Placenta previa accreta

OBJECTIVES: The purpose of our study was to assess the relationship between previous cesarean section and placenta previa accreta and to estimate the incidence of placenta accreta et previa accreta as the indication for peripartum hysterectomy. MATERIALS AND METHODS: The records of all patients delivered with the diagnosis of placenta previa accreta during the period from 1992-2002 at Hospital in Chojnice were reviewed. Statistical analyses were carried out to determine the relationship between previous cesarean section and subsequent development of placenta previa accreta. We conducted a retrospective analysis of indications for peripartum hysterectomy. RESULTS: From a total 28,177 women, who delivered at the Chojnice Hospital, 15(0.05%) patients had placenta accreta, 63(0.2%) placenta previa. Among placenta previa deliveries 22(34.9%) patients had previous cesarean section. Out of 15 patients with placenta accreta 10(66.7%) had placenta previa. Incidence of placenta accreta per case of placenta previa was 158.7 per 1000. The incidence of placenta previa accreta significantly increased in those with previous post cesarean scars. This incidence increased as the number of previous cesarean sections increased. The most common indication for peripartum hysterectomy was placenta accreta--48.4%, incidence of placenta previa accreta was accounts for 32.3% of all indications. CONCLUSIONS: The association between placenta previa accreta and prior cesarean section was confirmed. The incidence of placenta accreta increased as the number of previous cesarean sections increased. 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. The most common indication for peripartum hysterectomy in this study was placenta previa accreta.     

The likelihood of placenta previa with greater number of cesarean deliveries and higher parity

OBJECTIVE: To examine the relationship between prior cesarean delivery and placenta previa. METHODS: A hospital-based, case-control study was conducted in which 316 multiparous women with placenta previa were identified. Controls consisted of 2051 multiparous women with spontaneous vaginal deliveries. Information on prior cesarean delivery was examined in three forms: as a dichotomous variable, as an ordinal variable, and as a set of three indicator variables for one, two, and three or more cesarean deliveries. Multivariable logistic regression modeling was used to obtain an adjusted estimate of this association. RESULTS: Women with a prior cesarean delivery were more likely to have a placenta previa than those without (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.21, 2.08). The likelihood of placenta previa increased as both parity and number of cesarean deliveries increased. Thus, the adjusted OR for a primiparous woman with one cesarean delivery was 1.28 (95% CI 0.82, 1.99). For a woman who has four or more deliveries with only a single cesarean delivery, the OR increases to 1.72 (95% CI 1.12, 2.64). This trend continues with greater parity and a greater number of cesarean deliveries such that the likelihood of placenta previa for a woman with parity greater than four and greater than four cesarean deliveries was OR 8.76 (95% CI 1.58, 48.53). CONCLUSION: This study supports the association between prior cesarean delivery and placenta previa and demonstrates that the joint effect of parity and prior cesarean delivery is greater than that of either variable alone.     

Previous cesarean delivery and risks of placenta previa and placental abruption

OBJECTIVE: To examine the association between cesarean delivery and previa and abruption in subsequent pregnancies. METHODS: A retrospective cohort study of first 2 (n = 156,475) and first 3 (n = 31,102) consecutive singleton pregnancies using the 1989-1997 Missouri longitudinally linked data were performed. Relative risk (RR) was used to quantify the associations between cesarean delivery and risks of previa and abruption in subsequent pregnancies, after adjusting for several confounders. RESULTS: Rates of previa and abruption were 4.4 (n = 694) and 7.9 (n = 1,243) per 1,000 births, respectively. The pregnancy after a cesarean delivery was associated with increased risk of previa (0.63%) compared with a vaginal delivery (0.38%, RR 1.5, 95% confidence interval [CI] 1.3-1.8). Cesarean delivery in the first and second births conferred a two-fold increased risk of previa in the third pregnancy (RR 2.0, 95% CI 1.3-3.0) compared with first two vaginal deliveries. Women with a cesarean first birth were more likely to have an abruption in the second pregnancy (0.95%) compared with women who had a vaginal first birth (0.74%, RR 1.3, 95% CI 1.2-1.5). Two consecutive cesarean deliveries were associated with a 30% increased risk of abruption in the third pregnancy (RR 1.3, 95% CI 1.0-1.8). A second pregnancy within a year after a cesarean delivery was associated with increased risks of previa (RR 1.7, 95% CI 0.9-3.1) and abruption (RR 1.5, 95% CI 1.1-2.3). CONCLUSION: A cesarean first birth is associated with increased risks of previa and abruption in the second pregnancy. There is a dose-response pattern in the risk of previa, with increasing number of prior cesarean deliveries. A short interpregnancy interval is associated with increased risks of previa and abruption. LEVEL OF EVIDENCE: II-2.     

