The impact of menstrual cycle on the safety of elective thyroid surgery

Introduction

In recent years, the global incidence of thyroid cancer has increased significantly, with a marked sex disparity: the male-to-female ratio is approximately 3:7, making women the high-risk group for thyroid cancer (1). Currently, surgical intervention remains the most direct and effective treatment for thyroid cancer, with unilateral thyroid lobectomy and total thyroidectomy being the most commonly performed procedures (2).

For women of reproductive age, hormonal fluctuations associated with the menstrual cycle represent key physiological factors that require attention during the perioperative period. The cyclical changes in estrogen and progesterone levels may theoretically influence surgical risks, including intraoperative bleeding, postoperative hematoma formation, and infection rates, by regulating coagulation factor activity and immune cell function (3-8). Traditional clinical wisdom generally holds that menstruating women exhibit relatively abnormal coagulation and reduced immunity, making this period a relative contraindication for surgery. However, no definitive reports or clinical guidelines explicitly prohibit thyroid surgery during menstruation, and high-quality evidence on the specific impact remains lacking.

Therefore, this retrospective descriptive study systematically examines the impact of the menstrual cycle on the safety of elective thyroid surgery in a cohort of 318 women of reproductive age with regular menstrual cycles. It evaluates multiple dimensions, including baseline physiological indicators, coagulation function, immune function, and surgical outcomes, aiming to provide a reference for the clinically rational selection of surgical timing and for optimizing perioperative management. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0231/rc).

Methods

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of The First Hospital of Jilin University (No. 2025-527) and individual consent for this retrospective analysis was waived.

Study population

The study population was women of reproductive age who underwent routine thyroid surgery at the Department of Thyroid Surgery, The First Hospital of Jilin University, between January 2023 and April 2025.

Inclusion criteria

The inclusion criteria were as follows: (I) aged 15–49 years, meeting the definition of reproductive age; (II) a history of regular menstrual cycles (cycle length of 21–35 days, duration of 3–7 days) over the preceding year; (III) underwent a unilateral thyroid lobectomy or a total thyroidectomy; (IV) good preoperative baseline health status, with no autoimmune diseases (e.g., systemic lupus erythematosus and rheumatoid arthritis); and (V) surgery was performed by the same primary surgeon, with consistent surgical team composition and perioperative management protocols.

Exclusion criteria

The exclusion criteria were as follows: (I) irregular menstrual cycle (cycle variation >7 days) or incomplete baseline clinical data; (II) compromised immune function (e.g., on long-term immunosuppressive therapy) or underlying metabolic disorders (e.g., uncontrolled diabetes mellitus or hyperthyroidism); (III) history of ovarian, uterine, or vaginal surgery that may affect the menstrual cycle; (IV) coagulation disorders (e.g., hemophilia or clotting factor deficiency) or taking antiplatelet medications (e.g., aspirin or clopidogrel) before surgery; (V) Hashimoto’s thyroiditis; and (VI) taking any form of sex hormone medication, including oral contraceptives.

Surgical procedure

All thyroid procedures were performed by the same primary surgeon using a standardized technique. The surgical approach involved a low-collar transverse incision, elevation of the subplatysmal flap, and separation of the midline strap muscles. Total thyroidectomy was performed with meticulous capsular dissection to identify and preserve the recurrent laryngeal nerves and parathyroid glands. The superior and inferior thyroid arteries were ligated individually at the thyroid capsule. When parathyroid glands were inadvertently devascularized or could not be preserved in situ, they were autotransplanted into the sternocleidomastoid muscle. Bipolar coagulation was used to maintain hemostasis meticulously throughout the procedure. A closed-suction drainage tube (10 Fr) was routinely placed in the thyroid bed and brought out through a separate stab incision, connected to a negative-pressure reservoir. The wound was closed in layers.

Menstrual cycle grouping

Patients’ menstrual cycle data, including cycle length, date of last menstrual period, menstrual duration, and menstrual status on the day of surgery, were collected from their electronic medical records. Different cycle lengths were standardized to a 28-day cycle using the following formula (9):

Adjusted day of the cycle=14×day of the cycle at the time of surgeryLength of the follicular phase(cycle length of the patient -14)[1]

Based on the adjusted day of the cycle, patients were placed into the following menstrual phase groups: menstrual phase, the patient was menstruating on the day of surgery, follicular phase, the patient was not menstruating on the day of surgery and had a standardized cycle of 0–14 days, and luteal phase, the patient was not menstruating on the day of surgery and had a standardized cycle of 15–28 days.

