Concomitant endometriosis in malignant and borderline ovarian tumours.

The aim of the study was to reveal the prevalence of concomitant endometriosis in malignant and borderline ovarian tumours. A retrospective analysis was performed of 530 patients with malignant ovarian tumours and 131 with borderline ovarian tumours, who underwent surgery in our hospital between 1995 and 2011. Forty-eight (7.3%) of 661 patients with malignant and borderline ovarian tumours were associated with endometriosis. Of the 48 endometriosis cases, 73% of those were atypical. Infertility was noted in 38% of patients with endometriosis-associated ovarian tumours. The most frequently endometriosis-associated subtypes were endometrioid (33%) and clear cell (18%) histologies. Of endometriosis-associated endometrioid and clear cell ovarian tumours, 70% were early stage and 60% were premenopausal. The prevalence of concomitant endometriosis in borderline tumours (12%) was found to be significantly higher than that found in the malignant ones (6%; p = .02). Of 32 endometriosis-associated malignant ovarian tumours, 69% were FIGO stages I and II. In conclusion, ovarian endometriosis is seen with both malignant and borderline ovarian tumours, the association being significant with borderline tumours. Fortunately, the endometriosis-associated malignant ovarian tumours are mostly early stage. Impact statement What is already known on this subject? Epidemiologic data suggest that endometriosis has malignant potential. However, a subgroup of women with endometriosis at a high risk for ovarian cancer is yet to be clarified. Currently, endometriosis and ovarian cancer association does not seem to have a clinical implication. What do the results of this study add? The findings of this study revealed that nearly 75% of endometriosis-associated ovarian tumours were of atypical endometriosis. Half of endometriosis-associated ovarian tumour cases were of endometrioid/clear cell histology and 70% were early-stage. Endometriosis was significantly associated with borderline ovarian tumours and the endometriosis-associated malignant ovarian tumours were mostly early stage. What are the implications of these findings for clinical practice and/or further research? Additional studies need to be conducted to develop screening approaches for malignant transformation or an association in women with endometriosis. Till that time, a change of current clinical practices cannot be justified. However, counselling and treating women with endometriosis who are at high risk for cancer coexistence or conversion is encouraged.

Evaluation of vitamin C and vitamin E for prevention of postoperative adhesion: a rat uterine horn model study.

AIM: To investigate the effectiveness of intraperitoneal vitamin C (VC) and vitamin E (VE) in the prevention of postoperative adhesion formation in a rat uterine horn model. METHODS: Twenty-eight Wistar albino rats were divided into four groups in which: control group, the abdomen was opened and closed without any intervention; adhesion group, a 2-cm linear incision was performed on the uterine horn and closed; VC group, VC was administrated i.p., and 15 min later a 2-cm incision was performed on the uterine horn and closed; and VE group, VE was administrated i.p., and 15 min later a 2-cm incision was performed on the uterine horn and closed. Re-laparotomy was performed 15 days later. Right uterine horn adhesions were evaluated according to macromorphological characteristics and tissue sections were further examined for fibrosis, angiogenesis and vascular endothelial growth factor (VEGF), type I collagen and malondialdehyde (MDA) scoring. Kruskal-Wallis anova and Mann-Whitney U-test were utilized for statistical analysis. RESULTS: Adhesion area and also strength were significantly lower in the VC group and the VE group compared with the adhesion group. Fibrosis and angiogenesis scores were observed to be significantly higher in the adhesion group compared with the VC group and the VE group. MDA and VEGF immunoreactivity were also found to be significantly lower in the VC group and the VE group compared with the adhesion group. However, there was no significant difference between the VC group and the VE group with respect to all the above parameters. CONCLUSION: Administration of VC or VE i.p. was observed to be effective in the prevention of postoperative adhesion formation in an experimental model.

Maternal plasma levels of interleukin-6, C-reactive protein, vitamins C, E and A, 8-isoprostane and oxidative status in women with preterm premature rupture of membranes.

OBJECTIVE: Preterm premature rupture of membranes (PPROM) is associated with significant maternal and perinatal morbidity. This study examined maternal oxidative stress in PPROM. METHODS: This was a prospective cross-sectional study conducted in a university hospital. A total of 72 pregnant women were recruited into two groups, those with PPROM (38 cases) and those without PPROM (34 controls) matched for gestational age. Plasma interleukin-6, C-reactive protein, vitamins C, E and A, 8-isoprostane, total oxidant status (TOS) and antioxidant status (TAS) were determined for all study participants and the data were compared between the PPROM and control groups. RESULTS: Both case and control groups were comparably matched in age, parity, gestational age and smoking status. There was a significant association between low 8-isoprostane, low vitamin C and high total oxidant status and the occurrence of PPROM (p < 0.001). CONCLUSIONS: Plasma vitamin C and 8-isoprostane levels were lower and TOS higher in women with PPROM. Further research is needed to identify robust biological markers for the prevention and also prognosis of PPROM.

Impact of luteal phase hysteroscopy and concurrent endometrial biopsy on subsequent IVF cycle outcome.

PURPOSE: Endometrial biopsy preceding implantation in in vitro fertilization (IVF) treatment causes a type of injury which facilitates implantation. Pre-treatment hysteroscopic evaluation of uterine cavity also raises the success in IVF. This study investigates whether office hysteroscopy and concurrent endometrial biopsy performed in the luteal phase, on the day of GnRH agonist initiation for long protocol, improves subsequent IVF outcome. METHODS: A prospective, nonrandomized, controlled study of 128 normoresponder women was performed: In 70 women (study group), office hysteroscopy and concurrent endometrial biopsy were performed on the day of GnRH agonist initiation preceding ET cycle and in 58 women (control group), GnRH agonist was initiated without any intervention. However, uterine cavity was shown to be normal with hysteroscopy within the previous 6 months in those women. Implantation and pregnancy rates were compared between the groups. RESULTS: Intrauterine pathologies were observed in 28 % of women in the study group. Implantation rate (38 vs. 25 %; p = 0.04) and pregnancy rate per ET (67 vs. 45 %; p = 0.01) were found to be significantly higher in the study group compared to the control group. CONCLUSION: Office hysteroscopy and concurrent endometrial biopsy performed in the luteal phase, on the day of GnRH agonist initiation for long protocol, provide direct evaluation of the uterine cavity immediately before ET cycle and also significantly improve the implantation and IVF outcome.

What is the impact of Th1/Th2 ratio, SOCS3, IL17, and IL35 levels in unexplained infertility?

Implantation necessitates complex interactions among the developing embryo, decidualizing endometrium, and developing maternal immune tolerance and/or alterations in cellular and humoral immune responses. Overstimulation of T helper 1 (Th1) or Th2 cytokines in systemic and local environments, alterations of the prevalence of IL17 and regulatory T cell (Treg) cytokines have also been suggested to contribute to the pathogenesis of implantation failure. We aimed to investigate the plasma levels of IL4, IL6, IL10, TNFα, IFNγ, TGFß, IL17, IL35, and SOCS3 in infertile and fertile women. This case-control study was conducted with 80 women suffering from unexplained infertility and 40 fertile women. Peripheral venous blood samples were drawn on day 21 of the menstrual cycle. The extracted plasma samples were assayed by an enzyme linked immunosorbent assay. Statistical analysis was performed using SPSS version 16.0. Our main findings were as follows: despite the significantly high IL17 and IL35 plasma levels of infertile women, IL35/IL17 ratio was significantly lower in the infertile group compared with that in the fertile group; SOCS3 plasma levels showed an inverse relation with plasma levels of all cytokines except IL35; increased plasma IL17 levels (>3.42 pg/mL) have a negative impact on fertility; TNFα/IL10, IFNγ/IL10, IFNγ/IL6, and IFNγ/IL4 ratios were significantly higher in infertile group compared with those in the fertile group. It is not possible to show the major immunological factor(s) of unexplained infertility, but our findings point out that the decreased suppressor activity of the immune system may play a role in implantation failure.

Lower extremity venous Doppler evaluation in patients undergoing laparoscopic gynecological operations.

BACKGROUND: Laparoscopy is established as a standard of care in a variety of gynecological pathologies. Pneumoperitoneum and reverse Trendelenburg positioning during laparoscopy have been claimed to increase thrombosis risk, albeit these proposals are still controversial. The aim of this study was to assess lower extremity venous blood flow by Doppler sonography in patients undergoing laparoscopic gynecological surgeries. PATIENTS AND METHODS: A prospective, nonrandomized, controlled study was designed to compare lower extremity venous Doppler measurements in patients undergoing diagnostic and operative gynecological laparoscopies. In the period from May 2010 to April 2011, in total, 96 patients operated on for various gynecological complaints excluding malignancy were enrolled in the study. Thirty-two of these patients underwent diagnostic laparoscopy, 34 underwent operative laparoscopy, and 30 underwent open surgery. Lower extremity venous blood flow was investigated by Doppler sonography in patients the day before surgery and 24 hours afterward. Preoperative and postoperative Doppler measurements were obtained from bilateral common and superficial femoral, bilateral great saphenous, and bilateral popliteal veins. RESULTS: Lower extremity venous Doppler measurements were similar in diagnostic and operative laparoscopy groups. Femoral venous blood flow measurements were observed to be similar, but great saphenous and popliteal blood flows were found to be significantly decreased in the open surgery group compared with laparoscopic operations. CONCLUSIONS: The laparoscopic approach in gynecological surgery is not associated with an adverse effect on lower extremity blood flow and seems not to bring an additional risk of thrombosis.

Effect of ovarian stimulation with recombinant follicle-stimulating hormone, gonadotropin-releasing hormone agonist and antagonists, on follicular fluid stem cell factor and serum urocortin 1 levels on the day of oocyte retrieval.

PURPOSE: To compare the serum and follicular fluid (FF) concentrations of stem cell factor (SCF) as well as the serum urocortin 1 (UCN1) concentration in gonadotropin-releasing hormone antagonist (GnRH-ant) and gonadotropin-releasing hormone agonist (GnRH-a) protocols for controlled ovarian hyperstimulation (COH) in IVF patients. METHODS: Follicular fluids and blood samples of 42 infertile women undergoing COH for IVF-embryo transfer with either GnRH agonist (n = 22) or GnRH antagonist (n = 20) protocols from 2010 to 2011 were collected during oocyte retrieval. SCF concentrations of serum and FF were assessed by sandwich enzyme immunoassay using ELISA Kit for SCF kid. Serum UCN1 concentration were measured using commercially available enzyme-linked immunosorbent assay. RESULTS: Concentrations of serum UCN1, serum and FF SCF were similar in the two groups. The serum SCF levels correlated strongly with the follicular SCF levels (r = 0.770, p < 0.001). The mean implantation rate, biochemical and clinical pregnancy rate and live birth rate per cycle were also similar in the groups. CONCLUSIONS: These observations suggest that there is no significant difference in follicular microenvironment in terms of SCF and UCN1 between agonist and antagonist protocols.

Female obesity and assisted reproductive technologies.

Obesity has grown to epidemic proportions, and currently nearly half of the reproductive-age women are overweight or obese. Risks, success rates, and economic aspects of infertility treatments in obese women have been extensively investigated. Unfavorable ovarian stimulation characteristics like increased gonadotropin consumption, fewer selected follicles, and lower number of retrieved oocytes have been observed in obese women undergoing assisted reproductive technologies (ART). There seems to be a strong association between increased body mass index and lower pregnancy and live-birth rates and increased miscarriage rate. Coexisting factors like age and polycystic ovary syndrome status have also been blamed for these adverse effects. The mechanisms underlying those adverse outcomes, whether ovarian or endometrial, still remain to be fully elucidated. Moreover, maternal, perinatal, and neonatal complications have also been reported to be higher in obese pregnant women. Hence in some countries strict restrictions exist for access to elective fertility treatment in obese women. However, it is controversial if these policies are socially and ethically acceptable. Furthermore, because weight reduction is not an easy task, it may lead to the decreased probability of conception due to the advancing reproductive age for many obese women. Thus weight reduction should be encouraged and patients counseled accordingly, but whether restriction for fertility treatment is implemented in obese women remains a matter of debate. There remains much to be known regarding the association between obesity and ART.

A comparative study on oxidative and antioxidative markers of serum and follicular fluid in GnRH agonist and antagonist cycles.

OBJECTIVE: To determine whether concentrations of oxidative stress markers of follicular fluid and serum are different in GnRH agonist protocol from GnRH antagonist protocol. MATERIAL AND METHOD: This was a cross-sectional study. Eighty-four women undergoing controlled ovarian stimulation with either GnRH agonist (n = 39) or GnRH antagonist protocols (n = 45) for IVF/ICSI treatment were assigned by a physician. Blood was obtained at the time of oocyte retrieval, and follicular fluid (FF) from the mature follicles of each ovary was centrifuged and frozen until analysis. Malondialdehyde (MDA), nitric oxide (NO), protein carbonyl (PC), hydroxyl proline (OH-P), sodium oxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GSH-Px), adenosine deaminase (ADA) and xanthine oxidase (XO) were assessed in the serum and follicular fluid of each participants. RESULTS: The mean serum concentrations of GSH-Px, GSH and MDA were lower in the GnRH antagonist group compared to GnRH agonist group, but mean serum SOD was higher in the GnRH antagonist group. The mean follicular SOD, ADA and NO were higher in GnRH antagonist group than GnRH agonist group. The IVF/ICSI outcomes were similar in both groups. CONCLUSION(S): GnRH antagonist protocol is associated with increased oxidative stress. The relation of GnRH analogues with oxidative stress and its implication in follicular growth needs to be addressed in further studies.

Association of kisspeptin-10 levels with abortus imminens: a preliminary study.

PURPOSE: To investigate the association between kisspeptin 10 (Kp-10) levels and early pregnancy bleeding and perinatal outcome. METHODS: A total of 20 pregnant women with the complaint of vaginal bleeding during 7-18 gestational weeks and 20 healthy gestational week matched pregnant women were included in the study. Maternal plasma Kp-10 levels were measured with the enzyme immunoassay method. Adverse pregnancy outcomes like intrauterine growth restriction, preterm delivery, preeclampsia and low birth weight were evaluated in both groups. RESULTS: Maternal plasma Kp-10 levels (p = 0.01) and birth weight (p = 0.06) were found to be lower in women with bleeding. Intrauterine growth restriction, preterm delivery and intrauterine exitus were noted more commonly in women with bleeding (10 vs. 0%, 25 vs. 15% and 20 vs. 0%, p = 0.08). Preeclampsia were developed in 5% of both groups. Kp-10 levels showed positive correlation with gestational week (p = 0.02) and ALT levels (p = 0.02). CONCLUSION: [corrected] Kp-10 levels were found lower in women with early pregnancy bleeding.

Coexistence of adenomyosis in women operated for benign gynecological diseases.

BACKGROUND: To compare demographic, clinical and histopathological characteristics of women diagnosed with adenomyosis (AG) after hysterectomy to those of women diagnosed with leiomyoma (LG) and to investigate the predisposing factors for AG. METHODS: This study was carried out on 204 patients who underwent gynecologic surgery for various indications except for gynecologic malignancy between January 2005 and December 2009 and whose histopathological analysis of hysterectomy/myomectomy specimen revealed either AG or LG. Women with AG and those with LG were compared with respect to age, parity, menstrual pattern, history of induced abortion, history of prior uterine surgery, smoking, dysmenorrhea, dyspareunia, chronic pelvic pain and coexisting endometrial and ovarian pathologies. RESULTS: The mean age of our patients was 51 ± 8 years (range 28-85), 40% of them were postmenopausal, and 64% had a history of uterine surgery. The mean age (p = 0.014), gravida (p = 0.018), parity (p = 0.017) and previous endometrial sampling (p < 0.01) were significantly higher in AG. Main symptoms were abnormal uterine bleeding (39%), dysmenorrhea (63%) and nonmenstrual pelvic pain (62%). Age (p = 0.01), menometrorrhagia (p = 0.02) and endometrial sampling (p < 0.01) were the significant covariants in binary logistic regression for AG. CONCLUSION: AG is an enigmatic disease frequently causing gynecologic complaints and endomyometrial junction deterioration during endometrial sampling may be a trigger point for developing AG.

Heterotopic pregnancy following bilateral tubal ligation: case report.

CASE REPORT: A 38-year-old woman presented, one year after bilateral tubal ligation, with vaginal bleeding, vomiting, and stupor. Ten days earlier, she had submitted to a dilatation and curettage for an unexpected intrauterine pregnancy. At the time of this presentation there was rebound tenderness and guarding on abdominal examination, and a 2.5 cm right adnexal mass was detected on transvaginal ultrasound together with free fluid in the pelvis. The serum level of beta-hCG was 8522 mIU/ml. At laparoscopy a right tubal pregnancy and a large haematocele in the pouch of Douglas were detected. A right salpingectomy and a bipolar electrocoagulation of the left tubo-cornual junction were performed laparoscopically. CONCLUSION: Pregnancy after tubal sterilisation may be heterotopic and this possibility should be considered in the differential diagnosis.

Efficacy of melatonin and hyaluronate/carboxymethylcellulose membrane in preventing adhesion reformation following adhesiolysis in a rat uterine model.

AIM: To evaluate the efficacy of hyaluronate/carboxymethylcellulose (HA/CMC) membrane and melatonin separately and in combination in reducing adhesion reformation following adhesiolysis of surgically induced adhesions in a rat uterine horn adhesion model. METHODS: A randomized, prospective study was carried out in a university animal laboratory. Ninety-eight female Sprague-Dawley albino rats were operated on. Following infliction of standard lesions, all the animals underwent second operations after one week. In all the animals, there were dense and vascular adhesions only between the uterine horns. These adhesions were lysed. Following the completion of adhesiolysis, the animals were randomized before closure of the abdomen to one of four groups (melatonin, HA/CMC membrane, combination of melatonin and HA/CMC membrane, control group). Seven days after the second surgery, the third operations were carried out and adhesions were scored. The main outcome measures were type, tenacity, and extent of adhesions. Total adhesion scores were determined. RESULTS: Adhesion scores in the melatonin and HA/CMC membrane groups were similar, and significantly lower than those in the control group (P < 0.001). Adhesion scores in the combination group were lower than those in the other three groups (P < 0.001). CONCLUSION: Melatonin and HA/CMC membrane are both effective separately in preventing adhesion reformation following adhesiolysis, but in combination they are significantly more beneficial.

Myometrial cystic formation after local methotrexate application into cornual gestational sac: a case report of an unexpected complication.

Cornual pregnancy is a rare type of ectopic pregnancy, and diverse therapeutic options exist for the management. Medical treatment despite high initial beta HCG values is not thought to be safe. We reported a 39-year-old woman with an initial beta HCG value of 22000 mIU/mL and diagnosed of a cornual pregnancy. Patient was managed successfully with the administration of combined systemic and ultrasonographically guided local injection of methotrexate into the gestational sac. During followup with serial beta hcg measurements, 27 × 20 mm cystic area in myometrium has been detected. Beta hcg <1 mIU/mL value was reached three months later, and this cystic area resolved spontaneously. Systemic methotrexate administration combined with ultrasound-guided local methotrexate injection into the gestational sac might be considered as the first-line treatment in the management of hemodynamically stable patients having cornual pregnancy even with high beta HCG values and risk of myometrial cystic formation.

Psychologic influence of male factor infertility on men who are undergoing assisted reproductive treatment: a preliminary study in a Turkish population.

OBJECTIVE: To investigate the psychologic impact of male factor infertility on men in couples undergoing assisted reproductive treatment in Turkey. STUDY DESIGN: A prospective study was carried out in a total of 105 men: 43 with male factor, 31 with female factor and 31 with unexplained infertility diagnoses. The men answered questionnaires-State Trait Anxiety Inventory, State Trait Anger Expression Inventory and Beck Depression Inventory-during treatment. The scores from each questionnaire were analyzed and compared according to the infertility diagnosis. RESULTS: No significant differences were found in measures of anxiety, anger or depression among men with male factor, female factor and unexplained infertility. CONCLUSION: In the current preliminary study performed on a group of Turkish men who applied for in vitro fertilization treatment, it was found that male factor infertility as the cause of the couple's infertility problem did not have an adverse effect on the psychologic status of men undergoing assisted reproductive treatment. It is suggested that men's psychologic adjustment to their own infertility diagnosis does not indicate that they are psychologically ill.

The significance of the number of CGG repeats and autoantibodies in premature ovarian failure.

The objective of this study was to determine whether there was a threshold for the number of CGG repeats in the FMR1 (fragile X) gene in premature ovarian ageing and premature ovarian failure and to investigate the association of this sequence with serum concentrations of anti-Müllerian hormone (AMH), inhibin B, anti-thyroid and anti-adrenal autoantibodies. In this prospective randomized controlled preliminary study, the number of triple CGG repeats and serum concentrations of FSH, AMH and aforementioned autoantibodies were evaluated in 79 women who were younger than 40 years old. FSH concentrations were between 12 and 50 IU/ml (premature ovarian ageing) in 30 women and were higher than 50 IU/ml (premature ovarian failure) in nine women; FSH concentrations were normal in 40 women. All women whose FSH concentrations were higher than 12 IU/ml had CGG repeats greater than 30. No women whose FSH concentrations were normal had a repeat number above 30. There was no significant relationship between the levels of antibodies and either CGG repeat numbers or FSH concentrations. In conclusion, the number of CGG repeats between 30 and 40 might be used to predict premature ovarian ageing and premature ovarian failure in infertile women.

