Clinical risk factors for placenta previa–placenta accreta,☆☆,

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Abstract

OBJECTIVE: Our purpose was to define the clinical risk factors associated with placenta previa–placenta accreta. STUDY DESIGN: Hospital records were reviewed of all cases of placenta accreta confirmed histologically between January 1985 and December 1994. Additionally, we reviewed the records of all women with placenta previa and all those undergoing cesarean hysterectomy during the same period. Multiple Iogistic regression analysis was used to identify independent clinical risk factors for placenta accreta. RESULTS: Among 155,670 deliveries, 62 (1/2510) were complicated by histologically confirmed placenta accreta. Placenta accreta occurred in 55 of 590 (9.3%) women with placenta previa and in 7 of 155,080 (1/22,154) without placenta previa (relative risk 2065, 95% confidence interval 944 to 4516, p < 0.0001). Among women with placenta previa, advanced maternal age (≥35 years) and previous cesarean delivery were independent risk factors for placenta accreta. Placenta accreta was present in 36 of 124 (29%) cases in which the placenta was implanted over the uterine scar and in 4 of 62 (6.5%) cases in which it was not (relatiave risk 4.5, 95% confidence interval 1.68 to 12.07). Among women with placenta previa, the risk of placenta accreta ranged from 2% in women <35 years old with no previous cesarean deliveries to almost 39% in women with two or more previous cesarean deliveries and an anterior or central placenta previa. CONCLUSION: Placenta accreta occurs in approximately 1 of 2500 deliveries. Among women with placenta previa, the incidence is nearly 10%. In this high-risk group advanced maternal age and previous cesarean section are independent risk factors.(Am J Obstet Gynecol 1997;177:210-4)

Section snippets

Material and methods

Hospital records were reviewed of all cases of placenta accreta confirmed by histologic examination of hysterectomy specimens between Jan. 1, 1985, and Dec. 31, 1994. Additionally, we reviewed the records of all women undergoing cesarean hysterectomy and all women with placenta previa during the same period. Multiple logistic regression analysis was used to identify independent risk factors for placenta accreta. Relative risks were calculated with Taylor series 95% confidence intervals. A p

Results

During the study period, there were 155,670 deliveries at Los Angeles County/University of Southern California Women's Hospital. One hundred twenty-seven (1/1226) cesarean hysterectomies were performed with an operative diagnosis of placenta accreta. In 65 cases (52%) histologic findings did not confirm the diagnosis of placenta accreta. The remaining 62 cases (48%) were confirmed histologically and are the subjects of our report. Among these, 47 were placenta accreta, 11 were placenta increta,

Comment

Although earlier reports accepted clinical recognition of abnormal placental adherence as the basis for diagnosis of placenta accreta,3, 4 recent studies have distinguished between suspected and histologically confirmed cases.1, 5, 6, 7 In this series clinical suspicion of placenta accreta was an unreliable predictor of histologic findings, correctly identifying only 48% of cases. Therefore we confined our analysis to histologically confirmed cases. We recognize that exclusion of unconfirmed

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    From the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Los Angeles County/University of Southern California Women's and Children's Hospital.

    ☆☆

    Reprint requests: David A. Miller, MD, LAC+USC Women's and Children's Hospital, Department of Obstetrics and Gynecology, Room 5K-40, 1240 North Mission Road, Los Angeles, CA 90033.

    6/1/81387

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