An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome
Farquhar, C. (2005). An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome. Current opinion in obstetrics & gynecology, 17(4), 347-353. https://doi.org/10.1097/01.gco.0000175351.18308.3a
Farquhar C. An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome. Curr Opin Obstet Gynecol. 2005;17(4):347-353. doi:10.1097/01.gco.0000175351.18308.3a
Farquhar, Cynthia. "An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome." Current opinion in obstetrics & gynecology, vol. 17, no. 4, 2005, pp. 347-353.
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Women with polycystic ovarian syndrome are typically anovulatory and require ovulation induction. Ovarian wedge resection was the first treatment for anovulation but was eventually abandoned because of the increased risk of postsurgical adhesions and as medical ovulation induction with clomiphene and gonadotrophins was introduced. However, with the advent of laparoscopy, there has been a return to surgical approaches. The potential advantages of laparoscopic surgery include avoidance of hyperstimulation and the lowered costs make ovarian surgery an attractive alternative to gonadotrophins.
Recent Findings
Clinical trials in New Zealand and the Netherlands have compared costs of laparoscopic ovarian drilling with gonadotrophins. The total cost of treatment in the Netherlands study for the ovarian drilling group was euro 4664 and for the gonadotrophins group was euro 5418. Without the cost of monitoring and the diagnostic laparoscopy then the difference was euro 2110 in favour of ovarian drilling. It was estimated that the cost per term pregnancy would be euro 14,489 for gonadotrophin and euro 11,301 for ovarian drilling (22% lower). The higher rates of multiple pregnancy in the gonadotrophin group were considered to be responsible for the increased costs. In the New Zealand trial the costs of a live birth were one-third lower in the group that underwent laparoscopic ovarian diathermy compared with those women who received gonadotrophins (NZ$19,640 and 29,836, respectively).
Summary
Treating women with clomiphene-resistant polycystic ovarian syndrome with laparoscopic ovarian diathermy results in reduced direct and indirect costs. The reduction in multiple pregnancies makes the alternative of surgery particularly attractive.
Duffy JMN et al., 2020·Human Reproduction·Free full text on PubMed Central
Can a core outcome set to standardize outcome selection, collection and reporting across future infertility research be developed? A minimum data set, known as a core outcome set, has been developed for randomized controlled trials (RCTs) and systematic reviews evaluating potential treatments for infertility. Complex issues, including a failure to consider the perspectives of people with fertility problems when selecting outcomes, variations in outcome definitions and the selective reporting of outcomes on the basis of statistical analysis, make the results of infertility research difficult to interpret. STUDY DESIGN, SIZE, A three-round Delphi survey (372 participants from 41 countries) and consensus development workshop (30 participants from 27 countries). MAIN The core outcome set consists of: viable intrauterine pregnancy confirmed by ultrasound (accounting for singleton, twin and higher multiple pregnancy); pregnancy loss (accounting for ectopic pregnancy, miscarriage, stillbirth and termination of pregnancy); live birth; gestational age at delivery; birthweight; neonatal mortality; and major congenital anomaly. Time to pregnancy leading to live birth should be reported when applicable. Embedding the core outcome set within RCTs and systematic reviews should ensure the comprehensive selection, collection and reporting of core outcomes. Research funding bodies, the SPIRIT statement, and over 80 specialty journals, including Cochrane Gynaecology and Fertility Group, Fertility and Sterility and Human Reproduction, have committed to implementing this core outcome set.
Nisenblat V et al., 2016·The Cochrane database of systematic reviews·Free full text on PubMed Central
About 10% of women of reproductive age suffer from endometriosis, a costly chronic disease causing pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice to accurately diagnose endometriosis. This review assessed the diagnostic accuracy of combinations of different non-invasive testing modalities for endometriosis and provided a summary of all the reviews in the non-invasive tests for endometriosis series.
To estimate the diagnostic accuracy of any combination of non-invasive tests for the diagnosis of pelvic endometriosis (peritoneal and/or ovarian or deep infiltrating) compared to surgical diagnosis as a reference standard. The combined tests were evaluated as replacement tests for diagnostic surgery and triage tests to assist decision-making to undertake diagnostic surgery for endometriosis.
