Do women with placenta praevia without antepartum haemorrhage require hospitalization?

Risk of preterm birth for placenta previa or low-lying placenta and possible preventive interventions: A systematic review and meta-analysis

Objective

To investigate the risk of preterm birth in women with a placenta previa or a low-lying placenta for different cut-offs of gestational age and to evaluate preventive interventions.

Search and methods

MEDLINE, EMBASE, CENTRAL, Web of Science, WHO-ICTRP and clinicaltrials.gov were searched until December 2021. Randomized controlled trials, cohort studies and case-control studies assessing preterm birth in women with placenta previa or low-lying placenta with a placental edge within 2 cm of the internal os in the second or third trimester were eligible for inclusion. Pooled proportions and odds ratios for the risk of preterm birth before 37, 34, 32 and 28 weeks of gestation were calculated. Additionally, the results of the evaluation of preventive interventions for preterm birth in these women are described.

Results

In total, 34 studies were included, 24 reporting on preterm birth and 9 on preventive interventions. The pooled proportions were 46% (95% CI [39 - 53%]), 17% (95% CI [11 - 25%]), 10% (95% CI [7 - 13%]) and 2% (95% CI [1 - 3%]), regarding preterm birth <37, <34, <32 and <28 weeks in women with placenta previa. For low-lying placentas the risk of preterm birth was 30% (95% CI [19 - 43%]) and 1% (95% CI [0 - 6%]) before 37 and 34 weeks, respectively. Women with a placenta previa were more likely to have a preterm birth compared to women with a low-lying placenta or women without a placenta previa for all gestational ages. The studies about preventive interventions all showed potential prolongation of pregnancy with the use of intramuscular progesterone, intramuscular progesterone + cerclage or pessary.

Conclusions

Both women with a placenta previa and a low-lying placenta have an increased risk of preterm birth. This increased risk is consistent across all severities of preterm birth between 28-37 weeks of gestation. Women with placenta previa have a higher risk of preterm birth than women with a low-lying placenta have. Cervical cerclage, pessary and intramuscular progesterone all might have benefit for both women with placenta previa and low-lying placenta, but data in this population are lacking and inconsistent, so that solid conclusions about their effectiveness cannot be drawn.

Systematic review registration

PROSPERO https://www.crd.york.ac.uk/prospero/, identifier CRD42019123675.

Risk factors for preterm delivery with placenta previa

AIMS

To identify factors associated with preterm delivery in cases of sonographically identified placenta previa.

METHODS

Pregnancies with sonographic evidence of placenta previa at ≥ 28 weeks were identified. Demographic information, antepartum course, and delivery information were extracted from electronic medical records. Statistical analysis was performed with Fisher's exact test, Mann-Whitney U, Spearman's ρ (correlation), and logistic regression. Continuous data are presented as median (interquartile range).

RESULTS

Of 113 singleton pregnancies with placenta previa, 54 (48%) delivered at term and 59 (52%) delivered preterm. Fifty-one (45%) experienced antepartum bleeding at a median gestational age of 31 weeks (29-33 weeks) with a median interval of 20 days (11-33 days) between first bleeding episode and delivery. Women with antepartum bleeding were more likely to be delivered for hemorrhage (36 of 51 vs. 8 of 62, P<0.001) and delivered emergently (40 of 51 vs. 14 of 62, P<0.001). Antepartum bleeding before 34 weeks had a positive predictive value of 88% for preterm birth and 83% for emergent delivery.

CONCLUSION

In pregnancies with placenta previa, antepartum bleeding is a strong predictor of preterm delivery.

Management of women with major placenta praevia without haemorrhage: A questionnaire-based survey of Irish obstetricians

Our aim was to determine individual management of women with major placenta praevia without antepartum haemorrhage (APH) using a questionnaire-based study. Placenta praevia complicates one in 200 pregnancies. It is associated with maternal mortality of 0.03%. The maternal, fetal and neonatal morbidity and mortality are due to the complications of haemorrhage and prematurity. APH due to placenta praevia is unpredictable and this may explain the traditional inpatient approach to management. This approach may be justified in those with bleeding, it is questionable in those who have not bled. A total of 121 obstetricians replied (63%), to 192 questionnaires sent out. Of these, 48 obstetricians would admit all women with major placenta praevia without APH, while 69 would manage them on an outpatient basis. When asked whether or not they agreed with outpatient management, 21 agreed strongly, 51 tended to agree, 23 tended to disagree and 13 disagreed strongly. Over half of the obstetricians adopt an outpatient management approach.

