Placenta previa and previous cesarean section

The possible impact of the universal two-child policy on pregnancy outcomes

PURPOSE

The implementation of the universal two-child policy contributes to adverse pregnancy outcomes, but how the policy change leads to adverse pregnancy outcomes is not well elaborated. In this study, we aimed to compare maternal characteristics and complications, accessed the change in the proportion of maternal characteristics and maternal complications, and evaluated the mediation of maternal characteristics on maternal complications.

METHODS

Demographic and clinical data of three-level sample facilities were extracted from China's National Maternity Near Miss Obstetrics Surveillance System from Jan 1, 2012 to May 31, 2021. The associations between the universal two-child policy and maternal risk factors, the universal two-child policy and maternal complications, and maternal risk factors and maternal complications were evaluated using multivariate logistic regression analyses, with odds ratios (ORs) and 95% confidence intervals (CIs). Mediation analysis was used to estimate the potential mediation effects on the associations between the policy and maternal complications. Population-attributable fractions (PAF) were conducted to quantify the maternal complications burden attributable to the implementation of the universal two-child policy.

RESULTS

In the context of the universal two-child policy, the incidence of maternal near miss, antepartum or intrapartum complication, and post-partum complication increased at municipal- and county-level sample facilities. After adjusting for covariables, there were significant associations between the universal two-child policy and maternal risk factors (P < 0.001), the universal two-child policy and an increased risk of maternal complications (P < 0.001), and maternal risk factors and maternal complications(P < 0.001). The effects of the universal two-child policy on maternal near miss and medical disease were significantly mediated by maternal risk factors with mediation proportions of 19.77% and 4.07% at the municipal-level sample facility, and mediation proportions for 2.72% at the county-level sample facility on medical disease. The universal two-child policy contributed 19.34%, 5.82%, 8.29%, and 46.19% in the incidence of the maternal near miss, antepartum or intrapartum complication, post-partum complication, and medical disease at municipal-level sample facility, respectively. The corresponding PAF% at county-level sample facility was 40.49% for maternal near miss, 32.39% for the antepartum or intrapartum complication, 61.44% for post-partum complication, and 77.72% for medical disease. For provincial-level sample facility, the incidence of maternal near miss, antepartum or intrapartum complications, and medical diseases decreased (P < 0.05) and no statistically significant difference occurred in the incidence of post-partum complications.

CONCLUSIONS

In the context of the universal two-child policy, the incidence of maternal near miss, antepartum or intrapartum complication, and post-partum complication increased at municipal- and county-level sample facility. Maternal risk factors may play a mediating role in the effect of policy change and maternal complications. Provincial hospitals have been able to improve the quality of perinatal health care and reduce adverse pregnancy outcomes by adjusting their obstetric service strategies in the context of the new birth policy.

Retained Morbidly Adherent Placenta Presenting as a Myometrial Mass in Patients With Vaginal Bleeding: A Case Series and Review of Current Literature

ABSTRACT

The differential diagnosis for a uterine mass and vaginal bleeding after abortion or delivery is broad and includes both benign and malignant causes. A rare etiology for this condition is retained morbidly adherent placenta. Few cases of retained morbidly adherent placenta presenting as a myometrial mass in the setting of vaginal bleeding have been described in the medical literature. In this case series and review of the current literature, we describe the ultrasound features of 3 retained morbidly adherent placentae, along with correlative magnetic resonance imaging findings.

Risk of placenta previa in second birth after first birth cesarean section: a population-based study and meta-analysis

BACKGROUND

OBJECTIVE

To compare the risk of placenta previa at second birth among women who had a cesarean section (CS) at first birth with women who delivered vaginally.

METHODS

Retrospective cohort study of 399,674 women who gave birth to a singleton first and second baby between April 2000 and February 2009 in England. Multiple logistic regression was used to adjust the estimates for maternal age, ethnicity, deprivation, placenta previa at first birth, inter-birth interval and pregnancy complications. In addition, we conducted a meta-analysis of the reported results in peer-reviewed articles since 1980.