The relationship of placenta previa and history of induced abortion.

OBJECTIVES: We evaluated the risk of placenta previa being associated with a history of induced abortion by different surgical procedures. METHODS: Cases (n=192) were women who had a singleton delivery complicated by placenta previa at a major obstetric care hospital in western Washington state between April 1, 1990 and December 31, 1992. Controls (n=622) were women with singleton deliveries not complicated by placenta previa or abruption. Odds ratios, determined by logistic regression, approximate the relative risks. RESULTS: Vacuum aspiration abortion was not associated with an increased risk of placenta previa (OR 0.9, 95% CI 0.6-1.5). However, the risk of placenta previa increased with the number of sharp curettage abortions (OR 2.9, 95% CI 1.0-8.5 for > or =3). CONCLUSIONS: Risk of placenta previa may be increased in a dose response fashion by multiple sharp curettage abortions. However, vacuum aspiration does not confer an increased risk, and may be a better alternative.     

Predicting placental abruption and previa in women with a previous cesarean delivery

The purpose of this study was to determine if placental abruption or previa in women with a history of a prior cesarean delivery (CD) can be predicted. A retrospective cohort study of pregnant women with previous CD was conducted in 17 centers between 1996 and 2000. Women developing placenta previa or abruption in the subsequent pregnancy were compared with those without these complications. Bivariate and multivariable techniques were used to develop predictive models for placenta previa or abruption. The area under the receiver-operator characteristic curves, sensitivity, specificity, and accuracy of the models were compared. Among 25,076 women with prior CD, there were 361 (15 per 1000 births) with placenta previa and 309 (13 per 1000 births) with abruption. The significant risk factors for these complications include advanced maternal age, Asian race, increased parity, illicit drug use, history of spontaneous abortion, and three or more prior cesarean deliveries. Prediction models for abruption and previa had poor sensitivity (12% and 13% for abruption and previa, respectively). In women with at least one prior cesarean delivery, the risk factors for placental previa and abruption can be identified. However, prediction models combining these risk factors were too inefficient to be useful.     

Early preterm delivery due to placenta previa is an independent risk factor for a subsequent spontaneous preterm birth

ABSTRACT: BACKGROUND: To determine whether patients with placenta previa who delivered preterm have an increased risk for recurrent spontaneous preterm birth. METHODS: This retrospective population based cohort study included patients who delivered after a primary cesarean section (n = 9983). The rate of placenta previa, its recurrence, and the risk for recurrent preterm birth were determined. RESULTS: Patients who had a placenta previa at the primary CS pregnancy had an increased risk for its recurrence [crude OR of 2.65 (95 % CI 1.3-5.5)]. The rate of preterm birth in patients with placenta previa in the primary CS pregnancy was 55.9 %; and these patients had a higher rate of recurrent preterm delivery than the rest of the study population (p < .001). Among patients with placenta previa in the primary CS pregnancy, those who delivered preterm had a higher rate of recurrent spontaneous preterm birth regardless of the location of their placenta in the subsequent delivery [OR 3.09 (95 % CI 2.1-4.6)]. In comparison to all patients with who had a primary cesarean section, patients who had placenta previa and delivered preterm had an independent increased risk for recurrent preterm birth [OR of 3.6 (95 % CI 1.52-8.51)]. CONCLUSIONS: Women with placenta previa, who deliver preterm, especially before 34 weeks of gestation, are at increased risk for recurrent spontaneous preterm birth regardless to the site of placental implantation in the subsequent pregnancy. Thus, strict follow up by high risk pregnancies specialist is recommended.     

