Visualisation of microvascular flow in benign uterine disorders: a pilot study of a new diagnostic technique.

Background: Uterine disorders have clear overlapping symptoms and ultrasound discrimination is not always easy. Accurately measuring vascularity is of diagnostic and prognostic value. Power Doppler is limited to imaging only the larger vessels. Assessment of the microvasculature requires advanced machine settings. Objectives: In this pilot study, we aimed to test the feasibility of microvascular flow imaging of benign uterine disorders. Material and Methods: Two experienced gynaecologists (JH, RL) randomly applied power Doppler and MV-flowTM mode during a single day, in ten patients each visiting the outpatient clinic. Images of eight patients were labelled with a diagnosis by the attending physicians and collected as coded data. Main outcome measures: Microvascular flow images of normal uterine architecture including the fallopian tube, and of benign disorders such as fibroids, adenomyosis, endometriosis and uterine niches were collected. For both Doppler techniques, qualitative descriptive evaluation of the vascular architecture and a quantitative vascular index of fibroids were provided. Finally, we evaluated the effect of the cardiac cycle. Results: All microvascular flow images showed more distinctive vascular structures than visible on power Doppler. Calculating a vascular index for fibroids on 2D MV-flowTM images was easily performed on-site. During the cardiac cycle a higher vascular index (VI 75.2) is obtained in systole as compared with diastole (VI 44.0). Conclusion: Microvascular flow imaging allowed detailed visualisation of the uterine vascular architecture and is easy to use. What is new?: Microvascular flow imaging may be of added value for diagnosing uterine disorders, as well as for pre- and post-operative assessment of suited surgical techniques. Yet, validation with histology and clinical outcomes is required.

The definition, diagnosis, and symptoms of the uterine niche - A systematic review.

Of all neonates, 21% are delivered by cesarean section (CS). A long-term maternal complication of an SC is a uterine niche. The aim of this review is to provide an overview of the current literature on imaging techniques and niche-related symptomatology. We performed systematic searches on imaging and niche symptoms. For both searches, 87 new studies were included. Niche evaluation by transvaginal sonography (TVS) or contrast sonohysterography (SHG) proved superior over hysteroscopy or magnetic resonance imaging. Studies that used SHG in a random population identified a niche prevalence of 42%-84%. Niche prevalence differed based on niche definition, symptomatology, and imaging technique. Most studies reported an association with gynecological symptoms, poor reproductive outcomes, obstetrical complications, and reduced quality of life. In conclusion, non-invasive TVS and SHG are the superior imaging modalities to diagnose a niche. Niches are prevalent and strongly associated with gynecological symptoms and poor reproductive outcomes.

Aetiology, risk factors and preventive strategies for niche development: A review.

The increase in caesarean sections (CS) has resulted in an increase in women with a uterine niche. The exact aetiology of niche development has yet to be elucidated but is likely multifactorial. This study aimed to give a systematic overview of the available literature on histopathological features, risk factors and results of preventive strategies on niche development to gain more insight into the underlying mechanisms. Based on current published data histopathological findings associated with niche development were necrosis, fibrosis, inflammation, adenomyosis and insufficient approximation. Patient-related risk factors included multiple CS, BMI and smoking. Labour-related factors were CS before onset of labour, extended cervical dilatation, premature rupture of membranes and presenting part of the fetus at CS below the pelvic inlet. Preventive strategies should focus on the optimal level of incision, training of surgeons and full-thickness closure of the myometrium (single or double-layer) using non-locking sutures. Conflicting data exist concerning the effect of endometrial inclusion. Future studies without heterogeneity in population, using standardized performance of the CS after proper training and using standardized niche evaluation with a relevant core outcome set are required to allow meta-analyses and to develop evidence-based preventive strategies. These studies are needed to reduce the prevalence of niches and prevent complications in subsequent pregnancies such as caesarean scar pregnancies.

The barriers and needs of transgender men in pregnancy and childbirth: A qualitative interview study.