We did not restrict the searches to particular study designs, language or publication dates. We searched CENTRAL to July 2015, MEDLINE and EMBASE to May 2015, as well as the following databases to April 2015: CINAHL, PsycINFO, Web of Science, LILACS, OAIster, TRIP, ClinicalTrials.gov, DARE and PubMed.
We considered published, peer-reviewed, randomised controlled or cross-sectional studies of any size, including prospectively collected samples from any population of women of reproductive age suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE). We included studies comparing the diagnostic test accuracy of a combination of several testing modalities with the findings of surgical visualisation of endometriotic lesions.
Three review authors independently collected and performed a quality assessment of the data from each study by using the QUADAS-2 tool. For each test, the data were classified as positive or negative for the surgical detection of endometriosis and sensitivity and specificity estimates were calculated. The bivariate model was planned to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery were a sensitivity of 0.94 and a specificity of 0.79 to detect endometriosis. We set the criteria for triage tests at a sensitivity of 0.95 and above and a specificity of 0.50 and above, which 'rules out' the diagnosis with high accuracy if there is a negative test result (SnOUT test), or a sensitivity of 0.50 and above and a specificity of 0.95 and above, which 'rules in' the diagnosis with high accuracy if there is a positive result (SpIN test).
Eleven eligible studies included 1339 participants. All the studies were of poor methodological quality. Seven studies evaluated pelvic endometriosis, one study considered DIE and/or ovarian endometrioma, two studies differentiated endometrioma from other ovarian cysts and one study addressed mapping DIE at specific anatomical sites. Fifteen different diagnostic combinations were assessed, including blood, urinary or endometrial biomarkers, transvaginal ultrasound (TVUS) and clinical history or examination. We did not pool estimates of sensitivity and specificity, as each study analysed independent combinations of the non-invasive tests.Tests that met the criteria for a replacement test were: a combination of serum IL-6 (cut-off >15.4 pg/ml) and endometrial PGP 9.5 for pelvic endometriosis (sensitivity 1.00 (95% confidence interval (CI) 0.91 to 1.00), specificity 0.93 (95% CI, 0.80, 0.98) and the combination of vaginal examination and transvaginal ultrasound (TVUS) for rectal endometriosis (sensitivity 0.96 (95% CI 0.86 to 0.99), specificity 0.98 (95% CI 0.94 to 1.00)). Tests that met the criteria for SpIN triage tests for pelvic endometriosis were: 1. a multiplication of urine vitamin-D-binding protein (VDBP) and serum CA-125 (cut-off >2755) (sensitivity 0.74 (95% CI 0.60 to 0.84), specificity 0.97 (95% CI 0.86 to 1.00)) and 2. a combination of history (length of menses), serum CA-125 (cut-off >35 U/ml) and endometrial leukocytes (sensitivity 0.61 (95% CI 0.54 to 0.69), specificity 0.95 (95% CI 0.91 to 0.98)). For endometrioma, the following combinations qualified as SpIN test: 1. TVUS and either serum CA-125 (cut-off ≥25 U/ml) or CA 19.9 (cut-off ≥12 U/ml) (sensitivity 0.79 (95% CI 0.64 to 0.91), specificity 0.97 (95% CI 0.91 to 1.00)); 2. TVUS and serum CA 19.9 (cut-off ≥12 U/ml) (sensitivity 0.54 (95% CI 0.37 to 0.70), specificity 0.97 (95% CI 0.91 to 1.0)); 3-4. TVUS and serum CA-125 (cut-off ≥20 U/ml or cut-off ≥25 U/ml) (sensitivity 0.69 (95% CI 0.49 to 0.85), specificity 0.96 (95% CI 0.88 to 0.99)); 5. TVUS and serum CA-125 (cut-off ≥35 U/ml) (sensitivity 0.52 (95% CI 0.33 to 0.71), specificity 0.97 (95% CI 0
Nisenblat V et al., 2016·The Cochrane database of systematic reviews·Free full text on PubMed Central
About 10% of reproductive-aged women suffer from endometriosis, a costly chronic disease causing pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but is expensive and carries surgical risks. Currently, there are no non-invasive or minimally invasive tests available in clinical practice to accurately diagnose endometriosis. Although other reviews have assessed the ability of blood tests to diagnose endometriosis, this is the first review to use Cochrane methods, providing an update on the rapidly expanding literature in this field.
