Increased incidence of placenta praevia and accreta with previous caesareans – A hypothesis for causation

Evaluation of Association Between Adenomyosis and Cesarean Scar Defect

PURPOSE

This study aims to investigate and compare quantitative factors of the cesarean scar defect (CSD) in symptomatic patients with and without uterine adenomyosis.

METHOD

This study was conducted as a case-control study. Patients who met the inclusion criteria were divided into two groups: with adenomyosis (case) and without adenomyosis (control). The demographic data, medical history, and sonohysterography findings were extracted from the patient's documents and archived images.

RESULT

During 2 years, 310 symptomatic women with a history of previous cesarean section underwent sonohysterography. Among them, 204 patients met the inclusion criteria. The most common chief complaints were post-menstrual bleeding (34.3%) and prolonged bleeding (27%). Cesarean scar depth and width significantly differed between these two groups, and patients with underlying adenomyosis had significantly larger defects (P-value of .009 and .005, respectively). Mean RMT/AMT ratio was 31.83% in the case group and 42.88% in the control group. In our study, RMT/AMT ratios were significantly lower in the case group (P-value of .001). In addition, we performed analysis on a subgroup of patients with one prior cesarean section. Similar results were achieved with a lower RMT/AMT ratio in case group (mean of 31.20% in case group and 46.47% in control group; P-value of .000).

CONCLUSION

Our study showed a strong association between the presence of adenomyosis and larger clinically more significant CSDs. To establish a causative relationship, we suggest a prospective cohort study to follow up the patients and compare the evolution of CSD in patients with and without adenomyosis.

Knowledge Gaps in Placenta Accreta Spectrum

Since its first description early in the 20th Century, placenta accreta and its variants have changed substantially in incidence, risk factor profile, clinical presentation, diagnosis and management. While systematic use of diagnostic tools and a multidisciplinary team care approach has begun to improve patient outcomes, the condition's pathophysiology, epidemiology, and best practices for diagnosis and management remain poorly understood. The use of large databases with broadly accepted terminology and diagnostic criteria should accelerate research in this area. Future work should focus on non-traditional phenotypes, such as those without placenta previa-preventive strategies, and long term medical and emotional support for patients facing this diagnosis. KEY POINTS: · Placenta accreta spectrum research may be improved with standardized terminology and use of large databases.. · Placenta accreta prediction should move beyond ultrasound with the addition of biomarkers, and needs to extend to those without traditional risk factors.. · Future research should identify practices that can prevent future accreta development..

Correlation Between Previous Caesarean Section and Adverse Maternal Outcomes Accordingly With Robson Classification: Systematic Review and Meta-Analysis

Background: The increasing rates of Caesarean section (CS) beyond the WHO standards (10–15%) pose a significant global health concern.

Objective: Systematic review and meta-analysis to identify an association between CS history and maternal adverse outcomes for the subsequent pregnancy and delivery among women classified in Robson classification (RC).

Search Strategy: PubMed/Medline, EbscoHost, ProQuest, Embase, Web of Science, BIOSIS, MEDLINE, and Russian Science Citation Index databases were searched from 2008 to 2018.

Selection Criteria: Based on Robson classification, studies reporting one or more of the 14 adverse maternal outcomes were considered eligible for this review.

Data Collection: Study design data, interventions used, CS history, and adverse maternal outcomes were extracted.

Main Results: From 4,084 studies, 28 (n = 1,524,695 women) met the inclusion criteria. RC group 5 showed the highest proportion among deliveries followed by RC10, RC7, and RC8 (67.71, 32.27, 0.02, and 0.001%). Among adverse maternal outcomes, hysterectomy had the highest association after preterm delivery OR = 3.39 (95% CI 1.56–7.36), followed by Severe Maternal Outcomes OR = 2.95 (95% CI 1.00–8.67). We identified over one and a half million pregnant women, of whom the majority were found to belong to RC group 5.

Conclusions: Previous CS was observed to be associated with adverse maternal outcomes for the subsequent pregnancies. CS rates need to be monitored given the prospective risks which may occur for maternal and child health in subsequent births.

The higher incision at upper part of lower uterine segment in caesarean section can decrease the incidence of placenta accreta spectrum

Caesarean section rate and placenta accreta spectrum prevalence are in continuous increase during last years. Multiple hypotheses can explain the abnormal adherence of placenta trophoblast to the myometrium. By reviewing the surgical techniques used in caesarean section, we hypothesize that the higher uterine incision at upper part of lower segment could decrease the abnormal placentation in next pregnancies.