Women with placenta praevia and antepartum haemorrhage have a worse outcome than those who do not bleed before delivery

We set out to assess the maternal and neonatal outcomes of women with placenta praevia and antepartum haemorrhage (APH) between 1991 and 1997, compared with woman with a diagnosed placenta praevia who did not bleed. The demographic data, maternal and perinatal outcomes of 159 women with antepartum haemorrhage were compared with 93 women without antepartum haemorrhage in a retrospective study. Women with antepartum haemorrhage had the diagnosis of placenta praevia confirmed at an earlier gestation. More women with antepartum haemorrhage received antenatal steroids and tocolytic agents, and had emergency caesarean sections. The majority of women with bleeding had an emergency caesarean section for antepartum haemorrhage and more delivered early because of fetal distress. There were more preterm deliveries in women with antepartum haemorrhage. The mean birth weight was 2.69 kg in the women with antepartum haemorrhage and 3.06 kg in those without. More infants in the bleeding group had a low Apgar score at the first minute, respiratory distress syndrome, and admission to special baby care and neonatal intensive care unit. It is concluded that there is an increased risk of premature delivery in women with antepartum haemorrhage and placenta praevia. Aggressive management, tocolysis and cervical cerclage should be explored further to improve the perinatal outcome. Women without antepartum haemorrhage can be managed on an outpatient basis.

Common problems and emergencies in the obstetric patient

Physicians not used to caring for pregnant patients may feel uncomfortable dealing with the many routine problems that can occur during a pregnancy. Other than true obstetric emergencies, which are usually cared for by obstetricians and family physicians, and the common problems of pregnancy can often be cared for by any primary care physician. Given the litigious nature of our society, especially in the realm of obstetrics, it does behoove the physician caring for pregnant women to be aware of the standards of care. When in doubt, it would be prudent to consult with a physician that routinely provides care to pregnant women.

Major placenta praevia should not preclude out-patient management

OBJECTIVE

To review current management of women with major and minor placenta praevia in view of the recommendations made in the RCOG guideline 2001. To assess whether out-patient care was detrimental to pregnancy outcome.

STUDY DESIGN

Retrospective observational study at the Simpson Memorial Maternity Pavilion, Edinburgh (a tertiary referral centre). One hundred and sixty-one women with major and minor placenta praevia between 1994 and 2000 were separated into those who experienced bleeding (antepartum haemorrhage (APH)) and those who had no bleeding during pregnancy (non-APH). Statistical analysis was carried out using SPSS.

RESULTS

There were 129 women (80%) in the APH group. Forty-three were out-patients at the time of delivery and 63% had a major degree of praevia. Thirty-two women were in the non-APH group. Sixty-eight were managed as out-patients and 50% had a major degree of praevia. Women with a major degree of praevia were not significantly more likely to experience bleeding. Women with APH were significantly more likely to be delivered early, by emergency caesarean section (C/S), of lower birthweight babies who required neonatal admission than the non-APH group.

CONCLUSION

There is a place for out-patient management of women with placenta praevia. Caution is required with increasing number of bleeds but not degree of praevia.

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.

Third-trimester transvaginal ultrasonography in placenta previa: does the shape of the lower placental edge predict clinical outcome?

OBJECTIVE

To evaluate the clinical significance of the shape of the lower placental edge in women with transvaginal sonographic diagnosis of placenta previa.

DESIGN

A prospective observational study at a tertiary teaching hospital.

POPULATION

A total of 104 women with confirmed transvaginal sonographic diagnosis of placenta previa before 32 weeks' gestation.

METHODS

Initial transvaginal sonography was performed at between 28 and 32 weeks' gestation in 138 patients with either strong clinical suspicion or previous abdominal sonographic diagnosis of placenta previa in the early third trimester. The lower placental edge was found to be positioned over the internal cervical os in 33 women (complete previa) and within 3 cm from it in 71 women (low-lying placenta). Patients with low-lying placenta were followed up by serial transvaginal sonographic examinations until delivery; detailed information including the placental location (anterior or posterior), the distance of its edge from the internal cervical os and its thickness were recorded. The clinical outcomes of the 17 who had a thick-edge low-lying placenta were compared with those who had a thin-edge one (54 women). In patients with complete placenta previa, demographic data, the shape of the lower placental edge whenever transvaginal sonography visualized it, and the clinical outcomes were documented. The incidence of major complications in thick-edge or central placenta was compared to that in the thin-edge group.