To evaluate blood biomarkers as replacement tests for diagnostic surgery and as triage tests to inform decisions on surgery for endometriosis. Specific objectives include:1. To provide summary estimates of the diagnostic accuracy of blood biomarkers for the diagnosis of peritoneal, ovarian and deep infiltrating pelvic endometriosis, compared to surgical diagnosis as a reference standard.2. To assess the diagnostic utility of biomarkers that could differentiate ovarian endometrioma from other ovarian masses.
We did not restrict the searches to particular study designs, language or publication dates. We searched CENTRAL to July 2015, MEDLINE and EMBASE to May 2015, as well as these databases to 20 April 2015: CINAHL, PsycINFO, Web of Science, LILACS, OAIster, TRIP, ClinicalTrials.gov, DARE and PubMed.
We considered published, peer-reviewed, randomised controlled or cross-sectional studies of any size, including prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE). We included studies comparing the diagnostic test accuracy of one or more blood biomarkers with the findings of surgical visualisation of endometriotic lesions.
Two authors independently collected and performed a quality assessment of data from each study. For each diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis, and we calculated sensitivity and specificity estimates. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient datasets were available. The predetermined criteria for a clinically useful blood test to replace diagnostic surgery were a sensitivity of 0.94 and a specificity of 0.79 to detect endometriosis. We set the criteria for triage tests at a sensitivity of ≥ 0.95 and a specificity of ≥ 0.50, which 'rules out' the diagnosis with high accuracy if there is a negative test result (SnOUT test), or a sensitivity of ≥ 0.50 and a specificity of ≥ 0.95, which 'rules in' the diagnosis with high accuracy if there is a positive result (SpIN test).
We included 141 studies that involved 15,141 participants and evaluated 122 blood biomarkers. All the studies were of poor methodological quality. Studies evaluated the blood biomarkers either in a specific phase of the menstrual cycle or irrespective of the cycle phase, and they tested for them in serum, plasma or whole blood. Included women were a selected population with a high frequency of endometriosis (10% to 85%), in which surgery was indicated for endometriosis, infertility work-up or ovarian mass. Seventy studies evaluated the diagnostic performance of 47 blood biomarkers for endometriosis (44 single-marker tests and 30 combined tests of two to six blood biomarkers). These were angiogenesis/growth factors, apoptosis markers, cell adhesion molecules, high-throughput markers, hormonal markers, immune system/inflammatory markers, oxidative stress markers, microRNAs, tumour markers and other proteins. Most of these biomarkers were assessed in small individual studies, often using different cut-off thresholds, and we could only perform meta-analyses on the data sets for anti-endometrial antibodies, interleukin-6 (IL-6), cancer antigen-19.9 (CA-19.9) and CA-125. Diagnostic estimates varied significantly between studies for each of these biomarkers, and CA-125 was the only marker with sufficient data to reliably assess sources of heterogeneity.The mean sensitivities and specificities of anti-endometrial antibodies (4 studies, 759 women) were 0.81 (95% confidence interval (CI) 0.76 to 0.87) and 0.75 (95% CI 0.46 to 1.00). For IL-6, with a cut-off value of > 1.90 to 2.00 pg/ml (3 studies, 309 women), sensitivity was 0.63 (95% CI 0.52 to 0.75) and specificity was 0.69 (95% CI 0.57 to 0.82). For CA-19.9, with a cut-off value of > 37.0 IU/ml (3 studies, 330 women), sensitivity was 0.36 (95% CI 0.26 to 0.45) and specificity was 0.87 (95% CI 0.75 to 0.99).Studies assessed CA-125 at different thresholds, demonstrating the following mean sensitivities and specificities: for cut-off > 10.0 to 14.7 U/ml: 0.70 (95% CI 0.63 to 0.77) and 0.64 (95% CI 0.47 to 0.82); for cut-off >
Bordewijk EM et al., 2020·The Cochrane database of systematic reviews·Free full text on PubMed Central