Pregnancy outcomes for women with placenta previa in relation to the number of prior cesarean deliveries

OBJECTIVE: To estimate the association between the number of prior cesarean deliveries and pregnancy outcomes among women with placenta previa. METHODS: Women with a placenta previa and a singleton gestation were identified in a concurrently collected database of cesarean deliveries performed at 19 academic centers during a 4-year period. Maternal and perinatal outcomes were analyzed after stratifying by the number of cesarean deliveries before the index pregnancy. RESULTS: Of the 868 women in the analysis, 488 had no prior cesarean delivery, 252 had one prior cesarean delivery, 76 had two prior cesarean deliveries, and 52 had at least three prior cesarean deliveries. Multiple measures of maternal morbidity (eg, coagulopathy, hysterectomy, pulmonary edema) increased in frequency as the number of prior cesarean deliveries rose. Even one prior cesarean delivery was sufficient to increase the risk of an adverse maternal outcome (a composite of transfusion, hysterectomy, operative injury, coagulopathy, venous thromboembolism, pulmonary edema, or death) from 15% to 23%, which corresponded, in multivariable analysis, to an adjusted odds ratio of 1.9 (95% confidence interval 1.2-2.9). Conversely, gestational age at delivery and adverse perinatal outcome (a composite measure of respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage grade 3 or 4, seizures, or death) were unrelated to the number of prior cesarean deliveries. CONCLUSION: Among women with a placenta previa, an increasing number of prior cesarean deliveries is associated with increasing maternal, but not perinatal, morbidity. LEVEL OF EVIDENCE: II.     

Legal abortion and placenta previa

Legal abortion has been postulated to be a risk factor for placenta previa in subsequent pregnancies. To examine this hypothesis, we analyzed the deliveries of 28,665 women. We identified 68 women who had had placenta previa and compared their obstetric histories with those of 68 controls randomly selected from the same group of deliveries. The crude risk ratio for women with a history of one or more legal abortions was 1.4 (95% confidence interval, 0.5 to 3.6; p greater than 0.05). Standardizing the crude risk ratio for the effects of age and gravidity reduced the risk ratio to 1.1 (95% confidence interval, 0.4 to 2.8). In this predominantly black population legal abortion does not appear to have a significant association with placenta previa in subsequent pregnancies.     

Abnormal placentation: twenty-year analysis

OBJECTIVE: This study was undertaken to determine whether the rate of abnormal placentation is increasing in conjunction with the cesarean rate and to evaluate incidence, risk factors, and outcomes. STUDY DESIGN: Cases from 1982-2002 were identified by histopathologic or strong clinical criteria. Risk factors were assessed in a matched case-control study, and analyzed using conditional logistic regression models. RESULTS: There were 64,359 deliveries, with cesarean rates increasing from 12.5% (1982) to 23.5% (2002). The overall incidence of placenta accreta was 1 in 533. Significant risk factors for placenta accreta in our final analysis included advancing maternal age (odds ratio [OR] 1.13, 95% CI 1.089-1.194, P < .0001), 2 or more cesarean deliveries (OR 8.6, 95% CI 3.536-21.078, P < .0001), and previa (OR 51.4, 95% CI: 10.646-248.390, P < .0001). CONCLUSION: The rate of placenta accreta increased in conjunction with cesarean deliveries; the most important risk factors were previous cesarean delivery, previa, and advanced maternal age.     

Relationship between placenta previa and maternal age, parity and prior caesarean deliveries

OBJECTIVE: The purpose of this study was to determine the incidence of placenta previa and to asses the relationship between the incidence of placenta previa and maternal age, parity, prior abortion and cesarean deliveries. MATERIALS AND METHODS: The records of all patients with the diagnosis of placenta previa during the period between 1992 and 2002 at Hospital in Chojnice were reviewed. To determine the relationship between the incidence of placenta previa and maternal age, parity, prior abortion and cesarean deliveries the statistical analyses were carried out. The level of significance was set at 0.05. RESULTS: From a total 11,091 deliveries 24 (0.2%) women had placenta previa. The occurrence of placenta previa increased with maternal age and was the highest in women aged 35 or older--0.8% of all deliveries and the lowest in women aged <25 years--0.07%. The incidence of placenta previa in women with previous deliveries was significantly higher compared to the group of primiparas and increased as the number of prior deliveries increased. The association between previous abortion and cesarean section and placenta previa was not confirmed. CONCLUSION: Advancing maternal age and multiparity appears to increase the occurrence of placenta previa. In this study the relationship between previous abortion and cesarean section was not confirmed.     