Endometrium-free uterine closure technique and abnormal placental implantation in subsequent pregnancies

BACKGROUND

Abnormal placentation can result in massive hemorrhage, which is the leading cause of severe maternal morbidities and mortality in its management. Over the past 50 years, the incidence of placenta previa (PP), abnormal implantation of the placenta, and cesarean scar pregnancy have continued to rise. This coincides with the well-documented parallel rise in the rate of cesarean deliveries, the performance of multiple repeat cesarean deliveries and the adoption of newer uterine closure techniques. However, no studies have examined the role of uterine closure techniques in abnormal placentation in women with a history of a prior cesarean delivery.

OBJECTIVE

To assess the practicality of one specific uterine closure technique at cesarean delivery and to evaluate the relationship between previous cesarean delivery and subsequent development of abnormal implantation of the placenta, as well as neonatal and other perioperative outcomes after receiving an endometrium-free uterine closure technique.

METHODS

This retrospective observational study considered cesarean deliveries (n = 727) and subsequent vaginal births after cesarean delivery (n = 109) among total deliveries (n = 4496) performed in private practice at NYU Langone Health from 1985 to 2015. All cesarean deliveries were performed using the endometrium-free uterine closure technique. The primary outcome was the incidence of abnormal implantation of the placenta in subsequent pregnancies. The secondary outcomes were neonatal and maternal complications, specifically postoperative hemoglobin and hematocrit concentration losses. The association between independent variables and outcomes were evaluated using mixed-effect regression models.

RESULTS

In contrast to published data, independent of the number of repeat cesarean deliveries, the presence of 26 (3.1%) PPs and of 366 (43.8%) anterior placentas, there were no patients with abnormal implantation of the placenta in a cesarean scar, neither prenatally nor at delivery. Maternal hemorrhage, postoperative and neonatal complications did not reach clinical significance. The statistical analysis revealed that, when compared with women who had fewer repeat cesarean deliveries using endometrium-free uterine closure technique, those with the most had a lesser risk of forming PP and less blood loss, as measured by both hematocrit and hemoglobin evaluation.

CONCLUSION

In this retrospective cohort study, the exclusion of the endometrium during the endometrium-free uterine closure technique was associated with fewer placental abnormalities in subsequent pregnancies and reduced life-threatening maternal morbidity for future cesarean deliveries.

Effect of site of placentation on pregnancy outcomes in patients with placenta previa

INTRODUCTION

We aimed to evaluate the site of placentation on the pregnancy outcomes of patients with placenta previa.

METHODS

This retrospective study included 678 cases of placenta previa. Basic information and pregnancy outcome data were collected. Differences between the different placenta previa positions and pregnancy outcomes were compared using the chi-square and independent t tests. Logistic and multiple regression analyses were used to calculate the odds ratios (ORs) to determine the risk factors for PAS disorders and postpartum hemorrhage and evaluate the effect of placental attachment site on pregnancy outcomes.

RESULTS

There was no significant difference between the PAS disorders rate and the incidence of complete placenta previa depending on the type of placentation; however, placental attachment site influenced the pregnancy outcome. Placental attachment to the anterior wall was associated with shorter gestational age, low birth weight, lower Apgar score, higher prenatal bleeding rate, increased postpartum hemorrhage, longer duration of hospitalization, and higher blood transfusion and hysterectomy rates compared to cases with lateral/posterior wall placenta. Placental attachment at the incision site of a previous cesarean section significantly increased the incidence of complete placenta previa and PAS disorders compared with placental attachment at a site without incision, but did not significantly influence pregnancy outcomes. Placental attachment to the anterior wall was an independent risk factor for postpartum hemorrhage in patients with placenta previa. Placental attachment to a previous incision site was an independent risk factor for PAS disorders.

CONCLUSION

The site of placental attachment in patients with placenta previa has an important influence on the pregnancy outcome. When the placenta is located on the anterior wall, clinicians should pay attention to the adverse pregnancy outcomes and the possibility of massive postpartum hemorrhage. In cases of placental attachment to the uterine incision site, physicians should be highly vigilant regarding the occurrence of PAS disorders.

Association between first caesarean delivery and adverse outcomes in subsequent pregnancy: a retrospective cohort study

Background

Few studies have explored the association between a previous caesarean section (CS) and adverse perinatal outcomes in a subsequent pregnancy, especially in women who underwent a non-indicated CS in their first delivery. We designed this study to compare the perinatal outcomes of a subsequent pregnancy in women who underwent spontaneous vaginal delivery (SVD) or CS in their first delivery.

Methods

This retrospective cohort study included women who underwent singleton deliveries at the International Peace Maternity and Child Health Hospital from January 2013 to December 2016. Data on the perinatal outcomes of all the women were extracted from the medical records. Multivariate logistic regression was conducted to assessed the association between CS in the first delivery and adverse perinatal outcomes in the subsequent pregnancy.