A total of 318 patients meeting the eligibility criteria were enrolled, of whom 119 underwent unilateral thyroid lobectomy and 199 underwent total thyroidectomy. In the unilateral thyroid lobectomy group, 29 patients underwent surgery during the menstrual phase, 28 during the follicular phase, and 62 during the luteal phase. In the total thyroidectomy group, 52 patients underwent surgery during the menstrual phase, 46 during the follicular phase, and 101 during the luteal phase.

Observation indicators

Baseline data

The following baseline data were recorded: age, height, body weight, body mass index (BMI), fasting blood glucose, and thyroid function indicators [triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), parathyroid hormone (PTH), and thyroglobulin (Tg)].

Coagulation function indicators

The following coagulation function indicators were recorded: thrombin time (TT), activated partial thromboplastin time (APTT), prothrombin time (PT), international normalized ratio (INR), prothrombin ratio (PTR), prothrombin activity (PTA), fibrinogen (FBG), and complete blood count parameters [red blood cell count (RBC), hemoglobin (Hb) level, hematocrit (Hct) level, platelet count (PLT), and platelet volume (PV)].

Immune function indicators

The following immune function indicators were recorded: white blood cell count (WBC), neutrophil percentage (Neu%), absolute neutrophil count (Neu#), lymphocyte percentage (Lym%), absolute lymphocyte count (Lym#), monocyte percentage (Mon%), absolute monocyte count (Mon#), and immune inflammation scores [Systemic Immune Inflammation Index (SII), Systemic Inflammatory Response Index (SIRI), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR)].

Operative and postoperative recovery indicators

The following operative and postoperative recovery indicators were recorded: operative duration, intraoperative blood loss, 24-hour postoperative drainage volume, 48-hour postoperative drainage volume, total hospital length of stay, postoperative hospital stay; postoperative complications and medication use, pain score [on Visual Analog Scale (VAS) from 0 to 10], analgesic use rate, antiemetic use rate, and incidence of fever (body temperature ≥38.5 ℃).

Statistical analysis

All data analyses were performed using SPSS Statistics (version 27.0; IBM Corp., Armonk, NY, USA), and two-tailed P values <0.05 were considered statistically significant. Bar charts were created using GraphPad Prism (version 10.3.1; GraphPad Software, Boston, MA, USA). Normally distributed continuous variables are presented as means ± standard deviations and were compared between groups using t-tests. Non-normally distributed continuous variables are presented as medians (interquartile ranges) and were compared between groups using Wilcoxon rank-sum tests. Categorical variables are presented as counts (percentages) and were compared between groups using Pearson’s χ² test or Fisher’s exact test. The P values for pairwise comparisons among multiple groups were corrected for multiple testing using the Bonferroni method.

Results

Comparison of baseline parameters across menstrual phases

Comparisons of baseline data among the three menstrual phase groups are presented in Table 1. Most baseline parameters, including age, height, weight, BMI, fasting blood glucose, PTH, TSH, T4, and Tg, did not differ significantly among groups (P>0.05). Although T3 differed significantly among groups (P<0.05), all patients remained within the normal reference range.

Comparison of coagulation and immune function indicators across menstrual phases

Coagulation-related (TT, APTT, PT, INR, PTR, PTA, FBG, RBC, Hb, Hct, PLT, and PV) and immune function (Neu%, Neu#, Lym%, Lym#, Mon%, SII, SIRI, NLR, PLR, and LMR) indicators are compared among menstrual phase groups in Table 2. Most coagulation-related and immune function indicators did not differ significantly among groups (P>0.05). Although WBC and Mon# differed significantly among groups (P<0.05), all patients remained within normal reference ranges.

In pairwise comparisons among the three menstrual phase groups, T3, WBC, and Mon# showed significant differences (Table 3). T3 levels were significantly higher in the luteal phase group than in the menstrual phase group (P=0.004); however, they did not differ significantly between the menstrual and follicular phase groups or between the follicular and luteal phase groups. WBC and Mon# were significantly higher in the luteal phase group than in the follicular phase group (P=0.03 and P=0.04, respectively); however, they did not differ significantly between the menstrual and follicular phase groups or between the menstrual and luteal phase groups (P>0.05, Figure 1).