Placenta previa/accreta and prior cesarean section

To assess the relationship between increasing numbers of previous cesarean sections and the subsequent development of placenta previa and placenta accreta, the records of all patients presenting to labor and delivery with the diagnosis of placenta previa between 1977 and 1983 were examined. Of a total of 97,799 patients, 292 (0.3%) had a placenta previa. The risk of placenta previa was 0.26% with an unscarred uterus and increased almost linearly with the number of prior cesarean sections to 10% in patients with four or more. The effect of advancing age and parity on the incidence of placenta previa was much less dramatic. Patients presenting with a placenta previa and an unscarred uterus had a 5% risk of clinical placenta accreta. With a placenta previa and one previous cesarean section, the risk of placenta accreta was 24%; this risk continued to increase to 67% (two of three) with a placenta previa and four or more cesarean sections. Possible mechanisms and clinical implications are discussed.     

Previous preterm cesarean delivery and risk of subsequent uterine rupture

OBJECTIVE: To determine if women with a history of a previous preterm cesarean delivery experienced an increased risk of subsequent uterine rupture compared with women who had a previous nonclassic term cesarean delivery. METHODS: A prospective observational study was performed in singleton gestations that had a previous nonclassic cesarean delivery from 1999 to 2002. Women with a history of a previous preterm cesarean delivery were compared with women who had a previous term cesarean delivery. Women who had both a preterm and term cesarean delivery were included in the preterm group. RESULTS: A prior preterm cesarean delivery was significantly associated with an increased risk of subsequent uterine rupture (0.58% compared with 0.28%, P<.001). When women who had a subsequent elective cesarean delivery were removed (remaining n=26,454) women with a previous preterm cesarean delivery were still significantly more likely to sustain a uterine rupture (0.79% compared with 0.46%, P=.001). However, when only women who had a subsequent trial of labor were included, there was still an absolute increased risk of uterine rupture, but it was not statistically significant (1.00% compared with 0.68%, P=.081). In a multivariable analysis controlling for confounding variables (oxytocin use, two or more previous cesarean deliveries, a cesarean delivery within the past 2 years, and preterm delivery in the current pregnancy), patients with a previous preterm cesarean delivery remained at an increased risk of subsequent uterine rupture (P=.043, odds ratio 1.6, 95% confidence interval 1.01-2.50) compared with women with previous term cesarean delivery. CONCLUSION: Women who have had a previous preterm cesarean delivery are at a minimally increased risk for uterine rupture in a subsequent pregnancy when compared with women who have had previous term cesarean deliveries.     

Pregnancy outcome following recurrent spontaneous abortions

OBJECTIVE: The purpose of the present study was to examine the association between spontaneous consecutive recurrent abortions and pregnancy complications such as hypertensive disorders, abruptio placenta, intrauterine growth restriction and cesarean section (CS) in the subsequent pregnancy. METHODS: A population-based study comparing all singleton pregnancies in women with and without two or more consecutive recurrent abortions was conducted. Deliveries occurred during the years 1988-2002. Stratified analysis, using a multiple logistic regression model was performed to control for confounders. RESULTS: During the study period 154,294 singleton deliveries occurred, with 4.9% in patients with history of recurrent consecutive abortions. Using a multivariate analysis, with backward elimination, the following complications were significantly associated with recurrent abortions-advanced maternal age, cervical incompetence, previous CS, diabetes mellitus, hypertensive disorders, placenta previa and abruptio placenta, mal-presentations and PROM. A higher rate of CS was found among patients with previous spontaneous consecutive recurrent abortions (15.9% versus 10.9%; OR = 1.6; 95% CI, 1.5-1.7; P < 0.001). Another multivariate analysis was performed, with CS as the outcome variable, controlling for confounders such as placenta previa, abruptio placenta, diabetes mellitus, hypertensive disorders, previous CS, mal-presentations, fertility treatments and PROM. A history of recurrent abortion was found as an independent risk factor for CS (OR = 1.2; 95% CI, 1.1-1.3; P < 0.001). About 58 cases of inherited thrombophilia were found between the years 2000-2002. These cases were significantly more common in the recurrent abortion as compared to the comparison group (1.2% versus 0.1%; OR = 11.1; 95% CI, 6.5-18.9; P < 0.001). CONCLUSION: A significant association exists between consecutive recurrent abortions and pregnancy complications such as placental abruption, hypertensive disorders and CS. This association persists after controlling for variables considered to coexist with recurrent abortions. Careful surveillance is required in pregnancies following recurrent abortions, for early detection of possible complications.     

