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.

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.

Feasibility study for performing uterus transplantation in the Netherlands

STUDY QUESTION

Is it feasible to perform uterus transplantations (UTx) in a tertiary centre in the Netherlands?

SUMMARY ANSWER

Considering all ethical principles, surgical risks and financial aspects, we have concluded that at this time, it is not feasible to establish the UTx procedure at our hospital.

WHAT IS KNOWN ALREADY

UTx is a promising treatment for absolute uterine factor infertility. It is currently being investigated within several clinical trials worldwide and has resulted in the live birth of 19 children so far. Most UTx procedures are performed in women with the Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, a congenital disorder characterized by absence of the uterus. In the Netherlands, the only possible option for these women for having children is adoption or surrogacy.

STUDY DESIGN SIZE DURATION

We performed a feasibility study to search for ethical, medical and financial support for performing UTx at the Amsterdam UMC, location VUmc.

PARTICIPANTS/MATERIALS SETTING METHODS

For this feasibility study, we created a special interest group, including gynaecologists, transplant surgeons, researchers and a financial advisor. Also, in collaboration with the patients' association for women with MRKH, a questionnaire study was performed to research the decision-making in possible recipients. In this paper, we present an overview of current practices and literature on UTx and discuss the results of our feasibility study.

MAIN RESULTS AND THE ROLE OF CHANCE

A high level of interest from the possible recipients became apparent from our questionnaire amongst women with MRKH. The majority (64.8%) positively considered UTx with a live donor, with 69.6% having a potential donor available. However, this 'non-life-saving transplantation' requires careful balancing of risks and benefits. The UTx procedure includes two complex surgeries and unknown consequences for the unborn child. The costs for one UTx are calculated to be around €100 000 and will not be compensated by medical insurance. The Clinical Ethics Committee places great emphasis on the principle of non-maleficence and the 'fair distribution of health services'.

LIMITATIONS REASONS FOR CAUTION

In the Netherlands, alternatives for having children are available and future collaboration with experienced foreign clinics that offer the procedure is a possibility not yet investigated.

WIDER IMPLICATIONS OF THE FINDINGS

The final assessment of this feasibility study is that that there are not enough grounds to support this procedure at our hospital at this point in time. We will closely follow the developments and will re-evaluate the feasibility in the future.

STUDY FUNDING/COMPETING INTERESTS

This feasibility study was funded by the VU Medical Center (Innovation grant 2017). No conflicts of interest have been reported relevant to the subject of all authors.

TRIAL REGISTRATION NUMBER

n.a.

Single- versus double-layer closure of the caesarean (uterine) scar in the prevention of gynaecological symptoms in relation to niche development - the 2Close study: a multicentre randomised controlled trial

BACKGROUND

Double-layer compared to single-layer closure of the uterus after a caesarean section (CS) leads to a thicker myometrial layer at the site of the CS scar, also called residual myometrium thickness (RMT). It possibly decreases the development of a niche, which is an interruption of the myometrium at the site of the uterine scar. Thin RMT and a niche are associated with gynaecological symptoms, obstetric complications in a subsequent pregnancy and delivery and possibly with subfertility.

METHODS

Women undergoing a first CS regardless of the gestational age will be asked to participate in this multicentre, double blinded randomised controlled trial (RCT). They will be randomised to single-layer closure or double-layer closure of the uterine incision. Single-layer closure (control group) is performed with a continuous running, unlocked suture, with or without endometrial saving technique. Double-layer closure (intervention group) is performed with the first layer in a continuous unlocked suture including the endometrial layer and the second layer is also continuous unlocked and imbricates the first. The primary outcome is the reported number of days with postmenstrual spotting during one menstrual cycle nine months after CS. Secondary outcomes include surgical data, ultrasound evaluation at three months, menstrual pattern, dysmenorrhea, quality of life, and sexual function at nine months. Structured transvaginal ultrasound (TVUS) evaluation is performed to assess the uterine scar and if necessary saline infusion sonohysterography (SIS) or gel instillation sonohysterography (GIS) will be added to the examination. Women and ultrasound examiners will be blinded for allocation. Reproductive outcomes at three years follow-up including fertility, mode of delivery and complications in subsequent deliveries will be studied as well. Analyses will be performed by intention to treat. 2290 women have to be randomised to show a reduction of 15% in the mean number of spotting days. Additionally, a cost-effectiveness analysis will be performed from a societal perspective.

