Looking back to look forward: Has the time arrived for active management of obstetricians in placenta accreta spectrum?

Placenta accreta spectrum (PAS) is a relatively new obstetric condition which, until recently, was poorly understood. The true incidence is unknown because of the poor quality and heterogeneous diagnostic criteria. Classification systems have attempted to provide clarity on how to grade and diagnose PAS, but these are no longer reflective of our current understanding of PAS. This is particularly true for placenta percreta, which referred to extrauterine disease, as recent studies have demonstrated that placental villi associated with PAS have minimal potential to invade beyond the uterine serosa. It is accepted that PAS is a direct consequence of previous iatrogenic uterine injury, most commonly a previous cesarean section. Here, we "look back to look forwards"-starting with the primary predisposing factor for PAS, an iatrogenic uterine injury and subsequent wound healing. We then consider the evolution of definitions and diagnostic criteria of PAS from its first description over a century ago to current classifications. Finally, we discuss why modifications to the current classifications are needed to allow accurate diagnosis of this rare but life-threatening complication, while avoiding overdiagnosis and potential patient harm.

Parametric Solid Models of the At-Term Uterus From Magnetic Resonance Images

Birthing mechanics are poorly understood, though many injuries during childbirth are mechanical, like fetal and maternal tissue damage. Several biomechanical simulation models of parturition have been proposed to investigate birth, but many do not include the uterus. Additionally, most solid models rely on segmenting anatomical structures from clinical images to generate patient geometry, which can be time-consuming. This work presents two new parametric solid modeling methods for generating patient-specific, at-term uterine three-dimensional geometry. Building from an established method of modeling the sagittal uterine shape, this work improves the uterine coronal shape, especially where the fetal head joins the lower uterine wall. Solid models of the uterus and cervix were built from five at-term patients' magnetic resonance imaging (MRI) sets. Using anatomy measurements from MRI-segmented models, two parametric models were created-one that employs an averaged coronal uterine shape and one with multiple axial measurements of the coronal uterus. Through finite element analysis, the two new parametric methods were compared to the MRI-segmented high-fidelity method and a previously published elliptical low-fidelity method. A clear improvement in the at-term uterine shape was found using the two new parametric methods, and agreement in principal Lagrange strain directions was observed across all modeling methods. These methods provide an effective and efficient way to generate three-dimensional solid models of patient-specific maternal uterine anatomy, advancing possibilities for future research in computational birthing biomechanics.

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.

Isthmoceles - Accuracy of imaging diagnosis and clinical correlation with histology: A prospective cohort study

Background

Isthmoceles are a growing clinical concern.

Objectives

To evaluate the accuracy of diagnosis of isthmoceles by imaging and to correlate the dimensions with clinical symptoms and histopathology.

Materials and Methods

Prospective study of women (n=60) with ≥1 C-section undergoing hysterectomy. Isthmoceles were measured by imaging before surgery and macroscopically on the specimen after hysterectomy, followed by histological analysis.

Main outcome measures

Accuracy of isthmocele diagnosis, correlation with clinical symptoms, and histopathological findings.

Result

By imaging, isthmoceles were slightly deeper (P=0.0176) and shorter (P=0.0045) than macroscopic measurements. Differences were typically small (≤3mm). Defined as an indentation of ≥2 mm at site of C-section scar, imaging diagnosed 2 isthmoceles consequently not seen by histology and missed 3. Number of prior C-sections increased isthmocele severity but neither the incidence nor the remaining myometrial thickness (RMT) did. Severity correlated positively with symptoms and histology. However, clinical use was limited. Histological analysis revealed presence of thick wall vessels in 100%, elastosis in 40%, and adenomyosis in 38%. Isthmocele lining was asynchronous with the menstrual phase in 31%.

Conclusions

Dimensions of isthmoceles by imaging were largely accurate with occasionally large differences observed. Number of C-sections did not increase isthmocele incidence, only severity. Indication for surgery remains clinical, considering dimensions and symptoms.

What is new?

Dimensions of isthmoceles should be confirmed before surgery since uterine contractions might change those dimensions. Symptoms increase with dimensions of isthmoceles but are not specific. Endometrial lining within the isthmocele can be asynchronous with the menstrual phase.

Uterine wound healing after caesarean section: A systematic review

The rate of caesarean section (CS) is increasing worldwide. Defects in uterine healing have a major gynaecological and obstetric impact (uterine rupture, caesarean scar defect, caesarean scar pregnancy, placenta accreta spectrum). The complex process of cellular uterine healing after surgery, and specifically after CS, remains poorly understood in contrast to skin wound healing. This literature review on uterine wound healing was mainly based on histological observations, particularly after CS. The primary objective of the review was to examine the effects of CS on uterine tissue at the cellular level, based on histological observations. The secondary objectives were to describe the biomechanical characteristics and the therapies used to improve scar tissue after CS. This review was performed using PRISMA criteria, and PubMed was the data source. The study included all clinical and animal model studies with CS and histological analysis of the uterine scar area (macroscopic, microscopic, immunohistochemical and biomechanical). Twenty studies were included: 10 human and 10 animal models. In total, 533 female humans and 511 female animals were included. Review articles, meeting abstracts, case series, case reports, and abstracts without access to full-text were excluded. The search was limited to studies published in English. No correlation was found between cutaneous and uterine healing. The histology of uterine scars is characterized by disorganized smooth muscle, fibrosis with collagen fibres and fewer endometrial glands. As for skin healing, the initial inflammation phase and mediation of some growth factors (particularly connective tissue growth factor, vascular endothelial growth factor, platelet-derived growth factor, tumour necrosis factor α and tumour necrosis factor β) seem to be essential. This initial phase has an impact on the subsequent phases of proliferation and maturation. Collagen appears to play a key role in the initial granulation tissue to replace the loss of substance. Subsequent maturation of the scar tissue is essential, with a decrease in collagen and smooth muscle restoration. Unlike skin, the glandular structure of uterine tissue could be responsible for the relatively high incidence of healing defects. Uterine scar defects after CS are characterized by an atrophic disorganized endometrium with atypia and a fibroblastic highly collagenic stromal reaction. Concerning immunohistochemistry, one study found a decrease in tumour necrosis factor β in uterine scar defects. No correlation was found between biomechanical characteristics (particularly uterine strength) and the presence of a collagenous scar after CS. Based on the findings of this review, an illustration of current understanding about uterine healing is provided. There is currently no validated prevention of caesarean scar defects. Various treatments to improve uterine healing after CS have been tested, and appeared to have good efficacy in animal studies: alpha lipoic acid, growth factors, collagen scaffolds and mesenchymal stem cells. Further prospective studies are needed.

Uterine Cesarean Scar Tissue-An Immunohistochemical Study

Background and Objectives: Wound healing encompasses a multitude of factors and entails the establishment of interactions among components of the basement membrane. The quantification of particle concentrations can serve as valuable biomarkers for assessing biomechanical muscle properties. The objective of this study was to examine the immunoexpression and immunoconcentration of myometrial collagen type VI, elastin, alpha-smooth muscle actin, and smooth muscle myosin heavy chain, as well as the expression of platelets and clusters of differentiation 31 in the uterine scar following a cesarean section (CS). Materials and Methods: A total of 177 biopsies were procured from a cohort of pregnant women who were healthy, specifically during the surgical procedure of CS. The participants were categorized into seven distinct groups. Group 1 consisted of primiparas, with a total of 52 individuals. The subsequent groups were organized based on the duration of time that had elapsed since their previous CS. The analysis focused on the immunoexpression and immunoconcentration of the particles listed. Results: No significant variations were observed in the myometrial immunoconcentration of collagen type VI, elastin, smooth muscle myosin, and endothelial cell cluster of differentiation 31 among the analyzed groups. The concentration of alpha-smooth muscle actin in the myometrium was found to be significantly higher in patients who underwent CS within a period of less than 2 years since their previous CS, compared to those with a longer interval between procedures. Conclusions: Our findings indicate that the immunoconcentration of uterine myometrial scar collagen type VI, elastin, smooth muscle myosin heavy chain, alpha-smooth muscle actin, and endothelial cell marker cluster of differentiation 31 remains consistent regardless of the duration elapsed since the previous CS. The findings indicate that there are no significant alterations in the biomechanical properties of the uterine muscle beyond a period of 13 months following a CS.