Figure 1 Pairwise comparisons between different menstrual cycle groups. (A) T3 pairwise comparisons. (B) WBC pairwise comparisons. (C) Mon# pairwise comparisons. ns, not significant; *, P<0.05. Group A: menstrual phase group; Group B: follicular phase group; Group C: luteal phase group. Mon#, absolute monocyte count; T3, triiodothyronine; WBC, white blood cell count.

Comparison of surgical and postoperative recovery indicators across menstrual phases by surgery type

Surgical and postoperative recovery indicators are compared across menstrual phase groups in the unilateral thyroid lobectomy and total thyroidectomy groups in Table 4. In the unilateral thyroid lobectomy group, operating time, intraoperative blood loss, 24-hour postoperative drainage volume, 48-hour postoperative drainage volume, hospital length of stay, postoperative discharge time, pain score, analgesic usage rate, antiemetic usage rate, and fever incidence did not differ significantly among the three menstrual phase subgroups (P>0.05). In the total thyroidectomy group, postoperative 24-hour drainage volume differed significantly among the three menstrual phase subgroups (P=0.029); however, the median drainage volume was identical across all three subgroups (40 mL). However, postoperative 48-hour drainage volume and other surgical and recovery indicators did not differ significantly among menstrual phase subgroups.

In the unilateral thyroid lobectomy group, pairwise comparisons of postoperative 24- and 48-hour drainage volumes among the three menstrual phase subgroups revealed no significant differences (P>0.05). In the total thyroidectomy group, 24-hour postoperative drainage volumes were significantly higher in the menstrual phase group than in the luteal and follicular phase groups (P<0.05). In contrast, 48-hour postoperative drainage volumes did not differ significantly among the menstrual phase subgroups (Figure 2).

Figure 2 Comparison of drainage volume at 24 hours postoperatively versus 48 hours postoperatively across different menstrual cycles. (A) Postoperative 24-hour drainage volume in the unilateral thyroid lobectomy group. (B) Postoperative 48-hour drainage volume in the unilateral thyroid lobectomy group. (C) Postoperative 24-hour drainage volume in the total thyroid lobectomy group. (D) Postoperative 48-hour drainage volume in the total thyroid lobectomy group. ns, not significant; *, P<0.05; **, P<0.01. Group A: menstrual phase group; Group B: follicular phase group; Group C: luteal phase group.

Univariate and multivariate linear stepwise regression of postoperative 24-hour drainage volume

Univariate and multivariate linear stepwise regression analyses were conducted to examine the effects of various clinical indicators on 24-hour postoperative drainage volume (Table 5 and Figure 3). Only operative time was identified as an independent risk factor for postoperative 24-hour drainage volume (β=1.33, 95% confidence interval: 0.61–2.06, P<0.001).

Figure 3 Multifactorial analysis of postoperative drainage volume at 24 hours: forest plot. BMI, body mass index; CI, confidence interval; INR, international normalized ratio; Ref, reference; SE, standard error.

Discussion

This study is the first to examine the impact of the menstrual cycle on the safety of routine thyroid surgery. Through stratified analyses of 318 menstruating women of reproductive age undergoing thyroid surgery, it systematically examined the effects of the menstrual cycle on surgical safety across multiple dimensions, including baseline physiological indicators, coagulation function, immune function, and surgical outcomes. The core finding indicates that the menstrual cycle has a minimal effect on the safety of thyroid surgery, and menstruation is not an absolute contraindication for thyroid surgery.

This study found significant differences in T3 levels across menstrual phases, with higher levels in the luteal phase group than in the menstrual phase group. This finding may be related to fluctuations in estrogen levels during the menstrual cycle. Estrogen stimulates the liver to synthesize serpin family A member 7 [SERPINA7, formerly thyroxine-binding globulin (TBG)] (10,11), which binds to T3, thereby elevating total T3 levels. Relatively higher estrogen levels during the luteal phase may indirectly contribute to elevated total T3 levels. Notably, this physiological difference indirectly supports the accuracy of our menstrual cycle classification based on patients’ history. However, T3 levels varied within the normal reference range in our study cohort and did not reach levels sufficient to impact metabolic function or surgical tolerance. Thus, such fluctuations represent physiological regulation without clinical significance.