DISCUSSION

This RCT will provide insight in the outcomes of single- compared to double-layer closure technique after CS, including postmenstrual spotting and subfertility in relation to niche development measured by ultrasound.

TRIAL REGISTRATION

Dutch Trial Register ( NTR5480 ). Registered 29 October 2015.

Sonographic examination of uterine niche in non-pregnant women: a modified Delphi procedure

OBJECTIVE

To generate guidance for detailed uterine niche evaluation by ultrasonography in the non-pregnant woman, using a modified Delphi procedure amongst European experts.

METHODS

Twenty gynecological experts were approached through their membership of the European Niche Taskforce. All experts were physicians with extensive experience in niche evaluation in clinical practice and/or authors of niche publications. By means of a modified Delphi procedure, relevant items for niche measurement were determined based on the results of a literature search and recommendations of a focus group of six Dutch experts. It was predetermined that at least three Delphi rounds would be performed (two online questionnaires completed by the expert panel and one group meeting). For it to be declared that consensus had been reached, a consensus rate for each item of at least 70% was predefined.

RESULTS

Fifteen experts participated in the Delphi procedure. Consensus was reached for all 42 items on niche evaluation, including definitions, relevance, method of measurement and tips for visualization of the niche. A niche was defined as an indentation at the site of a Cesarean section with a depth of at least 2 mm. Basic measurements, including niche length and depth, residual and adjacent myometrial thickness in the sagittal plane, and niche width in the transverse plane, were considered to be essential. If present, branches should be reported and additional measurements should be made. The use of gel or saline contrast sonography was preferred over standard transvaginal sonography but was not considered mandatory if intrauterine fluid was present. Variation in pressure generated by the transvaginal probe can facilitate imaging, and Doppler imaging can be used to differentiate between a niche and other uterine abnormalities, but neither was considered mandatory.

CONCLUSION

Consensus between niche experts was achieved regarding ultrasonographic niche evaluation. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Technical aspects of the laparoscopic niche resection, a step-by-step tutorial

The technique of a laparoscopic niche resection is described in ten steps and alternative steps for future studies are discussed.

3D power Doppler in uterine fibroids; influence of gain, cardiac cycle and off-line measurement techniques

This study answers the question of whether ultrasound machine settings and the cardiac cycle can influence 3D power Doppler (3D PD) indices in the evaluation of uterine fibroid vascularisation. These parameters were reported to affect the vascular indices and cause undesired variation. 3D PD ultrasound was performed using three different gain settings: a fixed predetermined gain (50 dB), a higher gain (65 dB) and an individualised subjectively most optimal gain. Two consecutive 3D PD sweeps were taken to evaluate the effect of the cardiac cycle. A predetermined most optimal fixed gain setting was not different from the individually most optimal chosen gain in vascular assessment of fibroids. A higher gain corresponded with a significantly higher vascular index (VI). Potential variation during the cardiac cycle does not disturb the VI in fibroids.

Why do niches develop in Caesarean uterine scars? Hypotheses on the aetiology of niche development

Caesarean section (CS) results in the occurrence of the phenomenon 'niche'. A 'niche' describes the presence of a hypoechoic area within the myometrium of the lower uterine segment, reflecting a discontinuation of the myometrium at the site of a previous CS. Using gel or saline instillation sonohysterography, a niche is identified in the scar in more than half of the women who had had a CS, most with the uterus closed in one single layer, without closure of the peritoneum. An incompletely healed scar is a long-term complication of the CS and is associated with more gynaecological symptoms than is commonly acknowledged. Approximately 30% of women with a niche report spotting at 6-12 months after their CS. Other reported symptoms in women with a niche are dysmenorrhoea, chronic pelvic pain and dyspareunia. Given the association between a niche and gynaecological symptoms, obstetric complications and potentially with subfertility, it is important to elucidate the aetiology of niche development after CS in order to develop preventive strategies. Based on current published data and our observations during sonographic, hysteroscopic and laparoscopic evaluations of niches we postulate some hypotheses on niche development. Possible factors that could play a role in niche development include a very low incision through cervical tissue, inadequate suturing technique during closure of the uterine scar, surgical interventions that increase adhesion formation or patient-related factors that impair wound healing or increase inflammation or adhesion formation.