Evaluation of Cesarean section scar using saline contrast sonohysterography in women with previous Cesarean scar pregnancy

OBJECTIVE

To evaluate Cesarean scar defects using saline contrast sonohysterography (SCSH) in women with a history of Cesarean scar pregnancy (CSP).

METHODS

A cohort of 38 non-pregnant women with a history of CSP treated with combined local and systemic methotrexate was investigated prospectively by SCSH. For the purpose of analysis, they were classified, according to the modified Delphi consensus criteria for CSP in early gestation, into three subgroups based on the depth of the gestational sac herniation in the midsagittal plane. Subgroup A included eight (21.1%) cases, in which the largest part of the gestational sac protruded towards the uterine cavity; Subgroup B included 20 (52.6%) cases, in which the largest part of the gestational sac was embedded in the myometrium; and Subgroup C included 10 (26.3%) cases, in which the gestational sac was located partially outside the outer contour of the cervix or uterus.

RESULTS

SCSH revealed that all women in Subgroup C had a uterine niche. The median niche length (P = 0.006) and depth (P = 0.015) were significantly greater in Subgroup C than in Subgroups A or B. The median residual myometrial thickness (RMT) was significantly lower in Subgroup C than in Subgroups A or B (P = 0.006).

CONCLUSIONS

Women with prior CSP who had a gestational sac protruding beyond the serosal line had a significantly greater niche length and depth, and lower RMT. This knowledge may guide individualized risk counseling. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Current status and challenges in uterine myometrial tissue engineering

The uterus undergoes significant modifications throughout pregnancy to support embryo development and fetal growth. However, conditions like fibroids, adenomyosis, cysts, and C-section scarring can cause myometrial damage. The importance of the uterus and the challenges associated with myometrial damage, and the need for alternative approaches are discussed in this review. The review also explores the recent studies in tissue engineering, which involve principles of combining cells, scaffolds, and signaling molecules to create functional uterine tissues. It focuses on two key approaches in uterine tissue engineering: scaffold technique using decellularized, natural, and synthetic polymer and 3D bioprinting. These techniques create supportive structures for cell growth and tissue formation. Current treatment options for myometrial damage have limitations, leading to the exploration of regenerative medicine and integrative therapies. The review emphasizes the potential benefits of tissue engineering, including more effective and less invasive treatment options for myometrial damage. The challenges of developing biocompatible materials and optimizing cell growth and differentiation are discussed. In conclusion, uterine tissue engineering holds promise for myometrial regeneration and the treatment of related conditions. This review highlights the scientific advancements in the field and underscores the potential of tissue engineering as a viable approach. By addressing the limitations of current treatments, tissue engineering offers new possibilities for improving reproductive health and restoring uterine functionality. Future research shall focus on overcoming challenges and refining tissue engineering strategies to advance the field and provide effective solutions for myometrial damage and associated disorders.

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.

Adipocytes in the Uterine Wall during Experimental Healing and in Cesarean Scars during Pregnancy

We have suggested that adipocytes in uterine scars may affect the development of the placenta accrete spectrum (PAS). In the experimental part, we explored adipocytes in the uterine wall by the twelfth sexual cycle after surgery. In the clinical part, we investigated adipocyte clusters in the cesarean scar of pregnant women with and without PAS. The uterine wall was evaluated in gross and histological sections using morphometry, histochemistry (hematoxylin and eosin stain, Mallory stain), and immunohistochemistry for FABP4 (adipocyte markers), CD68, CD163, CD206 (macrophages), CD 34 (endothelium), cytokeratin 8 (epithelium), aSMA (smooth muscle cells). The design included an experimental study on Sprague-Dawley rats (n = 18) after a full-thickness surgical incision on the seventh (n = 6), 30th (n = 6), and 60th day (n = 6). The clinical groups include pregnant women without uterine scars (n = 10), pregnant women with a uterine scar after previous cesarean sections (n = 10), and women with PAS (n = 11). Statistical processing was carried out using nonparametric methods. Comparisons were conducted using the Mann-Whitney U-test and Kruskal-Wallis test. Statistical significance was considered at p < 0.05. On the seventh day, the rat uterine horn was enveloped by adipose tissue, which contained crown-like structures with FABP4+, CD68+, CD206+, and CD163+ cells. FABP4+ cells in the uterine wall were absent by the 30th day. The number of CD206+ and CD163+ cells in the adipose tissue decreased by the 30th day. On the 60th day, the attachment of fat tissue was revealed in the form of single strands. The serous layer around the damaged area totally recovered on the 60th day. FABP4+ cells were not detected in the uterine wall samples from pregnant women without a previous cesarean section. Adipocytes were found in the scar during non-complicated pregnancy and with PAS. Reducing the number of CD68+ cells in adipocyte clusters, there were in myometrium with PAS. Increased CD206+ and CD163+ cells were revealed in uterine adipocyte clusters of the group. According to the experimental finding, adipocytes should be absent in the uterine wall by the 12th sexual cycle after a full-thickness surgical incision. The presence of adipocyte clusters in cesarean scar indicated the disturbance of cell interaction. Differences in the numbers of CD206 and CD163 cells in adipocyte clusters between groups with and without PAS may be indirect evidence that uterine adipocytes affect the development of PAS.

Abnormal Uterine Involution May Lead to Atony and Postpartum Hemorrhage: A Hypothesis, With Review of the Evidence

Uterine involution has 2 major components-(1) involution of vessels; and (2) involution of myometrium. Involution of vessels was addressed by Rutherford and Hertig in 1945; however, involution of myometrium has received little attention in the modern literature. We suggest that the pathophysiology of myometrial involution may lead to uterine atony and postpartum hemorrhage. The myometrium dramatically enlarges due to gestational hyperplasia and hypertrophy of myocytes, caused by hormonal influences of the fetal adrenal cortex and the placenta. After delivery, uterine weight drops rapidly, with physiologic involution of myometrium associated with massive destruction of myometrial tissue. The resulting histopathology, supported by scientific evidence, may be termed "postpartum metropathy," and may explain the delay of postpartum menstrual periods until the completion of involution. When uterine atony causes uncontrolled hemorrhage, postpartum hysterectomy examination may be the responsibility of the perinatal pathologist.Postpartum metropathy may be initiated when delivery of the baby terminates exposure to the hormonal influence of the fetal adrenal cortex, and may be accelerated when placental delivery terminates exposure to human chorionic gonadotrophin (HCG). This hypothesis may explain why a prolonged third stage of labor, and delays in management, are risk factors for severe hemorrhage due to uterine atony.

Keloids, hypertrophic scars, and uterine fibroid development: a prospective ultrasound study of Black and African American women

OBJECTIVE

To examine the association between keloids, hypertrophic scars, and uterine fibroid incidence as well as growth. Both keloids and fibroids are fibroproliferative conditions that have been reported to be more prevalent among Blacks than Whites, and they share similar fibrotic tissue structures, including extracellular matrix composition, gene expression, and protein profiles. We hypothesized that women with a history of keloids would have greater uterine fibroid development.

DESIGN

A prospective community cohort study (enrollment 2010-2012) with 4 study visits over 5 years to conduct standardized ultrasounds to detect and measure fibroids ≥0.5 cm in diameter, assess the history of keloid and hypertrophic scars, and update covariates.

SETTING

Detroit, Michigan area.

PATIENTS

A total of 1,610 self-identified Black and/or African American women aged 23-35 years at enrollment without a previous clinical diagnosis of fibroids.

EXPOSURE(S)

Keloids (raised scars that grow beyond the margins of the original injury) and hypertrophic scars (raised scars that stay within the bounds of the original injury). Because of the difficulties in distinguishing keloids and hypertrophic scars, we separately examined the history of keloids and the history of either keloids or hypertrophic scars (any abnormal scarring) and their associations with fibroid incidence and growth.

