Accurate prenatal discrimination of placenta accreta spectrum from uterine dehiscence is necessary to ensure optimal management

Accuracy of sonographic lower segment thickness and prediction of vaginal birth after caesarean in a resourced-limited setting; Prospective study

OBJECTIVES

To assess the accuracy of ultrasound measurement of the lower uterine segment (LUS) thickness against findings at laparotomy, and to investigate its correlation with the success rate of vaginal birth after one previous caesarean delivery (CD) in a resource-limited setting.

DESIGN

Prospective study.

SETTING

Obstetrics and Gynaecology department in a tertiary hospital in Ghana.

POPULATION

Women with one previous CD undergoing either a trial of labour (TOLAC) or elective CD.

METHODS

Myometrial lower uterine segment thickness (mLUS) and full lower uterine segment thickness (fLUS) were measured with transvaginal ultrasound (TVUS). The women were managed according to local protocols with the clinicians blinded to the ultrasound measurements. The LUS was measured intraoperatively for comparison with ultrasound measurements.

MAIN OUTCOME MEASURES

Lower uterine segment findings at laparotomy, successful vaginal birth.

RESULTS

A total of 311 pregnant women with one previous CD were enrolled; 147 women underwent elective CD and 164 women underwent a TOLAC. Of the women that underwent TOLAC, 96 (58.5%) women had a successful vaginal birth. The mLUS was comparable to the intraoperative measurement in the elective CD group with LUS thickness <5 mm (bias of 0.01, 95% CI -0.10 to 0.12 mm) whereas fLUS overestimated LUS <5 mm (bias of 0.93, 95% CI 0.80-1.06 mm). Successful vaginal birth rate correlated with increasing mLUS values (odds ratio 1.30, 95% CI 1.03-1.64). Twelve cases of uterine defect were recorded. LUS measurement ≤2.0 mm was associated with an increased risk of uterine defects with a sensitivity of 91.7% (95% CI 61.5-99.8%) and specificity of 81.8% (95% CI 75.8-86.8%).

CONCLUSION

Accurate TVUS measurement of the LUS is technically feasible in a resource-limited setting. This approach could help in making safer decisions on mode of birth in limited-resource settings.

Three-dimensional volume rendering ultrasound for assessing placenta accreta spectrum severity and discriminating it from simple scar dehiscence

BACKGROUND

Prenatal ultrasound discrimination between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta is challenging both prenatally and intraoperatively, which often leads to overtreatment. In addition, accurate prenatal prediction of surgical difficulty and morbidity in placenta accreta spectrum is difficult, which precludes appropriate multidisciplinary planning. The advent of advanced 3-dimensional volume rendering and contrast enhancement techniques in modern ultrasound systems provides a comprehensive prenatal assessment, revealing details that are not discernible in traditional 2-dimensional imaging.

OBJECTIVE

This study aimed to evaluate the use of 3-dimensional volume rendering ultrasound techniques in determining the severity of placenta accreta spectrum and distinguishing between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta.

STUDY DESIGN

A prospective, cohort study was conducted between July 2022 and July 2023 in the fetal medicine unit of Dr Soetomo Academic General Hospital, Surabaya, Indonesia. All pregnant individuals with anterior low-lying placenta or placenta previa with a previous caesarean section who were referred with suspicion of placenta accreta spectrum were consented and screened using the standardised 2-dimensional and Doppler ultrasound imaging. Additional 3-dimensional volumes were obtained from the sagittal section of the uterus with a filled urinary bladder. These were analyzed by rotating the region of interest to be perpendicular to the uterovesical interface. The primary outcomes were the clinical and histologic severity in the cases of placenta accreta spectrum and correct diagnosis of dehiscence with nonadherent placenta underneath. The strength of association between ultrasound and clinical outcomes was determined. Multivariate logistic regression analyses and diagnostic testing of accuracy were used to analyze the data.

