Pilot study of MRI/ultrasound fusion imaging in postpartum assessment of Cesarean section scar

Establishment and Evaluation of a Stable and Reliable Rat Model of Cesarean Scar Diverticulum

Cesarean scar diverticulum (CSD), a common complication of cesarean sections linked to poor uterine incision healing, has been hindered by the lack of standardized animal models. This study establishes a stable and reproducible CSD rat model, addressing this gap and providing a critical foundation for exploring pathological mechanisms and advancing therapies. The CSD model was established in 120 female rats (sham: 20; control/experimental: 50 each) via surgical resection and LPS injection. CSD formation was validated by B-mode/contrast-enhanced ultrasound. Histopathology (H&E, Masson's trichrome) quantified collagen deposition and neutrophil infiltration. Immunofluorescence (Collagen I, α-SMA) and immunohistochemistry (TNF-α, IL-6, iNOS) assessed fibrosis and inflammation. Quantitative analyses utilized confocal microscopy and ImageJ. Data were analyzed by SPSS 20.0. The LPS-induced CSD model showed higher detection rates (48% vs. 25%, p < 0.001), further enhanced by intrauterine saline (65% vs. 37.5%, p < 0.05) and SF6 contrast ultrasound (70% vs. 45%, p < 0.05). Histopathology revealed endometrial thinning, 250% neutrophil influx (p < 0.001), and elevated collagen deposition (p < 0.05). Fibrosis markers (Collagen I, α-SMA+ cells) and proinflammatory mediators (IL-6, TNF-α, iNOS) were significantly upregulated (p < 0.05), with CD68+ macrophages 3.2-fold higher in CSD lesions (p < 0.01). This study innovatively establishes a surgical-LPS-induced rat model of CSD that faithfully recapitulates clinical-pathological hallmarks, including characteristic endometrial-myometrial injury, fibrotic remodeling, and chronic inflammatory microenvironment. Overcoming limitations of conventional approaches, this model provides a standardized platform for unlocking pathogenesis and advancing targeted therapies for CSD.

Superb microvascular imaging for assessment of post-cesarean myometrial blood flow from 1 to 4 weeks after operation: A preliminary study

PURPOSE

To evaluate superb microvascular imaging for measuring puerperal myometrial microvascular blood flows at incisional sites following cesarean delivery.

METHODS

Twenty postpartum women (singleton births) were studied: 10 with cesarean and 10 with transvaginal deliveries. All cesarean cases were first operational delivery with lower uterine incision, repaired with double-layer suture. At 1 and 4 weeks postpartum, the uterus was delineated using transvaginal ultrasonography with superb microvascular imaging. Separate regions of interest were created for anterior myometrium of the isthmus and the body. The microvascular flow profile in three circular sampling points placed in a region of interest was quantified and expressed as vascular density. The vascular density ratio of the uterine isthmus to the body was compared between one and four weeks for both groups. Wilcoxon's signed-rank test was used to assess statistical significance (set at p < 0.05).

RESULTS

In cesarean deliveries, the vascular density ratio of the uterine isthmus to the body increased from 1 (median: 0.51, range: 0.30-0.68) to 4 weeks (0.99, 0.85-1.60), whereas no changes were noted in transvaginal deliveries.

CONCLUSION

Superb microvascular imaging can effectively measure myometrial microvascular blood flow recovery at cesarean incision sites, indicating its potential as a tool for monitoring postpartum wound healing.

Short interval pregnancy is associated with pathology severity in placenta accreta spectrum (PAS)

OBJECTIVE

Placenta accreta spectrum (PAS) is a continuum of invasive pathologies associated with significant maternal morbidity and mortality. Pregnancies with short intervals present additional complications which may result from suboptimal wound healing. The impact of short interval pregnancy on placental invasion is unknown our primary objective was to characterize the impact of short interval pregnancy in the subsequent invasive degree of PAS.

METHODS

Here we present a retrospective case-control analysis of 133 patients with pathology-confirmed PAS who presented to our Placenta Accreta program and assessed for the impact of short interval pregnancy (<18 months) as an independent risk factor for the development of advanced pathology.

RESULTS

33.8% (45/133) of patients with PAS had pregnancies complicated by short intervals between gestations. Short interval pregnancies were significantly associated with placenta percreta/increta pathology (p = .006). Ordinal logistic regression showed an inversely proportional relationship between short-interval pregnancy and the degree of placental invasion (OR 2.91 [95% CI 1.02, 4.05]).

CONCLUSION

Short interval pregnancies are at increased risk for greater degrees of placenta invasion seen in placenta increta and percreta when compared to interpregnancy interval >18 months. This relationship is inversely proportional and consistent at shorter intervals. Thus, when counseling patients on their overall risk of placental invasive pathology, short interval pregnancy may be considered a significant risk factor.

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.

Association between deficient cesarean delivery scar and cesarean scar syndrome

INTRODUCTION

The aim of our study was to compare long-term morbidity after elective and emergency cesarean delivery (CD).

METHODS

A prospective cohort study was conducted in 200 women delivered by CD. Ultrasound examinations were performed transvaginally at 6 weeks and 18 months after CD. Clinical data were collected at the time of CD and after 18 months.

RESULTS

In the group of 200 women, 29% underwent emergency and 71% elective CD. Then, 6 weeks and 18 months after CD, a severe scar defect was present in 7% and 5%, respectively (P = .4). After 18 months of CD, 17% (34/200) of women had evidence of adhesions of the vesicouterine pouch. Severe CD scar defects were significant predictors for adhesion formation in vesicouterine pouch (OR 3.14, 95% CI, 1.54-4.74), pelvic pain (OR 1.68, 95% CI, 0.22-3.14), dysmenorrhea (OR 2.12, 95% CI, 0.74-3.50), and dyspareunia (OR 1.38, 95% CI, 0.09-2.67). Uterine scar defects detected at 6 weeks after elective CD were detectable at 18 months in only 40% of cases, whereas uterine scar defects after emergency CD were still detectable in 87% of cases.

CONCLUSION

Uterine scar defects are more frequent at 18 weeks after emergency CD, than after elective CD (40% vs 87%). Women with severe scar defects have higher risk of adhesion formation, dysmenorrhea, dyspareunia, and chronic pelvic pain.

The use of image fusion in prenatal medicine

Fusion imaging (FI), the simultaneous display of the same anatomical region using two imaging modalities, has been used in other areas of medicine for both diagnosis and guiding interventions. Examples include positron emission tomography-computed tomography (PET-CT) imaging in oncology and ultrasound-magnetic resonance imaging (US-MRI) fusion in biopsies of the prostate gland. The underlying principle is to take advantage of the complementary information in each modality to improve accuracy, be it diagnostic accuracy or targeting accuracy in biopsies. For example, PET-CT overlays the metabolic activity of lesions on the superb spatial and anatomical detail of CT. While the historical mainstay of fetal imaging has been ultrasound, advances in ultrafast MR imaging together with advances in fetal MRI over the past two decades, have resulted in the opportunity to explore fusion imaging in fetal medicine. We present an overview of the principles of US-MRI fusion imaging in prenatal medicine, report our local experience, and review the literature in this emerging area. We share our perspective on how FI can improve diagnostic confidence, be used as an educational tool, and potentially enhance guidance in certain fetal procedures.