Polycystic ovary syndrome (PCOS) is a common condition affecting 8% to 13% of reproductive-aged women. In the past clomiphene citrate (CC) used to be the first-line treatment in women with PCOS. Ovulation induction with letrozole should be the first-line treatment according to new guidelines, but the use of letrozole is off-label. Consequently, CC is still commonly used. Approximately 20% of women on CC do not ovulate. Women who are CC-resistant can be treated with gonadotrophins or other medical ovulation-induction agents. These medications are not always successful, can be time-consuming and can cause adverse events like multiple pregnancies and cycle cancellation due to an excessive response. Laparoscopic ovarian drilling (LOD) is a surgical alternative to medical treatment. There are risks associated with surgery, such as complications from anaesthesia, infection, and adhesions. To evaluate the effectiveness and safety of LOD with or without medical ovulation induction compared with medical ovulation induction alone for women with anovulatory polycystic PCOS and CC-resistance. We searched the Cochrane Gynaecology and Fertility Group (CGFG) trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two trials registers up to 8 October 2019, together with reference checking and contact with study authors and experts in the field to identify additional studies. We included randomised controlled trials (RCTs) of women with anovulatory PCOS and CC resistance who underwent LOD with or without medical ovulation induction versus medical ovulation induction alone, LOD with assisted reproductive technologies (ART) versus ART, LOD with second-look laparoscopy versus expectant management, or different techniques of LOD. Two review authors independently selected studies, assessed risks of bias, extracted data and evaluated the quality of the evidence using the GRADE method. The primary effectiveness outcome was live birth and the primary safety outcome was multiple pregnancy. Pregnancy, miscarriage, ovarian hyperstimulation syndrome (OHSS), ovulation, costs, and quality of life were secondary outcomes. This updated review includes 38 trials (3326 women). The evidence was very low- to moderate-quality; the main limitations were due to poor reporting of study methods, with downgrading for risks of bias (randomisation and allocation concealment) and lack of blinding. Laparoscopic ovarian drilling with or without medical ovulation induction versus medical ovulation induction alone Pooled results suggest LOD may decrease live birth slightly when compared with medical ovulation induction alone (odds ratio (OR) 0.71, 95% confidence interval (CI) 0.54 to 0.92; 9 studies, 1015 women; I2 = 0%; low-quality evidence). The evidence suggest that if the chance of live birth following medical ovulation induction alone is 42%, the chance following LOD would be between 28% and 40%. The sensitivity analysis restricted to only RCTs with low risk of selection bias suggested there is uncertainty whether there is a difference between the treatments (OR 0.90, 95% CI 0.59 to 1.36; 4 studies, 415 women; I2 = 0%, low-quality evidence). LOD probably reduces multiple pregnancy rates (Peto OR 0.34, 95% CI 0.18 to 0.66; 14 studies, 1161 women; I2 = 2%; moderate-quality evidence). This suggests that if we assume the risk of multiple pregnancy following medical ovulation induction is 5.0%, the risk following LOD would be between 0.9% and 3.4%. Restricting to RCTs that followed women for six months after LOD and six cycles of ovulation induction only, the results for live birth were consistent with the main analysis. There may be little or no difference between the treatments for the likelihood of a clinical pregnancy (OR 0.86, 95% CI 0.72 to 1.03; 21 studies, 2016 women; I2 = 19%; low-quality evidence). There is uncertainty about the effect of LOD compared with ovulation induction alone on miscarriage (OR 1.11, 95% CI 0.78 to 1.59; 19 studies, 1909 women; I2 = 0%; low-quality evidence). OHSS was a very rare event. LOD may reduce OHSS (Peto OR 0.25, 95% CI 0.07 to 0.91; 8 studies, 722 women; I2 = 0%; low-quality evidence). Unilateral LOD versus bilateral LOD Due to the small sample size, the quality of evidence is insufficient to justify a conclusion on live birth (OR 0.83, 95% CI 0.24 to 2.78; 1 study, 44 women; very low-quality evidence). There were no data available on multiple pregnancy. The likelihood of a clinical pregnancy is uncertain between the treatments, due to the quality of the evidence and the large heterogeneity between the studies (OR 0.57, 95% CI 0.39 to 0.84; 7 studies, 470 women; I2 = 60%, very low-quality evidence). Due to the small sample size, the quality of evidence is not sufficient to justify a conclusion on miscarriage (OR 1.02, 95% CI 0.31 to 3.33; 2 studies, 131 women; I2 = 0%; very low-quality evidence). Other comparisons