Reproducibility of three-dimensional ultrasound for the measurement of a niche in a caesarean scar and assessment of its shape

doi:10.1016/j.ejogrb.2015.02.018

European Journal of Obstetrics & Gynecology and Reproductive Biology

Volume 188, May 2015, Pages 39-44

https://doi.org/10.1016/j.ejogrb.2015.02.018 Get rights and content

Abstract

Objective

To evaluate the inter- and intraobserver agreement for measurement of the size and volume of a niche and assessment of the shape, with the use of three-dimensional (3D) ultrasound.

Study design

In this reproducibility study, 20 3D ultrasound volumes of uteri with a niche were selected, based on complete visualisation of the uterus and niche in both the longitudinal and transversal plane. Niche measurements were performed off-line twice by one observer and once by another observer. Niche measurements and assessment of shape were performed in the longitudinal and transversal plane, and niche volume in the longitudinal plane.

The mean difference, 95% limits of agreement, the intraclass correlation coefficient (ICC) and Cohen's kappa were calculated to assess the inter- and intraobserver agreement.

Results

The interobserver agreement was excellent for all niche measurements (ICC >0.86), including depth and residual myometrial thickness (RMT), except for width at niche base in the transversal plane (ICC 0.74) and niche volume (ICC 0.79), which were classified as good agreement. Wide limits of agreement and a high mean difference were found for maximal width in the transversal plane.

The intraobserver agreement was excellent for all measurements (ICC >0.80), except for RMT in the longitudinal and transversal plane, which were classified as good agreement (ICC 0.73 and 0.62, respectively). Wide limits of agreement were found for maximal width and width at niche base in the transversal plane.

The overall agreement in the transversal plane was lower than in the longitudinal plane, but still all in the range of good agreement. The inter- and intraobserver agreement was good to poor for the assessment of niche shape.

Conclusion

Using 3D ultrasound, various niche parameters, including depth (both perpendicular to niche base and maximal depth), maximal width, width at niche base, RMT and volume, can be measured with a high level of agreement, in particular if measured in the longitudinal plane.

Introduction

Since the turn of the century, the interest for the uterine niche has increased. A niche can be observed during sonography at the site of the uterine caesarean scar and has been defined as any indentation representing myometrial discontinuity at the site of a caesarean scar that communicates with the uterine or cervical cavity [1]. The diagnostic method for the detection of a niche is mainly transvaginal sonography (TVS) and contrast-enhanced sonohysterography (SHG). The prevalence of a niche in a random population of women with a history of caesarean section (CS) differs between 24% and 70% for TVS and between 56% and 84% for SHG [1].

Apart from the well-known complications, such as uterine rupture and caesarean scar pregnancy, there are indications that a niche is responsible for symptoms, such as postmenstrual spotting [2], [3], [4], [5] and subfertility [3]. One study reported a relatively large volume of a niche in women with postmenstrual spotting [2] and another study reported a larger width of the niche in women with postmenstrual spotting, dysmenorrhea and chronic pelvic pain [5]. Interest is growing to learn which niches are responsible for symptoms. Therefore, different classifications for niches have been used, based on size [6], [7] or shape [2]. However, there is no agreement about a definition for the various subgroups of niches, neither how to measure the niche.

In order to be able to compare studies concerning niche prevalence, classification, size and symptoms, we formulated definitions for the used niche parameters and methods for assessment that may be used for future studies. No studies have been performed up to now, in which the reproducibility of the measurement of a niche was evaluated in non-pregnant women. The objective of the current study is to evaluate the inter- and intraobserver agreement for measurement of the size and volume of a niche, and assessment of the shape, with the use of 3D ultrasound volumes.

Section snippets

Materials and methods

This inter- and intraobserver study was conducted in January 2014 at the Department of Obstetrics and Gynaecology of the VU University Medical Center in Amsterdam. Transvaginal ultrasound images of uteri without using contrast in women with a history of CS were stored for research purposes between 2007 and 2012. The images were performed using an Accuvix ultrasound machine (Medison, Hoofddorp, The Netherlands; currently Samsung Medison) in women with their bladder empty. Stored 3D volumes,

Interobserver agreement

Table 1 shows the interobserver agreement for niche measurements in the longitudinal plane, demonstrating excellent reproducibility for most measurements. The ICC for RMT was 0.97, with the Bland–Altman plot (Fig. 5) showing narrow 95% limits of agreement and all measurements situated around the mean. The ICC's for depth perpendicular to niche base (ICC 0.92), maximal depth (ICC 0.94), maximal width (ICC 0.97) and width at niche base (ICC 0.90) were also excellent, although width at niche base

Main findings

We demonstrated that both depth perpendicular to niche base and maximal depth can be measured with a high level of agreement. The level of agreement is also high for maximal width and width at niche base if measured in the longitudinal plane, but lower for the same measurements in the transversal plane. Measurement of RMT and volume are reasonably reproducible, as the intraobserver agreement for RMT and interobserver agreement for volume were moderate. Agreement on the assessment of niche shape

Condensation

Various niche parameters can be measured with a high level of agreement with the use of 3D ultrasound, in particular if measured in the longitudinal plane.