RESULTS

The rate of placenta previa at second birth for women with vaginal first births was 4.4 per 1000 births, compared to 8.7 per 1000 births for women with CS at first birth. After adjustment, CS at first birth remained associated with an increased risk of placenta previa (odds ratio = 1.60; 95% CI 1.44 to 1.76). In the meta-analysis of 37 previously published studies from 21 countries, the overall pooled random effects odds ratio was 2.20 (95% CI 1.96-2.46). Our results from the current study is consistent with those of the meta-analysis as the pooled odds ratio for the six population-based cohort studies that analyzed second births only was 1.51 (95% CI 1.39-1.65).

CONCLUSIONS

There is an increased risk of placenta previa in the subsequent pregnancy after CS delivery at first birth, but the risk is lower than previously estimated. Given the placenta previa rate in England and the adjusted effect of previous CS, 359 deliveries by CS at first birth would result in one additional case of placenta previa in the next pregnancy.

Placenta previa-accreta: risk factors and complications

OBJECTIVE

The purpose of this study was to identify risk factors and complications of placenta previa-accreta (PA).

STUDY DESIGN

Patients with placenta previa (n = 347) delivered over 20 years were reviewed, divided into PA (cases, n = 22) and no accreta (controls, n = 325), and compared.

RESULTS

Cases were older with a higher incidence of smoking and previous cesarean delivery (CS). Grandmultiparity, recurrent abortions, anterior/central placentae, and low socioeconomic status were similar. PA incidence increased with the number of previous CS: 1.9%, 15.6%, 23.5%, 29.4%, 33.3%, and 50.0% after 0, 1, 2, 3, 4, and 5 previous CS, respectively. Hypertensive disorders (odds ratio [OR] 13.9, 95%CI 2.1-91.2], P = .006), smoking (OR 3.4, 95%CI 1.1-10.2, P = .031) and previous CS (OR 7.9, 95%CI 1.7-37.4, P = .009) were selected by the stepwise logistic regression analysis as predictors of PA. Cases had a longer hospital stay, a higher estimated blood loss, and need for transfusion. Cesarean hysterectomy and hypogastric artery ligation were only performed in PA cases. The 2 groups had a similar delivery gestational age and neonatal outcome.

CONCLUSION

Hypertensive disorders, smoking, and previous cesarean are risk factors for accreta in placenta previa patients. Placenta previa-accreta is associated with higher maternal morbidity, but similar neonatal outcome compared with patients with an isolated placenta previa.

Etiology and risk factors for placenta previa: an overview and meta-analysis of observational studies

OBJECTIVE

Several clinical and epidemiologic studies have reported disparate data on the prevalence rate as well as risk factors associated with placenta previa--a major cause of third-trimester bleeding. We performed a systematic literature review and identified 58 studies on placenta previa published between 1966 and 2000.

STUDY DESIGN

Each study was reviewed independently by the two authors and was scored (on the basis of established criteria) on method of diagnosis of placenta previa and on quality of study design. We extracted data on the prevalence rate of placenta previa, as well as associations with various risk factors from each study. A meta-analysis was then performed to determine the extent to which different risk factors predispose women to placenta previa.

RESULTS

Our results showed that the overall prevalence rate of placenta previa was 4.0 per 1000 births, with the rate being higher among cohort studies (4.6 per 1000 births), USA-based studies (4.5 per 1000 births) and hospital-based studies (4.4 per 1000 births) than among case-control studies (3.5 per 1000 births), foreign-based studies (3.7 per 1000 births) and population-based studies (3.7 per 1000 births), respectively. Advancing maternal age, multiparity, previous Cesarean delivery and abortion, smoking and cocaine use during pregnancy, and male fetuses all conferred increased risk for placenta previa. Strong heterogeneity in the associations between risk factors and placenta previa were noted by study design, accuracy in the diagnosis of placenta previa and population-based versus hospital-based studies.

CONCLUSION

Future etiological studies on placenta previa must, at the very least, adjust for potentially confounding effects of maternal age, parity, prior Cesarean delivery and abortions.

Placenta previa: a 22-year analysis

OBJECTIVE

Our purpose was to identify what anesthetic method is safer for women with a placenta previa.

STUDY DESIGN

We retrospectively reviewed all women with placenta previa who underwent cesarean delivery during the period January 1, 1976-December 31, 1997 at Northwestern Memorial Hospital.