RESULTS

A total of 70 patients (56 with placenta accreta spectrum and 14 with scar dehiscence) were included in the analysis. Multivariate logistic regression of all 2-dimensional and 3-dimensional signs revealed the 3-dimensional loss of clear zone (P<.001) and the presence of bridging vessels on 2-dimensional Doppler ultrasound (P=.027) as excellent predictors in differentiating scar dehiscence and placenta accreta spectrum. The 3-dimensional loss of clear zone demonstrated a high diagnostic accuracy with an area under the curve of 0.911 (95% confidence interval, 0.819-1.002), with a sensitivity of 89.3% (95% confidence interval, 78.1-95.97%) and specificity of 92.9% (95% confidence interval, 66.1-99.8%). The presence of bridging vessels on 2-dimensional Doppler demonstrated an area under the curve of 0.848 (95% confidence interval, 0.714-0.982) with a sensitivity of 91.1% (95% confidence interval, 80.4-97.0%) and specificity of 78.6% (95% confidence interval, 49.2-95.3%). A subgroup analysis among the placenta accreta spectrum group revealed that the presence of a 3-dimensional disrupted bladder serosa with obliteration of the vesicouterine space was associated with vesicouterine adherence (P<.001).

CONCLUSION

Three-dimensional volume rendering ultrasound is a promising tool for effective discrimination between scar dehiscence with underlying nonadherent placenta and placenta accreta spectrum. It also shows potential in predicting the clinical severity with urinary bladder involvement in cases of placenta accreta spectrum.

Placenta Accreta Spectrum: Evaluation of classic and non-classic presentations, pathologic grading, and uterine scar dehiscence features in a modern institutional series

INTRODUCTION

The aim of this study is to document the distribution of classic versus non-classic presentation of Placenta Accreta Spectrum (PAS) disorders as well as grading categories by the Society for Pediatric Pathology (SPP) and FIGO systems in an institutional cohort of gravid hysterectomies. We also document the prevalence of uterine scar as a histologic correlate for uterine scar dehiscence, a phenomenon raised by some as central to PAS pathogenesis.

METHODS

PAS cases were assigned grade and designated as classic (anterior lower uterine segment implantation, prior C-section) or non-classic (implantation away from anterior lower uterine segment and/or no prior C-section). Features of dehiscence (uterine window, histologic evidence of scar) were recorded.

RESULTS

Sixty-two patients were included: 76 % had prior C-section; 55 % had other forms of uterine instrumentation. Classic PAS was recorded in 52 % patients; notably, 48 % had non-classic presentation; of these, all but one had prior instrumentation (curettage, myomectomy, laparoscopy). Uterine window was described in 53 % classic and 23 % non-classic PAS. Scar was demonstrated in 31 % classic and 23 % non-classic PAS; trichrome/reticulin stains were confirmatory. 32 % cases were SPP grade 1, 18 % grade 2, 18 % grade 3a and 32 % grade 3d. Grade 3 was significantly more common in classic (72 %) than non-classic (27 %) PAS.

DISCUSSION

While most PAS patients have classic presentation, a large subset does not; in addition, scar tissue is not identified histologically in most PAS hysterectomies; in these settings, PAS cannot be fully attributed to scar dehiscence. Uterine instrumentation often precedes non-classic PAS reinforcing the concept of decidual disruption as central to PAS pathogenesis. PAS grading as defined correlates with presentation (classic vs non-classic).

Placenta accreta spectrum care infrastructure: an evidence-based review of needed resources supporting placenta accreta spectrum care

The incidence of placenta accreta spectrum, the deeply adherent placenta with associated increased risk of maternal morbidity and mortality, has seen a significant rise in recent years. Therefore, there has been a rise in clinical and research focus on this complex diagnosis. There is international consensus that a multidisciplinary coordinated approach optimizes outcomes. The composition of the team will vary from center to center; however, central themes of complex surgical experts, specialists in prenatal diagnosis, critical care specialists, neonatology specialists, obstetrics anesthesiology specialists, blood bank specialists, and dedicated mental health experts are universal throughout. Regionalization of care is a growing trend for complex medical needs, but the location of care alone is just a starting point. The goal of this article is to provide an evidence-based framework for the crucial infrastructure needed to address the unique antepartum, delivery, and postpartum needs of the patient with placenta accreta spectrum. Rather than a clinical checklist, we describe the personnel, clinical unit characteristics, and breadth of contributing clinical roles that make up a team. Screening protocols, diagnostic imaging, surgical and potential need for critical care, and trauma-informed interaction are the basis for comprehensive care. The vision from the author group is that this publication provides a semblance of infrastructure standardization as a means to ensure proper preparation and readiness.

