Cesarean section scar measurements in non-pregnant women using three-dimensional ultrasound: a repeatability study

A transvaginal ultrasound-based diagnostic calculator for uterus post-cesarean scar defect

BACKGROUND

A cesarean scar defect (CSD) is incomplete healing of the myometrium at the site of a prior cesarean section (CS), complicating more than half of all cesarean sections. While transvaginal ultrasound (TVU) is the most common modality for diagnosing this defect, hysteroscopy remains the gold standard. We aimed to develop an efficient diagnostic tool for CSD among women with abnormal uterine bleeding (AUB) by integrating TVU findings and participants' demographic features.

METHODS

A single-center cross-sectional study was conducted on 100 premenopausal and non-pregnant women with a history of CS complaining of AUB without a known systemic or structural etiology. Each participant underwent a hysteroscopy followed by a TVU the next day. The defect dimensions in TVU, patients' age, and the number of previous CSs were integrated into a binary logistic regression model to evaluate their predictive ability for a hysteroscopy-confirmed CSD.

RESULTS

Hysteroscopy identified 74 (74%) participants with CSD. The variables age, the number of CSs, defect length, and defect width significantly contributed to the logistic regression model to diagnose CSD with odds ratios of 9.7, 0.7, 2.6, and 1.7, respectively. The developed model exhibited accuracy, sensitivity, and specificity of 88.00%, 91.89%, and 76.92%, respectively. The area under the receiver operating curve was 0.955 (P-value < 0.001).

CONCLUSION

Among non-pregnant women suspected of CSD due to AUB, looking at age, the number of previous CSs, and TVU-based defect width and length can efficiently rule CSD out.

Reproducibility of assessment of full-dilatation Cesarean section scar in women undergoing second-trimester screening for preterm birth

OBJECTIVE

To assess the reproducibility of a standardized method of measuring the Cesarean section (CS) scar, CS scar niche and their position relative to the internal os of the uterine cervix by transvaginal ultrasound in pregnant women with a previous full-dilatation CS.

METHODS

This was a prospective, single-center reproducibility study on women with a singleton pregnancy and a previous full-dilatation CS who underwent transvaginal ultrasound assessment of cervical length and CS scar characteristics at 14-24 weeks' gestation. The CS scar was identified as a hypoechogenic linear discontinuity of the myometrium at the anterior wall of the lower uterine segment or cervix. The CS scar niche was identified as an indentation at the site of the scar with a depth of at least 2 mm. The CS scar position was evaluated by measuring the distance to the internal cervical os. CS scar niche parameters, including its length, depth, width, and residual and adjacent myometrial thickness, were assessed in the sagittal and transverse planes. Qualitative reproducibility was assessed by agreement regarding visibility of the CS scar and niche. Quantitative reproducibility of CS scar measurements was assessed using three sets of images: (1) real-time two-dimensional (2D) images (real-time acquisition and caliper placement on 2D images by two operators), (2) offline 2D still images (offline caliper placement by two operators on stored 2D images acquired by one operator) and (3) three-dimensional (3D) volume images (volume manipulation and caliper placement on 2D images extracted by two operators). Agreement on CS scar visibility and the presence of a niche was analyzed using kappa coefficients. Intraobserver and interobserver reproducibility of quantitative measurements was assessed using Bland-Altman plots.

RESULTS

To achieve the desired statistical power, 72 women were recruited. The CS scar was visualized in > 80% of images. Interobserver agreement for scar visualization and presence of a niche in real-time 2D images was excellent (kappa coefficients of 0.84 and 0.85, respectively). Overall, reproducibility was higher for real-time 2D and offline 2D still images than for 3D volume images. The 95% limits of agreement (LOA) for intraobserver reproducibility were between ± 1.1 and ± 3.6 mm for all sets of images; the 95% LOA for interobserver reproducibility were between ± 2.0 and ± 6.3 mm. Measurement of the distance from the CS scar to the internal cervical os was the most reproducible 2D measurement (intraobserver and interobserver 95% LOA within ± 1.6 and ± 2.7 mm, respectively). Overall, niche measurements were the least reproducible measurements (intraobserver 95% LOA between ± 1.6 and ± 3.6 mm; interobserver 95% LOA between ± 3.1 and ± 6.3 mm). There was no consistent difference between measurements obtained by reacquisition of 2D images (planes obtained twice and caliper placed), caliper placement on 2D stored images or volume manipulation (planes obtained twice and caliper placed).

CONCLUSIONS

The CS scar position and scar niche in pregnant women with a previous full-dilatation CS can be assessed in the second trimester of a subsequent pregnancy using either 2D or 3D volume ultrasound imaging with a high level of reproducibility. Overall, the most reproducible CS scar parameter is the distance from the CS scar to the internal cervical os. The method proposed in this study should enable clinicians to assess the CS scar reliably and may help predict pregnancy outcome. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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.

Changes in lower uterine segment thickness during different gestational weeks in pregnant women qualified for trial of labor after cesarean section

Objective

To investigate the correlation between lower uterine segment thickness (LUST) and gestational weeks (GW) in women who attempted trial of labor after cesarean section (TOLAC) and to estimate the reference ranges of LUST.