MAIN OUTCOME MEASURE(S)

Fibroid incidence (new fibroid after a fibroid-free ultrasound at enrollment) was assessed using Cox proportional-hazards regression. Fibroid growth was assessed using linear mixed models. The estimates for the change in log volume per 18 months were converted to the estimated percentage difference in volume for scarring vs. no-scarring. Both incidence and growth models were adjusted for time-varying demographic, reproductive, and anthropometric factors.

RESULT(S)

Of the 1,230 fibroid-free participants, 199 (16%) reported ever having keloids, 578 (47%) reported keloids or hypertrophic scars, and 293 (24%) developed incident fibroids. Neither keloids (adjusted hazard ratio = 1.04; 95% confidence interval: 0.77, 1.40) nor any abnormal scarring (adjusted hazard ratio = 1.10; 95% confidence interval: 0.88, 1.38) were associated with fibroid incidence. Fibroid growth differed little by scarring status.

CONCLUSION(S)

Despite molecular similarities, self-reported keloid and hypertrophic scars did not show an association with fibroid development. Future research may benefit from the examination of dermatologist-confirmed keloids or hypertrophic scars; however, our data suggest little shared susceptibility for these 2 types of fibrotic conditions.

Fertility outcomes after hysteroscopic niche resection compared with expectant management in women with a niche in the uterine cesarean scar

OBJECTIVE

To determine whether hysteroscopic niche resection (HNR) and expectant management are suitable in women with fertility desire and a niche with a residual myometrium thickness (RMT) ≥ 2.5 mm.

STUDY DESIGN

This retrospective cohort study was conducted at International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China between September 2016 and December 2021. We reported the fertility outcomes between women (with fertility desire and a niche with RMT ≥ 2.5 mm) who received HNR or expectant management.

RESULTS

We studied 166 women, of whom 72 accepted HNR and 94 accepted expectant management. The HNR group included more symptomatic women, in terms of postmenstrual spotting or infertility. No differences were found regarding niche measures before treatment. The live birth rate was comparable in both groups (HNR versus expectant management as 55.5% versus 45.7%, risk ratio = 1.48, 95% Cl 0.80-2.75, p = 0.21). The pregnancy rate was higher in HNR group than that in expectant management group (n = 72.2% versus n = 56.4%, risk ratio = 2.01, 95% CI 1.04-3.88, p = 0.04). In a subgroup of women with infertility before entry in the study, HNR resulted in a significant higher live birth rate (p = 0.04) and pregnancy rate (p = 0.01).

CONCLUSION

In women with infertility with a symptomatic niche with RMT ≥ 2.5 mm, HNR may be superior to expectant management. This retrospective cohort biased selection against a randomized study, our results still need to be validated in the future with larger clinical multicenter randomized controlled trials.

Searching for placenta percreta: a prospective cohort and systematic review of case reports

BACKGROUND

Placenta percreta is described as the most severe grade of placenta accreta spectrum and accounts for a quarter of all cases of placenta accreta spectrum reported in the literature.

OBJECTIVE

We investigated the hypothesis that placenta percreta, which has been described clinically as placental tissue invading through the full thickness of the uterus, is a heterogeneous category with most cases owing to primary or secondary uterine abnormality rather than an abnormally invasive form of placentation.

STUDY DESIGN

We have evaluated the agreement between the intraoperative findings using the International Federation of Gynecology and Obstetrics classification with the postoperative histopathology diagnosis in a prospective cohort of 101 consecutive singleton pregnancies presenting with a low-lying placenta or placenta previa, a history of at least 1 prior cesarean delivery and ultrasound signs suggestive of placenta accreta spectrum. Furthermore, a systematic literature review of case reports of placenta percreta, which included histopathologic findings and gross images, was performed.

RESULTS

Samples for histologic examination were available in 80 of 101 cases of the cohort, which were managed by hysterectomy or partial myometrial resection. Microscopic examination showed evidence of placenta accreta spectrum in 65 cases (creta, 9; increta, 56). Of 101 cases included in the cohort, 44 (43.5%) and 54 (53.5%) were graded as percreta by observer A and observer B, respectively. There was a moderate agreement between observers. Of note, 11 of 36 cases that showed no evidence of abnormal placental attachment at delivery and/or microscopic examination were classified as percreta by both observers. The systematic literature review identified 41 case reports of placenta percreta with microscopic images and presenting symptomatology, suggesting that most cases were the consequence of a uterine rupture. The microscopic descriptions were heterogeneous, and all descriptions demonstrated histology of placenta creta rather than percreta.

CONCLUSION

Our study supported the concept that placenta accreta is not an invasive disorder of placentation but the consequence of postoperative surgical remodeling or a preexisting uterine pathology and found no histologic evidence supporting the existence of a condition where the villous tissue penetrates the entire uterine wall, including the serosa and beyond.

Prospective evaluation of impact of post-Cesarean section uterine scarring in perinatal diagnosis of placenta accreta spectrum disorder

OBJECTIVE

Standardized ultrasound imaging and pathology protocols have recently been developed for the perinatal diagnosis of placenta accreta spectrum (PAS) disorders. The aim of this study was to evaluate prospectively the effectiveness of these standardized protocols in the prenatal diagnosis and postnatal examination of women presenting with a low-lying placenta or placenta previa and a history of multiple Cesarean deliveries (CDs).

METHODS

This was a prospective cohort study of 84 consecutive women with a history of two or more prior CDs presenting with a singleton pregnancy and low-lying placenta/placenta previa at 32-37 weeks' gestation, who were referred for perinatal care and management between 15 January 2019 and 15 December 2020. All women were investigated using the standardized description of ultrasound signs of PAS proposed by the European Working Group on abnormally invasive placenta. In all cases, the ultrasound features were compared with intraoperative and histopathological findings. Areas of abnormal placental attachment were identified during the immediate postoperative gross examination and sampled for histological examination. The data of a subgroup of 32 women diagnosed antenatally as non-PAS who had complete placental separation at birth were compared with those of 39 cases diagnosed antenatally as having PAS disorder that was confirmed by histopathology at delivery.

RESULTS

Of the 84 women included in the study, 42 (50.0%) were diagnosed prenatally as PAS and the remaining 42 (50.0%) as non-PAS on ultrasound examination. Intraoperatively, 66 (78.6%) women presented with a large or extended area of dehiscence and 52 (61.9%) with a dense tangled bed of vessels or multiple vessels running laterally and craniocaudally in the uterine serosa. A loss of clear zone was recorded on grayscale ultrasound imaging in all 84 cases, while there was no case with bladder-wall interruption or with a focal exophytic mass. Myometrial thinning (< 1 mm) in at least one area of the anterior uterine wall was found in 41 (97.6%) of the 42 cases diagnosed as non-PAS on ultrasound and 37 (88.1%) of the 42 diagnosed antenatally as PAS. Histological samples were available for all 48 hysterectomy specimens with abnormal placental attachment and for the three cases managed conservatively with focal myometrial resection and uterine reconstruction. Villous tissue was found directly attached to the superficial myometrium (placenta creta) in six of these cases and both creta villous tissue and deeply implanted villous tissue within the uterine wall (placenta increta) were found in the remaining 45 cases. There was no evidence of percreta placentation on histology in any of the PAS cases. Comparison of the main antenatal ultrasound signs and perioperative macroscopic findings between the two subgroups correctly diagnosed antenatally (32 non-PAS and 39 PAS) showed no significant difference with respect to the distribution of myometrial thinning and the presence of a placental bulge on ultrasound and of anterior uterine wall dehiscence intraoperatively. Compared with the non-PAS subgroup, the PAS subgroup showed significantly higher placental lacunae grade (P < 0.001) and more often hypervascularity of the uterovesical/subplacental area (P < 0.001), presence of bridging vessels (P = 0.027) and presence of lacunae feeder vessels (P < 0.001) on ultrasound examination, and increased vascularization of the anterior uterine wall intraoperatively (P < 0.001).

CONCLUSIONS

Remodeling of the lower uterine segment following CD scarring leads to structural abnormalities of the uterine contour on both ultrasound examination and intraoperatively, independently of the presence of accreta villous tissue on microscopic examination. These anatomical changes are often reported as diagnostic of placenta percreta, including cases with no histological evidence of PAS. Guided histological examination could improve the overall diagnosis of PAS and is essential to obtain evidence-based epidemiologic data. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

OBJECTIVES

To evaluate the new ultrasound-based signs for the diagnosis of post-cesarean section uterine niche in nonpregnant women.

METHODS

We investigated prospectively a cohort of 160 consecutive women with one previous term cesarean delivery (CD) between December 2019 and 2020. All women were separated into two subgroups according to different stages of labor at the time of their CD: subgroup A (n = 109; 68.1%) for elective CD and CD performed in latent labor at a cervical dilatation (≤4 cm) and subgroup B (n = 51; 31.9%); for CD performed during the active stage of labor (>4 cm).

RESULTS

Overall, the incidence of a uterine niche was significantly (P < .001) higher in women who had an elective (20/45; 44.4%) compared with those who had an emergent (21/115; 18.3%) CD. Compared with subgroup B, subgroup A presented with a significantly (P = .012) higher incidence of uterine niche located above the vesicovaginal fold and with a significantly (P = .0002) lower proportion of cesarean scar positioned below the vesicovaginal fold. There was a significantly (P < .001) higher proportion of women with a residual myometrial thickness (RMT) > 3 mm in subgroup A than in subgroup B and a significant negative relationship was found between the RMT and the cervical dilatation at CD (r = -0.22; P = .008).

CONCLUSIONS

Sonographic cesarean section scar assessment indicates that the type of CD and the stage of labor at which the hysterotomy is performed have an impact on the location of the scar and the scarification process including the niche formation and RMT.

New insights into the etiopathology of placenta accreta spectrum

Placenta accreta has been described as a spectrum of abnormal attachment of villous tissue to the uterine wall, ranging from superficial attachment to the inner myometrium without interposing decidua to transmural invasion through the entire uterine wall and beyond. These descriptions have prevailed for more than 50 years and form the basis for the diagnosis and grading of accreta placentation. Accreta placentation is essentially the consequence of uterine remodeling after surgery, primarily after cesarean delivery. Large cesarean scar defects in the lower uterine segment are associated with failure of normal decidualization and loss of the subdecidual myometrium. These changes allow the placental anchoring villi to implant, and extravillous trophoblast cells to migrate, close to the serosal surface of the uterus. These microscopic features are central to the misconception that the accreta placental villous tissue is excessively invasive and have led to much confusion and heterogeneity in clinical data. Progressive recruitment of large arteries in the uterine wall, that is, helicine, arcuate, and/or radial arteries, results in high-velocity maternal blood entering the intervillous space from the first trimester of pregnancy and subsequent formation of placental lacunae. Recently, guided sampling of accreta areas at delivery has enabled accurate correlation of prenatal imaging data with intraoperative features and histopathologic findings. In more than 70% of samples, there were thick fibrinoid depositions between the tip of most anchoring villi and the underlying uterine wall and around all deeply implanted villi. The distortion of the uteroplacental interface by these dense depositions and the loss of the normal plane of separation are the main factors leading to abnormal placental attachment. These data challenged the classical concept that placenta accreta is simply owing to villous tissue sitting atop the superficial myometrium without interposed decidua. Moreover, there is no evidence in accreta placentation that the extravillous trophoblast is abnormally invasive or that villous tissue can cross the uterine serosa into the pelvis. It is the size of the scar defect, the amount of placental tissue developing inside the scar, and the residual myometrial thickness in the scar area that determine the distance between the placental basal plate and the uterine serosa and thus the risk of accreta placentation.

Development of the utero-placental circulation in cesarean scar pregnancies: a case-control study

BACKGROUND

Cesarean scar pregnancies carry a high risk of pregnancy complications including placenta previa with antepartum hemorrhage, placenta accreta spectrum, and uterine rupture.

OBJECTIVE

To evaluate the development of utero-placental circulation in the first half of pregnancy in ongoing cesarean scar pregnancies and compare it with pregnancies implanted in the lower uterine segment above a previous cesarean delivery scar with no evidence of placenta accreta spectrum at delivery STUDY DESIGN: This was a retrospective case-control study conducted in 2 tertiary referral centers. The study group included 27 women who were diagnosed with a live cesarean scar pregnancy in the first trimester of pregnancy and who elected to conservative management. The control group included 27 women diagnosed with an anterior low-lying placenta or placenta previa at 19 to 22 weeks of gestation who had first and early second trimester ultrasound examinations. In both groups, the first ultrasound examination was carried out at 6 to 10 weeks to establish the pregnancy location, viability, and to confirm the gestational age. The utero-placental and intraplacental vasculatures were examined using color Doppler imaging and were described semiquantitatively using a score of 1 to 4. The remaining myometrial thickness was recorded in the study group, whereas the ultrasound features of a previous cesarean delivery scar including the presence of a niche were noted in the controls. Both the cesarean scar pregnancies and the controls had ultrasound examinations at 11 to 14 and 19 to 22 weeks of gestation.

RESULTS

The mean color Doppler imaging vascularity score in the ultrasound examination at 6 to 10 weeks was significantly (P<.001) higher in the cesarean scar pregnancy group than in the controls. High vascularity scores of 3 and 4 were recorded in 20 of 27 (74%) cases of the cesarean scar pregnancy group. There was no vascularity score of 4, and only 3 of 27 (11%) controls had a vascularity score of 3. In 15 of the 27 (55.6%) cesarean scar pregnancies, the residual myometrial thickness was <2 mm. In the ultrasound examination at 11 to 14 weeks, there was no significant difference between the groups in the number of cases with an increased subplacental vascularity. However, 12 cesarean scar pregnancies (44%) presented with 1 or more placental lacunae whereas there was no case with lacunae in the controls. Of the 18 cesarean scar pregnancies that progressed into the third trimester, 10 of them were diagnosed with placenta previa accreta at birth, including 4 creta and 6 increta. In the 19 to 22 weeks ultrasound examination, 8 of the 10 placenta accreta spectrum patients presented with subplacental hypervascularity, out of which 6 showed placental lacunae.

CONCLUSION

The vascular changes in the utero-placental and intervillous circulations in cesarean scar pregnancies are due to the loss of the normal uterine structure in the scar area and the development of placental tissue in proximity of large diameter arteries of the outer uterine wall. The intensity of these vascular changes, the development of placenta accreta spectrum, and the risk of uterine rupture are probably related to the residual myometrial thickness of the scar defect at the start of pregnancy. A better understanding of the pathophysiology of the utero-placental vascular changes associated with cesarean scar pregnancies should help in identifying those cases that may develop major complications. It will contribute to providing counseling for women about the risks associated with different management strategies.

The relationship of myometrial histopathology (metropathy) to myometrial dysfunction and clinical manifestations

Myometrial morphology and myometrial physiology have been considered to be separate entities; however, observations of myometrial morphology and associated dysfunctions suggest a relationship between myometrial morphology and myometrial physiology that deserves further exploration. Although myometrial electrical activity can be monitored by electrohysterogram, the association of increased myometrial contractions with an increase in electrical activity (due to an increase in gap junctions) is typically not evaluated. Although the association of increased myometrial contractions with increase in pain can be monitored by tocometry and intrauterine pressure catheters, respectively, this is generally not done in the non-pregnant uteri. Although standard morphologic evaluations routinely include evaluation with special stains and immunohistochemistry in other organ systems, such as skeletal and cardiac muscle, these evaluations are not standard or routine for myometrium in hysterectomies. The purpose of this review is to discuss non-neoplastic myometrial histology, with consideration of the potential value of using tools to measure variations in myometrial physiology, in order to reliably correlate myometrial histology with myometrial function (and dysfunction).

Placenta Percreta Presents with Neoangiogenesis of Arteries with Von Willebrand Factor-Negative Endothelium

In placenta percreta cases, large vessels are present on the precrete surface area. As these vessels are not found in normal placentation, we examined their histological structure for features that might explain the pathogenesis of neoangiogenesis induced by placenta accreta spectrum disorders (PAS). In two patients with placenta percreta (FIGO grade 3a) of the anterior uterine wall, one strikingly large vessel of 2 cm length was excised. The samples were formalin fixed and paraffin-embedded. Gomori trichrome staining was used to evaluate the muscular layers and Weigert-Van Gieson staining for elastic fibers. Immunohistochemical staining of the vessel endothelium was performed for Von Willebrand factor (VWF), platelet endothelial cell adhesion molecule (CD31), Ephrin B2, and EPH receptor B4. The structure of the vessel walls appeared artery-like. The vessel of patient one further exhibited an unorderly muscular layer and a lack of elastic laminae, whereas these features appeared normal in the vessel of the other patient. The endothelium of both vessels stained VWF-negative and CD31-positive. In conclusion, this study showed VWF-negative vessel endothelia of epiplacental arteries in placenta accreta spectrum. VWF is known to regulate artery formation, as the absence of VWF has been shown to cause enhanced vascularization. Therefore, we suppose that PAS provokes increased vascularization through suppression of VWF. This process might be associated with the immature vessel architecture as found in one of the vessels and Ephrin B2 and EPH receptor B4 negativity of both artery-like vessels. The underlying pathomechanism needs to be evaluated in a greater set of patients.

Pregnancy outcomes of patients undergoing single-layer sutured laparoscopic myomectomy

AIM

In this study, we aimed to investigate the pregnancy outcomes of 102 patients who underwent laparoscopic myomectomy (LM) with single-layer suturing.

METHODS

This retrospective study included 102 women who underwent single-layer sutured LM in the obstetrics and gynaecology clinic of our hospital between September 2017 and April 2019.

RESULTS

A total of 102 patients underwent LM and colpotomy. Sixty-two patients were planning conception. Thirty-three (53.2%) of the sixty-two patients became pregnant until the study date. The mean age of the pregnant patients was 34 ± 8.2 years. In the pregnant patients, myoma localisation was anterior in 12 (50%), posterior in 7 (29%) and other in 5 (21%) patients. The mean duration between the operation and the first pregnancy was 10.2 months (2-24 months). Of the first pregnancies, 12 (50%) were between 0 and 6 months, and 12 (50%) were between 6 and 24 months to the operation. Twenty-four pregnant patients were delivered with caesarean section, six patients had a miscarriage and two patients resulted in intra-uterine pregnancy in the second trimester. Of these patients, eight were pregnant again, and eight were delivered by caesarean section. Curettage and dilatation were performed in six patients with miscarriage. None of the patients developed uterine rupture.

CONCLUSION

Single-layer closure of the uterine defect in LM is safe for subsequent pregnancies, and the risk of uterine rupture is low.

The Intraoperative Median Effective Dose of Oxytocin for Preventing Uterine Atony in Parturients with a Prior History of Caesarean Delivery

BACKGROUND AND OBJECTIVE

While oxytocin is commonly used for the prevention of uterine atony, its pharmacology may be affected by a prior history of caesarean delivery. The objective of this study was to determine the 50% effective dose (ED₅₀) of bolus oxytocin after caesarean delivery in parturients with and without prior caesarean delivery.

METHODS

This was a parallel-group, double-blind, dose-response study using Dixon's up-and-down sequential allocation method to estimate the ED₅₀ of bolus-administered oxytocin in parturients having caesarean delivery under combined spinal-epidural anaesthesia (CSE). Twenty-seven parturients with a history of prior caesarean delivery (With-PCD group) and 26 parturients with no such history (Without-PCD group) were enrolled. Oxytocin was administered as an intravenous bolus at a starting dose of 0.5 units, which was then increased or decreased by 0.25 units at a time. Uterine tone was assessed by the obstetrician as either 'adequate' or 'inadequate' 3 min after delivery of the fetus. Adverse effects, administration of additional uterotonic agents, and estimated blood loss were recorded.

RESULTS

The ED₅₀ of oxytocin was greater in the With-PCD group than in the Without-PCD group (0.95 units [95% CI 0.82-1.08] vs. 0.55 units [95% CI 0.38-0.73], P < 0.001). The overall incidence of adverse effects was higher in the With-PCD group than in the Without-PCD group (33.3% vs. 7.7%, P = 0.02).

CONCLUSION

The initial bolus dose of oxytocin needed to prevent uterine atony was higher in parturients with prior caesarean delivery than in parturients without prior caesarean delivery. Uterine scarring may contribute to the increased oxytocin requirements of the former group.

TRIAL REGISTRATION NUMBER

ChiCTR1900023474; investigator: Wei CN; date of registration: 30 May 2019.

Mechanical Effects of a Maylard Scar During a Vaginal Birth After a Previous Caesarean

Caesarean section is one of the most common surgeries worldwide, even though there is no evidence supporting maternal and perinatal long-term benefits. Furthermore, the mechanical behavior of a caesarean scar during a vaginal birth after caesarean (VBAC) is not well understood since there are several questions regarding the uterine wound healing process. The aim of this study is to investigate the biomechanical Maylard fiber reorientation and stiffness influence during a VBAC through computational methods. A biomechanical model comprising a fetus and a uterus was developed, and a chemical-mechanical constitutive model that triggers uterine contractions was used, where some of the parameters were adjusted to account for the matrix and fiber stiffness increase in the caesarean scar. Several mechanical simulations were performed to analyze different scar fibers arrangements, considering different values for the respective matrix and fibers stiffness. The results revealed that a random fiber arrangement in the Maylard scar has a much higher impact on its mechanical behavior during a VBAC than the common fibers arrangement present in the uninjured uterine tissue. An increase of the matrix scar stiffness exhibits a lower impact, while an increase of the fiber's stiffness has no significant influence.

Impact of location on placentation in live tubal and cesarean scar ectopic pregnancies

INTRODUCTION

The objective of this study was to evaluate the impact of implantation outside the normal intra-uterine endometrium on development of the gestational sac.

METHODS

We reviewed and compared the ultrasound measurements and vascularity score around the gestational sac in 69 women diagnosed with a live tubal ectopic pregnancy (TEP) and 54 with a cesarean scar ectopic pregnancy (CSP) at 6-11 weeks of gestation who were certain of their last menstrual period.

RESULTS

The rate of a fetus with a cardiac activity in the study population was significantly (P < 0.001) higher in CSPs than in TEPs. The median maternal age, gravidity and parity were significantly (P =.005; P < 0.001 and P < 0.001, respectively) lower in the TEP than in the CSP group. The number of gestational sac size <5th centile for gestational age was significantly (P < 0.001) higher in the TEP than in the CSP group. There were no differences between the groups for the other ultrasound measurements. In cases matched for gestational age, the gestational sac size was significantly (P < 0.001) smaller in the TEP compared to the CSP group. There was a significant (P < 0.001) difference in the distribution of blood flow score with CSP presenting with higher incidence of moderate and high vascularity than TEP.

DISCUSSION

Both TEP and CSP are associated with a higher rate of miscarriage than intrauterine pregnancies and the slow development of the gestation sac is more pronounced in TEPs probably as a consequence of a limited access to decidual gland secretions.

Maternal Serum VEGF Predicts Abnormally Invasive Placenta Better than NT-proBNP: a Multicenter Case-Control Study

The aim of this study was to test if maternal serum vascular endothelial growth factor (VEGF) or N-terminal pro B-type natriuretic peptide (NT-proBNP) predicts abnormally invasive placenta (AIP) better. Secondary objective was to test whether the serum levels of VEGF and NT-proBNP can predict the degree of invasion. In a multicenter case–control study design, gestational age-matched serum samples from pregnant women with AIP (n = 44) and uncomplicated pregnancies (n = 55) who had been enrolled at Charité – Universitätsmedizin Berlin, Germany and Centre Hospitalier Régional de la Citadelle in Liège, Belgium were analyzed. Maternal blood serum VEGF and NT-proBNP levels were immunoassayed from samples taken immediately before delivery (GA median: 35 weeks). Biomarker levels were compared between AIP and control group. The correlation of biomarker levels with the clinical AIP degree was assessed. The predictive biomarker ability was characterized through a multivariate regression model and receiver operating characteristic curves. Women with AIP had significantly lower maternal serum VEGF levels (AIP mean 285 pg/ml, 95% CI 248–322, vs. control: 391 pg/ml, 95% CI 356–426, p < 0.01) and higher NT-proBNP levels (AIP median 329 pg/ml, IQR 287–385, vs. control 295 pg/ml, IQR 273–356, p = 0.03). Maternal serum VEGF levels were able to predict AIP better (AUC = 0.729, 0.622–0.836, p < 0.001; VEGF + number of previous cesarean deliveries: AUC = 0.915, 0.853–0.977, p < 0.001). Maternal serum VEGF levels correlated inversely with the clinical AIP degree (r = − 0.32, p < 0.01). In short, maternal serum VEGF, more than NT-proBNP, can help in predicting AIP and hints at the degree of invasion.

The role of extracellular matrix in normal and pathological pregnancy: Future applications of microphysiological systems in reproductive medicine

IMPACT STATEMENT

Extracellular matrix in the womb regulates the initiation, progression, and completion of a healthy pregnancy. The composition and physical properties of extracellular matrix in the uterus and at the maternal-fetal interface are remodeled at each gestational stage, while maladaptive matrix remodeling results in obstetric disease. As in vitro models of uterine and placental tissues, including micro-and milli-scale versions of these organs on chips, are developed to overcome the inherent limitations of studying human development in vivo, we can isolate the influence of cellular and extracellular components in healthy and pathological pregnancies. By understanding and recreating key aspects of the extracellular microenvironment at the maternal-fetal interface, we can engineer microphysiological systems to improve assisted reproduction, obstetric disease treatment, and prenatal drug safety.

Ultrasound-histopathologic features of the utero-placental interface in placenta accreta spectrum

INTRODUCTION

The objective of this study was to evaluate the relationship between utero-placental vascular changes on ultrasound imaging and histopathologic findings according to the grade of villous invasion in placenta accreta spectrum (PAS).

METHODS

The ultrasound features of 31 patients with singleton pregnancies diagnosed prenatally with low-lying/placenta previa accreta were compared with histopathology findings following caesarean hysterectomy (n = 25) or partial myometrial resection (n = 6). The number and degree of transformation of arteries within the superficial layer of myometrium were recorded. Cytokeratin 7 (CK7) immunohistochemistry was used to complement H&E analysis.

RESULTS

All 31 patients presented with loss of clear zone, myometrial thinning and placenta lacunae. Subplacental hypervascularity and lacunae feeder vessels were found in 25 and nine cases, respectively. Large recent intervillous thromboses were found in one case with adherent villi and 12 cases with invasive villi, and showed a significantly different distribution according to lacunae scores. Thick basal plate fibrinoid deposits were found in all the areas of abnormally adherent and invasive villous tissue There was no significant difference in the mean count of partially remodeled vessels or vessels completely lacking remodeling according to the lacunae score and grade of placental invasiveness. EVT cells were arranged in superficial confluent sheets or superficial irregular clusters, or were scattered deep below the basal plate.

CONCLUSION

Placental ultrasound and histopathologic features associated with PAS are more pronounced in invasive cases suggesting that they are secondary to the haemodynamic effects of abnormally deep placentation and transformation of the radial and arcuate arteries.

Impact of placenta previa with placenta accreta spectrum disorder on fetal growth

OBJECTIVES

To evaluate fetal growth in pregnancies complicated by placenta previa with or without placenta accreta spectrum (PAS) disorder, compared with in pregnancies with a low-lying placenta.

METHODS

This was a multicenter retrospective cohort study of singleton pregnancies complicated by placenta previa with or without PAS disorder, for which maternal characteristics, ultrasound-estimated fetal weight and birth weight were available. Four maternal-fetal medicine units participated in data collection of diagnosis, treatment and outcome. The control group comprised singleton pregnancies with a low-lying placenta (0.5-2 cm from the internal os). The diagnosis of PAS and depth of invasion were confirmed at delivery using both a predefined clinical grading score and histopathological examination. For comparison of pregnancy characteristics and fetal growth parameters, the study groups were matched for smoking status, ethnic origin, fetal sex and gestational age at delivery.

RESULTS

The study included 82 women with placenta previa with PAS disorder, subdivided into adherent (n = 35) and invasive (n = 47) PAS subgroups, and 146 women with placenta previa without PAS disorder. There were 64 controls with a low-lying placenta. There was no significant difference in the incidence of small-for-gestational age (SGA) (birth weight ≤ 10^th percentile) and large-for-gestational age (LGA) (birth weight ≥ 90^th  percentile) between the study groups. Median gestational age at diagnosis was significantly lower in pregnancies with placenta previa without PAS disorder than in the low-lying placenta group (P = 0.002). No significant difference was found between pregnancies complicated by placenta previa with PAS disorder and those without for any of the variables. Median estimated fetal weight percentile was significantly lower in the adherent compared with the invasive previa-PAS subgroup (P = 0.047). Actual birth weight percentile at delivery did not differ significantly between the subgroups (P = 0.804).

CONCLUSIONS

No difference was seen in fetal growth in pregnancies complicated by placenta previa with PAS disorder compared with those without and compared with those with a low-lying placenta. There was also no increased incidence of either SGA or LGA neonates in pregnancies with placenta previa and PAS disorder compared with those with placenta previa with spontaneous separation of the placenta at birth. Adverse neonatal outcome in pregnancies complicated by placenta previa and PAS disorder is linked to premature delivery and not to impaired fetal growth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

A Comparison of Hysterectomies for Bleeding With Hysterectomies for Pain

Objectives. We recently suggested that increased intramural pressure may often explain pain and/or bleeding. Hysterectomies for bleeding tend to have outward bulges and endometrial vascular ectasia, while hysterectomies for pain tend to have deflection of pressure inward by subserosal ridges, which promote inner myometrial elastosis (IME). Study design. We analyzed causes of increased intramural pressure in 58 hysterectomies for pain and/or bleeding, excluding clinically fibroid uteri and prolapsed uteri. Postfixation photographs were used to avoid missing grossly obvious myometrial hyperplasia (MMH). Results. The most common cause of increased intramural pressure was grossly obvious MMH in 40/58 cases (69%). Other causes included clinically occult myomas (3 cases), adenomyosis (6 cases), and multifactorial causes (7 cases). Hysterectomies for bleeding weighed more than hysterectomies for pain ( P = .035). Hysterectomies for pain had more IME than hysterectomies for bleeding ( P = .029). Conclusions. When subserosal ridges deflect pressure inward, bulky MMH may cause pelvic pain and IME, but when they do not, bulkier MMH in heavier uteri may lead to both outward bulges and abnormal bleeding from endometrial vascular ectasia.

Recurrence of Basal Plate Myofibers, with Further Consideration of Pathogenesis

OBJECTIVES

Basal plate myofibers (BPMF) may indicate morbid adherence. We assessed recurrence and clinical progression of BPMF.

METHODS

In 5 years, 135 BPMF placentas were reported. Controls were the first 50 placentas in 2009, none of which had reported BPMF.

RESULTS

32% of BPMF patients had other placentas, with a recurrence rate of 100%. Actin stains were needed for diagnosis in 117/179 cases (65%). These cases had clinical features suggestive of morbid adherence in 69/117 (59%). 23/47 (49%) of BPMF recurrences progressed in severity, 5 to hysterectomy (11%). Thinning of the basal plate, perforating vessels, gaps in the basal plate, and villi under the basal plate were observed in BPMF placentas.

CONCLUSIONS

These findings appear to validate screening for BPMF. The 100% recurrence rate suggests evaluation for a heritable factor, i.e., protease inhibitor deficiency, which may explain pre-delivery basal plate damage.

Association of Retroplacental Blood With Basal Plate Myofibers

Objectives Diagnosed clinical abruption showing blood clot should be signed out in the pathology report as retroplacental hemorrhage with or without parenchymal indentation, and submitted clot separate from the placenta should be weighed. In our experience, some cases sent as clinical abruptions have been cases of morbid adherence. This study was undertaken to evaluate the association of retroplacental blood with basal plate myofibers (BPMF). Methods One hundred fifty-six placentas reviewed by a board-certified pediatric pathologist at a community hospital were evaluated for significant retroplacental blood. Basal plates were reviewed for deviations from normal. Results Of the 156 placentas, 33 (21%) had significant retroplacental blood; 21/156 (13%) had a separate clot, of which 11/21 (52%) had BPMF. Eleven BPMF-associated separate clots ranged from 10.5 to 60 g (average 23), while the clots of 10 cases with no demonstrated BPMF ranged from 19 to 440 g (average 82), tending to be larger ( p < .03). Basal plate damage prior to delivery was noted in both sets of placentas. BPMF placentas could have myometrial damage prior to delivery. Conclusions Since BPMF may confer a risk for accreta in a subsequent pregnancy, submission of a separate clot with the placenta should lead the pathologist to evaluate for basal plate myofibers on H&E and consider if there is an evidence-based indication to do an actin stain, before presuming a diagnosis of abruption.

A preliminary study of uterine scar tissue following cesarean section

AIM

To compare smooth muscle cells, type I collagen, and apoptosis of the lower uterine segment of women who had/without a prior cesarean delivery.

METHODS

Alpha smooth muscle actin (α-SMA), type I collagen, and nuclear apoptosis were compared between the groups from lower uterine segment. Twenty-eight controls and 82 with one prior cesarean delivery were included. The women with a prior cesarean section were classified by time since the surgery: ≤3 years, >3 and ≤5 years, >5 and ≤7 years, >7 and ≤9 years, and >9 years.

RESULTS

Smooth muscle volume density (VD) % was significantly lower in women who had cesarean sections in first three groups than in the controls (all, P<0.01). Type I collagen VD% was similar among all groups and the controls. The number of apoptotic nuclei in the lower uterine segment of the scarred group was greater up to 3 years after surgery and less than in the control at 7-9 years. The number of non-apoptotic nuclei in the scarred group was greater than controls up to 7 years after surgery.

CONCLUSION

The lower uterine segment scar becomes stable at 3 years after cesarean delivery, and by 9 years, the scar is mature.

A Review and Reconsideration of Nonneoplastic Myometrial Pathology

From 1861 to 1962, clinicopathologic research tried to explain the association of abnormal uterine bleeding with uterine enlargement. The etiology was theorized as metropathy, suggesting that myometrial dysfunction may predispose to abnormal uterine bleeding. Research reached a nadir in 1962, when a major review dismissed myometrial hypertrophy as a plausible explanation after prior rejections of the theories of chronic myometritis, fibrosis uteri, and subinvolution as causes of bleeding. Subsequent to this arose a crusade against unnecessary hysterectomies in the 1970s. Although myometrial hyperplasia was proposed in 1868, it is only in the past 25 years that tangible evidence has supported that idea. It now appears that clinically enlarged uteri are due to globoid outward bulging of the uterus, caused by increased intramural pressure—often unrelated to either uterine weight or myometrial thickness. Abnormal (dysfunctional) uterine bleeding may often be due to spontaneous rupture of thrombosed dilated endometrial vessels, due to the combined effects of obstructed venous drainage by increased intramural pressure, and Virchow’s triad. Despite a century-old known association of parity with naturally occurring outer wall myometrial scars (fibrosis uteri with elastosis), it was not previously suggested that these may reflect healing reactions to muscle tears during labor and delivery. We now suggest that smaller, similar inner wall elastotic scars in the nerve-rich inner myometrium may explain many cases of pelvic pain. This review suggests that diverse pressure-related lesions may be present in clinically abnormal uteri that have been called “normal” since the crusade against unnecessary hysterectomy.

Postablation neuroma of the myometrium-a report of 5 cases

When hysterectomy is performed for chronic pelvic pain, routine pathology examination often provides no explanation. However, analysis of small uterine nerves using immunostains may help to address this deficiency. Small uterine nerves tend to be sparse or absent in wide areas of normal myometrium. Some studies of uterine nerves have suggested that endometriosis, adenomyosis, and fibroids are not inherently painful, with increased small nerves in the inner uterine wall associated with the history of pelvic pain. Although such areas may appear normal on hematoxylin and eosin (H&E), we have found a subtle inner wall lesion termed inner myometrial elastosis, best detected with trichrome or elastic stains, which may be a reaction to microscopic tears of inner myometrium. Such tears may induce increased inner wall innervation via the generation of nerve growth factor in granulation tissue. In the course of studying uterine nerves with immunostains, we found 5 cases with florid nerve proliferation, after deep endometrial ablation for abnormal uterine bleeding led to increased pelvic pain. We suggest that immunostains for postablation neuromas should be done in hysterectomies when pelvic pain increases after endometrial ablation. This may offer gynecologists and their patients an objective finding with a rational, scientific explanation for the pelvic pain.

Trauma and endometriosis. A review. May we explain surgical phenotypes and natural history of the disease?

OBJECTIVE

The study was performed to evaluate whether trauma is an initial event of development of endometriosis.

METHOD

Using Medline database from January 1960 up to December 2014, a systematic review was made of all published studies using the keywords trauma, healing, injury, infection, hyperperistaltism, stretch and endometriosis, adenomyosis and trauma. Studies and review articles written in French and/or in English related to the topic were included and reviewed independently by two authors.

RESULTS

The role of trauma is well-established for endometriotic lesions diagnosed in surgical scars. Various traumas including delivery, uterine curettage or incision, intraperitoneal hemorrhage, or occult pelvic inflammatory diseases could be involved to explain other localizations of the disease. Many data suggested that the healing process, particularly growth factors and the associated estrogen production, may facilitate the implantation and the growth of ectopic endometrial cells. After the initial, a traumatic event, the phenotype of the disease would depend on the tissue in which the endometriotic lesion grows.

CONCLUSIONS

The present literature review may support a potential role of a trauma as an initial event of endometriosis.

Placenta Accreta and Placenta Increta: An Approach to Pathogenesis Based on the Trophoblastic Differentiation Pathway

Morbid adherence remains a puzzling disease. This paper suggests that normal and morbidly adherent placentation may be viewed best in terms of trophoblastic stem cells and the mutually exclusive branches of the trophoblastic differentiation pathway-villous trophoblast (VT), interstitial and endovascular nonvillous trophoblast (NVT) at the implantation site, and a positional variation in the chorion. Based on cases of hysterectomies for morbid adherence seen over 30 years at a community hospital, analyzed with routine keratin stains, with actin and trichrome stains as indicated, and with attempts at ultrasonography-pathology correlation, we present selected observations. In true accreta, the site of morbid adherence was to dilated basal plate vessels infiltrated by endovascular NVT, with scant interstitial NVT, and normal myometrium. It appeared that excess blood flow into the placenta was due to excessively deep keratin-positive endovascular NVT that spread-independently of interstitial NVT-in an angiocentric fashion in both accreta and increta. Retroplacental abnormalities were due to myometrial destruction by interstitial NVT in increta, sometimes requiring actin stains for detection; and to an admixture of markedly dilated endometrial glands and vessels in true accreta, best appreciated with keratin stains. Variations of depth and extent in increta may be due to variations in myometrial tone, and in the protease-antiprotease balance. Morbidly adherent fetal membranes are described, and the role of caesarean section scars in incretas is addressed.