Absence of abnormal vascular changes on prenatal imaging aids in differentiating simple uterine scar dehiscence from placenta accreta spectrum: a case series

Accurate prenatal discrimination between a simple, non-adherent uterine scar dehiscence with an underlying placenta and the severe end of the placenta accreta spectrum is problematic as the two can appear similar on prenatal imaging. This may lead to the false diagnosis of placenta accreta spectrum resulting obstetric anxiety, overtreatment and potential iatrogenic morbidity. Despite potential similarities in the etiology, the manifestation and management of these two conditions is very different. The prenatal sonographic features of seven confirmed cases of simple uterine scar dehiscence with an underlying placenta previa were examined. The common sonographic features found for scar dehiscence was a thinned myometrium (<1 mm) overlying a generally homogenous placenta and a placental bulge. There was absence of lacunae and features of hypervascularity including bridging vessels. Our findings suggest accurate discrimination between a simple scar dehiscence with the placenta underlying it and placenta accreta spectrum can be made on prenatal ultrasound if the placenta is carefully examined for the vascular features unique to PAS.

A simple guide to ultrasound screening for placenta accreta spectrum for improving detection and optimizing management in resource limited settings

Placenta accreta spectrum is a pregnancy complication associated with severe morbidity and maternal mortality especially when not suspected antenatally and appropriate management instigated. Women in resource-limited settings are more likely to face adverse outcomes due to logistic, technical, and resource inadequacies. Accurate prenatal imaging is an important step in ensuring good outcomes because it allows adequate preparation and an appropriate management approach. This article provides a simple three-step approach aimed at guiding clinicians and sonographers with minimal experience in placental accreta spectrum through risk stratification and basic prenatal screening for this condition both with and without Doppler ultrasound.

Comprehensive surgical staging for placenta accreta spectrum

OBJECTIVE

To analyze how precise the surgical staging is after prenatal diagnosis of patients with placenta accreta spectrum (PAS).

MATERIAL AND METHODS

This was a retrospective cohort study that included 622 women diagnosed with placenta accreta spectrum who underwent surgery between 1 January 2000, and 1 January 2020, in public, private, and university hospitals in Buenos Aires, Argentina. Prenatal diagnosis included abdominal and transvaginal ultrasounds and T2-weighted MRI scans. Comprehensive surgical staging (CSS) was performed by dissecting the coalescence spaces of the pelvic fasciae, including the broad ligament and the colpouterine and retrouterine spaces. Once the compromised uterine wall (lateral, anterior or posterior) was identified, the characteristics of the lesion were evaluated. The lateral invasion was classified as type A when there was no placental tissue in the parametrial zone; type B when the placental tissue protruded laterally and was covered by serosa, and type C when the placental tissue included neoformed vessels. Involvement of the retrovesical space (anterior uterine wall) was classified as type A when no neoformed vessels and no firm adherence between nearby organs were present, type B when the retrovesical area partially adhered but the planes could be dissected, and type C when the lower dissection of the vesicouterine space was extremely adhered or impossible.The posterior uterine aspect was classified after exteriorizing the organ, with the placenta still inside. It was determined as type A when there was no evidence of placental invasion, type B when there was organ adherence or it showed a heterogeneous appearance of the posterior uterine wall above the peritoneal reflection, and type C when there was adherence to other organs or when the invasion or neovascularization was below the peritoneal reflection.

RESULTS

CSS increases the efficacy of prenatal studies, including ultrasound and MRI, by up to 50%. The diagnosis of type 2 (parametrial) PAS or low retrovesical invasion implied an immediate modification of the surgical tactics, vascular control, or a specific type of surgery. Additionally, deep interfacial dissection allowed the identification of healthy uterine tissue, modifying the initial indication of hysterectomy for a conservative reconstructive procedure.

CONCLUSIONS

Comprehensive surgical staging of PAS proved to be an excellent tool for determining the extent and specific topography of placental invasion.