only last for several years, which may be why it is perfect for periods when fertility is sought [3,5].
This review focuses on menstrual patterns following LOD, its effects on the ovary and local ovarian hormones, and how they contribute to changes in the menstrual pattern.We aim to evaluate the alterations in the menstrual cycle following LOD and highlight the changes in the ovarian reserve, AMH, inhibin B, LH, FSH, LH/FSH ratio, and testosterone.

Study Design
This systematic review was conducted with strict adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [6].Two independent coauthors performed the literature search through PubMed, ScienceDirect, and ProQuest, which initially yielded 14,457 publications.Keywords used consisted of a combination of "ovarian reserve", "laparoscopic ovarian drilling", "luteinizing hormone", "follicle-stimulating hormone", "inhibin", "LH/FSH ratio", "ovulation", and "testosterone" along with boolean operators "AND" and "OR", with the last search being conducted in April 2023.

Criteria for Study Selection
The search was further narrowed down by coauthors based on the following inclusion criteria: studies performed on humans; published between 2003 and 2023; full-text availability; explicit focus on the outcomes of LOD with respect to ovarian reserve, ovulation, or hormones; and peer-reviewed interventional or observational studies (i.e., clinical trials, cohort studies, case series studies, cross-sectional studies).Articles were excluded if they were duplicates, not in English, and involved a combination treatment method as their intervention.This review has been registered with the International Prospective Register of Systematic Reviews (CRD42024504304).

Assessment of Risk of Bias
Due to the significantly small sample sizes of the studies used, as well as certain regional variations observed, a high risk of bias was initially appraised by one coauthor.The other coauthor concluded that there was a moderate risk of bias due to explicit methodologies in a significant amount of the studies and replication of methods between studies.A final coauthor evaluated the articles and determined that the risk of bias was moderate due to the influence of methodology outweighing somewhat smaller sample sizes with respect to effect size in some studies.All three authors evaluated bias through the GRADE scale.However, results should still be interpreted carefully.

Data Extraction and Synthesis
Four independent coauthors extracted information from each article and input the information into a formatted Excel sheet to track specific values.In the same sheet, they also included the overall thought or idea each article was trying to convey concerning each result.A final author reviewed the extracted information while extracting their interpretation of the result.This author then compiled an outline synthesizing the agreed-upon result and the final, consensus-based output when conflict was present between the other coauthors.

Study Selection
Two independent authors identified 14,457 publications from 2003 to 2023 through PubMed, ScienceDirect, and ProQuest databases.The screening process followed the PRISMA workflow; 6752 duplicates were removed and 687 articles were excluded as these were published before 2003; 7018 publications underwent manual screening based on their title, study type, study participants, and abstract to ensure those selected fit our criteria, and were narrowed down to 125 articles.Four independent coauthors evaluated the remaining articles based on full-text analysis.Ultimately, a total of 38 studies were selected for analysis.Figure 1 shows the PRISMA flow diagram depicting the study selection.

Study Characteristics
Twenty cohort studies, three cross-sectional studies, two case series, and 12 randomized control trials were included in this systematic review.No study covered all components or hormones that formed part of our intended analysis but involved at least three to five primary outcomes.No study reported a long-term follow-up of PCOS over six months, but about half of the articles included pregnancy rate, which was not used in this review we focused on the direct effects of LOD.In all patients, PCOS was diagnosed based on Rotterdam criteria and supported by pre-LOD laboratory reports (Table 1).

Prospective nested cohort
Study (n = 38) A significant negative correlation was present between age and pre-and post-LOD AMH levels.
Amenorrhea was associated with a greater difference in AFC between pre and post-LOD of the right ovary.LOD led to a significant decrease in serum AMH, AFC, and ovarian volume, indicating a reduction in ovarian reserve.There was a notable increase in FSH levels post-treatment In females with PCOS, LOD significantly decreases serum AMH, AFC, and ovarian volume while increasing serum FSH.Amenorrhea was associated with a greater difference in AFC between pre and post-LOD of the right ovary Al-Ojaimi, 2004 [8] Bahrain