RESULTS

Of 93,384 deliveries, placenta previa was found in 514 women. Identifiable trends with time included an increasing incidence of placenta previa (r = 0.54, P <.01); cesarean hysterectomy (r = 0.54, P <.01); placenta accreta (r = 0.45, P <.03); and regional anesthesia (r = 0.84, P <.0001). The mean gestational age at delivery was 35.3 +/- 3.4 weeks and did not change with time. General anesthesia was used for delivery in 380 women and regional anesthesia was used for 134 women. Prior cesarean delivery and general anesthesia were independent predictors of the need for blood transfusion, but only prior cesarean delivery was a predictor of the need for hysterectomy. General anesthesia increased the estimated blood loss, was associated with a lower postoperative hemoglobin concentration, and increased the need for blood transfusion. Elective and emergent deliveries did not differ in estimated blood loss, in postoperative hemoglobin concentrations, or in the incidence of intraoperative and anesthesia complications. Regional and general anesthesia did not differ in the incidence of intraoperative and anesthesia complications.

CONCLUSIONS

In women with placenta previa, general anesthesia increased intraoperative blood loss and the need for blood transfusion. Regional anesthesia appears to be a safe alternative.

Previous cesarean section and abortion as risk factors for developing placenta previa

OBJECTIVE

To determine the risk of subsequent occurrence of placenta previa in women with a history of previous cesarean sections and/or spontaneous and induced abortions.

METHODS

A retrospective analysis of all single gestation deliveries at National University Hospital of Singapore from 1993-1997 was done. Women with placenta previa were identified by clinical or ultrasonographic diagnosis.

RESULTS

Of the 16,169 singleton deliveries, 164 women (1.0%) had placenta previa. Women with placenta previa had a significantly higher incidence of previous cesarean sections (p < 0.001). Among the 164 women with placenta previa, women with 1, 2, and 3 previous cesarean sections had 2.2 (95% CI 1.4, 3.4), 4.1 (95% CI 1.9, 8.8) and 22.4 (95% CI 6.4, 78.3) times increased risk of developing placenta previa respectively. Similarly, women with 2 or more previous abortions had a 2.1 (95% CI 1.2, 3.5) times increased risk of subsequently developing placenta previa.

CONCLUSION

There is a strong association between previous cesarean section and risk of subsequent development of placenta previa. This risk increased with the number of previous cesarean sections. Increasing frequency of abortions was also found to predispose a woman to placenta previa.

The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis

OBJECTIVE

Our purpose was to determine the incidence of placenta previa based on the available epidemiologic evidence and to quantify the risk of placenta previa based on the presence and number of cesarean deliveries and a history of spontaneous and induced abortion.

STUDY DESIGN

We reviewed studies on placenta previa published between 1950 and 1996 on the basis of a comprehensive literature search with use of MEDLINE and by identifying studies cited in the references of published reports. Studies were chosen for inclusion in the metaanalysis if the incidence of placenta previa and its cross-classification with either prior cesarean delivery or abortions (both spontaneous and induced) or both were available. We also extracted details about the study design (case-control or cohort study) and place where they were conducted (United States or other countries). Published case reports dealing with placenta previa and studies relating to abruptio placentae were excluded from this review. We also restricted the search to studies published in English. No attempts were made to locate any unpublished studies. Data from studies identified during the literature search were reviewed and abstracted by a single author. In case of discrepancies or when the information presented in a study was unclear, abstraction by a (blinded) second reviewer was sought to resolve the discrepancy.

RESULTS

Data on the incidence of placenta previa and its associations with previous cesarean delivery and abortions were abstracted. Subgroup analyses were performed to identify potential sources of heterogeneity by study design and place where they were conducted. Statistical methods used for the metaanalysis included the fixed-effects logistic regression model, whereas potential sources of heterogeneity among studies were evaluated by fitting random-effects models. The tabulation of 36 studies identified a total of 3.7 million pregnant women, of whom 13,992 patients were diagnosed with placenta previa. The reported incidence of placenta previa ranged between 0.28% and 2.0%, or approximately 1 in 200 deliveries. Women with at least one prior cesarean delivery were 2.6 (95% confidence interval 2.3 to 3.0) times at greater risk for development of placenta previa in a subsequent pregnancy. The results varied by study design, with case-control studies showing a stronger relative risk (relative risk 3.8, 95% confidence interval 2.3 to 6.4) than cohort studies did (relative risk 2.4, 95% confidence interval 2.1 to 2.8). Four studies, encompassing 170,640 pregnant women, provided data on the number of previous cesarean deliveries. These studies showed a dose-response pattern for the risk of previa on the basis of the number of prior cesarean deliveries. Relative risks were 4.5 (95% confidence interval 3.6 to 5.5) for one, 7.4 (95% confidence interval 7.1 to 7.7) for two, 6.5 (95% confidence interval 3.6 to 11.6) for three, and 44.9 (95% confidence interval 13.5 to 149.5) for four or more prior cesarean deliveries. Women with a history of spontaneous or induced abortion had a relative risk of placenta previa of 1.6 (95% confidence interval 1.0 to 2.6) and 1.7 (95% confidence interval 1.0 to 2.9), respectively. Substantial heterogeneity in the results of the metaanalysis was noted among studies.

CONCLUSION

There is a strong association between having a previous cesarean delivery, spontaneous or induced abortion, and the subsequent development of placenta previa. The risk increases with number of prior cesarean deliveries. Pregnant women with a history of cesarean delivery or abortion must be regarded as high risk for placenta previa and must be monitored carefully. This study provides yet another reason for reducing the rate of primary cesarean delivery and for advocating vaginal birth for women with prior cesarean delivery.

One or multiple previous cesarean sections are associated with similar increased frequency of placenta previa

OBJECTIVE

The purpose of this study was to determine whether multiple previous cesarean sections would be associated with a higher frequency of placenta previa in subsequent deliveries than in women with only one previous cesarean section.

STUDY DESIGN

Data of all pregnant women and deliveries were obtained from the computerized records of our department for the period 1985-1992. The study group included symptomatic placenta previa diagnosed by real time ultrasound or during labor. The data included maternal age, gravidity, parity and previous cesarean sections. Nulliparous women were excluded from the study.

RESULTS

There were 58,633 deliveries during the study period, including 284 patients with placenta previa (0.48%). Increasing maternal age was associated with a higher frequency of placenta previa. Similar results were found with increasing parity. A more significant trend was found with increasing number of previous abortions. Among placenta previa deliveries 21.1% of patients had previous cesarean section, and among normal deliveries only 10.9% had previous cesarean section (P < 0.0001). The frequency of placenta previa in women with previous normal deliveries was 0.79/1000; in women with one previous cesarean section 15.39/1000; with two previous cesarean section 13.91/1000; with three previous cesarean sections 10.37/1000. While the difference between none and one previous cesarean sections was highly significant (P < 0.0001), the difference between one and more cesarean sections was not significant.

CONCLUSION

Although the rate of placenta previa was significantly lower among deliveries without previous cesarean section in comparison with deliveries with one previous cesarean section, this difference was not enhanced with the increasing number of previous cesarean sections.

Placenta previa and previous cesarean section

OBJECTIVE

To assess the relationship between previous cesarean section and subsequent development of placenta previa and placenta previa with accreta.

METHOD

The records of all patients delivered with the diagnosis of placenta previa during the 10-year period from 1984 to 1993 were reviewed.

RESULTS

From a total of 50,485 deliveries, 421 (0.83%) had placenta previa, 43 (10.2%) of whom had a history of previous cesarean section. The incidence of placenta previa was significantly increased in those with a previous cesarean section (1.31%) compared with those with an unscarred uterus (0.75%) (R.R. 1.64). This risk increased as the number of previous cesarean sections increased (R.R. 1.53 for one previous section, 2.63 for two or more). The incidence of an anterior placenta previa and placenta accreta was significantly increased in those with previous cesarean scars. The incidence of placenta accreta was 1.18% among patients with placenta previa, 80% being in patients with previous cesarean section. The relative risk for placenta accreta in patients with placenta previa was 35 times higher in those with a previous cesarean section than in those with an unscarred uterus.

CONCLUSION

The association of previous cesarean section with placenta previa and placenta previa accreta is confirmed. Patients with an antepartum diagnosis of placenta previa who have had a previous cesarean section should be considered at high risk for developing placenta accreta.

Maternal and neonatal outcome in major placenta previa

A review of 96 cases of major degree placenta previa managed in King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia between 1988 and 1991 was carried out. A policy of "expectant management" with confinement in the hospital, blood transfusions in the antenatal period and cesarean section as the exclusive mode of delivery at maturity was practiced. Tocolytics and cervical cerclage were not used. There was no maternal mortality. The neonatal fetal mortality rate was 41.6/1000 while the incidence of neonatal respiratory distress syndrome was 18.7%. The results are compared with similar studies done elsewhere and analyzed with a view to improving the fetomaternal outcome.

Placenta praevia and accreta after previous caesarean section

A prospective study was undertaken to determine the relationship between previous caesarean section (CS), placenta praevia and placenta praevia accreta. Of 41,206 consecutive deliveries 1851 had had previous caesarean section and 222 had placenta praevia. Of the cases of placenta praevia, 175 occurred in the uterus and 47 occurred after previous CS. Placenta praevia complicated 2.54% of cases with a previous caesarean section compared with 0.44% of cases with no scar--a 5-fold increase. In patients with placenta praevia occurring with a previous scar, 18 were complicated by placenta accreta (38.2%) compared with only 8 (4.5%) in unscarred uteri. After one caesarean section, placenta praevia was complicated by accreta in 10% of cases and after two or more this was 59.2%. The risk of hysterectomy with placenta praevia and uterine scar was 10% but with placenta praevia accreta it was 66%. There was one maternal death in the placenta praevia accreta group.

Obstetric hysterectomy: Ramathibodi's experience 1969-1987

Obstetric hysterectomy was performed on 121 women at Ramathibodi Hospital, Bangkok, between 1969 and 1987, an incidence of 1:875 deliveries. Of 88 women whose records were available, 91% had emergency hysterectomy, with uterine atony as the most common indication (32.5%), followed by placenta accreta (26.2%), uterine rupture (10.0%), extension of cervical tear to the lower uterine segment (8.7%), broad ligament hematoma (6.2%) and placenta previa (5.0%). The intraoperative and postoperative problems included febrile morbidity (52%), intraoperative hypotension (41%), and disseminated intravascular coagulation (5.7%). Late complications included Sheehan's syndrome (3.4%), post-transfusion hepatitis (2.3%), hematoma (2.3%) and wound infection (2.3%).

The mid-trimester placenta previa: a prospective follow-up

One hundred and fifty-six mid-trimester sonograms were performed at our prenatal diagnostic unit. Twenty women were found to have a low-lying placenta or placenta previa and were followed by serial ultrasound examinations to observe changes in placental position. Eighty percent of women, i.e., 16/20, with a low-lying placenta had converted to normal implantation by the time of delivery. Most of the conversions had taken place at approx. 34 weeks of gestation. The patients with mid-trimester low-lying placenta had an increased risk of third-trimester bleeding, abruptio placentae and cesarean sections. The infants were also at risk of premature delivery. Patients with mid-trimester low-lying or placenta previa should be followed by ultrasound to monitor delivery.

True rupture/scar dehiscence in delivery following prior section

Fear of uterine rupture has led to the widespread practice of 'Once a section, always a section'. Between 1972 and 1982, 1498 patients with one or more previous cesarean sections were delivered at University College Hospital, Galway. Trial of labor was undertaken in 844 patients, while the remaining 654 patients underwent repeat elective section because they had two or more prior sections. Eight true ruptures and 22 scar dehiscences were found. Regional analgesia and oxytocin did not significantly affect the rate of true rupture. The mean parity with uterine rupture was five, and it occurred most frequently in the initial trial of labor. There were four perinatal deaths associated with true rupture. Failure to detect the already compromised fetus before labor and delivery, rather than the method of delivery, was responsible for fetal demise in some instances. Five true ruptures were found in the trial of labor group (i.e. a ratio of 1:169), with the loss of three babies. A further baby was stillborn in a mother who ruptured a classical scar before labor. There were no maternal deaths in trial-of-labor patients and one in the elective section group. Two patients with true rupture had their uterus repaired, and were subsequently delivered by section. Another two patients with bloodless dehiscence and no repair, had two subsequent elective repeat sections each, and the unrepaired scar dehiscence was not evident.

Elective caesarean hysterectomy. Indications and outcome: a 17-year experience of 140 cases

In an earlier report of 86 elective Caesarean hysterectomies (1970-1979) we showed that the operation was associated with few complications but a high blood transfusion rate. In this paper we report an extended series comprised of 140 cases (1970-1986), and compare results of the 1970's series with that of the 1980's. The operative and postoperative complications were minimal during the entire period. The blood transfusion rate which was 64% in 86 cases of the 1970-1979 period decreased to 17% in 54 cases of the 1980-1986. Our results show that Caesarean hysterectomy is a safe procedure with some long-term advantages; therefore this option should be discussed with women who ask for tubal sterilization at the time of Caesarean section.

Placenta praevia--a review with emphasis on the role of ultrasound

Considerable confusion exists in the literature as a result of the wide range of classification systems for placenta praevia (PP) and low-lying placenta. The discrepancy between frequency of low-lying placentas in the second trimester and PP at term reflects to a certain extent the lack of understanding of the anatomy and physiology of the pregnant uterus. It seems that 'placental conversion' is a real phenomenon and is probably due to the differential growth rates of the placenta and uterus. Maternal bladder overdistension and myometrial contractions account for only a small part of the discrepancy. Diagnostic ultrasound obviously has an important role in placental localization. The role of Magnetic Resonance Imaging remains to be determined. The management of patients with low-lying placenta diagnosed in the second trimester, and the frequency of repeat scans is determined largely by the management protocol of the attending obstetrician.

Anaesthetic management of patients with placenta accreta

The management of a 28-year-old primigravida with placenta accreta diagnosed during Caesarean section is described. A hysterectomy was required to control massive haemorrhage, and the patient made a full recovery. The increased incidence of placenta accreta over the last three decades is thought to be associated with the concomitant increased frequency of Caesarean section, resulting in an increased incidence of placenta praevia (1.9 per cent to 3.9 per cent). Patients with placenta praevia who have had a previous Caesarean section have a remarkably increased risk of placenta accreta. Management of placenta accreta is primarily by control of haemorrhage on delivery of the placenta. Control can be assisted by infrarenal cross-clamping of the aorta and/or intra-myometrial injection of prostaglandin F2 alpha which produces myometrial and vascular contraction. Identification of patients at increased risk, preparation for treatment and effective treatment of placenta accreta will minimize maternal morbidity and mortality.

Aetiological factors in placenta praevia--a case controlled study

The obstetric and gynaecological histories of 80 women with proven placenta praevia have been reviewed together with case controls matched for age and parity. There was a significant relation between placenta praevia and previous caesarean section (P less than 0.05), dilatation and curettage (P less than 0.01), spontaneous abortion (P less than 0.05) and evacuation of retained products of conception (P less than 0.05). Repeated uterine instrumentation was associated with increased risk of placenta praevia (P less than 0.001). We were unable to show any influence of previous termination of pregnancy. These findings are consistent with the hypothesis that endometrial/myometrium damage is a significant aetiological factor in low placental implantation.

The epidemiology and clinical history of asymptomatic midtrimester placenta previa

The current case-controlled study examines the epidemiologic factors and subsequent clinical history in 139 patients with asymptomatic low placentation and 137 patients with normal placental position diagnosed in the second and third trimesters by gray-scale ultrasonography. Increased maternal age or parity and previous endometrial or myometrial damage were significantly associated with asymptomatic midtrimester low implantation. Three percent of early low implantations persisted as instances of placenta previa at term. However, in low implantation, the antepartum course was associated with perinatal complications in 45% of patients. Statistically significant increases in third-trimester bleeding, abruptio placentae, and suspected intrauterine growth retardation were shown in the patients with low implantation, when compared to the control patients. Forty-two percent of the patients with low implantation were delivered by cesarean section. The need for cesarean delivery, loss of blood, and prolonged hospitalization were statistically increased in the patients with low implantation. Infants born to mothers with low implantation showed statistically significant increases in prematurity, low birth weight, and perinatal mortality when compared to infants born to control patients.