Regarding immune parameters, only WBC and Mon# differed significantly between the follicular and luteal phase groups, with higher values in the luteal phase group. This finding may relate to hormonal regulation of immune cells: gradually rising estrogen levels during the follicular phase may mildly suppress immune cell proliferation (5), while increased progesterone levels during the luteal phase can partially counteract this suppression (6). However, immune parameters remained within normal ranges in all three menstrual phase groups, and no significant differences were observed in postoperative infection-related indicators. Thus, menstrual cycle-related immune fluctuations are insufficient to compromise the body’s anti-infective capacity, partially contradicting the traditional belief that “menstruation significantly reduces immunity”.

Traditional clinical wisdom holds that menstruating women may exhibit coagulation abnormalities due to increased consumption of clotting factors caused by endometrial shedding, thereby elevating surgical bleeding risks (12). However, our study found no significant differences in core coagulation parameters, including TT, APTT, PT, FBG, and PLT, among the three menstrual phase groups. Moreover, intraoperative blood loss did not differ significantly between patients undergoing different surgical procedures, which may be explained as follows. Firstly, our study excluded patients with coagulation disorders or those taking antiplatelet medications, ensuring baseline stability of the coagulation system in the enrolled population. Secondly, although the thyroid gland has a rich vascular supply, it is supplied by relatively small-caliber vessels that are accessible and controllable under direct visualization. Nevertheless, meticulous hemostasis remains vital during thyroid surgery.

Intraoperative bleeding, even when not voluminous, can obscure the surgical field, compromise the identification of vital structures such as the recurrent laryngeal nerve and parathyroid glands, and potentially increase the risk of inadvertent injury. Though uncommon, postoperative hemorrhage represents a potentially life-threatening complication due to the risk of acute airway compression, necessitating prompt recognition and intervention. In our study cohort, no patient experienced a clinically significant postoperative hematoma requiring reoperation, suggesting that even minor coagulation fluctuations during menstruation did not result in clinically meaningful bleeding complications. However, our study was not specifically powered to detect rare events such as clinically significant postoperative hemorrhage.

Postoperative drainage volume is a crucial indicator of surgical safety. Our analysis revealed that, in the total thyroidectomy group, 24-hour postoperative drainage volumes were significantly higher in the menstrual phase subgroup than in the follicular and luteal phase subgroups; however, the absolute difference was small, with a median of 40 mL in all three subgroups. No such difference was observed in the unilateral thyroid lobectomy group. Moreover, both univariate and multivariate analyses of 24-hour postoperative drainage volume only identified operative duration as an independent risk factor. Crucially, this observed difference did not alter postoperative management—no patient required intervention for hematoma, and drainage tube removal time and hospital length of stay were unaffected. Notably, the routine use of cervical drains in elective thyroid surgery is increasingly being questioned in the era of enhanced recovery, and drainage volume is an imperfect surrogate for clinically significant bleeding. However, drainage volume remains a widely used objective and quantifiable measure of postoperative exudation and microbleeding in our institutional practice, serving as a quality assurance metric. Importantly, no patient experienced a clinically significant postoperative hematoma requiring reoperation—the most clinically relevant safety endpoint. The observed differences in drainage volume (median 40 mL in all three menstrual phase groups) did not influence clinical management, including the timing of drain removal or hospital discharge. However, our study was not specifically powered to detect rare events such as significant postoperative hemorrhage, which has an incidence of <1% in routine thyroid surgery. Nevertheless, the lack of any such events across all three menstrual phase groups provides additional reassurance.

Previous studies have suggested that hormonal fluctuations during menstruation may lower pain thresholds in women, leading to more pronounced postoperative pain and increased incidence of postoperative nausea and vomiting. For instance, Rao et al. found that pain thresholds to mechanical stimulation were lower during the premenstrual phase, resulting in more significant postoperative pain (13). A retrospective study by Beattie et al. revealed that women undergoing laparoscopy experienced a significantly higher incidence of postoperative nausea and vomiting during the first 8 days after anesthesia recovery (P<0.001) (14). However, unlike those studies, our results indicate that no significant differences in postoperative pain scores, analgesic use rates, antiemetic use rates, or fever incidence among the three menstrual phase groups. A possible explanation for this difference is that thyroid surgery pain primarily stems from neck muscle traction and incisions, with pain intensity related to surgical extent and procedural precision rather than hormonal fluctuations. Additionally, the standardized perioperative analgesia and antiemesis protocols employed by the surgical team in our study may have counteracted potential hormone-related effects.

Notably, the most common complications specific to thyroid surgery, including hypocalcemia resulting from parathyroid gland injury or devascularization, and dysphonia due to recurrent laryngeal nerve injury, are primarily determined by anatomical variations, disease characteristics (e.g., tumor invasion or Hashimoto’s inflammation), and surgeon experience. These complications are unlikely to be influenced by menstrual cycle-related physiological fluctuations in coagulation or immune function, as their pathogenesis is fundamentally mechanical and anatomical rather than hematological or immunological. Our study did not observe any differences in the incidence of these complications across the three menstrual phase groups, consistent with this biological reasoning.

Our findings are highly consistent with those of Lin et al. in vitreoretinal surgery (15), Das et al. in cardiac surgery (16), and Song et al. in ovarian cyst surgery (17): bleeding volume during procedures involving non-hormone-sensitive organs or surgical sites is unaffected by the menstrual cycle. However, some prior studies have indeed suggested a correlation between perioperative bleeding or healing outcomes in rhinoplasty (18) and breast reduction surgery (19) and the menstrual cycle. This discrepancy reflects the biological reality that the mammary glands, nasal mucosa, and endometrium are classic target organs for sex hormones, which directly regulate their vascular density and permeability (20,21). In contrast, the thyroid is not a primary target organ for estrogen and progesterone. Although it possesses a rich blood supply, its vascular endothelial cells and follicular epithelial cells do not express significant levels of sex hormone receptors, and its vasculature is not directly regulated by the menstrual cycle. The primary effect of sex hormones on the thyroid axis is indirect, mediated through hepatic synthesis of TBG. Therefore, extrapolating research conclusions from hormone-sensitive organs to thyroid surgery is scientifically unfounded. This distinction between hormone-sensitive and -insensitive tissues is a crucial conceptual framework for interpreting the literature on this topic.

However, our study had some limitations that should be acknowledged. Firstly, the single-center retrospective design and relatively limited sample size, particularly in the menstrual phase group, may have introduced selection bias. Secondly, the menstrual phase grouping relied on patients’ self-reported menstrual histories and on formula standardization, without employing serum hormone testing (e.g., luteinizing hormone and progesterone levels) to achieve precise staging, which may have introduced errors in grouping. Although the observed differences in T3 levels between menstrual phases provide indirect support for the validity of our grouping method, its subjective nature remains a significant limitation. Thirdly, since the study cohort comprised only women with regular menstrual cycles, our findings cannot be directly generalized to those with menstrual disorders (e.g., menorrhagia or polycystic ovary syndrome). Fourthly, since our study excluded women taking oral contraceptives or other sex hormone medications, our findings may not generalize to this population. Fifthly, the average postoperative hospital length of stay was longer in our study cohort than at Western medical centers, which reflects standard clinical practice in China, where patients are typically kept under observation for 48 hours after surgery before their drainage tubes are removed and they are discharged.

Our findings require validation in multicenter prospective studies that employ serum hormone testing to confirm menstrual cycle phases, enroll larger cohorts, and include patients with menstrual irregularities. Additionally, incorporating long-term postoperative follow-up indicators, such as incision healing time and thyroid function recovery, could provide more comprehensive evidence on the association between the menstrual cycle and thyroid surgery safety.