Risk of Bias in Included Studies
Using the GRADE scale as mentioned previously, and considering the procedures used throughout each study, and the populations, it was assessed whether replicability was seen across similar studies.The addition of case series also influenced this paper's overall risk of bias as their sample size was smaller and design more anecdotal.Overall, it was concluded that there was a medium risk of bias in the studies included in this review.
Kucuk and Kilic-Okman observed that 32% of their participants who previously experienced amenorrhea developed irregular menses following LOD [25].Masroor et al. observed that 47% of participants who previously had oligomenorrhea continued to experience it following LOD [21].Only one study classified LOD as unsuccessful due to the absence of spontaneous ovulation, and this was observed in 20% of their participants [29].In patients who underwent unilateral LOD, 33.3% had resumption of menstrual periods through induction compared to 28.9% of patients who underwent bilateral LOD [39].Al-Ojaimi's was the only other study to report trials of induction through human menopausal gonadotrophin, and they observed that 1.7% of participants remained anovulant [8].Hamed et al. reported a total ovulation rate was 50.8% [19].Variables such as inhibin B level, BMI, and age pre-LOD had no significant relation to previous and current menstruation cycles [9,21].
AFC and ovarian reserve: In patients with PCOS, the average antral follicle count (AFC), which gives physicians an idea as to how many follicles are viable, of both ovaries was 18.97 with a median of 31 [12,14,18,23,37].Api et al. reported that ultrasonographic evidence showed >10 follicles in each ovary at 6-8 mm in the peripheries [10].Following bilateral LOD, there was a significant decrease in AFC, with an average of 25.95% across most studies [7, 8, 12, 18, 22-24, 31, 33, 34].However, Sunj et al. observed no significant change in AFC one month post-op, and they only showed a slight initial decrease [42].The right and left ovarian AFC decreased significantly by 41.85% and 43.01%, respectively, following LOD, with a slight association with amenorrhea and no association or correlation with hyperandrogenism, age, or BMI [7].
Compared to bilateral LOD, there was no significant difference in AFC levels following unilateral LOD, and it remained higher in unilateral LOD compared to bilateral LOD [24,31].Sunj et al., however, found a 650% increase in AFC at six months following unilateral LOD compared to the levels at one month [42].
Before LOD, studies reported an average ovarian volume of 11.33 cm 3 , with one study observing that the right ovarian volume averaged 12.2 cm 3 and the left ovarian volume at 11.9 cm 3 [9,12,14,31,37].The ovarian volume also significantly decreased following bilateral LOD, by an average of 27.14% [12,24,38].Compared to conservative treatment, the ovarian volume was 72% smaller following bilateral LOD [12].Sunj et al. noted that these initial changes occurred during the first month and did not continue into the sixth month, which was not noted in other studies [42].The right and the left ovarian volume decreased significantly by an average of 30.1% and 32.3%, respectively, and showed no significant correlation or association with hyperandrogenism or amenorrhea [7,22].Sunj et al. noted an increase in ovarian volume by almost 1000% between one and six months following unilateral LOD [42].Regarding the overall health of the ovary, it was found that the flow index and vascularization index improved significantly, possibly contributing to spontaneous ovulation through the flow of hormones [22].Overall, LOD can affect the ovarian reserve transiently; however, the reserve may decrease following bilateral LOD [23,24].
Anti-Mullerian hormone: While it is clear that there is a decrease in the ovarian reserve and volume following LOD, there is some discrepancy in the alterations in AMH concentrations.The average amount of AMH present in patients with PCOS was 8.57 ng/mL, which is significantly higher than in healthy controls in most studies [7, 11-14, 16-18, 23, 27, 28, 30, 31, 33, 34, 37, 40, 41].Hendriks et al. observed a significant and immediate decrease in AMH concentrations following LOD, whereas the majority of studies found it continued for six months with an average decrease of 36.92% [7, 11, 12, 14, 17, 20-23, 27, 29-31, 33, 34, 40-42].Ogawa et al. observed that when compared to preoperative AMH concentrations, there was a 0.55% change in overall AMH concentrations per puncture in all patients.It is also noted that the percentage of AMH change is significantly increased in patients with a preoperative AMH level of >10 ng/mL, which correlates to an AMH concentration change of 66% per puncture [28].There was also no significant difference between AMH concentration decrease and unilateral versus bilateral LOD [30,31,42].However, four studies reported no significant change in AMH concentrations following LOD [13,16,18,37].
There was a split between age and AMH concentration decrease, with one study reporting an association and two observing none [7,28,29].Most studies also observed no association between BMI and AMH concentrations [7,21,23,29].However, one study extensively stratified age groups and found otherwise [28].
Participants with BMIs <25 kg/m 2 had a significantly higher percentage decrease in AMH concentration compared to those with a BMI >25 kg/m 2 [28].Participants with a BMI <18.5 kg/m 2 had the highest percentage decrease in AMH concentration, which correlated to a 1% change per puncture in this group, significantly higher than the other two BMI categories [28].Abulkassem et al. reported a significant correlation between AMH concentrations and hyperandrogenism or amenorrhea [7].Concerning menstrual cycle regulation, participants who were non-responders (no ovulation) had significantly higher AMH (>8.3 ng/mL) pre-LOD, which correlated to a 33.3% lower ovulation rate compared to the 100% ovulation rate in participants who had an AMH concentration <8.3 ng/mL [29].Lastly, there was a significantly positive correlation between AFC count and AMH concentrations, tying back to the concept that AMH is naturally a good predictor of ovarian reserve [16].However, the odds of AMH as a determinant of ovulation response significantly decreased one month following LOD [36].
Inhibin B: In PCOS patients, inhibin should theoretically be elevated.However, most concentrations charted reported an inhibin level of 54 pg/mL, which falls within the reference range [37].Amer et al. reported that inhibin B has a significant inverse correlation with BMI compared to its association with PCOS [9].Immediately following LOD, Hendriks et al. observed a significant decrease in inhibin B concentrations, which continued for five days following surgery [20].This roughly correlates with two studies that found a significant decrease in inhibin B concentrations six months following LOD, with an average of 13.45%.However, three other studies observed no statistically significant difference in inhibin B levels following LOD [24].
Luteinizing hormone: On average, the LH level was 11.54 IU/L, with Al-Ojaimi reporting that 62.9% of females in their study had elevated LH [8-10, 12-17, 19, 22, 23, 25, 26, 31-35, 38-40].Due to the reduction in the ovarian reserve and AMH, LH should theoretically be decreased following LOD, as was reported in the majority of studies: there was an average reduction of LH in these studies at 36.35% with no significant difference between unilateral and bilateral LOD [8-10, 15, 19, 25, 26, 29, 32-35, 38-41].However, several studies found no significant difference in LH values following LOD, but Hendrik et al. did notice an initial surge in LH five hours after LOD [12,14,16,17,20].Differences between responders were split, with one study finding no significant difference in LH concentrations while two studies observed a significant reduction of LH in responders only [17,29,35].Wu et al. evaluated the correlation between LH and BMI and found that the correlation between LH and leptin increased significantly by 120% following LOD.This correlates with the obese group only having a reduction of 33.46% in LH compared to 60.08% in the lean group following LOD [38].No other studies observed correlations between BMI and LH, but further analysis should be done to improve LOD.However, it is crucial to note that the odds of LH as a determinant for ovulation response were increased following LOD and may prove to be a reliable predictor of success [34,36,43].
Luteinizing hormone/follicle-stimulating hormone ratio: In PCOS, with the increase in LH and decrease in FH, there is an increase in the LH/FSH ratio, which was documented to be at an average of 2.3 [8-11, 13-15, 22, 25-27, 33-35, 38].Al-Ojaimi observed that the LH/FSH ratio was elevated in 45.9% of female participants [8].Of note, 100% of studies that evaluated the LH/FSH ratio observed a significant decrease following LOD at an average of 38.89% [8-11, 15, 25-27, 29, 33-35, 38, 41].Paramu observed no significant difference in the ratios between responders and non-responders [29].As with LH, there was also a correlation between LH/FSH ratio and leptin, which increased by 58.29% following LOD.This correlated with the LH/FSH ratio decreasing by 31.82% in the obese group compared to 1.09% in the lean group following LOD [38].While the change in concentration of FSH following LOD varied between studies, it was primarily evident that LH significantly increased.
Testosterone: Testosterone is typically increased in patients with PCOS and our review found it to be higher at an average of 3.24 nmol/L, with one study reporting a level as high as 11.68 nmol/L [8-10, 13-16, 18, 19, 22, 25, 32-35, 38, 39].Testosterone levels were significantly more elevated in patients with PCOS compared to controls, with elevated levels reported in at least 29.8% of females [8,37].Due to the usually prevalent decrease in LH, testosterone should theoretically be reduced following LOD.Hendriks et al. observed an immediate and significant decrease in testosterone following LOD that continued into day five [20].At six months following LOD, the majority of studies observed a significant decrease in testosterone concentration with an average of 31.05%[8-10, 15, 18, 19, 25, 29, 33-35, 38, 39].
This occurrence was also replicated with unilateral LOD, which had an average decrease of 36.31%[32,39].Three studies, however, observed no significant difference in testosterone concentrations following LOD [14,16,37].No significant difference was observed when LOD was performed through dose-adjusted measures [18].Paramu noted that testosterone concentrations were significantly higher preoperatively in non-responders than responders and positively correlated with AMH concentrations [29].Wu et al. noted a correlation between total testosterone and leptin, which increased significantly by 140% following LOD.This correlates to a total testosterone reduction of 15.84 in the obese group and 26.67% in the lean group following LOD [38].Following LOD, there was a decrease in the odds of testosterone being an indicator of ovulation response, which correlates with the significant percentage of participants who developed spontaneous ovulation [36].