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Cited by (25)

The definition, diagnosis, and symptoms of the uterine niche – A systematic review
2023, Best Practice and Research: Clinical Obstetrics and Gynaecology
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.
Change of the residual myometrial thickness during pregnancy in women who underwent laparoscopic niche resection compared with controls without niche surgery: a prospective comparative cohort study
2022, American Journal of Obstetrics and Gynecology
Citation Excerpt :
The measurements were randomly checked whether they corresponded to the original. Previous studies showed good to excellent inter- and intraobserver agreement on niche measurement.15 Patient characteristics and obstetrical and medical history, including number of previous CDs, were obtained in the first trimester of pregnancy at their first scan visit.
Reduced residual myometrial thickness before and during pregnancy is associated with uterine rupture or dehiscence after vaginal birth after cesarean delivery. Laparoscopic niche resection performed in case of gynecologic symptoms has shown to increase residual myometrial thickness 6 months after surgery.
This study aimed to evaluate the change in residual myometrial thickness from baseline value before pregnancy to the third trimester of pregnancy in women with and without laparoscopic niche resection and evaluate niche presence, niche size during pregnancy vs before pregnancy, and obstetrical outcomes, including uterine rupture and dehiscence in both study groups.
This was a prospective cohort study conducted in an academic medical center. Of note, 2 groups of pregnant women with a previously diagnosed niche were included: (1) women with a large symptomatic niche (residual myometrial thickness of <3 mm) followed by laparoscopic niche resection (LNR group) and (2) women with a niche without niche resection because of minimal symptoms or a residual myometrial thickness of ≥3 mm diagnosed before current pregnancy (expectant group). Participants underwent a transvaginal ultrasound at 12, 20, and 30 weeks of gestation. Changes in residual myometrial thickness and changes in niche measurements over time were analyzed with linear mixed models.
A total of 100 women were included, 61 in the LNR group and 39 in the expectant group. The change in residual myometrial thickness from baseline value before niche resection to the third trimester of pregnancy was +2.0 mm in the LNR group vs −1.6 mm in the expectant group (P<.001). Residual myometrial thickness decreased from the first trimester of pregnancy onward in both groups. Although residual myometrial thickness was thinner at baseline in the LNR group, it was thicker in the LNR group than in the expectant group during all trimesters: 3.2 mm (P<.001) in the first trimester of pregnancy, 2.5 mm (P<.001) in the second trimester of pregnancy, and 1.8 mm (P=.001) in the third trimester of pregnancy. Uterine dehiscence was reported in 1 of 50 women (2%) in the LNR group and 7 of 36 women (19%) in the expectant group (P=.007) and was related to the depth of niche–to–residual myometrial thickness ratio before pregnancy (after niche resection) and residual myometrial thickness in the second trimester of pregnancy. No uterine rupture was reported. Most patients received a scheduled cesarean delivery in both groups. There was more blood loss during subsequent cesarean delivery in the LNR group than in the expectant group.
Here, laparoscopic niche resection resulted in an increased residual myometrial thickness during a subsequent pregnancy. Moreover, a lower number of dehiscence was found in the LNR group than in the expectant group without niche surgery. Per-section blood loss was higher in the LNR group than in the expectant group. In general, laparoscopic niche resection is performed to improve gynecologic symptoms. Currently, there is no evidence to support a laparoscopic niche resection to improve obstetrical outcomes, but the trend toward more uterine dehiscence encourages further research.
Agreement between transvaginal ultrasound and saline contrast sonohysterography in evaluation of cesarean scar defect
2019, Journal of Gynecology Obstetrics and Human Reproduction
Citation Excerpt :
Improvements in the imaging procedures have facilitated the evaluation of CS scars both before and during pregnancy with identifying women prone to the aforementioned complications in subsequent pregnancies and providing a clinical guide for the management of pregnancy and delivery [3]. Evaluating CSD can be done by various tools including transvaginal sonography (TVS) [8] and contrast enhanced sonography (using gel or saline) [9,10], fewer reports of hysteroscopy [11,12] hysterosalpingography [13] and 3D ultrasonography [14]. However, there are controversial results regarding the efficacy of different techniques and their ability to detect uterine scar defects as well as related outcomes during later pregnancies [15].
