Placental location and risk of retained placenta in women with a previous cesarean section: A population-based cohort study

Placental Location Site and Associated Intrapartum, Postpartum, and Neonatal Complications: A Comprehensive Review and Meta-Analysis

Background/Objectives: Adverse intrapartum, postpartum, and neonatal complications have been linked to placenta implantations sites. However, different reviews have led to contrasting conclusions about placental locations and pregnancy outcomes. We aim to determine if there is a relationship between the placental implantation site and intrapartum, postpartum, and neonatal outcomes. Methods: The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed during this review. The literature search used PubMed, CINAHL, and Embase. Years searched was not a study limitation. Only articles in English were included. Two authors reviewed the abstracts. Results: Of 40 articles identified as specific to intrapartum, postpartum, and/or neonatal complications (with some articles overlapping categories), 19 included intrapartum complications, 19 included postpartum complications, and 22 included neonatal complications. Pregnancies with a midline placenta (compared to a lateral placenta) had a greater likelihood of macrosomia/LGA infant (odds ratio (OR), 1.52 (95% CI: 1.22-1.90)) and lesser likelihood to have non-cephalic presentation (OR, 0.17 (95% CI: 0.06-0.51)), FGR/SGA infant (OR, 0.68 (CI: 0.55-0.85)), and retained placenta (OR, 0.33 (95% CI: 0.22-0.50)). Pregnancies with a low-lying placenta (compared to within uterine corpus) were more likely to have non-elective cesarean section (OR, 1.94 (95% CI: 1.06-3.55)) and postpartum hemorrhage (OR 1.49 (95% CI: 1.12-1.97)). Conclusions: Significant associations between placental location site and intrapartum complications (non-cephalic presentation, non-elective cesarean section), postpartum complications (postpartum hemorrhage, retained placenta), and neonatal complications (FGR/SGA, Macrosomia/LGA) were identified. There were no significant associations identified between the placental location site and several neonatal complications, including Apgar < 7 at 5 min, NICU admission, IUFD, and neonatal death.

Association between placental location and cord insertion site with pre-eclampsia: a retrospective cohort study

OBJECTIVE

The relationship between placental location in pregnancies without previa and adverse pregnancy outcomes has not been well studied. Additionally, the impact of abnormal cord insertion sites remains controversial. Therefore, the objective of this study was to explore the adverse outcomes associated with placental location and abnormal cord insertion in nulliparous women and to assess their impact on pregnancy outcomes.

METHODS

This retrospective cohort study was conducted at a single tertiary hospital between January 2019 and June 2022. The study included nulliparous women with singleton pregnancies who delivered live infants and had available data on placental location and umbilical cord insertion site from a second- or third-trimester ultrasound. Placental location was categorized as anterior or posterior using transabdominal ultrasonography. The association between placental location/cord insertion site and pre-eclampsia was evaluated using multivariate logistic regression analysis. We compared the area under the curve to evaluate the impact of placental location and cord insertion site on pre-eclampsia.

RESULTS

A total of 2219 pregnancies were included in the study. Pre-eclampsia occurred significantly more frequently in the anterior group than in the posterior group (8.21% vs. 3.04%, p < .001). In multivariate analysis investigating the association between placental location and pre-eclampsia, anterior placenta and marginal cord insertion showed increased odds ratios for pre-eclampsia of 3.05 (95% confidence interval [CI] 1.68-6.58) and 3.64 (95% CI 1.90-6.97), respectively. Receiver operating characteristic (ROC) curves were constructed to predict pre-eclampsia using independent factors from multivariate analyses. Model I, including maternal age, pre-pregnancy body mass index, in vitro fertilization, chronic hypertension, overt diabetes, kidney disease, and hematologic diseases, achieved an area under the ROC curve of 0.70 (95% CI 0.65-0.75). Adding cord insertion site and placental location to the model (Model II) improved its predictive performance, resulting in an area under the ROC curve of 0.749 (95% CI 0.70-0.79, p = .02).

CONCLUSIONS

Anterior placenta and marginal cord insertion were associated with an increased risk of pre-eclampsia. Further studies on prospective cohorts are necessary to validate these findings.

Association between first-trimester ultrasound imaging of eccentric implantation and retained placenta

OBJECTIVES

To evaluate first-trimester ultrasound imaging of eccentric implantation in predicting the probability of retained placenta.

METHODS

A total of 61 cases with gestational sac eccentrically implanted in first-trimester ultrasound imaging was selected. Demographic and obstetric data were collected through data extraction of the electronic medical record at the time of delivery admission. Baseline characteristics (including age, gestational age of first-trimester ultrasound, size of gestational sac, gestational age of delivery), delivery outcomes (mode of delivery, retained placenta or placental fragments, blood loss, postpartum hemorrhage and postpartum ultrasound imaging) were collected and analyzed.

RESULTS

The risk difference for a woman with eccentric implantation to have a retained placenta was -0.18 (95% CI -0.28 to -0.08, p = 0.000) and the incidence of retained placenta in the study group was higher than in the control group (18% vs. 0%, p = 0.006). First-trimester ultrasound imaging of eccentric implantation was also found to be an independent risk factor for the incidence of inhomogeneous mass in postpartum ultrasound imaging (27.9% vs. 10.8%, adjusted OR 0.19, 95% CI 0.05 to 0.79, p = 0.012). Though 2 cases in the study group suffered postpartum hemorrhage, the risk difference for a woman with eccentric implantation to suffer postpartum hemorrhage was -0.03 (95% CI -0.08 to -0.01, not significant) and eccentric implantation did not increase postpartum hemorrhage rates (3.3% vs. 0%, not significant).

CONCLUSIONS

First-trimester ultrasound imaging of eccentric implantation was associated with an increased risk of retained placenta and inhomogeneous mass in postpartum ultrasound imaging.

Risk factors for retained placenta in a first pregnancy-A clinical trial

OBJECTIVE

To evaluate potential risk factors for retained placenta in a first pregnancy.

METHOD

This retrospective case-control study included all primigravida with a singleton, live, vaginal birth at 24 weeks or later, at a tertiary hospital, 2014-2020. The cohort was divided into those with retained placenta versus controls. Retained placenta was defined as the need for manual extraction of the placenta or portions of it, immediately postpartum. Maternal and delivery characteristics, and obstetric and neonatal adverse outcomes, were compared between groups. Multivariable regression was performed to reveal potential risk factors for retained placenta.

RESULTS

Among 10 796 women, 435 (4.0%) had retained placenta and 10 361 (96.0%) controls did not. Multivariable logistic regression revealed nine potential risk factors for retained placenta: abruption (adjusted odds ratio [aOR] 3.58, 95% confidence interval [CI] 2.36-5.43), hypertensive disorders (aOR 1.74, 95% CI 1.17-2.57), prematurity (<37 weeks, aOR 1.63, 95% CI 1.13-2.35), maternal age older than 30 years (aOR 1.55, 95% CI 1.27-1.90), intrapartum fever (aOR 1.48, 95% CI 1.03-2.11), lateral placentation (aOR 1.39, 95% CI 1.01-1.91), oxytocin administration (aOR 1.39, 95% CI 1.11-1.74), diabetes mellitus (aOR 1.35, 95% CI 1.01-1.79), and female fetus (aOR 1.26, 95% CI 1.03-1.53).

CONCLUSION

Retained placentas in first deliveries are associated with obstetric risk factors, some of which could be related to abnormal placentation.

Ultrasound for diagnosis of postpartum retained products of conception-How accurate we are?

OBJECTIVE

Postpartum retained products of conception (RPOC) can cause short- and long-term complications. Diagnosis is based on ultrasound examination and treated with hysteroscopy. This study evaluated the size of RPOC that can be related to a positive pathology result for residua.

MATERIALS AND METHODS

This retrospective cohort study included women who underwent hysteroscopy for postpartum RPOC diagnosed by ultrasound, 4/2014-4/2022. Demographics, intrapartum, sonographic, intraoperative, and post-operative data were retrieved. We generated a ROC curve and found 7 mm was the statistically sonographic value for positive pathology for RPOC. Data between women with sonographic RPOC ≤ 7 mm and > 7 mm were compared. Positive and negative predictive values were calculated for RPOC pathology proved which was measured by ultrasound.

RESULTS

Among 212 patients who underwent hysteroscopy due to suspected RPOC on ultrasound, 20 (9.4%) women had residua ≤ 7 mm and 192 (90.6%) had residua > 7 mm. The most common complaint was vaginal bleeding in 128 cases (60.4%); more so in the residua > 7 mm group (62.5% vs. 40%, p = .05). Among women with residua ≤ 7 mm, the interval from delivery to hysteroscopy was longer (117.4 ± 74.7 days vs. 78.8 ± 68.8 days, respectively; p = .02). Positive pathology was more frequent when residua was > 7 mm. PPV for diagnosis of 7 mm RPOC during pathology examination was 75.3% and NPV 50%.

CONCLUSIONS

Sonographic evaluation after RPOC showed that residua > 7 mm was statistically correlated with positive RPOC in pathology and PPV of 75% and NPV of 50%. Due to the high NPV and low complication rate of office hysteroscopy, clinicians should consider intervention when any RPOC are measured during sonographic examination to reduce known long-term complications.

Placental location and obstetrical-neonatal outcomes: A retrospective study

OBJECTIVE

To explore the potential association of lateral placentation with pregnancy outcome.

METHODS

The database of a tertiary medical center was searched for women who gave birth to a singleton neonate from 2012 to 2020 for whom placental location was documented during antepartum sonographic examination. Clinical data were compared between patients with a central (anterior/posterior/fundal) or lateral placenta using standard statistics. The primary outcome measure was neonatal birthweight, and secondary outcome measures were pregnancy complications and mode of delivery.

RESULTS

The cohort included 12 306 women: 11 608 (94%) with a central placenta and 698 (5.6%) with a lateral placenta. The lateral placenta group had higher rates (P < 0.05) of prior and current cesarean delivery, assisted delivery, and preterm birth. On multivariate regression analyses, placental location (adjusted odds ratio [aOR], 1.36; 95% confidence interval [CI], 1.11-1.66) and maternal age (aOR, 1.02; 95% CI, 1.01-1.03) were associated with risk of preterm birth. Lateral placenta (aOR, 1.22; 95% CI, 1.02-1.47), maternal age (aOR, 1.07; 95% CI, 1.06-1.08), parity (aOR, 0.32; 95% CI, 0.28-0.35), and prior cesarean delivery (aOR, 12.00; 95% CI, 10.60-13.60) were associated with risk of current cesarean delivery.

CONCLUSION

The findings suggest that lateral placentation may pose a risk of preterm birth and cesarean delivery compared with central placentation.

The Stockholm-Gotland perinatal cohort-A population-based cohort including longitudinal data throughout pregnancy and the postpartum period

BACKGROUND

Register-based reproductive and perinatal databases rarely contain detailed information from medical records or repeated measurements throughout pregnancy and delivery. This lack of enriched pregnancy and birth data led to the initiation of the Swedish Stockholm-Gotland Perinatal Cohort (SGPC).

OBJECTIVES

To describe the strengths of the SGPC, as well as the unique research questions that can be addressed using this cohort.

POPULATION

The SGPC is a prospectively collected, population-based cohort that includes all births (from 22 completed gestational weeks onwards) between 1 January 2008 and 15 June 2020 in the Stockholm and Gotland regions of Sweden (N 335,153 singleton and N 11,025 multiple pregnancies).

DESIGN

Descriptive study.

METHODS

The SGPC is based on the electronic medical records of women and their infants. The medical record system is used for all antenatal clinic visits and admissions, delivery and neonatal admissions, as well as postpartum clinical visits. SGPC has been further enriched with data linkages to 10 Swedish National Health Care and Quality Registers.

PRELIMINARY RESULTS

In contrast to other reproductive and perinatal databases available in Sweden, including the Medical Birth Register and the Pregnancy Register, SGPC contains highly detailed medical record data, including time-varying serial measurements for physiological parameters throughout pregnancy, delivery, and postpartum, for both mother and infant. These strengths have enabled studies that were previously inconceivable; the effects of serial measurements of pregnancy weight gain, changes in haemoglobin counts and blood pressure during pregnancy, fetal weight estimations by ultrasound, duration of stages and phases of labour, cervical dilatation and oxytocin use during delivery, and constructing reference curves for umbilical cord pH.

CONCLUSIONS

The SGPC-with its rich content, repeated measurements and linkages to numerous health care and quality registers-is a unique cohort that enables high-quality perinatal studies that would otherwise not be possible.

Risk factors and recurrence of cause-specific postpartum hemorrhage: A population-based study

OBJECTIVE

To explore risk profiles of the different types of postpartum hemorrhage (PPH >500ml or severe PPH >1500ml) and their recurrence risks in a subsequent delivery.

METHODS

With data from The Medical Birth Registry of Norway and Statistics Norway we performed a population-based cohort study including all singleton deliveries in Norway from 1967-2017. Multilevel logistic regression was used to calculate odds ratio (OR), with 95% confidence interval (CI), with different PPH types (PPH >500ml or PPH >1500ml (severe PPH) combined with retained placenta, uterine atony, obstetric trauma, dystocia, or undefined cause) as outcomes.

RESULT

We identified 277 746 PPH cases of a total of 3 003 025 births (9.3%) from 1967 to 2017. Retained placenta (and/or membranes) was most often registered as severe PPH (29.3%). Maternal, fetal, and obstetric characteristics showed different associations with the PPH types. Male sex of the neonate was associated with reduced risk of PPH. This effect was strongest on PPH due to retained placenta (adjusted OR, (aOR): 0.80, 95% CI 0.78-0.82), atony (aOR 0.92, 95% CI: 0.90-0.93) and PPH with undefined cause (aOR 0.96, 95% CI: 0.95-0.97). Previous cesarean section showed a strong association with PPH due to dystocia (aOR of 13.2, 95% CI: 12.5-13.9). Recurrence risks were highest for the same type: PPH associated with dystocia (aOR: 6.8, 95% CI: 6.3-7.4), retained placenta and/or membranes (aOR: 5.9, 95% CI: 5.5-6.4), atony (aOR: 4.0, 95% CI: 3.8-4.2), obstetric trauma (aOR: 3.9, 95% CI: 3.5-4.3) and PPH of undefined cause (aOR: 2.2, 95% CI: 2.1-2.3).

CONCLUSION

Maternal, fetal and obstetric characteristics had differential effects on types of PPH. Recurrence differed considerably between PPH types. Retained placenta was most frequently registered with severe PPH, and showed strongest effect of sex; delivery of a boy was associated with lower risk of PPH. Previous cesarean increased the risk of PPH due to dystocia.

The impact of lateral placenta on preeclampsia and small for gestational age neonates: a systematic review and meta-analysis

OBJECTIVES

We conducted a systematic review and meta-analysis to quantitatively summarize the present data on the association of prenatally identified lateral placenta in singleton pregnancies with small for gestational age (SGA) neonates, preeclampsia and other perinatal outcomes.

METHODS

From inception to November 2021, we searched PubMed/Medline, Scopus and The Cochrane Library for papers comparing the risk of SGA and preeclampsia, as well as other perinatal outcomes in singleton pregnancies with a prenatally identified lateral placenta to those with non-lateral placentas. The revised Newcastle-Ottawa Scale was used to evaluate the quality of eligible papers. The I² test was employed to evaluate the heterogeneity of outcomes among the studies. To investigate the possibility of publication bias, funnel plots were constructed. Prospero RN: CRD42021251590.

RESULTS

The search yielded 5,420 articles, of which 16 were chosen, comprising of 15 cohort studies and one case control study with a total of 4,947 cases of lateral and 96,035 of non-lateral placenta (controls) reported. SGA neonates were more likely to be delivered in cases with a lateral placenta (OR: 1.74; 95% CI: 1.54-1.96; p<0.00001; I²=47%). Likewise, placental laterality was linked to a higher risk of fetal growth restriction (OR: 2.18; 95% CI: 1.54-3.06; p<0.00001; I2=0%), hypertensive disorders of pregnancy (OR: 2.39; 95% CI: 1.65-3.51; p=0.0001; I²=80%), preeclampsia (OR: 2.92; 95% CI: 1.92-4.44; p<0.0001; I²=82%) and preterm delivery (OR: 1.65; 95% CI: 1.46-1.87; p<0.00001; I²=0%).

CONCLUSIONS

The prenatal diagnosis of a lateral placenta appears to be associated with a higher incidence of preeclampsia, fetal growth restriction, preterm delivery and SGA. This may prove useful in screening for these conditions at the second trimester anomaly scan.

Obstetric and Perinatal Outcomes After Assisted Reproductive Technology in Women With Cesarean Scar

Introduction

Assisted reproductive technology (ART) and previous Cesarean section (CS) are independently associated with the risk of adverse obstetric and perinatal outcomes in general. Few studies have focused on the association between adverse obstetric and perinatal outcomes and ART used in the high-risk population of women with previous CS.

Materials and Methods

A retrospective cohort study including 14,099 women with a previous delivery and a subsequent delivery between April 2014 and April 2020 was conducted at our hospital. We assessed the risk of adverse obstetric and perinatal outcomes in pregnancies conceived by ART in women with previous CS, using log-binomial regression models.

Results

In women with previous CS, ART singleton pregnancies were associated with an increased risk of maternal complications, such as pregnancy complications, placental anomalies of implantation, postpartum hemorrhage, and preterm birth (PTB), as compared to spontaneously conceived pregnancies. The implementation of ART and previous CS interacted in a synergistic manner to increase the likelihood of the placenta accreta spectrum in women with singleton pregnancies [adjusted relative risk (aRR) 5.30, 95% confidence interval (CI) 4.01–7.00; relative risk due to interaction: 1.41, 95%CI 0.07–2.75]. In women with previous CS who underwent ART, women with singletons conceived through intracytoplasmic sperm injection were at increased risk of velamentous placenta (aRR 2.46, 95%CI 1.35–4.48) compared with those with singletons conceived through in vitro fertilization (IVF), whereas women with singletons conceived through cleavage-stage embryo transfer (ET) were at increased risk of gestational diabetes mellitus (GDM) (aRR 1.74, 95%CI 1.16-2.60) than those with singletons conceived through blastocyst–stage ET.

Conclusion

Pregnancies conceived through ART were at increased risk for adverse obstetric and perinatal outcomes in women who had previously delivered by CS, particularly for placental anomalies of implantation. In women with previous CS undergoing ART, IVF and blastocyst–stage ET may be a relatively safe treatment.

Risk factors for non-adherent retained placenta after vaginal delivery: a systematic review

Background

Retained placenta represents a cause of maternal morbidity and mortality affecting 0.5–3% of all vaginal deliveries. The unpredictability of this condition makes difficult to develop predictive and preventive strategies to apply in clinical practice. This analysis collected and analyzed all known risk factors related to this obstetric complication.

Methods

A systematic literature review for all original research articles published between 1990 and 2020 was performed. Observational studies about retained placenta risk factors published in English language were considered eligible. Conference abstracts, untraceable articles and studies focused on morbidly adherent placenta were excluded. The included articles were screened to identify study design, number of enrolled patients and retained placenta risk factors investigated. All stages of the revision followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement.

Results

Thirty-five studies met the inclusion criteria. The reported retained placenta prevalence ranged from 0.5 to 4.8%. Maternal age, previous cesarean sections, previous dilation and curettage, previous retained placenta, labor induction, resulted as the most recurrent, independent risk factors for retained placenta. Previous estro-progestins therapy, morphological placental features (weight, shape, insertion of umbilical cord, implantation site), endometriosis, Assisted Reproductive Technologies, Apgar score are fascinating new proposal risk factors.

Conclusions

Old and new data are not enough robust to draw firm conclusions. Prospective and well-designed studies, based on a well agreed internationally retained placenta definition, are needed in order to clarify this potential dramatic and life-threatening condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03721-9.

CIRSE standards of practice on gynaecological and obstetric haemorrhage

This CIRSE Standards of Practice document provides best practices for obstetric haemorrhage embolisation (OHE) in the management of postpartum haemorrhage (PPH). The document is aimed at interventional radiologists involved in treating postpartum haemorrhage, and has been developed by a writing group established by the CIRSE Standards of Practice Committee.

CIRSE Standards of Practice documents are not clinical practice guidelines and do not intend to impose a standard of care, rather provide reasonable approaches to and best practices for specific interventional radiology treatments and techniques.