OBJECTIVE: Transgender and gender diverse individuals are individuals whose gender identity differs from their sex assigned at birth. The discordance between gender identity and sex assignment may cause significant psychological distress: gender dysphoria. Transgender individuals may choose to undergo gender-affirming hormone treatment or surgery, but some decide to (temporarily) refrain from surgery and gender affirming hormone treatment and hence retain the possibility to become pregnant. Pregnancy may enhance feelings of gender dysphoria and isolation. To improve perinatal care for transgender individuals and their health care providers, we conducted interviews to explore the needs and barriers of transgender men in family planning, pregnancy, childbirth, puerperium and perinatal care. DESIGN: In this qualitative study five in-depth semi-structured interviews were conducted with Dutch transgender men who had given birth while identifying on the transmasculine spectrum. The interviews were conducted online through a video remote-conferencing software program (n=4) or live (n=1). Interviews were transcribed verbatim. An inductive approach was used to find patterns and collect data from the participants' narratives and constant comparative method was adapted in analysing the interviews. MEASUREMENTS AND FINDINGS: The experiences of transgender men regarding the preconception period, pregnancy and puerperium and with perinatal care varied widely. Though all participants expressed overall positive experiences, their narratives emphasized they had to overcome substantial hurdles pursuing pregnancy. For instance the necessity to prioritise becoming pregnant over gender transitioning, lack of support by healthcare providers and increased gender dysphoria and isolation during pregnancy KEY CONCLUSIONS: Since pregnancy in transgender men enhances feelings of gender dysphoria, transgender men comprise a vulnerable group in perinatal care. Health care providers are perceived as feeling unaccustomed for the care of transgender patients, as they are perceived to often lack the right tools and knowledge to provide adequate care. Our findings help strengthen the foundation of insight in the needs and hurdles of transgender men pursuing pregnancy and therefore may guide health care providers to provide equitable perinatal care, and emphasize the necessity of patient-centred gender-inclusive perinatal care. A guideline including the option for consultation of an expertise center is advised to facilitate patient-centered gender-inclusive perinatal care.

Desire for children and fertility preservation in transgender and gender-diverse people: A systematic review.

The decision to pursue one's desire for children is a basic human right. For transgender and gender-diverse (TGD) people, gender-affirming care may alter the possibilities to fulfill one's desire for children due to the impact of this treatment on their reproductive organs. We systematically included 76 studies of varying quality describing the desire for children and parenthood; fertility counseling and utilization; and fertility preservation options and outcomes in TGD people. The majority of TGD people expressed a desire for children. Fertility preservation utilization rates were low as there are many barriers to pursue fertility preservation. The most utilized fertility preservation strategies include oocyte vitrification and sperm banking through masturbation. Oocyte vitrification showed successful outcomes, even after testosterone cessation. Sperm analyses when banking sperm showed a lower quality compared to cis male samples even prior to gender-affirming hormone treatment and an uncertain recovery of spermatogenesis after discontinuing treatment.

Uterine junctional zone and adenomyosis: comparison of MRI, transvaginal ultrasound and histology.

The uterine junctional zone is the subendometrial area in the myometrium that contributes to peristalsis and aids in spermatozoa and blastocyst transport. Alterations in the appearance of the junctional zone on transvaginal sonography (TVS) or magnetic resonance imaging (MRI) are associated with adenomyosis. The lack of standardization of description of its appearance and ill-defined boundaries on both histology and imaging hamper understanding of the junctional zone and limit its role in the diagnosis of adenomyosis. The objectives of this review were to investigate the accordance in definition of the junctional zone across different diagnostic approaches and to examine how imaging findings can be linked to histological findings in the context of diagnosis of adenomyosis. A comprehensive literature review was conducted of articles describing the appearance on imaging and the histological structure of the uterine junctional zone. Our review suggests that the junctional zone is distinguished from the middle and outer myometrium by gradual changes in smooth-muscle cell density, extracellular space, connective tissue, water content and vascular properties. However, while the signal intensity from the junctional zone to the middle myometrium changes abruptly on MRI, the histopathological changes are gradual and its border may be difficult or impossible to distinguish on two-dimensional TVS. Moreover, the thickness of the junctional zone measured on MRI is larger than that measured on TVS. Thus, these two imaging modalities reflect this zone differently. Although a thickened junctional zone is often used to diagnose adenomyosis on MRI, the presence of adenomyosis can be described more accurately as interruptions of the junctional zone by endometrial tissue, which leads to direct signs on imaging such as subendometrial lines and buds on two- and three-dimensional TVS or bright foci on MRI. The histopathological criteria for diagnosis are based on enlargement of the uterus with severe adenomyosis, and might not reflect its early stages. Clinicians should be aware that findings on MRI cannot be extrapolated readily to ultrasound. An understanding of this is necessary when investigating the uterine junctional zone as a functional unit and the association between visualization of direct features of adenomyosis in the junctional zone and clinical symptoms. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Can serum human epididymis protein 4 (HE4) support the decision to refer a patient with an ovarian mass to an oncology hospital?