Principal Findings
One of the main clinical criteria for PCOS is the clinical diagnosis of anovulation, which inherently affects the fertility rate.PCOS also includes polycystic ovaries, which are not only created by a hyperandrogenic state but promote this state through LH.AMH also plays a role in the ovulation and implantation of the fertilized egg, and it may also determine the success of LOD.LOD is often used as a last resort, ultimately to enable females to conceive; however, to do this, there needs to be some regulation in their menstrual patterns.LOD mechanically manipulates the ovaries and eggs within, which correlates to the reduced ovarian reserves concerning AFC and volume.This reduction leads to a decrease in the production of AMH and should decrease inhibin as the ovarian follicles produce these hormones; however, AMH was the only parameter to show a reduction.
It is unclear what the non-significant changes in inhibin B equate to, but it is in line with the lack of differences noted regarding FSH concentrations, which should have increased.LH, which contributes significantly to ovulation and the menstrual cycle's luteal phase, decreased significantly.This is consistent with spontaneous ovulations, as polycystic ovaries are penetrated by the drill, inhibiting its overproduction of LH and disrupting non-cystic ovaries.Significantly high levels of LH and significantly low levels of FSH may be predictors of LOD success, as this alignment of hormones allows for ovulation.A decrease in LH correlates with a decrease in testosterone as LH functions to increase androgen synthesis and concentrations.All of these contribute to the high amounts of spontaneous ovulation observed in studies that tracked this outcome.