Methods

A prospective cohort study was conducted between January 2019 and December 2020 at a tertiary‐care center in Foshan, China. A total of 2588 women who attempted TOLAC were included. LUST was measured in different trimesters using transabdominal ultrasound. Histograms were used to review the mean and standard deviations (SD) of LUST at different GW.

Results

The mean LUST of the patients were 6.90 ± 2.86, 4.36 ± 1.87, 2.83 ± 0.65, and 2.57 ± 0.51 mm in the first (12.10 ± 1.28 weeks), second (21.79 ± 3.40 weeks), middle third (34.28 ± 2.64 weeks), and late third (38.20 ± 1.00 weeks) trimesters, respectively. An inverse correlation was noted between LUST and uterine rupture in women who underwent a planned ERCD (P < 0.001), but not in women who attempted TOLAC during the late third trimester (P = 0.629).

Conclusion

LUST is inversely correlated with GW and decreases faster in the first and second trimesters than in the middle and late third trimesters. TOLAC should be approached with caution for pregnant women with a thin myometrium in late third trimester.

Lower uterine segement thickness measured by ultrasound is inversely correlated with gestation and decreases faster in the first two trimesters than in the third trimester.

Effectiveness of hysteroscopic resection of a uterine caesarean niche can be predicted: a prospective cohort study

This study aimed to develop and validate a model for the preoperative prediction of the effectiveness of hysteroscopic resection of a uterine cesarean niche in patients with postmenstrual spotting. The predictive model was developed in a primary prospective cohort consisting of 208 patients with niche treated by hysteroscopic resection. Multivariable logistic regression analysis was performed to develop the predictive model, which incorporated preoperative menstrual characteristics and magnetic resonance imaging (MRI) findings. Surgical efficacy was defined as a decrease in postmenstrual spotting duration of at least 3 days at the 3-month follow-up compared with baseline. The predictive model was presented with a nomogram, and the performance was assessed with respect to its calibration, discrimination, and clinical use. Internal validation was performed using tenfold cross-validation. The predictive factors in the final model were as follows: preoperative menstrual duration, thickness of the residual myometrium (TRM), length, TRM/thickness of the adjacent myometrium ratio, angle γ, area, and presence of a lateral branch of the niche. The model showed good performance in predicting the effectiveness of hysteroscopic niche resection. Incorporating the preoperative duration of the menstrual period and MRI findings of the niche into an easy-to-use nomogram facilitates the individualized prediction of the effectiveness of a hysteroscopic niche resection by 26 Fr resectoscope, but multicenter prospective studies are needed to validate it.

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.

Diagnosis of a defect in the uterine wall using 3D ultrasound in the 16th week of gestation

The 3D volumetric transabdominal study with rendering mode is a very useful tool to perform a detailed study of the uterine wall, and it allows us to create a safe and early strategy during pregnancy in uterine dehiscences, as we show in this case in the 16th week of gestation.

Assessment of the uterus with three-dimensional ultrasound in women undergoing ART

BACKGROUND

A detailed assessment of the uterus forms a pivotal part of the ART treatment process. The emergence of three-dimensional ultrasound (3D US) has provided clinicians with a highly powerful tool in this respect. Assessments with 3D US range from the reconstruction of anatomical planes elusive to conventional US, to the objective measurement of anatomical volumes and vascularization parameters. However, despite the ever increasing number of publications emerging in the literature, the question of which aspects of 3D US are of most clinical value remains a topic of debate.

OBJECTIVE AND RATIONALE

The objective of this review is to dissect which aspects of the 3D US assessment of the uterus are supported by a strong level of evidence to date, and should therefore be incorporated into current routine clinical practice.

SEARCH METHODS

We conducted a systematic search of the PubMed database up to May 2016, using a combination of text words and Medical Subject Headings (MeSH) pertaining to the 3D US assessment of the uterus. All articles published in the English language were screened to ascertain relevance to women of reproductive age; further citations were retrieved through manual reference list searching.

OUTCOMES

A multitude of predominantly observational studies were identified, which concerned a vast variety of 3D US uterine assessments. All articles unequivocally praised the non-invasive, cost-effective, highly acceptable and objective nature of 3D US. Studies regarding the value of assessing the endometrial volume and vascularization prior to embryo transfer appeared conflicting and inconsistent. Studies regarding the imaging of uterine pathology and identification of intratubal and intrauterine devices consistently reported high rates of diagnostic accuracy. A recent RCT did not show an improvement in clinical outcomes when comparing 3D versus 2D US during embryo transfer. However, preliminary studies suggested that 3D US is superior in determining the site of implantation, particularly in ambiguous cases such as interstitial and angular pregnancies. Finally, pilot studies have suggested that the further integration of 3D and possibly 4D US with surgical interventions of the uterus may be a promising prospect.

WIDER IMPLICATIONS

3D US may prove to be an invaluable tool in the assessment of the uterus within the context of ART. Currently, the aim should be to highlight the aspects of 3D US that are most evidence-based and valuable for patients, and to incorporate these into routine clinical practice.