to assess the agreement between saline contrast sonohysterography (SCSH) and transvaginal sonography (TVS) in the evaluation of cesarean section scar defect (CSD) regarding its width, depth, and shape and also in assessing the anterior myometrium, and residual myometrium related to the scar.
a prospective study during the period between August 2017 and January 2018 was conducted in which 102 consecutive participants underwent primary cesarean section in Ain Shams University Maternity Hospital were assessed six weeks after CS to evaluate for CSD presence by using both SCSH and TVS.
CSD could be detected only in 59.8% of women by TVS and 70.5% by SCSH with good agreement strength (Cohen kappa = 0.805). TVS was 84.72% sensitive and 100.00% specific in identifying CSD diagnosed by SCSH. The PPV, NPV, and accuracy of TVS were 100.00%, 73.17%, and 89.21%, respectively.
The mean anterior myometrial thickness (AMT) did not differ when assessed by both TVS and SCSH, while the mean niche width was 2.56 ± 1.98 mm with SCSH compared to 2.17 ± 1.63 mm with TVS(r = 0.954), and its mean depth was 2.76 ± 2.02 mm for SCSH and 1.57 ± 1.51 mm in TVS(r = 0.812). The mean residual myometrium was 10.09 ± 2.74 mm in SCSH while was 11.18 ± 2.50 mm for TVS(r = 0.914)
cesarean scar defects in non-pregnant women are better evaluated at SCSH than at unenhanced TVS as more defects detected by SCSH and better evaluation of its shape, borders and size.
Cesarean section scar measurements in non-pregnant women using three-dimensional ultrasound: A repeatability study
2016, European Journal of Obstetrics and Gynecology and Reproductive Biology
Citation Excerpt :
It is also safe to conclude that, following TVU and uterine volume acquisition, experienced colleagues can analyze these recordings and estimate the size of the niche and the RMT. There are rather wide both intra- and inter-observer LOAs of the niche measurements which have to be taken into account before taking any clinical implications of the measurements [23]. Our data show that ultrasound measurements remain subjective even with 3D volumes.
To evaluate intra- and inter-observer agreement in measurements of the cesarean scar niche and the residual myometrial thickness (RMT) using 3-dimensional (3D) transvaginal ultrasonography.
Fifty-eight uterine 3D volumes from women with deep cesarean scar niches were evaluated. 3D volumes were obtained six to fifteen months after a primary cesarean section. Evaluation of the 3D volume was performed in a standardized multiplanar view. Two observers independently obtained RMT, cesarean scar niche depth (D), length (L), width (W), and myometrium adjacent to the scar (M). Differences within and between observers were expressed in mm and were evaluated according to the Bland–Altman method including the calculation of limits of agreement (LOAs).
The intra-observer LOAs in mm were as follows: RMT: −3.7 to 4.0; D: −2.2 to 2.6; L: −3.6 to 4.2; W: −4.0 to 3.7; and M: −3.4 to 4.5. The inter-observer LOAs in mm were as follows: RMT: −3.2 to 4.1; D: −3.3 to 2.2; L: −3.4 to 4.2; W: −3.2 to 4.1; and M: −4.1 to 3.2.
In non-pregnant women, we found rather wide limits of agreement measuring the cesarean section scar niche and myometrium using 3D volumes. Whether 3D transvaginal ultrasonography provides clinical advantages compared to 2D TVU needs clarification.
Prevalence of and Factors Associated with Large Cesarean Scar Defects in Women at Six Weeks Postpartum
2023, Thai Journal of Obstetrics and Gynaecology
Incidence and ultrasonographic characteristics of cesarean scar niches after uterine closure by double-layer barbed suture: A prospective comparative study
2023, International Journal of Gynecology and Obstetrics

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Reproducibility of three-dimensional ultrasound for the measurement of a niche in a caesarean scar and assessment of its shape

Abstract

Objective

Study design

Results

Conclusion

Introduction

Section snippets

Materials and methods

Interobserver agreement

Main findings

Condensation

J Minim Invasive Gynecol

J Minim Invasive Gynecol

Prevalence, potential risk factors for development and symptoms related to the presence of uterine niches following cesarean section: systematic review

Ultrasound Obstet Gynecol

Ultrasound evaluation of the cesarean scar: relation between a niche and postmenstrual spotting

Ultrasound Obstet Gynecol

The cesarean delivery scar pouch: clinical implications and diagnostic correlation between transvaginal sonography and hysteroscopy

J Ultrasound Med

Cesarean section scar as a cause of abnormal vaginal bleeding: diagnosis by sonohysterography

J Ultrasound Med

Cesarean scar defect: correlation between cesarean section number, defect size, clinical symptoms and uterine position

Ultrasound Obstet Gynecol

High prevalence of defects in cesarean section scars at transvaginal ultrasound examination

Ultrasound Obstet Gynecol

Deficient lower-segment cesarean section scars: prevalence and risk factors

Ultrasound Obstet Gynecol