Comparison With Existing Literature
While LOD has been performed for over two decades, its pathomechanism is still not fully understood.It is known that destroying the ovarian cortex and stroma tissue reduces androgenic follicles [45].This review highlights that the androgenic follicles are the antral follicles, the reserves of the ovary, which is why certain hormone alterations may be observed.AMH has been found on numerous occasions, including in this review, to be significantly reduced following LOD, but it is unclear if this is due to actual damage [46].One study observed that LH and FSH significantly increased shortly after LOD for the initial two days, followed by a persistent decline in LH concentrations [45,46].FSH remains a matter of controversy in the literature in general and studies included in this review.The same goes with inhibin, as few reports of its concentration changes have been found in the literature.One aspect not observed in these studies is the changes in estrogen levels due to the destruction of the androgenic follicles.Strowitizki et al. reported that there should also be a decrease in the peripheral conversion of androgens to estrogens; however, no study focused on this possible effect [45].The changes observed in these hormones align with the spontaneous or improved ovulation cycle in females with PCOS [45][46][47].

Strength and Limitations
A major strength of this study is that we were able to compare the hormones across studies to track possible correlations based on the theoretics of this treatment modality.While we can conclude a uniform result, we can interpret that the treatment seems to follow expectations.Another strength pertains to the design of this review; we conducted a rather broad search to elucidate any hormone variation following LOD that may contribute to the return of spontaneous ovulations.This allowed for a concise algorithm to include all articles and narrow down the amount with the participation of four coauthors to reduce bias and determine the true impact of the results in the articles included.
This study has a few limitations.Primarily, the hormones were so spread out that there was no study continuity, and loose interpretations were based on inter-study connections, hindering the interpretation's impact.It is important to note that some studies did not describe the assay used to assess AMH, and it is known that the range of AMH varies significantly between the different assays.With that said, all studies that found a significant difference were used together, and the average obtained was based on those with the same assays.Hence, despite the varying numbers, the results are the same.The lack of studies on FSH and inhibin B can also considered be a limitation as FSH is the primary hormone in the follicular stage of the menstrual cycle, affecting menstrual regularities.It would be better to understand the relationship between inhibin B and FSH to correlate known pathophysiology to the alterations done through mechanical manipulation such as LOD.Finally, another limitation of this study is that it mostly focused on the Eastern region and included only a few studies involving Western regions.With the growing rate of PCOS in Western cultures, it is critical to analyze how individuals in these cultures are affected by this condition.

Conclusions
PCOS is an intricate endocrine/reproductive condition, and its incidence is on the rise globally.It affects multiple aspects of a patient's life, most prominently the ability to have a normal menstrual pattern and the ability to conceive.This review evaluated the former, including the ovarian reserve, AMH, inhibin B, LH, FSH, LH/FSH ratio, and testosterone, as they are the commonly altered hormones in PCOS.LOD was robustly successful in inducing spontaneous ovulation, and in most cases where ovulation did not return spontaneously or returned in an irregular state, ovulation could be caused by exogenous hormones, making LOD an appropriate last-resort treatment modality.Future research should focus a little more on the FSH and inhibin B alterations and interplay and how they may also contribute to ovulation resumption and solidify what these alterations are.Lastly, the inability to conceive is a major problem for most couples, and LOD has been shown in a few cases to lead to an increase in pregnancy rates.Further research should not only track the pregnancy rate associated with the use of LOD but also the effect on pregnancy, such as multiple gestations, as well as obstetric, maternal, and neonatal complications.

FIGURE 1 :
FIGURE 1: Prisma flow diagram illustrating the study selection* * [6] PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses