{"paper_id":"4b28eca1-7d3d-44d2-9ff3-b8491e040147","body_text":"R E S E A R C H Open Access\nEffects of intravenous tranexamic acid on\novarian reserve and intra-operative blood\nloss during laparoscopic cystectomy of\nendometriotic cyst: a pilot randomized\ncontrolled trial\nPrangthip Akkaranurakkul 1, Srithean Lertvikool 2, Woradej Hongsakorn 2, Orawin Vallibhakara 2, Siriluk Tantanavipas 2,\nKrissada Paiwattananupant 3, Wichai Ittichaikulthol 4, Apirom Vongsakulyanon 5, Sakda Arj-Ong Vallibhakara 6,\nMakaramas Anantaburana 2 and Areepan Sophonsritsuk 2*\nAbstract\nBackground: Strategies to preserve ovarian function after ovarian endometriotic cyst removal have been reported\nin many studies; however, no study has evaluated tranexamic acid administration during surgery.\nObjective: To evaluate feasibility of conducting a definitive trial and assessing the potential efficacy of tranexamic\nacid on ovarian reserve and intra-operative blood loss by comparing mean differences in anti-Müllerian hormone\n(AMH) levels following laparoscopic ovarian cystectomy between tranexamic acid and control groups.\nMaterials and methods: A parallel two-arm pilot trial was conducted with 40 participants with endometriotic cysts\nwho underwent laparoscopic ovarian cystectomy. They were randomized 1:1 to either 1 g tranexamic acid (TXA) or\nno TXA ( n = 20 per group). TXA was administered to the participants immediately after induction of general\nanesthesia and intubation. The primary outcome was the feasibility of conducting a definitive trial in terms of\ndesign and procedures (such as recruitment rate, retention, safety of intravenous 1 gm of TXA, sample size\nverification) and assess the efficacy of TXA on the ovarian reserve and intra-operative blood loss by comparing\nmean difference of AMH levels between TXA and control groups at pre- and 3 months post-surgery.\nResults: The recruitment and successful completion rates were 95% and 100%. Baseline characteristics were similar\nin the two groups. The mean difference of serum AMH levels (pre- and 3 months post-surgery) between the TXA\nand control groups was not significantly different. When performing a subgroup analysis, the mean difference of\nAMH levels (pre- and 3 months post-surgery) seemed to be higher in the bilateral than in the unilateral ovarian cyst\ngroup but not significantly different. Operating time was significantly longer in bilateral than in unilateral cysts. No\npost-operative complications or adverse effects were found.\n© The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,\nwhich permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give\nappropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if\nchanges were made. The images or other third party material in this article are included in the article's Creative Commons\nlicence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons\nlicence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain\npermission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.\nThe Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the\ndata made available in this article, unless otherwise stated in a credit line to the data.\n* Correspondence: areepan.sop@mahidol.ac.th\n2Reproductive Endocrinology and Infertility Unit, Department of Obstetrics\nand Gynaecology, Faculty of Medicine Ramathidodi Hospital, Mahidol\nUniversity, Praram 6 Rd., Phayatai, Bangkok 10400, Thailand\nFull list of author information is available at the end of the article\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 \nhttps://doi.org/10.1186/s40814-021-00907-y\n\nConclusion: The full randomized controlled trial for evaluating effects of TXA administration during laparoscopic\ncystectomy for endometrioma on ovarian reserve was shown to be feasible. Several modifications should be added\nfor improving feasibility, for example, increasing the TXA dose, modifying TXA administration, focusing on either\npatients with unilateral or bilateral ovarian cysts, and exploring other outcome measures, e.g., surgeons ’ satisfaction.\nTrial registration: Thai Clinical Trials Registry, TCTR20190424002, Registered 24 April 2019.\nKeywords: Anti-fibrinolytic Agents, Anti-Mullerian hormone, Endometriosis, Ovarian reserve, Tranexamic acid\nKey messages regarding feasibility\n/C15What uncertainties existed regarding the feasibility\nof this study?\nUncertainty regarding recruitment and retention of\npatients who have ovarian endometriotic cysts\nundergoing laparoscopic cystectomy and\nadministration of tranexamic acid to preserve\novarian function.\nUncertainty regarding the ability of patients to\ncomplete the study.\n/C15What are the key feasibility findings?\nThe recruitment and retention of patients was\nfeasible and showed zero rate of incompleteness of\nthe study\n/C15What are the implications of the feasibility findings\nfor the design of the main study?\nModifications of study design would be needed for\nconducting the full randomized controlled trial.\nMany suggestions for the next study include a\nprobable increase in the dosage of tranexamic acid, a\nstudy on similar patients with either unilateral or\nbilateral ovarian cyst, and investigation of other\noutcome variables.\nIntroduction\nOvarian endometriosis (endometriomas) is a common\ngynecological disease that occurs up to 10% of repro-\nductive women and the prevalence of disease is up to 20\nto 50% in infertile women [ 1–3]. The clinical presenta-\ntions include pelvic pain, progressive dysmenorrhea,\ndyspareunia, and subfertility. The presence of endome-\ntriomas has the potential to destroy healthy ovarian tis-\nsues that leads to decreased ovarian function [ 4],\nproblems with ovulation [ 5], and primary ovarian insuffi-\nciency [ 6]. The most effective treatment for endometrio-\ntic cyst is controversial. The first-line management of\nendometriotic cyst, a diameter larger than 3 cm, is a lap-\naroscopic ovarian cystectomy [ 7]. Moreover, manage-\nment of endometrioma larger than 3 cm in women who\nhave an infertility problem should consist of ovarian\ncystectomy prior to assisted reproductive technologies to\nimprove pelvic pain or help perform the oocyte retrieval\nprocedure without difficulties [ 8]. Although laparoscopic\novarian cystectomy provides the lowest recurrence and\nthe highest chance of spontaneous pregnancy rate, risk\nof significant ovarian injury can occur. Ovarian injury is\nthought to be caused by loss of healthy ovarian follicles\nduring surgery and inflammation caused by surgical\ntrauma or vascular injury. Recent data have demon-\nstrated that surgical treatment of endometriotic cyst\nhave an adverse effect on ovarian reserve [ 9]. Inadvertent\nremoval of normal ovarian tissue is one of the reasons\nfor the reduction in ovarian reserve during cystectomy\n[10]. Serum anti-Müllerian hormone (AMH) is the most\nreliable and practical measurable marker for ovarian re-\nserve [ 11]. This hormone reflects the number of high-\nquality oocytes within the ovaries. AMH is secreted by\ngranulosa cells in women of reproductive age. Several\nstudies have demonstrated a decrease in AMH levels\nafter laparoscopic cystectomy of endometriomas [ 12–\n14]. In our study, AMH was used to evaluate ovarian re-\nserve. The advantage of AMH over other ovarian serum\nmarkers is fairly constant levels, and hormone levels can\nbe measured on any day of the menstrual cycle. AMH\nlevels are reliable for predicting fertility and helping phy-\nsicians identify women at risk of premature ovarian in-\nsufficiency [ 15, 16].\nMany gynecologists try to find strategies to preserve\novarian function. We hypothesized that if a decrease\nin blood loss during surgery occurs, the surgeon\ncould view the operative field clearly and could per-\nform the operation smoothly with less use of bipolar\ncoagulation. As a result, vascular and healthy ovarian\ntissue damage would be decreased. In the present\nstudy, we use tranexamic acid (TXA) as a pharmaco-\nlogical tool for reducing bleeding during surgery.\nTXA has been widely used during surgery to decrease\nbleeding and wound complications [ 17–19]. The rec-\nommended standard dose is 1 g every 6 to 8 h in\ngeneral fibrinolysis [ 20] .H o w e v e r ,t h ed o s ec o u l db e\nincreased in case of excessive bleeding but should not\nexceed a maximum daily dose of 4 g [ 21].\nThe objectives of this study were to evaluate the feasi-\nbility of conducting a definitive trial in terms of design\nand procedures (such as recruitment rate, retention,\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 2 of 10\n\nsafety of intravenous 1 g of TXA, and sample size verifi-\ncation) and assess TXA efficacy on ovarian reserve and\nintra-operative blood loss by comparing the mean differ-\nence of AMH levels between TXA and control groups.\nAMH was measured pre- and at 3 months post-surgery.\nMaterials and methods\nThis study was a double-blind randomized controlled\ntrial (RCT) conducted between May 2019 and November\n2020. The study was approved by the Ethical Clearance\nCommittee on Human Related to Researches Involving\nHuman Subjects and Faulty of Medicine Ramathibodi\nHospital Mahidol University (No. MURA2019/245) and\nwas registered on the Thai Clinical Trial Registry\n(TCTR). This study was conducted in accordance with\nthe 1964 Helsinki Declaration.\nReproductive women ages 19 –45 years who were plan-\nning to undergo laparoscopic cystectomy for unilateral\nor bilateral endometriotic cysts were invited to partici-\npate in the study. Inclusion criteria included several pa-\nrameters: (1) unilateral/bilateral endometriotic cyst with\ntypical ultrasonography characteristics [ 22], (2) ovarian\ncyst size 3 –10 cm, (3) no previous use of oral hormones\n3 months prior to the study, (4) no history of taking\ndepot-medroxyprogesterone acetate or gonadotropin re-\nleasing hormone agonist within 9 months prior to the\nstudy, and (5) willingness to participate in the study. Ex-\nclusion criteria included several parameters: (1) preg-\nnancy and post-menopausal status, (2) history of allergy\nor contraindications to TXA, (3) underlying disease,\nsuch as thromboembolic disease, which contradicts the\nuse of TXA, (4) pre-operative AMH level < 0.5 ng/ml,\nand/or (5) history of previous ovarian surgical interven-\ntion. Eligible participants were enrolled in the present\nstudy and signed the consent forms. The participants\nwere randomly assigned either: (1) TXA and (2) un-\ntreated or control. Blocks of four were randomized with\na 1:1 ratio by an independent nurse and concealed in a\nlabeled envelope. Serum samples were collected before\nlaparoscopic ovarian cystectomy. For the intervention\ngroup, TXA 1 g intravenously was administered by anes-\nthesiologists within 10 min before making skin incision.\nSurgeons were blinded to the participant groups. Lap-\naroscopic surgery was performed with the standard op-\nerating procedure by the endoscopic staff in the\nRamathibodi hospital. All surgeons ( n = 5) had compar-\nable surgical skills and experience with laparoscopy.\nBriefly, after general anesthesia was administered, the\nparticipants laid in the Trendelenburg position. The pri-\nmary trocar was placed at the umbilicus with 2 to 3\naccessory ports. Ovarian cystectomy was initiated by an\nincision over the wall of ovarian cyst through the cortex.\nThe cyst wall was mobilized by sharp and blunt dissec-\ntion and removed from the ovarian cortex. The inner\novarian stroma was coagulated with bipolar electro-\ncautery (20 –30 W current) to achieve satisfactory\nhemostasis and approximation. The ovarian cortex was\nclosed with an absorbable suture (2 –0o r3 –0). Blood\nloss was calculated by anesthesiologists as the difference\nbetween the total amounts of suction and irrigation. All\nintra- and post-operative complications occurring within\n3 months of the operation were recorded. The partici-\npants were scheduled for follow-up appointments at 3\nmonths post-surgery. Sera were collected for measure-\nment of post-surgery AMH levels.\nOutcomes\nThe primary objective of this study was to evaluate the\nfeasibility of conducting a definitive trial in terms of sev-\neral parameters: (1) recruitment rate, (2) successful com-\npletion of the study procedures, (3) safety of intravenous\n1 g of TXA, and (4) verification of the sample size calcu-\nlation for the full RCT using intravenous 1 g of TXA on\novarian function preservation in patient who undergoing\novarian cystectomy. Recruitment and successful comple-\ntion rate observed in the pilot which are considered feas-\nible for the full RCT were not less than 90% of all\neligible patients and 95% of all enrolled patients, respect-\nively. Safety of intravenous 1 g of TXA is defined as no\nserious adverse drug reaction (ADR). Serious ADR de-\nnoted as any unfavorable medical occurrence that at 1 g\nTXA: (i) resulted in death; or (ii) was life-threatening; or\n(iii) prolonged hospital stay; or (iv) resulted in significant\nhandicap; or (v) required medical or surgical interven-\ntion to prevent a permanent defect of a body function or\nstructure; or (vi) was a malignancy or a congenital\nanomaly [ 23].\nThe secondary objectives included assessments of\nTXA efficacy on ovarian reserve and intra-operative\nblood loss by comparing mean difference of AMH levels\nbetween TXA and control groups. AMH was assessed\npre-operatively and at 3 months post-surgery. AMH was\nquantified using an electrochemiluminescence assay\n(ECLIA; Elecsys® AMH assay, Roche Diagnostics) by a\ntechnician who was unaware of participant allocation.\nSample size\nThe intended sample size for the present study had been\nestimated using a formula calculated based on the prob-\nability of observing problems occurring in target study\nsubjects with a chosen level of confidence. P(x >0 )=1\n– (1 − π)n. Where x indicates as number of participants\n(of the n participant). The formula is: n = ln(1 − γ)/ln(1\n− π)i f π designates the problem probability and γ de-\nnotes certain threshold of confidence by 100% × γ (such\nas 95% CI, γ is 0.95) [ 24, 25]. The calculator is available\nat http://www.pilotsamplesize.com).\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 3 of 10\n\nThe lowest recruitment rate approximately 5 –10%\nwith at 95% confidence interval was used to calculate for\nthe present study. Twenty-eight to 58 participants were\nneeded for the unsuccessful recruitment rate of 5 –10%.\nWe chose 40 participants to enroll in the present study\nand estimated that it would require 15 months, includ-\ning a 3-month follow-up, to complete the study.\nStatistical methods\nSoftware program SPSS version 21.0 (SPSS Inc., Chicago,\nUSA) was used for statistical analysis. The Pearson ’s chi-\nsquare and Student ’s t tests were applied to compare\ncategorical and continuous parametric data, respectively.\nThe Mann –Whitney test was used to compare nonpara-\nmetric continuous data, that is, serum AMH levels be-\nfore and after surgery and the difference in AMH levels\n(pre- and 3-month post-surgery). P values < 0.05 were\nconsidered to be statistically significant. The median dif-\nference and 95% confidence interval (CI) of difference\nwere calculated by Stata Statistical Software: Release\n15.0 (College Station, TX, USA) and Hodges-Lehmann\nmedian methods. ( https://www.real-statistics.com/non-\nparametric-tests/mann-wh itney-test/mann-whitney-\nmedian-confidence-interval/)\nResults\nRecruitment, recruitment rate, and the successful\ncompletion of the study procedures\nEnrollment took place from May 2019 through Au-\ngust 2020, and the 3-month follow-up was completed\nin November 2020. The timeline for recruitment was\ndelayed by 4 months because of the start of the cor-\nonavirus 2019 (COVID-19) pandemic in Thailand.\nThe operations for benign conditions, which included\nlaparoscopic cystectomy, were temporarily halted for\n4 months in our hospital. Of the total 42 participants\nwho were invited to participate in this study, 40 par-\nticipants were recruited and randomized into two\ngroups. The recruitment rate was 95%. All of them\ncompleted a 3-month follow-up, as shown in Fig. 1.\nWe made a phone call to the participants if they\nmissed the follow-up day and invited them to visit on\nthe next day. The rate of successful completion of the\nstudy procedures was 100%.\nFig. 1 Flow chart of the study\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 4 of 10\n\nBaseline and outcome characteristics\nThe baseline demographic characteristics of the partici-\npants are presented in Table 1. The two groups were\nsimilar in mean age, body mass index, parity, the max-\nimum diameter of ovarian cyst, laterality of lesions, and\nAmerican Society of Reproductive Medicine (ASRM)\nstage of endometriotic cyst. The surgical outcomes were\ncompared in treatment and control groups. Estimated\nblood loss, post-operative complications, and length of\nhospital stay were all similar in the two groups. How-\never, operating time in TXA group was longer than in\nthe control group. Pre-operative AMH levels were also\nsimilar between patients in the TXA and control groups\n(2.9 ± 1.5 and 2.4 ± 1.8 ng/ml, respectively) as shown in\nTable 2. At 3 months post-surgery, serum AMH levels\nof the TXA and control groups decreased significantly.\nMeans difference of pre- and 3-month post-operative\nAMH of TXA and control groups were 0.89 (95% CI\n0.39 to 1.38) ng/ml and 0.83 (95% CI 0.30 to 1.37) ng/\nml, respectively (Table 3). However, the mean difference\nof serum AMH level (pre-and 3-month post-surgery) be-\ntween the TXA and control groups was not significantly\ndifferent (0.05; 95% CI − 0.65 to 0.76). The mean differ-\nence in serum AMH level (pre-and 3-month post-\nsurgery) was 0.7 ± 1.2 and 0.8 ± 1.0 ng/ml in the control\nand TXA groups, respectively (Table 2). No post-\noperative complications or adverse effects were found,\nand none of the participants required a blood\ntransfusion.\nIn our study, we analyzed the outcomes between uni-\nlateral and bilateral ovarian cysts. There were no signifi-\ncant differences in the mean difference of AMH levels\n(pre- and 3-month post-operation) between unilateral\nand bilateral ovarian cysts ( − 0.61; 95%CI − 1.32 to\n0.11). Moreover, operating time was significantly longer\nin patients with bilateral ovarian cysts than those with\nunilateral ovarian cysts, as shown in Table 4. We also\nanalyzed subgroups consisting of pre- and 3-month\nTable 1 Baseline characteristics\nCharacteristics Tranexamic acid\n(n = 20)\nmean +S Do r n (%)\nControl\n(n = 20)\nmean +S Do r n (%)\nAge (years) 30.6 ± 4.6 32.3 ± 4.9\nBody mass index (kg/m 2) 20.2 ± 2.5 20.6 ± 3.7\nParity, n (%)\nNulliparous 19 (95%) 19 (95%)\nParous 1 (5%) 1 (5%)\nMaximum diameter of ovarian cyst (cm) 5.8 ± 1.8 5.4 ± 1.4\nNumber of ovarian cyst side, n (%)\nUnilateral 14 (70%) 12 (60%)\nBilateral 6 (30%) 8 (40%)\nASRM stage, n (%)\nStage 3 15 (75%) 11 (55%)\nStage 4 5 (25%) 9 (45%)\nNote: ASRM American Society of Reproductive Medicine, SD standard deviation\nTable 2 Outcomes between treatment and control groups\nTranexamic acid\n(n = 20)\nmean + SD or median (IQR)\nControl\n(n = 20)\nmean + SD or median (IQR)\nMean or median difference 95% CI\nPre-operative AMH (ng/ml) 2.9 ± 1.5 2.4 ± 1.8 0.50 − 0.56 to 1.56\nPost-operative AMH (ng/ml) 2.0 ± 1.5 1.6 ± 1.1 0.40 − 0.44 to 1.24\nDifference of AMH level (ng/ml) a 0.8 ± 1.0 0.7 ± 1.2 0.10 − 0.61 to 0.81\nOperative time (min) 130.0 (82.5) 120 (106.3) 0 − 35.00 to − 30.00\nEstimated blood loss (ml) 50.0 (50.0) 65.0 (150) 0 − 50.00 to 0\nLength of hospital stay (days) 1.8 ± 0.4 1.9 ± 0.4 − 0.10 − 0.36 to 0.16\nNote: AMH anti-Müllerian hormone, IQR interquartile range, SD standard deviation, CI confidence interval\naDifference of AMH level = pre-operative AMH-post-operative AMH\n*The test of significance for pilot trials is not helpful as such studies are not designed for statistical significance\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 5 of 10\n\npost-surgery AMH levels by comparing control and\nTXA groups for each unilateral and bilateral ovarian cyst\ngroup. The mean difference of AMH levels in the TXA\nand control groups in women with unilateral ovarian\ncyst was not significantly different (0.06, 95%CI − 0.86\nto 0.98). Operating time and blood loss were not signifi-\ncantly different between TXA and control groups as\nshown in Table 5. The mean difference in AMH levels\nin the TXA and control groups in women with bilateral\novarian cyst was not significantly different (0.22, 95%CI\n− 0.98 to 1.42). Operating times and blood loss were also\nnot significantly different between TXA and control\ngroups as shown in Table 6.\nVerification of sample size calculation for the full RCT\nWe then performed the statistical calculation for power\nfrom our results using the mean difference between pre-\nand post-surgery AMH levels and SD for TXA and con-\ntrol groups were 0.8 ± 0.1 and 0.7 ± 1.2, respectively. The\npower was only 4.2% ( www.openepi.com). We also calcu-\nlated the sample size for future full-scale randomized con-\ntrol studies addressing the effects of TXA on ovarian\nreserve during laparoscopic ovarian cystectomy for endo-\nmetrioma with the formula comparing two means. Our\nrevised sample size calculation verified 1915 experimental\nand 1915 control participants to allow for rejection of the\nnull hypothesis with probability (power) 0.8 and type I\nerror probability of 0.05. With a 10% allowance for drop-\nouts, the total sample size would be 4214.\nDiscussion\nThe present pilot study demonstrated that conducting a\nlarge randomized double-blind controlled trial would be\nfeasible with some modifications. Our results do not rule\nout the benefit of the administration of intravenous\nTXA immediately before laparoscopic cystectomy in pa-\ntients with endometriotic cysts. TXA seems beneficial\nfor blood loss when we analyzed subgroups of unilateral\nand bilateral ovarian cyst patients. However, several\nmodifications should be made to improve feasibility,\nsuch as increasing the TXA dosage, modifying TXA ad-\nministration, studying women either with unilateral or\nbilateral ovarian cysts, increasing the follow-up interval,\nand examining other outcomes, e.g., ease of surgery and\nsurgeon’s satisfaction.\nThe present study ’s recruitment and retention rate\nwas high because TXA administration is quite a safe\nintervention and could be theoretically beneficial to pa-\ntients. The follow-up time after surgery is short, and\nfollow-up visits are often needed to prevent the recur-\nrence of the disease. These factors could increase the\nwillingness of patients to come back for follow-up ap-\npointments. The delay in recruitment in the present\nstudy was unavoidable because of the global pandemic.\nThe laparoscopic cystectomy for endometriotic cysts\ncaused a decrease in ovarian reserve at 3 months after\nsurgery. Results from our study were similar to the\nothers [ 26–28]. The proposed mechanisms for decreas-\ning ovarian reserve include inadvertent removal of\nTable 3 Outcomes between pre- and post-operative AMH levels\nPre-operative AMH\nmean +S D\n(ng/ml) (n = 20)\nPost-operative AMH\nmean +S D\n(ng/ml) (n = 20)\nMean difference 95% CI\nTranexamic acid 2.9 ± 1.5 2.0 ± 1.5 0.90 − 0.06 to 1.86\nControl 2.4 ± 1.8 1.6 ± 1.4 0.80 − 0.23 to 1.83\nNote: AMH anti-Müllerian hormone, SD standard deviation, CI confidence interval\n*The test of significance for pilot trials is not helpful as such studies are not designed for statistical significance\nTable 4 Outcomes between women with bilateral and unilateral ovarian cysts\nUnilateral ovarian cyst\n(n = 26)\nmean + SD or median\n(IQR)\nBilateral ovarian cyst ( n =\n14)\nmean + SD or median (IQR)\nMean or median\n0difference\n95% CI\nDifference of AMH level (ng/\nml)a\n0.5 ± 1.1 1.2 ± 1.0 − 0.7 − 1.41 to 0.01\nEstimated blood loss (ml) 50 (35) 100 (150) − 50.00 − 100.00 to 0\nLength of hospital stay (days) 2 (0) 1.9 (0) 0.00 0 to 0\nOperation time (min) 124.4 ± 38.8 181.6 ± 71.3 − 57.2 − 92.26 to −\n22.14\nNote: AMH anti-Müllerian hormone, SD standard deviation, CI confidence interval\naDifference of AMH level = pre-operative AMH-post-operative AMH\n*The test of significance for pilot trials is not helpful as such studies are not designed for statistical significance\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 6 of 10\n\nnormal ovarian tissue during cystectomy and thermal in-\njury. Ovarian parenchymal tissue and primordial follicle\nof normal ovarian tissue were observed in the specimens\ncollected from the surgeries [ 29, 30]. Electrocauteriza-\ntion, such as bipolar electrosurgery, which is often used\nto control bleeding during laparoscopic cystectomy,\ncould damage ovarian follicles [ 31].\nSeveral strategies have been reported to prevent\novarian reserve decline after laparoscopic ovarian sur-\ngery, including different sur gical techniques, chemical\nagents, and medications [ 32–34]. Ovarian cystectomy\nreduced ovarian reserve after surgery more than ovar-\nian ablation (or vaporization) and deroofing; however,\ncyst recurrence was found more often in patients\ntreated with ovarian ablation and deroofing than cyst-\nectomy [ 26, 35]. A systematic review involving 1047\npatients demonstrated that laparoscopic ovarian su-\nture preserved ovarian function more than bipolar\nelectrosurgery did. A hemostatic sealant agent was su-\nperior to bipolar coagulation. Ultrasonic electrosur-\ngery was equal to bipolar coagulation [ 36]. However,\nstudies of the effect of TXA on ovarian reserve in\nlaparoscopic cystectomy, have not been previously\nreported.\nTXA is widely used to decrease blood loss in many sit-\nuations. TXA (trans-4-(Aminomethyl) cyclohexanecar-\nboxylic acid) is a synthetic derivative of the amino acid\nlysine that competitively inhibits the activation of plas-\nminogen to plasmin and is a competitive inhibitor of\ntissue plasminogen activator. It inhibits the lysine-\nbinding sites of plasminogen, resulting in inhibition of\nplasminogen activation and fibrin binding to plasmino-\ngen and, therefore, leads to impairment of fibrinolysis.\nHigh doses of TXA reduce plasmin formation [ 37].\nMany strong pieces of evidence demonstrate that TXA\ncauses a reduction in blood loss during major surgery. A\nlarge systematic review of several RCTs in 10,488 surgi-\ncal patients comparing TXA/no TXA administration\n(placebo) demonstrated that TXA contributes to a re-\nduction in approximately one-third of blood transfusion\nrequirements [ 19]. The dosage of TXA for local fibrin-\nolysis treatment is 0.5 to 1 g (equivalent to 15 mg/kg)\nby intravenous injection every 6 to 8 h while the dosage\nfor general fibrinolysis treatment is a single dose of 1 g\nor 10 mg/kg by intravenous injection [ 38]. The meta-\nanalysis by Heyns et al. suggested that the most\nfrequently used single dose for a reduction of peri-\noperative estimated blood loss in several types of oper-\nation was 15 mg/kg [ 39]. A study by Abbasi et al.\ncompared two doses of TXA, i.e., 5 and 15 mg/kg dur-\ning sinus endoscopy surgery [ 40]. The study demon-\nstrated that the administration of TXA 15 mg/kg\nreduced more blood loss and more surgeons satisfied\nsurgical field than those of TXA 5 mg/kg. Therefore,\nt h es i n g l ed o s eo fT X A1g( e q u i v a l e n tt o1 5t o2 0m g /\nkg) was selected to explore in the present study. How-\never, a single dose of TXA up to 100 mg/kg had been\nreported in coronary artery surgery [ 41].\nTable 5 Outcomes between treatment and control group in women with unilateral ovarian cyst\nTranexamic acid ( n = 14)\nmean +S Do r\nmedian (IQR)\nControl\n(n = 12)\nmean +S Do r\nmedian (IQR)\nMean or median difference 95% CI\nDifference of AMH level (ng/ml) a 0.6 ± 1.0 0.5 ± 1.2 0.10 − 0.79 to 0.99\nEstimated blood loss (ml) 50 (18) 77.5 (60.8) 0 − 30.00 to 10.00\nLength of hospital stay (days) 2 (0) 2 (0) 0 0 to 0\nOperation time (min) 131.0 ± 38.0 116.7 ± 39.9 14.30 − 17.27 to 45.97\nNote: AMH anti-Müllerian hormone, SD standard deviation, CI confidence interval\naDifference of AMH level = pre-operative AMH-post-operative AMH\n*The test of significance for pilot trials is not helpful as such studies are not designed for statistical significance\nTable 6 Outcomes between treatment and control groups in women with bilateral ovarian cysts\nTranexamic acid\n(n =6 )\nmean + SD or median (IQR)\nControl\n(n =8 )\nmean + SD or median (IQR)\nMean or median difference 95% CI\nDifference of AMH level (ng/ml) a 1.3 ± 1.0 1.1 ± 1.0 0.22 − 0.98 to 1.42\nEstimated blood loss (ml) 100 (75) 150 (175) − 50.00 − 150.00 to 50.00\nLength of hospital stay (days) 2 (0) 2 (0) 0.00 − 1.00 to 1.00\nOperation time (min) a 156.7 ± 60.9 200.4 ± 76.5 − 43.71 − 126.58 to 39.16\nNote: AMH anti-Müllerian hormone, SD standard deviation, CI confidence interval\naDifference of AMH level = pre-operative AMH-post-operative AMH\n*The test of significance for pilot trials is not helpful as such studies are not designed for statistical significance\nAkkaranurakkul et al. Pilot and Feasibility Studies           (2021) 7:171 Page 7 of 10\n\nThe present study did not demonstrate any beneficial\neffect of TXA for reducing blood loss. Blood loss from\nthe use TXA was less than that in control but not sig-\nnificantly different (50 vs 60 ml). The possible explan-\nation for the different results when compared to the\nprevious meta-analysis could be the smaller amount of\nblood loss in the present study. Because the amount of\nblood loss was small (only 50 –60 ml), consequently, the\ndifference of amount blood loss between TXA and the\ncontrol group was even smaller and difficult to assess\nprecisely. Moreover, the laterality of the ovarian cyst\ncould have interfered with the results. In general, pa-\ntients with unilateral ovarian cystectomy showed less\nblood loss during surgery than bilateral procedures.\nOur study was the first report to evaluate the benefit\nof TXA on ovarian reserve, which administered before\nlaparoscopic ovarian cystectomy by measured mean dif-\nference AMH level preoperative and 3 months after sur-\ngery. We did not find that intra-operative TXA can help\npreserve ovarian function. Although the sample size of\nthe present study was small, our revised sample size cal-\nculation verified 4214 participants to allow for rejection\nof the null hypothesis. Therefore, it is very unlikely that\nfuture study could be conducted with an enormous sam-\nple size, even studying in multi-centers.\nOvarian laterality is a significant factor impacting ovar-\nian reserve in patients undergoing cystectomy. Based on\nprevious studies, bilateral cystectomy was statistically as-\nsociated with a significant reduction in AMH levels and\novarian reserve compared to the unilateral cystectomy\ngroup [ 28, 42]. However, our study demonstrated a de-\ncrease in serum AMH levels post-surgery more in the\nbilateral than in the unilateral cysts, but these results did\nnot present a significant difference. This finding could\nhave occurred because the sample size was not calcu-\nlated according to laterality. Few side effects of TXA\nhave ever been reported [ 37], which is consistent with\nour study.\nThe strengths of the study were evaluated. Our study\nwas a pioneer and a double-blinded RCT study, and sur-\ngeons with the same experience levels performed the\nsurgery. Our study had limitations, including short-term\nfollow-up and no assessment of other ovarian reserve\nmarkers (follicle-stimulating hormone [FSH], inhibin-B)\nor sonographic markers. The present study results will\nhelp guide future studies of ovarian reserve reduction\nprevention during ovarian surgery in terms of optimal\ndosage and administration methods of tranexamic acid,\nlaterality of ovarian cysts, and other outcome variables,\ne.g., surgeons ’ satisfaction and ease of the operation.\nConclusions\nThe results from the present study support the feasibility\nof conducting the full RCT for the intravenous TXA\nadministration during laparoscopic cystectomy for endo-\nmetrioma. Several modifications should be added to\nachieve the full RCT, such as increasing the TXA dose,\nfocusing on patient subgroups (either with unilateral or\nbilateral ovarian cysts), exploring surgeons ’ satisfaction,\nand follow-up periods longer than 3 months.\nAbbreviations\nASRM: American Society of Reproductive Medicine; AMH: Anti-Müllerian\nhormone; CI: Confidence interval; COVID-19: Coronavirus 2019;\nECLIA: Electrochemiluminescence assay; FSH: Follicle stimulating hormone;\nPPH: Post-partum hemorrhage; RCT: Random controlled trial; STD: Standard\ndivision; TXA: Tranexamic acid; TCTR: Thai Clinical Trial Registry\nAcknowledgements\nWe thank all faculty of Department of Anaesthesiology for their assisting in\nthe study. We also thank nurses at the gynecologic out-patient clinic for their\nsupport in management of patients.\nAuthors’ contributions\nPA, WI, and AS contributed in the study design, conception, planning, and\nimplementation strategy. PA and MA contributed in data collection and\nmanagement and recruitment strategy. PA, SL, WH, OV, ST, and KP\ncontributed in data collection. SV contributed in the data analysis and\ninterpretation. PA and AS contributed in the writing the manuscript. All\nauthors have read and approved the final manuscript.\nFunding\nThis research is supported by Faulty of Medicine Ramathibodi Hospital\nMahidol University.\nAvailability of data and materials\nThe datasets generated and/or analyzed during the current study are\navailable from the corresponding author on request.\nDeclarations\nEthics approval and consent to participate\nOur study protocol was reviewed and approved by the Ethical Clearance\nCommittee on Human\nRelated to Researches Involving Human Subjects and Faulty of Medicine\nRamathibodi Hospital Mahidol University (No. MURA2019/245). Written\ninformed consent was obtained for all participants before the initiation of\nthe study procedures.\nConsent for publication\nNot applicable\nCompeting interests\nThe authors declare that they have no competing interests.\nAuthor details\n1Department of Obstetrics and Gynaecology, Faculty of Medicine\nRamathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.\n2Reproductive Endocrinology and Infertility Unit, Department of Obstetrics\nand Gynaecology, Faculty of Medicine Ramathidodi Hospital, Mahidol\nUniversity, Praram 6 Rd., Phayatai, Bangkok 10400, Thailand. 3Gynecologic\nOncology Unit, Department of Obstetrics and Gynaecology, Faculty of\nMedicine Ramathidodi Hospital, Mahidol University, Bangkok 10400, Thailand.\n4Department of Anesthesiology, Faculty of Medicine Ramathidodi Hospital,\nMahidol University, Bangkok 10400, Thailand. 5Department of Pathology,\nFaculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok\n10400, Thailand. 6ASEAN Institute for Health Development, Mahidol\nUniversity, Nakorn Pathom 73170, Thailand.\nAkkaranurakkul et al. 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