Conclusions

This study represents the first systematic evaluation of the impact of menstrual cycle phase on thyroid surgery safety, demonstrating that the menstrual cycle has minimal impact on perioperative outcomes. Although our findings largely confirm current clinical practice rather than refuting it, this confirmatory evidence has practical value: it provides formal data to reassure surgeons and patients, supports the elimination of unnecessary surgical delays based on traditional concerns, and reinforces that under standardized perioperative management and meticulous surgical techniques, performing thyroid surgery during menstruation is safe and feasible. Therefore, the menstrual cycle should not be considered a contraindication for scheduling routine thyroid surgery.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0231/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0231/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0231/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0231/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of The First Hospital of Jilin University (No. 2025-527) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Tang M, Li J, Sun M, et al. Global, regional, and national trends in thyroid cancer burden (1990-2021): Insights from the GBD 2021 study. Biomol Biomed 2025;25:2680-95. [Crossref] [PubMed]
2. Ringel MD, Sosa JA, Baloch Z, et al. 2025 American Thyroid Association Management Guidelines for Adult Patients with Differentiated Thyroid Cancer. Thyroid 2025;35:841-985. [Crossref] [PubMed]
3. Knol HM, Kemperman RF, Kluin-Nelemans HC, et al. Haemostatic variables during normal menstrual cycle. A systematic review. Thromb Haemost 2012;107:22-9.
4. Feuring M, Christ M, Roell A, et al. Alterations in platelet function during the ovarian cycle. Blood Coagul Fibrinolysis 2002;13:443-7. [Crossref] [PubMed]
5. Angele MK, Schwacha MG, Ayala A, et al. Effect of gender and sex hormones on immune responses following shock. Shock 2000;14:81-90. [Crossref] [PubMed]
6. Tan IJ, Peeva E, Zandman-Goddard G. Hormonal modulation of the immune system - A spotlight on the role of progestogens. Autoimmun Rev 2015;14:536-42. [Crossref] [PubMed]
7. Hughes SM, Levy CN, Katz R, et al. Changes in concentrations of cervicovaginal immune mediators across the menstrual cycle: a systematic review and meta-analysis of individual patient data. BMC Med 2022;20:353. [Crossref] [PubMed]
8. Sahin Aydınyurt H, Yuncu YZ, Tekin Y, et al. IL-6, TNF-α levels and periodontal status changes during the menstrual cycle. Oral Dis 2018;24:1599-605. [Crossref] [PubMed]
9. Findikcioglu K, Findikcioglu F, Sezgin B, et al. The impact of the menstrual cycle on intra-operative and postoperative bleeding in abdominoplasty patients. J Plast Reconstr Aesthet Surg 2012;65:e338-43. [Crossref] [PubMed]
10. Sparre LS, Brundin J, Carlström K, et al. Oestrogen and thyroxine-binding globulin levels in early normal pregnancy. Acta Endocrinol (Copenh) 1987;114:298-304. [Crossref] [PubMed]
11. Torre F, Calogero AE, Condorelli RA, et al. Effects of oral contraceptives on thyroid function and vice versa. J Endocrinol Invest 2020;43:1181-8. [Crossref] [PubMed]
12. Lebech AM, Kjaer A. Lipid metabolism and coagulation during the normal menstrual cycle. Horm Metab Res 1989;21:445-8. [Crossref] [PubMed]
13. Rao SS, Ranganekar AG, Saifi AQ. Pain threshold in relation to sex hormones. Indian J Physiol Pharmacol 1987;31:250-4.
14. Beattie WS, Lindblad T, Buckley DN, et al. The incidence of postoperative nausea and vomiting in women undergoing laparoscopy is influenced by the day of menstrual cycle. Can J Anaesth 1991;38:298-302. [Crossref] [PubMed]
15. Lin Z, Moonasar N, Wu RH, et al. The Impact of the Menstrual Cycle on Perioperative Bleeding in Vitreoretinal Surgery. J Ophthalmol 2017;2017:9549284. [Crossref] [PubMed]
16. Das D, Hasija S, Chauhan S, et al. Is menstruation a valid reason to postpone cardiac surgery? Ann Card Anaesth 2022;25:311-7. [Crossref] [PubMed]
17. Song T, Kim MK, Kim ML, et al. Effect of menstrual phase on the surgical treatment of ovarian cysts. J Obstet Gynaecol 2017;37:919-23. [Crossref] [PubMed]
18. Findikcioglu K, Findikcioglu F, Demirtas Y, et al. Effect of the menstrual cycle on intraoperative bleeding in rhinoplasty patients. Eur J Plast Surg 2009;32:77-81.
19. Sariguney Y, Demirtas Y, Findikcioglu F, et al. Proper timing of breast reduction during the menstrual cycle. Ann Plast Surg 2004;53:528-31. [Crossref] [PubMed]
20. Paulsson B, Gredmark T, Burian P, et al. Nasal mucosal congestion during the menstrual cycle. J Laryngol Otol 1997;111:337-9. [Crossref] [PubMed]
21. Nir D, Weissman A, Drugan A, et al. Effect of estrogen on eustachian tube performance. Am J Otol 1991;12:119-21.