RESULTS

Women having a low-lying placenta with a thick edge had a significantly higher rate of antepartum hemorrhage (P = 0.0002), abdominal delivery (P = 0.02), abnormally adherent placenta (P = 0.012) and low birth weight (P = 0.006) than those in whom the placental edge was thin. Cesarean hysterectomy was required in six patients with complete placenta previa because of severe peripartum hemorrhage; all of them had either central or thick-edge placenta accreta.

CONCLUSION

Women with placenta previa are at a relatively higher risk of developing complications if the lower placental edge is thick. Integration of the shape of the lower placental edge into transvaginal sonographic assessment of placenta previa may improve the prediction of mode of delivery and clinical outcome.

Placental migration and mode of delivery in placenta previa: transvaginal sonographic assessment during the third trimester

BACKGROUND

The objective of this study was to assess the role of serial transvaginal sonography (TVS) in predicting placental migration and mode of delivery in pregnancy complicated by placenta previa during the third trimester.

PATIENTS AND METHODS

In this prospective observational study, all the cases had confirmed diagnosis of placenta previa before 32 weeks' gestation. TVS was performed between 28 and 32 weeks' gestation for 287 patients with either clinical suspicion or previous sonographic diagnosis of placenta previa. The lower placental edge was found to cover the internal cervical os, or was found to be within 3 cm from it in 63 patients. A two-weekly TVS was performed for every patient until delivery, or until migration of the lower placental edge to a distance of more than 3 cm from the internal cervical os was observed. Detailed information on the placental position, its distance from the internal cervical os, and its relation to the presenting part were recorded at each examination.

RESULTS

Placental migration to a distance of more than 3 cm from the internal cervical os occurred in 24 patients (38%) by 36 weeks' gestation. Of the 63 patients, 19 (30.2%) delivered vaginally. The last scan of these patients revealed that the distance between the internal cervical os and the lower placental margin were more than 2 cm and 3 cm in the anterior and posterior placenta previa, respectively, and the presenting parts were below the placental margin. Placental migration was not observed sonographically in any of the eight patients with posterior placenta previa when its lower edge was initially located within 1 cm from the internal os. It was also not observed in either the 16 patients with total placenta previa, or in any of the other patients beyond 36 weeks' gestation.

CONCLUSION

Posterior placenta previa lying within 1 cm from the internal cervical os and total placenta previa do not migrate during the third trimester. On the other hand, other types of placenta previa may migrate but not beyond 36 weeks' gestation. The mode of delivery does not depend only on the placental degree but also on the placental position (anterior or posterior), and the relationship between the presenting part and the lower placental edge.

Pregnancies complicated by placenta praevia: what is appropriate management?

OBJECTIVE

To review the outcome of pregnancies complicated by placenta praevia over a three-year period (1991-1993) and to describe in detail the antenatal course and the events leading to delivery, assessing retrospectively whether there are clinical features predictive of outcome and whether outpatient management would be reasonable.

DESIGN

A retrospective review of the case records of women with a pregnancy complicated by placenta praevia.

SETTING

A tertiary referral teaching hospital in Edinburgh.

RESULTS

There were 15,930 deliveries in the study period. Fifty-eight women (0.4%) had a placenta praevia in the third trimester, 42 of whom (72%) had at least one episode of bleeding. Overall, 62% of the women had a major praevia with no differences in the grade of praevia between those women who did or did not have bleeding. Both diagnosis and delivery occurred significantly earlier in women with antepartum bleeding than in those without (median gestation at diagnosis 28.6 weeks versus 33.3 weeks (P < 0.01) and at delivery 36.0 weeks versus 37.1 weeks (P = 0.04), respectively). Delivery by emergency caesarean section was more common in women with bleeding (62% versus 38%). An increasing number of bleeding episodes experienced by individuals was not associated with significant differences in outcomes. Rapid emergency delivery for bleeding was necessary for three women, in none of whom could the bleeding have been predicted.

CONCLUSIONS

The clinical outcomes of placenta praevia are highly variable and cannot be predicted confidently from antenatal events. Nonetheless, in the majority of cases with or without bleeding and irrespective of the degree of praevia, outpatient management would appear safe and appropriate.