Risks associated with cesarean sections in women with placenta previa

Estimating the radiation dose to the fetus during prophylactic internal iliac occlusion in patients with abnormal placentation

AIMS

To evaluate the estimated fetal radiation dose during prophylactic internal iliac arterial occlusion in patients with abnormal placenta and to estimate the risk of radiation induced cancer in child age.

METHODS

Prophylactic occlusion of the internal iliac arteries during Caesarean section was performed in 42 patients with placenta praevia and/or placenta accreta spectrum. Fogarty embolectomy catheters were used for prophylactic occlusion of the internal iliac arteries. All procedures were performed in the hybrid operating room using Philips Allura Xper FD 20 X-ray system. Low dose X-ray fluoroscopy (7.5 frames per second) was used. The CODE (Conceptus dose estimation) Software was used to estimate the fetal dose and the risk of radiation induced carcinoma.

RESULTS

Fluoroscopy times required for insertion of Fogarty catheters were 0.5-4.2 min (mean: 1.7 min, median: 1.5 min). The estimated radiation dose to the fetus was 0.26-3.36 mGy (mean: 1.49 mGy, median: 1.25 mGy). The risk of radiation induced cancer in child age was 0.01-0.04% (mean 0.02%, median 0.01%). One patient developed thrombosis of a common femoral artery.

CONCLUSION

Prophylactic occlusion of the internal iliac arteries is a simple and safe procedure with minimal risk of complications and with a very low estimated radiation dose to the fetus.

Factors associated with placenta praevia in primigravidas and its pregnancy outcome

Aim. To examine the factors associated with placenta praevia in primigravidas and also compare the pregnancy outcomes between primigravidas and nonprimigravidas. Method. A retrospective cohort study was conducted in women who underwent caesarean section for major placenta praevia in a tertiary university hospital from January 2007 till December 2013. Medical records were reviewed. Result. Among 243 with major placenta praevia, 56 (23.0%) were primigravidas and 187 (77.0%) were nonprimigravidas. Factors associated with placenta praevia in the primigravidas were history of assisted conception (P = 0.02) and history of endometriosis (P = 0.01). For maternal outcomes, the nonprimigravidas required earlier delivery than primigravidas (35.76 ± 2.54 weeks versus 36.52 ± 1.95 weeks, P = 0.03) and had greater blood loss (P = 0.04). A vast majority of the primigravidas had either posterior type II or type III placenta praevia. As for neonatal outcomes, the Apgar score at 1 minute was significantly lower for the nonprimigravidas (7.89 ± 1.72 versus 8.39 ± 1.288.39 ± 1.28, P = 0.02). Conclusion. This study highlighted that endometriosis and assisted conception were highly associated with placenta praevia in primigravida. Understanding the pregnancy outcomes of women with placenta praevia can assist clinicians in identifying patients who are at higher risk of mortality and morbidity. Identifying potential risk factors in primigravida may assist in counseling and management of such patients.

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.

Risk factors for peripartum blood transfusion in women with placenta previa: a retrospective analysis

BACKGROUND

The incidence of placenta previa has been increasing. It is of a great importance to determine the clinical risk factors for peripartum blood transfusion in women with placenta previa in an effort to anticipate cases of severe hemorrhage.

METHODS

A total of 129 consecutive cases of placenta previa (64 cases of complete placenta previa and 65 cases of marginal placenta previa), including 43 cases requiring blood transfusion, were retrospectively analyzed. Maternal and neonatal clinical data were examined with univariate and multivariate logistic regression analyses for potential risk factors for peripartum blood transfusion.

RESULTS

The independent risk factors for blood transfusion were maternal age greater than 34 years (adjusted odds ratio [OR]=3.7; 95% confidence interval [CI]=1.5-7.5, p<0.05), history of having undergone dilatation and curettage more than once (adjusted OR=4.8; 95% CI=1.1-26.2, p<0.05), and complete placenta previa (adjusted OR=2.6, 95% CI=1.2-5.9, p<0.05). Body mass index, gravidity, parity, previous cesarean section, antepartum hemorrhage, use of tocolytic agents, gestational age at delivery, preoperative anemia, emergent surgery, birth weight, and Apgar score were not associated with the incidence of blood transfusion.

CONCLUSION

Risk factors for blood transfusion in women with placenta previa are advanced maternal age, repeat dilatation and curettage, and complete placenta previa. Women with placenta previa who are at risk for blood transfusion should be carefully managed with sufficient preparation for blood transfusion.

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.

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.