Placenta accreta--summary of 10 years: a survey of 310 cases

The objective was to study the incidence, risk factors, and outcome of pregnancies complicated by placenta accreta in our population. Retrospective analysis of all deliveries between the years 1990-2000, and identification of all cases of placenta accreta, defined by clinical or histological criteria. For comparison purposes we defined two sub-groups: (i) all cases that ended with severe outcome and (ii) all patients who had a previous event of placenta accreta in one or more of their previous deliveries. We evaluated the potential risk factors leading to these conditions. The SPSS software package was used for statistical analysis. Univariate and multivariate analyses were performed by stepwise logistic regression. The study covered 34 450 deliveries from which 310 cases of placenta accreta were diagnosed (0.9 per cent). The risk factors associated with placenta accreta were previous cesarean delivery (12 per cent), advanced maternal age, high gravidity, multiparity, previous curettage and placenta previa (10 per cent). Hysterectomy was performed in 11 patients (3.5 per cent) with one case of maternal death, whereas 21 per cent of the patients required postpartum blood products transfusion. Antenatal diagnosis of placenta accreta or percreta by ultrasound or MRI, was achieved only in eight of the cases. In the sub-group of 15 patients (4.8 per cent) with severe outcome, the only significant risk factors were increased parity (O.R.=1.29, 95 per cent CI 1.056-1.585), anteriorly low placenta (O.R.=6.1, 95 per cent CI 1.4-25.3) and repeated cases of caesarean sections (O.R.=3.3, 95 per cent CI 0.9-12.5), whereas in the 49 (16 per cent) patients with repeated cases of placenta accreta the only significant risk factor was the number of deliveries (O.R.=1.5, 95 per cent CI 1.0-2.2). Repeated cesarean delivery, high parity, and anteriorly low placental location are associated with severe outcome in case of placenta accreta. Women with repeated events of placenta accreta may have better outcome and a genetic factor may serve as a cause for this condition.     

Placenta previa: obstetric risk factors and pregnancy outcome

Objective: To determine the incidence, obstetric risk factors and perinatal outcome of placenta previa. Study design: All singleton deliveries at our institution between 1990 and 1998 complicated with placenta previa were compared with those without placenta previa. Results: Placenta previa complicated 0.38% ( n = 298) of all singleton deliveries ( n = 78 524). A back-step multiple logistic regression model found the following factors to be independently correlated with the occurrence of placenta previa: maternal age above 40 years (OR 3.1, 95% CI 2.0-4.9), infertility treatments (OR 3.1, 95% CI 1.8-5.6), a previous Cesarean section (OR 1.8, 95% CI 1.4-2.4), a history of habitual abortions (OR 1.3, 95% CI 1.3-2.7) and Jewish ethnicity (OR 1.3, 95% CI 1.1-1.8). Pregnancies complicated with placenta previa had significantly higher rates of second-trimester bleeding (OR 156.0, 95% CI 87.2-277.5), pathological presentations (OR 7.6, 95% CI 5.7-10.1), abruptio placentae (OR 13.1, 95% CI 8.2-20.7), congenital malformations (OR 2.6, 95% CI 1.5-4.2), perinatal mortality (OR 2.6, 95% CI 1.1-5.6), Cesarean delivery (OR 57.4, 95% CI 40.7-81.4), Apgar scores at 5 min lower than 7 (OR 4.4, 95% CI 2.3-8.3), placenta accreta (OR 3.6, 95% CI 1.1-9.9) postpartum hemorrhage (OR 3.8, 95% CI 1.2-10.5), postpartum anemia (OR 5.5, 95% CI 4.4-6.9) and delayed maternal and infant discharge from the hospital (OR 10.9, 95% CI 7.3-16.1) as compared to pregnancies without placenta previa. In a multivariable analysis investigating risk factors for perinatal mortality, the following were found to be independent significant factors: congenital malformations, placental abruption, pathological presentations and preterm delivery. In contrast, placenta previa and Cesarean section were found to be protective factors against the occurrence of perinatal mortality while controlling for confounders. Conclusion: Although an abnormal implantation per se was not an independent risk factor for perinatal mortality, placenta previa should be considered as a marker for possible obstetric complications. Hence, the detection of placenta previa should encourage a careful evaluation with timely delivery in order to reduce the associated maternal and perinatal complications.     

Placenta previa: obstetric risk factors and pregnancy outcome.

OBJECTIVE: To determine the incidence, obstetric risk factors and perinatal outcome of placenta previa. STUDY DESIGN: All singleton deliveries at our institution between 1990 and 1998 complicated with placenta previa were compared with those without placenta previa. RESULTS: Placenta previa complicated 0.38% (n = 298) of all singleton deliveries (n = 78 524). A back-step multiple logistic regression model found the following factors to be independently correlated with the occurrence of placenta previa: maternal age above 40 years (OR 3.1, 95% CI 2.0-4.9), infertility treatments (OR 3.1, 95% CI 1.8-5.6), a previous Cesarean section (OR 1.8, 95% CI 1.4-2.4), a history of habitual abortions (OR 1.3, 95% CI 1.3-2.7) and Jewish ethnicity (OR 1.3, 95% CI 1.1-1.8). Pregnancies complicated with placenta previa had significantly higher rates of second-trimester bleeding (OR 156.0, 95% CI 87.2-277.5), pathological presentations (OR 7.6, 95% CI 5.7-10.1), abruptio placentae (OR 13.1, 95% CI 8.2-20.7), congenital malformations (OR 2.6, 95% CI 1.5-4.2), perinatal mortality (OR 2.6, 95% CI 1.1-5.6), Cesarean delivery (OR 57.4, 95% CI 40.7-81.4), Apgar scores at 5 min lower than 7 (OR 4.4, 95% CI 2.3-8.3), placenta accreta (OR 3.6, 95% CI 1.1-9.9) postpartum hemorrhage (OR 3.8, 95% CI 1.2-10.5), postpartum anemia (OR 5.5, 95% CI 4.4-6.9) and delayed maternal and infant discharge from the hospital (OR 10.9, 95% CI 7.3-16.1) as compared to pregnancies without placenta previa. In a multivariable analysis investigating risk factors for perinatal mortality, the following were found to be independent significant factors: congenital malformations, placental abruption, pathological presentations and preterm delivery. In contrast, placenta previa and Cesarean section were found to be protective factors against the occurrence of perinatal mortality while controlling for confounders. CONCLUSION: Although an abnormal implantation per se was not an independent risk factor for perinatal mortality, placenta previa should be considered as a marker for possible obstetric complications. Hence, the detection of placenta previa should encourage a careful evaluation with timely delivery in order to reduce the associated maternal and perinatal complications.     

Identifying risk factors for peripartum cesarean hysterectomy. A population-based study

OBJECTIVE: To determine the incidence of, and obstetric risk factors for, emergency peripartum hysterectomy. STUDY DESIGN: A population-based study comparing all singleton deliveries between the years 1988 and 1999 that were complicated with peripartum hysterectomy to deliveries without this complication. Statistical analysis was performed with multiple logistic regression analysis. RESULTS: Emergency peripartum hysterectomy complicated 0.048% (n = 56) of deliveries in the study (n = 117,685). Independent risk factors for emergency peripartum hysterectomy from a backward, stepwise, multivariable logistic regression model were: uterine rupture (OR = 521.4, 95% CI 197.1-1379.7), placenta previa (OR = 8.2, 95% CI 2.2-31.0), postpartum hemorrhage (OR = 33.3, 95% CI 12.6-88.1), cervical tears (OR = 18.0, 95% CI 6.2-52.4), placenta accreta (OR = 13.2, 95% CI 3.5-50.0), second-trimester bleeding (OR = 9.5, 95% CI 2.3-40.1), previous cesarean section (OR = 6.9, 95% CI 3.7-12.8) and grand multiparity (> 5 deliveries) (OR = 3.4, 95% CI 1.8-6.3). Newborns delivered after peripartum hysterectomy had lower Apgar scores (< 7) at 1 and 5 minutes than did others (OR = 11.5, 95% CI 6.2-20.9 and OR = 27.4, 95% CI 11.2-67.4, respectively). In addition, higher rates of perinatal mortality were noted in the uterine hysterectomy vs. the comparison group (OR = 15.9, 95% CI 7.5-32.6). Affected women were more likely than the controls to receive packed-cell transfusions (OR = 457.7, 95% CI 199.2-1105.8) and had lower hemoglobin levels at discharge from the hospital (9.9 +/- 1.3 vs. 12.8 +/- 5.7, P < .001). CONCLUSION: Cesarean deliveries in patients with suspected placenta accreta, specifically those performed due to placenta previa in women with a previous uterine scar, should involve specially trained obstetricians. In addition, detailed informed consent about the possibility of emergency peripartum hysterectomy and its associated morbidity should be obtained.     