Ovarian stimulation in women with high and low body mass index: GnRH agonist versus GnRH antagonist.

This study evaluated women with a high body mass index (BMI) (>40 kg/m(2)) and low BMI (<18 kg/m(2)) undergoing assisted reproduction treatment and determined whether the type of gonadotrophin-releasing hormone (GnRH) analogue used has an impact on cycle parameters and outcome. The study analysed 65 women with high BMI and 118 with low BMI. In the former group, polycystic ovarian syndrome was significantly more prevalent in the agonist long protocol (ALP) group (P=0.01) and gonadotrophin consumption was lower, peak oestradiol concentrations and total number of oocytes retrieved were higher in the ALP group compared with the antagonist (ANT) group. Implantation rate (IR), pregnancy rate (PR) per embryo transfer and early pregnancy loss rate (EPLR) were similar in both stimulation groups, with overall rates of 21.6%, 55.4% and 44.4%, respectively. In women with low BMI, peak oestradiol concentrations, total oocytes retrieved, mature oocytes and transferred embryos were higher in the ALP group compared with ANT group. IR, PR/embryo transfer and EPLR were similar in both groups, with overall rates of 24.3%, 52.5% and 16.1%, respectively. In all patients, no difference was found between ALP and ANT protocols concerning treatment outcome. Contrary to the reasonable EPLR observed in women with low BMI, the high rate found in women with high BMI is remarkable.

Elevated maternal serum alpha-fetoprotein levels in patients with subchorionic hematoma.

Subchorionic hematoma might be associated with poor pregnancy outcome. Two intra cytoplasmic sperm injection pregnancies complicated with subchorionic hematoma were found to have elevated mid-trimester maternal serum alpha-fetoprotein levels. One of them had miscarriage at 16 weeks' gestation and the other delivered a healthy baby by cesarean section. The valid interpretation of triple test result might be complicated by subchorionic hematoma. Therefore, it is better not to order triple test in such cases to avoid unnecessarily provoking the anxiety of the couple.

The effects of letrozole and melatonin on surgically induced endometriosis in a rat model: a preliminary study.

OBJECTIVE: To determine the effects of letrozole and melatonin on surgically induced endometriosis in a rat endometriosis model. DESIGN: Prospective, randomized, controlled, experimental study. SETTING: Experimental Research Center of Yeditepe University (YUDETAM). ANIMAL(S): Thirty female, nonpregnant, nulligravid Wistar-Hannover albino rats. INTERVENTION(S): Surgical induction of endometriosis, administration of estrogen for 2 weeks, and laparotomy; administration of letrozole or melatonin for 2 weeks after induction of endometriosis, and laparotomy; administration of estrogen for 2 weeks and necropsy. MAIN OUTCOME MEASURE(S): The volume and histopathologic scores of endometriotic foci, and levels of superoxide dismutase, catalase, and malondialdehyde in the peritoneal fluid. RESULT(S): The mean volumes of the endometriotic foci were 99.6 +/- 18.8 mm(3), 21.5 +/- 7.4 mm(3), and 29.2 +/- 17.5 mm(3), and histopathologic scores were 2.5 +/- 0.7, 2.0 +/- 0.8, and 1.7 +/- 0.9 in the melatonin group at the end of the second, fourth, and sixth weeks, respectively. The mean volumes of the endometriotic foci were 75.9 +/- 26.3 mm(3), 29.8 +/- 14.7 mm(3), and 121.2 +/- 35.1 mm(3) and the histopathologic scores were 2.5 +/- 0.5, 2.2 +/- 0.8, and 2.7 +/- 0.4 in the letrozole group at the end of the second, fourth, and sixth weeks, respectively. In the melatonin group, peritoneal fluid superoxide dismutase and catalase levels increased statistically significantly. CONCLUSION(S): Melatonin caused more pronounced regression of endometriotic foci when compared with letrozole in a rat model. After the cessation of melatonin treatment, the recurrence rate was lower than that observed after the cessation of letrozole treatment.