Results

CS delivery in the subsequent pregnancy was more likely for women who underwent CS in their first birth than for women with previous SVD (97.3% versus 13.2%). CS in the first birth was also associated with a significantly increased risk of adverse outcomes in the subsequent pregnancy, especially in women who underwent a non-indicated CS. Adverse perinatal outcomes included pregnancy-induced hypertension [adjusted odds ratio (OR), 95% confidence interval (CI): 2.20, 1.59–3.05], gestational diabetes mellitus (1.82, 1.57–2.11), gestational anaemia (1.27, 1.05–1.55), placenta previa (3.18, 2.15–4.71), placenta accreta (2.75, 1.75–4.31), and polyhydramnios (2.60, 1.57–4.31) in the mother and preterm delivery (1.37, 1.06–1.78), low birth weight (3.78, 2.07–6.90), macrosomia (5.04, 3.95–6.44), and neonatal jaundice (1.72, 1.39–2.14) in the baby.

Conclusions

CS in the first delivery markedly increases the risk of repeated CS and maternal-fetal complications in the subsequent pregnancy, especially in women with a non-indicated CS.

Etiology of Cesarean Uterine Scar Defect (Niche): Detailed Critical Analysis of Hypotheses and Prevention Strategies and Peritoneal Closure Debate

There is an increasing incidence of cesarean scar (CS) defect/niche and its sequelae, probably not entirely explained by better diagnosis or rising cesarean rate. Discussion of possible etiological factors has received scant attention but would be important to formulate preventive strategies. Meaningful informative studies on long-term sequelae of cesarean section are very difficult and none are available for causation of CS defect. Hence, it is crucial to identify key areas in etiology of CS defect for focused research. This practical review proposes an "ischemia and mal-apposition hypothesis for CS niche", stating that the surgical technique of uterine incision closure is the most important determinant of CS defect formation. Other factors such as cervical location incision, adhesion formation and patient specific factors seem far less important in etiology. Rather than the headline theme of "single versus double-layer closure of uterus", the finer details of surgical technique which achieve good apposition without inducing tissue ischemia seem more important. Different techniques are discussed and it is proposed that continuous, non-locking absorbable sutures in two layers, without including much of decidua and without undue tight (constricting/devasculaizing) pulling of sutures are likely to result in good healing of uterine scar. Single-layer technique may be best reserved for thin myometrial edges especially during repeat cesareans. Adhesions between uterine isthmus and bladder/abdominal wall seem common associations but not causative for CS niche. It would be desirable to prove these surgical principles by good quality prospective randomized "quantitative" studies but the wait may be very long and this should not hinder the adoption of good surgical principles. Science is much cognitive and not just empirical. To consider a related example, the current recommendation of non-suturing of peritoneal layers during cesarean is mistakenly based on short-term irrelevant surrogate outcomes like analgesic requirements and time-saving, many of which have been already disproven. Evidence is presented recommending simple quick techniques of peritoneal closure to prevent adhesions. More analytical debate in surgical techniques is needed to inspire engaged, critical and insightful practitioners rather than unquestioning dependence on weak evidence/guidance.

Histopathology of Placenta Creta: Chorionic Villi Intrusion into Myometrial Vascular Spaces and Extravillous Trophoblast Proliferation are Frequent and Specific Findings With Implications for Diagnosis and Pathogenesis

Placenta creta is characterized by invasion of placental villi into the myometrium in the setting of a dysfunctional or absent decidua. Histopathologic diagnosis of placenta creta is important, particularly in cases of hysterectomy because of unanticipated intractable postpartum hemorrhage. Previous studies have documented a higher amount and depth of myometrial infiltration by the implantation site intermediate trophoblast compared with controls. In addition, we have anecdotally observed chorionic villi in myometrial vascular spaces in specimens with placenta creta. The aim of this study was to explore the prevalence and specificity of these features. Sixty-one postpartum hysterectomies, 44 with placenta creta and 17 without were reviewed. Villous intrusion into vascular spaces was recorded. Using immunohistochemistry for GATA3, the amount of intermediate trophoblast (number of positive cells in five 40× fields) and depth of trophoblast myometrial infiltration were assessed. Mean gestational ages of the creta group (34.4 yr; range, 20-43 yr) and control group (35 yr; range, 25-51 yr) were comparable. Presence of chorionic villi in myometrial vascular spaces was frequent in placenta creta: 31/44 versus 1/17 controls (70.4% vs. 5.8%, P<0.0001). This finding was more common in the percreta (87.5%) and increta (84%) than in the accreta (27.2%, P=0.0008). Mean depth of trophoblast myometrial invasion was greater in cretas (47.9%) than in controls (14.5%, P=0.004). Likewise, mean distance of deepest trophoblast to serosa was shorter in the cretas (7.3 mm) than in controls (23.8 mm, P<0.0001). These differences were, however, attributable to placentas increta and percreta. When only accretas and controls were compared, the myometrial depth of trophoblast was similar. The mean intermediate trophoblast cell count in the placental bed was greater in cretas (664) than in controls (288, P<0.0001). Such difference was seen in all creta cases despite the type (accreta 639, increta 676, percreta 661). A trophoblast count of ≥100 cells/high-power field was seen in 75.8% of cretas and 11.1% of controls (P=0.0009). For the first time, we document the finding of chorionic villi intrusion into myometrial vascular spaces, which is highly specific of placenta creta. In addition, assessment of the amount of intermediate trophoblast using GATA3 immunohistochemistry can assist in the diagnosis. We hypothesize that placental invasion in placenta creta is due, at least partially, to transformation of low-resistance myometrial vessels leading to subsequent protrusion of villi into their lumens, in the context of absent decidua.