Antepartum risk factors associated with peripartum cesarean hysterectomy in women with placenta previa

The objective of this study was to identify antepartum risk factors for peripartum hysterectomy in women with placenta previa. The medical records of women with placenta previa who underwent cesarean section (C/S) were reviewed retrospectively. Data regarding the reproductive history and peripartum outcomes were analyzed. Multivariable analysis was used to identify factors independently associated with hysterectomy. During an 8.5-year period, 346 cases of placenta previa were identified in 24,987 deliveries (1.4%). An emergent hysterectomy was performed in 31 patients (9.0%). Multiparity, total previa, history of abortion, C/S, and placenta previa was more common in the hysterectomy group. An increasing number of abortions and C/S were associated with a higher frequency of hysterectomy. By the multivariable analysis, previous abortion, previous C/S, and total previa were significant risk factors for hysterectomy. We concluded that in women with placenta previa, history of abortion as well as prior C/S, and a total previa are strong antepartum risk factors for peripartum hysterectomy.     

Blood transfusion and cesarean delivery

OBJECTIVE: To evaluate risks for intraoperative or postoperative packed red blood cell transfusion in women who underwent cesarean delivery. METHODS: This was a 19-university prospective observational study. All primary cesarean deliveries from January 1, 1999, to December 31, 2000, and all repeat cesareans from January 1, 1999, to December 31, 2002, were included. Trained, certified research nurses performed systematic data abstraction. Primary and repeat cesarean deliveries were analyzed separately. Univariable analyses were used to inform multivariable analyses. RESULTS: A total of 23,486 women underwent primary cesarean delivery, of whom 762 (3.2%) were transfused (median 2 units, 25th% to 75th% 2-3 units). A total of 33,683 women underwent repeat [corrected] cesarean delivery, and 735 (2.2%) were transfused (median 2 units, 25th% to 75th% 2-4 units). Among primary cesareans, general anesthesia (odds ratio [OR] 4.2, 95% confidence interval [CI] 3.5-5.0), placenta previa (OR 4.8, CI 3.5-6.5) and severe (hematocrit less than 25%) preoperative anemia (OR 17.0, CI 12.4-23.3) increased the odds of transfusion. Among repeat cesareans, the risk was increased by general anesthesia (OR 7.2, CI 5.9-8.7), a history of five or more prior cesareans (OR 7.6, CI 4.0-14.3), placenta previa (OR 15.9, CI 12.0-21.0), and severe preoperative anemia (OR 19.9, CI 14.5-27.2). CONCLUSION: Overall, the risk of transfusion in association with cesarean is low. However, both severe preoperative maternal anemia and placenta previa are associated with markedly increased risks. The former argues for optimizing maternal antenatal iron status to avoid severe anemia and the latter for careful perioperative planning when previa complicates cesarean. LEVEL OF EVIDENCE: II-2.     

Placenta previa and antepartum hemorrhage after previous cesarean section

A prospective study was conducted to determine the risk of placenta previa and unexplained antepartum hemorrhage after a previous cesarean section (CS). Of a total of 24,644 patients, 81 (0.33%) had a placenta previa which demanded abdominal delivery. The risk of placenta previa was 0.25% with an unscarred uterus and 1.22% in patients with one or more previous CS (the difference was statistically significant p less than 0.001). The corresponding figures for unexplained antepartum hemorrhage were 0.40% and 3.81%, respectively (p less than 0.001). Patients presenting with a placenta previa and a scarred uterus had a 16% risk of undergoing cesarean hysterectomy because of placenta accreta and severe hemorrhage compared to 3.6% in patients with placenta previa and an unscarred uterus. In conclusion, cesarean deliveries predispose to placenta previa, placenta accreta and antepartum hemorrhage during subsequent pregnancies. This relationship has to be considered in the cost-benefit equation for decision of route of delivery.