Real-time elastography for assessment of uterine disorders

OBJECTIVES

Sonoelastography is an ultrasound-imaging technique that measures tissue strain. The aim of this study was to define, in a systematic manner, specific sonoelastographic characteristics of the myometrium, fibroids and adenomyosis, to evaluate the feasibility of sonoelastography in patients with suspected gynecological pathology and to compare the results with histology and/or magnetic resonance imaging (MRI)-based diagnoses.

METHODS

We performed a prospective observational cohort study between 2009 and 2011. Two-hundred and eighteen women with suspected gynecological pathology underwent routine transvaginal ultrasound and additional real-time sonographic elastography. Sixty-nine of the 218 women underwent MRI and/or histological examination and were included in the final analysis. Acquisition of elastographic images was standardized. We analyzed the elastographic characteristics of myometrium, fibroids and adenomyosis. An independent observer, unaware of clinical, histological or MRI findings, evaluated the recorded elastographic images and cineloops. These elastographic-based diagnoses were compared with histology and/or MRI diagnoses.

RESULTS

With elastography, the uterus was well delineated from the surrounding bowel. The myometrium was uniform in color in 49% of the cases, with a main color of purple or dark blue, indicating stiffer tissue. Fibroids and adenomyosis had different elastographic characteristics and different color patterns. In general, fibroids were darker and adenomyosis was brighter than adjacent myometrium. The agreement between elastography-based diagnosis of fibroids and adenomyosis with MRI-based diagnosis was excellent; with histology-based diagnosis, agreement was substantial for fibroids and adenomyosis.

CONCLUSIONS

Elastography is able to identify clear discriminating characteristics of the uterus, fibroids and adenomyosis, and elastography-based diagnoses are in excellent agreement with those of MRI. Agreement between elastography-based diagnosis of adenomyosis and histology is substantial but not optimal.

Implementation of uterine artery embolisation for symptomatic uterine fibroids: an inventory

The validity of uterine artery embolisation (UAE ) as an alternative treatment for hysterectomy to treat symptomatic uterine fibroids has been well established. Despite its favourable outcomes, UAE is still only marginally applied in the Netherlands. The aim of this inventory is to identify factors which either restrict or facilitate the implementation of UAE. Gynaecologists and interventional-radiologists in three hospitals in Amsterdam were interviewed by means of questionnaires. One of these hospitals had ample experience in UAE for uterine fibroids, one hospital had just started providing this treatment, and one hospital did not perform UAE. Also patients with symptomatic fibroids who were scheduled for either UAE or hysterectomy were interviewed about the counselling for UAE. The following obstacles in the implementation of UAE were found: lack of knowledge about UAE , absence of a multidisciplinary protocol, and above all, the absence of UAE as one of the treatment options in the Dutch national guideline on the management of menorrhagia. 75% of all patients claimed to be well informed about UAE by their gynaecologist. Our recommendations for the implementation of UAE are: 1) adding UAE to the Dutch guideline for the management of menorrhagia with clearly defined indications and contraindications; 2) educating gynaecologists about UAE; 3) composing a patient information leaflet and a website, and 4) arranging a protocol in a multidisciplinary team.

[Uterine artery embolisation in the treatment of uterine fibroids: outcomes of randomised trials]

In the past so years, uterine artery embolisation has gained popularity in the treatment of uterine fibroids compared with traditional surgical interventions. This was based on promising results from a few non-randomised studies, which reported success rates of 95 to 98%. Were these rates accurate? Two recent randomised studies (the Dutch EMMY trial and the Scottish REST trial) showed that, in patients with symptomatic uterine fibroids, the time to recovery and return to work was significantly shorter after embolisation than after surgery (hysterectomy or myomectomy). However, embolisation was insufficiently effective in approximately 20% of patients, who required further treatment. Despite this, quality of life after one and two years in both treatment arms were identical. Embolisation, therefore, may be a valid treatment alternative in patients with symptomatic fibroids who are candidates for hysterectomy.