Morbidity associated with cesarean delivery in the United States: is placenta accreta an increasingly important contributor?

OBJECTIVE

The purpose of this study was to examine cesarean delivery morbidity and its predictors in the United States.

STUDY DESIGN

We used 2000-2011 Nationwide Inpatient Sample data to identify cesarean deliveries and records with 12 potential cesarean delivery complications, including placenta accreta. We estimated cesarean delivery morbidity rates and rate changes from 2000-2011, and fitted Poisson regression models to assess the relative incidence of morbidity among repeat vs primary cesarean deliveries and explore its predictors.

RESULTS

From 2000-2011, 76 in 1000 cesarean deliveries (97 in 1000 primary and 48 in 1000 repeat cesarean deliveries) were accompanied by ≥1 of 12 complications. The unadjusted composite cesarean delivery morbidity rate increased by 3.6% only among women with a primary cesarean delivery (P < .001); the unadjusted rate of placenta accreta increased by 30.8% only among women with a repeat cesarean deliveries (P = .025). The adjusted rate of overall composite cesarean delivery morbidity decreased by 1% annually from 2000-2011 (P < .001). Compared with women with a primary cesarean delivery, those women who underwent a repeat cesarean delivery were one-half as likely (incidence rate ratio, 0.50; 95% CI, 0.49-0.50) to experience a complication, but 2.13 (95% CI, 1.98-2.29) times more likely to have a placenta accreta diagnosis. Both cesarean delivery morbidity and placenta accreta were positively associated with age >30 years, non-Hispanic black race/ethnicity, the presence of a chronic medical condition, and delivery in urban, teaching, or larger hospitals.

CONCLUSION

Overall, cesarean delivery morbidity declined modestly from 2000-2011, but placenta accreta became an increasingly important contributor to repeat cesarean delivery morbidity. Clinicians should maintain a high index of suspicion for abnormal placentation and make adequate preparations for patients who need cesarean deliveries.

Evaluating Midwifery Units (EMU): a prospective cohort study of freestanding midwifery units in New South Wales, Australia

OBJECTIVE

To compare maternal and neonatal birth outcomes and morbidities associated with the intention to give birth in two freestanding midwifery units and two tertiary-level maternity units in New South Wales, Australia.

DESIGN

Prospective cohort study.

PARTICIPANTS

494 women who intended to give birth at freestanding midwifery units and 3157 women who intended to give birth at tertiary-level maternity units. Participants had low risk, singleton pregnancies and were at less than 28(+0) weeks gestation at the time of booking.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes were mode of birth, Apgar score of less than 7 at 5 min and admission to the neonatal intensive care unit or special care nursery. Secondary outcomes were onset of labour, analgesia, blood loss, management of third stage of labour, perineal trauma, transfer, neonatal resuscitation, breastfeeding, gestational age at birth, birth weight, severe morbidity and mortality.

RESULTS

Women who planned to give birth at a freestanding midwifery unit were significantly more likely to have a spontaneous vaginal birth (AOR 1.57; 95% CI 1.20 to 2.06) and significantly less likely to have a caesarean section (AOR 0.65; 95% CI 0.48 to 0.88). There was no significant difference in the AOR of 5 min Apgar scores, however, babies from the freestanding midwifery unit group were significantly less likely to be admitted to neonatal intensive care or special care nursery (AOR 0.60; 95% CI 0.39 to 0.91). Analysis of secondary outcomes indicated that planning to give birth in a freestanding midwifery unit was associated with similar or reduced odds of intrapartum interventions and similar or improved odds of indicators of neonatal well-being.

CONCLUSIONS

The results of this study support the provision of care in freestanding midwifery units as an alternative to tertiary-level maternity units for women with low risk pregnancies at the time of booking.