INTRODUCTION: The value of serum human epididymis protein 4 (HE4) in guiding referral decisions in patients with an ovarian mass remains unclear, because the majority of studies investigating HE4 were performed in oncology hospitals. However, the decision to refer is made at general hospitals with a low ovarian cancer prevalence. We assessed accuracies of HE4 in differentiating benign or borderline from malignant tumors in patients presenting with an ovarian mass at general hospitals. METHOD: Patients with an ovarian mass were prospectively included between 2017 and 2021 in nine general hospitals. HE4 and CA125 were preoperatively measured and the risk of malignancy index (RMI) was calculated. Histological diagnosis was the reference standard. RESULTS: We included 316 patients, of whom 195 had a benign, 39 had a borderline and 82 had a malignant ovarian mass. HE4 had the highest AUC of 0.80 (95%CI 0.74-0.86), followed by RMI (0.71, 95%CI 0.64-0.78) and CA125 (0.69, 95%CI 0.62-0.75). Clinical setting significantly influenced biomarker performances. Applying age-dependent cut-off values for HE4 resulted in a better performance than one cut-off. Addition of HE4 to RMI resulted in a 32% decrease of unnecessary referred patients, while the number of correctly referred patients remained the same. CONCLUSION: HE4 is superior to RMI in predicting malignancy in patients with an ovarian mass from general hospitals. The addition of HE4 to the RMI improved HE4 alone. Although, there is still room for improvement, HE4 can guide referral decisions in patients with an ovarian mass to an oncology hospital.

How to use power Doppler ultrasound in transvaginal assessment of uterine fibroids.

Measuring vascularization in uterine fibroids is important for their diagnosis, treatment and prognosis. Vascularization can be measured by power Doppler ultrasound. The power Doppler signal depends on fibroid characteristics and on a variety of ultrasound-machine settings. Literature describing which machine settings influence the power Doppler signal is limited. Each manufacturer names settings and presets at their own discretion, with little information available publicly. Consistency of machine settings is important for correct interpretation of images in daily practice and is essential in yielding reproducible data for research. The aims of this paper, drawing from both a literature search and semistructured interviews with ultrasound-machine engineers and clinical experts in gynecological ultrasound, were: (1) to provide comprehensive background information on ultrasound physics and fibroid characteristics; (2) to present an overview of machine settings relevant to both two- and three-dimensional power Doppler, including power Doppler frequency, pulse repetition frequency, gain, wall-motion filter, acoustic power, persistence and signal rise; and (3) to provide a step-by-step tutorial on the optimal settings for vascular evaluation of uterine fibroids using power Doppler. The step-by-step tutorial comprises six steps to optimize the power Doppler signal, create a preset and acquire a reliable three-dimensional volume. This step-by-step tutorial should help research groups and clinicians to use power Doppler correctly and reproducibly in the evaluation of uterine fibroids. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Consensus on revised definitions of Morphological Uterus Sonographic Assessment (MUSA) features of adenomyosis: results of modified Delphi procedure.