Due to lack of evidence and very low-quality data there is uncertainty whether there is a difference for any of the following comparisons: LOD with IVF versus IVF, LOD with second-look laparoscopy versus expectant management, monopolar versus bipolar LOD, and adjusted thermal dose versus fixed thermal dose. AUTHORS' Laparoscopic ovarian drilling with and without medical ovulation induction may decrease the live birth rate in women with anovulatory PCOS and CC resistance compared with medical ovulation induction alone. But the sensitivity analysis restricted to only RCTs at low risk of selection bias suggests there is uncertainty whether there is a difference between the treatments, due to uncertainty around the estimate. Moderate-quality evidence shows that LOD probably reduces the number of multiple pregnancy. Low-quality evidence suggests that there may be little or no difference between the treatments for the likelihood of a clinical pregnancy, and there is uncertainty about the effect of LOD compared with ovulation induction alone on miscarriage. LOD may result in less OHSS. The quality of evidence is insufficient to justify a conclusion on live birth, clinical pregnancy or miscarriage rate for the analysis of unilateral LOD versus bilateral LOD. There were no data available on multiple pregnancy.
Does unilateral volume-adjusted laparoscopic diathermy increase the chances of ovulation in women with polycystic ovary syndrome (PCOS)? Although unilateral laparoscopic ovarian drilling (ULOD) using adjusted thermal doses was more efficient than bilateral laparoscopic ovarian drilling (BLOD) using fixed doses, the chances of ovulation were improved in patients irrespective of the technique used. The adjustment of the thermal dose to ovarian volume in BLOD increases ovulation and pregnancy rates compared with fixed-dose treatment, but BLOD causes the formation of adhesions, particularly on the left ovary, and increases the risk of damage to ovarian tissue. In contrast, ULOD with a fixed thermal dose minimizes the risk of ovarian tissue damage, and can increase the activity in both right and left ovaries, although this varies in humans and in other species. STUDY DESIGN, SIZE, This prospective, longitudinal, study, between September 2009 and January 2013, included 96 infertile women with PCOS who were unresponsive to clomiphene citrate treatment and had underwent either ULOD or BLOD. After surgery, the groups were followed up for 6 months to assess ovulatory response. PARTICIPANTS/MATERIALS, SETTING, Patients were assigned to two groups; one group underwent laparoscopic ovarian drilling of the right ovary alone, while both ovaries were treated in the second group. The ULOD group (n = 49) received thermal doses adjusted to the volume of the right ovary (60 J/cm³). The BLOD group (n = 47) received fixed doses of 600 J per ovary, regardless of its volume. The two treatment groups were matched by the number of participants, age and baseline parameters. MAIN The ovulation rate during the first menstrual cycle after LOD was significantly higher in the ULOD group than in the BLOD group [73 versus 49%; absolute risk reduction (ARR), -0.25; 95% confidence interval (CI), -0.44 to -0.03; P = 0.014]. Treatment with ULOD on the right ovary significantly increased the chances of ovulation in patients with a larger right ovary compared with those who had a smaller right ovary (100 versus 36%; ARR, -0.64; 95% CI, -0.84 to -0.37; P = 0.004). Interestingly, the chances of ovulation were also significantly higher in patients in the BLOD group who had a larger right ovary compared with those who had a smaller right ovary (88 versus 33%; ARR, -0.55; 95% CI, -0.73 to -0.28; P = 0.002). The pregnancy rate was also significantly higher in patients with a larger right ovary compared with those with a smaller right ovary, regardless of the treatment group. LIMITATIONS, The 6-month follow-up was too short to demonstrate any long-term differences in the ovulation rates. Future research should therefore extend the follow-up beyond 6 months. Another limitation is that ULOD was used to treat only the right ovary. Future studies should investigate whether ULOD treatment of the larger ovary, whether left or right, would significantly increase the ovulation rate. This study represents an advance in the determination of the optimal laparoscopic treatment for women with PCOS, as it was shown that improved results can be achieved using less thermal energy in volume-adjusted ULOD.