Abnormal expression of leiomyoma cytoskeletal proteins involved in cell migration

Uterine leiomyomas are monoclonal tumors. Several factors are involved in the neoplastic transformation of the myometrium. In our study we focused on dysregulated cytoskeletal proteins in the leiomyoma as compared to the myometrium. Paired tissue samples of ten leiomyomas and adjacent myometria were obtained and analyzed by two‑dimensional gel electrophoresis (2-DE). Mass spectrometry was used for protein identification, and western blotting for 2-DE data validation. The values of ten cytoskeletal proteins were found to be significantly different: eight proteins were upregulated in the leiomyoma and two proteins were downregulated. Three of the upregulated proteins (myosin regulatory light polypeptide 9, four and a half LIM domains protein 1 and LIM and SH3 domain protein 1) are involved in cell migration, while downregulated protein transgelin is involved in replicative senescence. Myosin regulatory light polypeptide 9 (MYL9) was further validated by western blotting because it is considered to be a cell migration marker in several cancers and could play a key role in leiomyoma development. Our data demonstrate significant alterations in the expression of cytoskeletal proteins involved in leiomyoma growth. A better understanding of the involvement of cytoskeletal proteins in leiomyoma pathogenesis may contribute to the identification of new therapeutic targets and the development of new pharmacological approaches.

Histochemical and functional improvement of adipose-derived stem cell-based tissue-engineered cartilage by hyperbaric oxygen/air treatment in a rabbit articular defect model

Cartilage is exposed to compression forces during joint loading. Therefore, exogenous stimuli are frequently used in cartilage tissue engineering strategies to enhance chondrocyte differentiation and extracellular matrix (ECM) secretion. In this study, human adipose-derived stem cells were seeded on a gelatin/polycaprolactone scaffold to evaluate the histochemical and functional improvement of tissue-engineered cartilage after hyperbaric oxygen/air treatment in a rabbit articular defect model. Behavior tests showed beneficial effects on weight-bearing and rear leg-supporting capacities after treatment of tissue-engineered cartilage with 2.5 ATA oxygen or air. Moreover, positron emission tomography images and immunohistochemistry staining demonstrated hydroxyapatite formation and increased ECM synthesis, respectively, at the tissue-engineered cartilage graft site after high pressure oxygen/air treatment. Based on these results, we concluded that hyperbaric oxygen and air treatment can improve the quality of tissue-engineered cartilage in vivo by increasing the synthesis of ECM.

A Study of Myometrial Growth and Development

STUDY OBJECTIVE

To evaluate myometrial growth and development.

DESIGN

Thirty-five autopsy uteri, ranging from 10 weeks' gestation to age 18 years, acquired over 3 decades from 2 hospitals, were studied based on specimen availability, photographed for documentation, and reviewed at the end of the study. Most were embedded in toto, with 1 block and 1 slide per case. Some were immunostained for actin, CD10, MIB-1, and/or trichrome stain for collagen and muscle. Myometrial thickness was measured by ocular micrometry when sections were nontangential and analyzed by paired-sample t tests and bivariate linear regression.

SETTING

Two university-affiliated hospitals.

RESULTS

From 20 to 34 weeks, lateral wall corpus thickness increased 6-fold, with a 4- to 6-fold perinatal burst of growth (P < .01) and a drop in thickness after the neonatal period (P = .013). The corpus was thicker than the dome (P < .01) but less thick than the lower uterine segment (P = .087). The lower uterine segment was fully muscular in the second trimester, becoming more fibrous near term. Intramural, subserosal, and inframucosal myometaplasia were observed, as primitive stromal cells turned into muscle cells. Myometrial proliferation was brisk in the second trimester but greatly diminished in the perinatal period. Pressure effects from myometrial tone were observed during development. There was a pubertal burst of inframucosal myometaplasia.

CONCLUSIONS

Myometaplasia accounted for most myometrial growth, especially in the perinatal and pubertal bursts of growth. Pressure effects, related to myometrial tone, appeared to affect myometrial development. True endocervix, with a fibrous wall and mucinous epithelium, appeared late in development.

The extracellular matrix contributes to mechanotransduction in uterine fibroids

The role of the extracellular matrix (ECM) and mechanotransduction as an important signaling factor in the human uterus is just beginning to be appreciated. The ECM is not only the substance that surrounds cells, but ECM stiffness will either compress cells or stretch them resulting in signals converted into chemical changes within the cell, depending on the amount of collagen, cross-linking, and hydration, as well as other ECM components. In this review we present evidence that the stiffness of fibroid tissue has a direct effect on the growth of the tumor through the induction of fibrosis. Fibrosis has two characteristics: (1) resistance to apoptosis leading to the persistence of cells and (2) secretion of collagen and other components of the ECM such a proteoglycans by those cells leading to abundant disposition of highly cross-linked, disoriented, and often widely dispersed collagen fibrils. Fibrosis affects cell growth by mechanotransduction, the dynamic signaling system whereby mechanical forces initiate chemical signaling in cells. Data indicate that the structurally disordered and abnormally formed ECM of uterine fibroids contributes to fibroid formation and growth. An appreciation of the critical role of ECM stiffness to fibroid growth may lead to new strategies for treatment of this common disease.

Myometrial hyperplasia mimics the clinical presentation of uterine fibroids: a report of 3 cases

The clinical diagnosis of fibroid uterus is based on physical examination findings and/or ultrasound. However, it is not uncommon for routine pathology examination to report no significant fibroids in such cases. Myometrial hyperplasia (MMH) is a structural variation with irregular zones of hypercellularity and increased nucleus/cell ratio that appears in adolescence, can progress during the childbearing years, and can sometimes cause grossly detectable bulges on pathologic examination. MMH can be inframucosal, intramural (microscopic), or subserosal. Three premenopausal women with a preoperative diagnosis of fibroids on pelvic examination, and/or sonograms, underwent hysterectomies. In all the 3 cases, the Myoma Index (number of fibroids×size of largest fibroid) indicated insignificant fibroids. The pathology simulating fibroids was firm, bulging inframucosal MMH. Firm, bulging MMH can mimic uterine fibroids on ultrasound and physical examination. In hysterectomies for fibroid uterus with a Myoma Index <3.7, it is recommended that pathologists evaluate for MMH as the possible explanation for the findings on physical examination and/or ultrasound.

Changes in Cesarean section scar dimensions during pregnancy: a prospective longitudinal study

OBJECTIVES

To describe changes in Cesarean section (CS) scars longitudinally throughout pregnancy, and to relate initial scar measurements, demographic variables and obstetric variables to subsequent changes in scar features and to final pregnancy outcome.

METHODS

In this prospective observational study we used transvaginal sonography (TVS) to examine the CS scar of 320 consecutive pregnant women at 11-13, 19-21 and 32-34 weeks' gestation. For scars visible on TVS, the hypoechoic part was measured in three dimensions and the residual myometrial thickness (RMT) was also measured. Analyses were carried out using one-way repeated measures ANOVA and mixed modeling. The incidence of subsequent scar rupture was recorded.

RESULTS

The CS scar was visible in 284/320 cases (89%). Concerning length and depth of the hypoechoic part of the scar and RMT, the larger the initial scar measurement, the larger the decrease observed during pregnancy. For the hypoechoic part of the scar, the width increased on average by 1.8 mm per trimester, while the depth and length decreased by 1.8 and 1.9 mm, respectively (false discovery rate P < 0.0001). Mean RMT in the first trimester was 5.2 mm and on average decreased by 1.1 mm per trimester. Two cases (0.62%) of uterine scar rupture were confirmed following a trial of vaginal delivery; these had a mean RMT of 0.5 mm at second scan and an average decrease of 2.6 mm over the course of pregnancy.

CONCLUSION

This study establishes reference data and confirms that the dimensions of CS scars change throughout pregnancy. Scar rupture was associated with a smaller RMT and greater decrease in RMT during pregnancy. There is the potential to test absolute values and observed changes in CS scar measurements as predictors of uterine scar rupture and outcome in trials of vaginal birth after Cesarean section.