OBJECTIVES: To evaluate whether the Morphological Uterus Sonographic Assessment (MUSA) features of adenomyosis need to be better defined and, if deemed necessary, to reach consensus on the updated definitions. METHODS: A modified Delphi procedure was performed among European gynecologists with expertise in ultrasound diagnosis of adenomyosis. To identify MUSA features that might need revision, 15 two-dimensional (2D) video recordings (four recordings also included three-dimensional (3D) still images) of transvaginal ultrasound (TVS) examinations of the uterus were presented in the first Delphi round (online questionnaire). Experts were asked to confirm or refute the presence of each of the nine MUSA features of adenomyosis (described in the original MUSA consensus statement) in each of the 15 videoclips and to provide comments. In the second Delphi round (online questionnaire), the results of the first round and suggestions for revision of MUSA features were shared with the experts before they were asked to assess a new set of 2D and 3D still images of TVS examinations and to provide feedback on the proposed revisions. A third Delphi round (virtual group meeting) was conducted to discuss and reach final consensus on revised definitions of MUSA features. Consensus was predefined as at least 66.7% agreement between experts. RESULTS: Of 18 invited experts, 16 agreed to participate in the Delphi procedure. Eleven experts completed and four experts partly finished the first round. The experts identified a need for more detailed definitions of some MUSA features. They recommended use of 3D ultrasound to optimize visualization of the junctional zone. Fifteen experts participated in the second round and reached consensus on the presence or absence of ultrasound features of adenomyosis in most of the still images. Consensus was reached for all revised definitions except those for subendometrial lines and buds and interrupted junctional zone. Thirteen experts joined the online meeting, in which they discussed and agreed on final revisions of the MUSA definitions. There was consensus on the need to distinguish between direct features of adenomyosis, i.e. features indicating presence of ectopic endometrial tissue in the myometrium, and indirect features, i.e. features reflecting changes in the myometrium secondary to presence of endometrial tissue in the myometrium. Myometrial cysts, hyperechogenic islands and echogenic subendometrial lines and buds were classified unanimously as direct features of adenomyosis. Globular uterus, asymmetrical myometrial thickening, fan-shaped shadowing, translesional vascularity, irregular junctional zone and interrupted junctional zone were classified as indirect features of adenomyosis. CONCLUSION: Consensus between gynecologists with expertise in ultrasound diagnosis of adenomyosis was achieved regarding revised definitions of the MUSA features of adenomyosis and on the classification of MUSA features as direct or indirect signs of adenomyosis. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Definition and sonographic reporting system for Cesarean scar pregnancy in early gestation: modified Delphi method.

OBJECTIVE: To develop a standardized sonographic evaluation and reporting system for Cesarean scar pregnancy (CSP) in the first trimester, for use by both general gynecology and expert clinics. METHODS: A modified Delphi procedure was carried out, in which 28 international experts in obstetric and gynecological ultrasonography were invited to participate. Extensive experience in the use of ultrasound to evaluate Cesarean section (CS) scars in early pregnancy and/or publications concerning CSP or niche evaluation was required to participate. Relevant items for the detection and evaluation of CSP were determined based on the results of a literature search. Consensus was predefined as a level of agreement of at least 70% for each item, and a minimum of three Delphi rounds were planned (two online questionnaires and one group meeting). RESULTS: Sixteen experts participated in the Delphi study and four Delphi rounds were performed. In total, 58 items were determined to be relevant. We differentiated between basic measurements to be performed in general practice and advanced measurements for expert centers or for research purposes. The panel also formulated advice on indications for referral to an expert clinic. Consensus was reached for all 58 items on the definition, terminology, relevant items for evaluation and reporting of CSP. It was recommended that the first CS scar evaluation to determine the location of the pregnancy should be performed at 6-7 weeks' gestation using transvaginal ultrasound. The use of magnetic resonance imaging was not considered to add value in the diagnosis of CSP. A CSP was defined as a pregnancy with implantation in, or in close contact with, the niche. The experts agreed that a CSP can occur only when a niche is present and not in relation to a healed CS scar. Relevant sonographic items to record included gestational sac (GS) size, vascularity, location in relation to the uterine vessels, thickness of the residual myometrium and location of the pregnancy in relation to the uterine cavity and serosa. According to its location, a CSP can be classified as: (1) CSP in which the largest part of the GS protrudes towards the uterine cavity; (2) CSP in which the largest part of the GS is embedded in the myometrium but does not cross the serosal contour; and (3) CSP in which the GS is partially located beyond the outer contour of the cervix or uterus. The type of CSP may change with advancing gestation. Future studies are needed to validate this reporting system and the value of the different CSP types. CONCLUSION: Consensus was achieved among experts regarding the sonographic evaluation and reporting of CSP in the first trimester. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Lessons learned during implementation of MR-guided High-Intensity Focused Ultrasound treatment of uterine fibroids.

BACKGROUND: Although promising results have been reported for Magnetic Resonance image-guided High-Intensity Focused Ultrasound (MR-HIFU) treatment of uterine fibroids, this treatment is not yet widely implemented in clinical practice. During the implementation of a new technology, lessons are learned and an institutional learning-curve often has to be completed. The primary aim of our prospective cohort study was to characterize our learning-curve based on our clinical outcomes. Secondary aims included identifying our lessons learned during implementation of MR-HIFU on a technical, patient selection, patient counseling, medical specialists and organizational level. RESULTS: Our first seventy patients showed significant symptom reduction and improvement of quality of life at 3, 6 and 12 months after MR-HIFU treatment compared to baseline. After the first 25 cases, a clear plateau phase was reached in terms of failed treatments. The median non-perfused volume percentage of these first 25 treatments was 44.6% (range: 0-99.7), compared to a median of 74.7% (range: 0-120.6) for the subsequent treatments. CONCLUSIONS: Our findings describe the learning-curve during the implementation of MR-HIFU and include straightforward suggestions to shorten learning-curves for future users. Moreover, the lessons we learned on technique, patient selection, patient counseling, medical specialists and organization, together with the provided supplements, may be of benefit to other institutions aiming to implement MR-HIFU treatment of uterine fibroids. Trial registration ISRCTN14634593. Registered January 12, 2021-Retrospectively registered, https://www.isrctn.com/ISRCTN14634593 .

The effect of a hysteroscopic niche resection compared with Levonorgestrel-releasing intrauterine device on postmenstrual spotting in patients with a symptomatic niche in the uterine cesarean scar: A prospective cohort study.

OBJECTIVE: To compare the effect of a hysteroscopic niche resection with a Levonorgestrel-releasing intrauterine device (LNG-IUD, 52 mg) on postmenstrual spotting duration in patients with a symptomatic niche in the uterine cesarean scar. STUDY DESIGN: This prospective cohort study was conducted at the International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiaotong University, China. Patients with postmenstrual spotting symptomatic niches were allocated to hysteroscopy group or LNG-IUD group based on the shared medical decision-making approach, and were followed up for 1 year after treatment. MAIN OUTCOME MEASURES: The primary outcome was reduced postmenstrual spotting days at 6th month after treatment. Secondary outcomes were effectiveness rate (proportion of patients with spotting days reduced by at least 50% from baseline), menstrual characteristics, menstruation satisfaction, direct medical costs, complications and side effects. RESULTS: 78 out of the 82 eligible patients were included, 36 patients in both group finished 1-year follow-up. Reduced spotting days at the 6th month was 7 days in LNG-IUD group, significantly higher than 5 days in hysteroscopy group, P = 0.004; The effectiveness rate increased over time within 1 year after the insertion of LNG-IUD (63.89%, 83.33%, 88.89%, 88.89%, P for trend = 0.006), while no trend change was observed in hysteroscopy group (71.05%, 71.05%, 66.67%, 61.11%, P for trend = 0.77). The mean direct medical costs were 817[785,856] $ in the hysteroscopy group and 243[239,255] $ in the LNG-IUD group (p＜0.001). 2 patients removed IUD and 2 patients reported weight gain of more than 5 kg and breast distended pain in LNG-IUD group; 2 patients got pregnant in hysteroscopy group. No serious complications were observed in both groups. CONCLUSIONS: LNG-IUD is more effective in the treatment of postmenstrual spotting from the 6th month onwards than a hysteroscopic niche resection in patients with a symptomatic niche at lower direct costs.

Comparing levonorgestrel intrauterine system versus hysteroscopic resection in patients with postmenstrual spotting related to a niche in the caesarean scar (MIHYS NICHE trial): protocol of a randomised controlled trial.

INTRODUCTION: Recently, the rate of caesarean sections (CS) worldwide has risen and CS-associated complications such as niche have increased substantially. Until now, evidence-based clinical guidelines for the treatment of niche-related symptoms remain absent. In patients with postmenstrual spotting, it has not been studied if the effect of levonorgestrel 52 mg intrauterine system (LNG-IUS 52 mg) is superior to that of hysteroscopy. This study will answer the question of whether LNG-IUS 52 mg is more effective in improving postmenstrual spotting than hysteroscopic niche resection in women with niche-related spotting at 6 months after randomisation. METHODS AND ANALYSIS: This is a randomised controlled trial. A total of 208 women with postmenstrual spotting related to niche in the caesarean uterine scar of at least 2 mm and residual myometrium of at least 2.2 mm evaluated by MRI will be included. Women desiring to conceive within 1 year, with contraindications for LNG-IUS 52 mg or hysteroscopic surgery will be excluded. After informed consent is obtained, eligible women will be randomly allocated to LNG-IUS 52 mg or hysteroscopic niche resection at 1:1. The primary outcome is the efficacy in reducing postmenstrual spotting at 6 months after randomisation. The secondary outcomes include menstrual pattern, total days of blood loss per month, rate of amenorrhoea, side effects and complications.We will use a Visual Analogue Scale for chronic pelvic pain, urological symptoms and women's satisfaction (five-point Likert scale). ETHICS AND DISSEMINATION: The study was approved by the local medical ethics committee and by the Institutional Review Board of the International Peace Maternity and Child Health Hospital, Shanghai, China (No. GKLW 2019-08). Participants will sign a written informed consent before participation. The results of this study will be submitted to a peer-reviewed journal for publication. TRIAL REGISTRATION NUMBER: ChiCTR1900025677.

Fibroid vascularisation assessed with 3D Power Doppler as predictor for fibroid related symptoms and quality of life; a pilot study.

BACKGROUND: Uterine fibroids present differently, from well vascularised up to calcified, with some causing heavy menstrual bleeding (HMB). OBJECTIVES: To investigate the association between fibroid vascularisation and HMB, other fibroid related symptoms and quality of life (QOL). MATERIALS AND METHODS: A single centre pilot study was carried out in the Netherlands. Women with a maximum of two fibroids who chose expectant management were included. 3D sonography including power doppler was performed at baseline and at 3, 6 and 12 months follow up. Women were asked to complete the Pictorial Blood Assessment Chart (PBAC) and Uterine Fibroid Symptom and Quality of Life (UFS-QOL) questionnaires at every visit. MAIN OUTCOME MEASURE: Main outcome measure: The association between fibroid vascularisation and HMB. RESULTS: 53 women were included in the study. Baseline fibroid vascularisation, measured as vascular index (VI) is associated with PBAC score; a 1% higher VI at baseline leads to an 11 point increase in PBAC score over time (RC 10.99, p=0.05, 95% CI -0.15 - 22.12). After correction for the baseline variables ethnicity and fibroid type the association becomes stronger (P<0.05). Fibroid volume at baseline and HMB are also associated: a 1 cm3 larger fibroid leads to 0.6 points increase in PBAC score over time (RC 0.56, p=0.03, 95% CI 0.05 - 1.07). CONCLUSIONS: Conclusions: This study highlights that both fibroid vascularisation and fibroid volume may be associated with an increase in menstrual blood loss, other fibroid related symptoms and QOL over time. WHAT IS NEW?: What is new? We used 3D power doppler to predict symptomatic fibroids.

Septum resection in women with a septate uterus: a cohort study.

STUDY QUESTION: Does septum resection improve reproductive outcomes in women with a septate uterus? SUMMARY ANSWER: In women with a septate uterus, septum resection does not increase live birth rate nor does it decrease the rates of pregnancy loss or preterm birth, compared with expectant management. WHAT IS KNOWN ALREADY: The septate uterus is the most common uterine anomaly with an estimated prevalence of 0.2-2.3% in women of reproductive age, depending on the classification system. The definition of the septate uterus has been a long-lasting and ongoing subject of debate, and currently two classification systems are used worldwide. Women with a septate uterus may be at increased risk of subfertility, pregnancy loss, preterm birth and foetal malpresentation. Based on low quality evidence, current guidelines recommend removal of the intrauterine septum or, more cautiously, state that the procedure should be evaluated in future studies. STUDY DESIGN, SIZE, DURATION: We performed an international multicentre cohort study in which we identified women mainly retrospectively by searching in electronic patient files, medical records and databases within the time frame of January 2000 until August 2018. Searching of the databases, files and records took place between January 2016 and July 2018. By doing so, we collected data on 257 women with a septate uterus in 21 centres in the Netherlands, USA and UK. PARTICIPANTS/MATERIALS, SETTING, METHODS: We included women with a septate uterus, defined by the treating physician, according to the classification system at that time. The women were ascertained among those with a history of subfertility, pregnancy loss, preterm birth or foetal malpresentation or during a routine diagnostic procedure. Allocation to septum resection or expectant management was dependent on the reproductive history and severity of the disease. We excluded women who did not have a wish to conceive at time of diagnosis. The primary outcome was live birth. Secondary outcomes included pregnancy loss, preterm birth and foetal malpresentation. All conceptions during follow-up were registered but for the comparative analyses, only the first live birth or ongoing pregnancy was included. To evaluate differences in live birth and ongoing pregnancy, we used Cox proportional regression to calculate hazard rates (HRs) and 95% CI. To evaluate differences in pregnancy loss, preterm birth and foetal malpresentation, we used logistic regression to calculate odds ratios (OR) with corresponding 95% CI. We adjusted all reproductive outcomes for possible confounders. MAIN RESULTS AND THE ROLE OF CHANCE: In total, 257 women were included in the cohort. Of these, 151 women underwent a septum resection and 106 women had expectant management. The median follow-up time was 46 months. During this time, live birth occurred in 80 women following a septum resection (53.0%) compared to 76 women following expectant management (71.7%) (HR 0.71 95% CI 0.49-1.02) and ongoing pregnancy occurred in 89 women who underwent septum resection (58.9%), compared to 80 women who had expectant management (75.5%) (HR 0.74 (95% CI 0.52-1.06)). Pregnancy loss occurred in 51 women who underwent septum resection (46.8%) versus 31 women who had expectant management (34.4%) (OR 1.58 (0.81-3.09)), while preterm birth occurred in 26 women who underwent septum resection (29.2%) versus 13 women who had expectant management (16.7%) (OR 1.26 (95% CI 0.52-3.04)) and foetal malpresentation occurred in 17 women who underwent septum resection (19.1%) versus 27 women who had expectant management (34.6%) (OR 0.56 (95% CI 0.24-1.33)). LIMITATIONS, REASONS FOR CAUTION: Our retrospective study has a less robust design compared with a randomized controlled trial. Over the years, the ideas about the definition of the septate uterus has changed, but since the 257 women with a septate uterus included in this study had been diagnosed by their treating physician according to the leading classification system at that time, the data of this study reflect the daily practice of recent decades. Despite correcting for the most relevant patient characteristics, our estimates might not be free of residual confounding. WIDER IMPLICATIONS OF THE FINDINGS: Our results suggest that septum resection, a procedure that is widely offered and associated with financial costs for society, healthcare systems or individuals, does not lead to improved reproductive outcomes compared to expectant management for women with a septate uterus. The results of this study need to be confirmed in randomized clinical trials. STUDY FUNDING/COMPETING INTEREST(S): A travel for JFWR to Chicago was supported by the Jo Kolk Studyfund. Otherwise, no specific funding was received for this study. The Department of Obstetrics and Gynaecology, University Medical Centre, Groningen, received an unrestricted educational grant from Ferring Pharmaceutical Company unrelated to the present study. BWM reports grants from NHMRC, personal fees from ObsEva, personal fees from Merck, personal fees from Guerbet, other payment from Guerbet and grants from Merck, outside the submitted work. The other authors declare no conficts of interest. TRIAL REGISTRATION NUMBER: N/A.