Clomiphene citrate therapy has been found to improve the infertility rate in women suffering from polycystic ovarian disease (PCOD). However, there still exists a group of women with PCOD who fail to respond to clomiphene citrate or human menopausal gonadotropin/human chorionic gonadotropin or urofollitropin/chorionic gonadotropin treatment, an ovarian wedge resection by laparotomy approach which has been known for 50 years. Within the last decade, translaparoscopic electrocautery and laser drilling techniques have been utilized. In 1986, a translaparoscopic carbon dioxide laser ovarian wedge resection was introduced for resistant PCOD. This paper describes the surgical principle of a translaparoscopic carbon dioxide laser ovarian wedge resection. This type of treatment results in a 75% crude conception rate, with a 67% rate of healthy live birth. There was an 8% postsurgical adhesion rate among 12 cases that were incorporated into the study. This mode of therapy may prove to be very useful, safe, easy to perform, and cost effective as a second-line therapy for resistant PCOD in cases where medical inductions fail to achieve ovulation.
Ovarian laparoscopic resection was applied to 23 sterile patients affected with polycystic ovarian disease (PCOD) resistant to different pharmacological treatments, in order to induce ovulation. After resection, 56% of the patients had spontaneous ovulatory cycles and 13 pregnancies arose. Ten of the pregnancies were spontaneous and three followed treatment with clomiphene. Hormone changes were assessed in 15 patients, including five with spontaneous menstruation but without ovulation and five with persistent amenorrhoea for 3 months after resection. A significant decrease in both androstenedione and testosterone levels occurred in all patients. These decreases were not related to the clinical results of resection. Luteinizing hormone (LH) did not vary greatly in any group after resection. Mean values and mean pulsatility of follicle stimulating hormone (FSH) increased significantly only in pregnant patients or those with spontaneous ovulatory cycles. The results of gonadotrophin-releasing hormone (GnRH) assays did not change after resection. The mechanisms involved in the resumption of cyclic function of the hypophyseal-ovarian axis after resection are discussed briefly.
Cost and Access › Cost of Care › Cost Effectiveness · Reproductive Surgery › Ovarian Surgery › Ovarian Reserve Preservation · Infertility › Ovulation Induction › Gonadotropin Therapy
PMID 15976539 15976539 DOI 10.1097/01.gco.0000175351.18308.3a 10.1097/01.gco.0000175351.18308.3a Farquhar et al. 2005, Farquhar 2005
Cite this article
Farquhar, C. (2005). An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome. Current opinion in obstetrics & gynecology, 17(4), 347-353. https://doi.org/10.1097/01.gco.0000175351.18308.3a
Farquhar C. An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome. Curr Opin Obstet Gynecol. 2005;17(4):347-353. doi:10.1097/01.gco.0000175351.18308.3a
Farquhar, Cynthia. "An economic evaluation of laparoscopic ovarian diathermy versus gonadotrophin therapy for women with clomiphene citrate-resistant polycystic ovarian syndrome." Current opinion in obstetrics & gynecology, vol. 17, no. 4, 2005, pp. 347-353.