Treatment with an antifibrinolytic such as tranexamic acid is known to reduce death from bleeding in patients with trauma and post-partum hemorrhage. Now a new meta-analysis has found strong evidence that even a short delay in treatment reduces the survival benefit from tranexamic acid administration. The data, based on more than 40,000 patients with traumatic or post-partum bleeding, showed:
immediate treatment with tranexamic acid improved survival by more than 70% compared with placebo.
the survival benefit from tranexamic acid decreased by about 10% for every 15 minutes of treatment delay up until 3 hours, after which there was no benefit.
Uncommon complication of pregnancy. Usually diagnosed on routine ultrasound done for other reasons, but may present with painless vaginal bleeding in the second or third trimester.
Classified according to the placental relationship to the cervical os as complete, partial, marginal, or low-lying.
Bleeding in placenta previa may be (or become) torrential, and appropriate monitoring should be performed. Digital vaginal examination should not be performed on women with active vaginal bleeding until the position of the placenta is known with certainty.
Most seen on early ultrasound will resolve spontaneously.
Cesarean section will eventually be necessary in all cases of complete placenta previa. Cesarean sections may be complicated by excessive bleeding and the need for cesarean hysterectomy (or uterine artery embolization, or other interventional radiology procedure), and should only be performed by experienced physicians.
Placenta previa (PP) is defined as the placenta overlying the cervical os. It can be complete, partial, marginal, or low lying. Partial, marginal, and low-lying PP may resolve as pregnancy progresses. In women with a scarred uterus (most commonly from a prior cesarean section), PP may be associated with an abnormally adherent placenta, where the placenta attaches to the myometrial layer of the uterus. Vasa previa, where the fetal vessels lie over the internal cervical os, is an associated condition.
In this monograph we refer to all varieties of invasive placentation as abnormally adherent placenta. There are 3 commonly defined variants: placenta accreta (where chorionic villi attach to the myometrium, rather than being restricted within the decidua basalis), placenta increta (where the chorionic villi invade into the myometrium), and placenta percreta (where the chorionic villi invade through the myometrium and sometimes into adjoining tissue).  Although these distinctions are important to consultants, they do not change management decisions for primary care providers.
Family and Community Medicine
Southern Illinois University School of Medicine
JRA has acted as an expert witness for the US Dept of Justice. JRA has received an honorarium for the development of learning material for Social Determinants of Health and Care Coordination for Relias Learning.
Clinical Family and Community Medicine
Residency Program Director
SIU Quincy Family Medicine
Southern Illinois University
THM declares that he has no competing interests.
Dr Janet R. Albers and Dr Thomas H. Miller would like to gratefully acknowledge Dr Robert Ewart and Dr Matthew Hagermeyer, previous contributors to this monograph. RE and MH declare that they have no competing interests.
Head of Department of Obstetrics and Gynecology
Mosul College of Medicine
YTJ declares that he has no competing interests.
Consultant in Family Medicine
Parker D Sanders and Isabella Sanders Professor of Primary Care
JB declares that he has no competing interests.
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