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Obstetrical Prognosis after Placental Abruption
Abstract & Commentary
In a recent study from Japan, Toivonen and colleagues set out to determine how much more susceptible women experiencing placental abruption were to having a recurrence of this problem in a subsequent pregnancy. They scanned a database which encompassed 14,326 deliveries during a one-year period at a busy university hospital. Fifty-nine patients who had a history of abruption in a previous pregnancy were identified, and the outcomes of these pregnancies were then compared with those from pregnancies without a recurrent abruption, and against those of the overall study population. Toivonen et al only included diagnoses made after 20 weeks.
The incidence of abruption in those having had this condition in a previous pregnancy was 11.9%, compared with a rate in the rest of the population of 0.7%. The recurrent abruptors had a very high rate of prematurity (100%), low birth weight (85.7%), low 5-minute Apgar scores (28.6%), and perinatal mortality (14%). Interestingly, those with a history of abruption who did not repeat had a rate of adverse outcome that was no different in any category from that of the overall population (Toivonen S, et al. Fetal Diagn Ther. 2004;19:336-341).
Comment by John C. Hobbins, MD
We are often asked by our patients what the chances are of having a repeat of what, at worst, was a disaster for them or, at the least, a vexing lifestyle altering experience. Since there has been little in the literature on this, I have waffled on the answer. Now I can say that there is a 90% chance it will not recur and, if it does not, the individual’s chances of having perinatal problems are no different than anyone not having had this experience in a previous pregnancy. Unfortunately, that cannot be said of those who do have a recurrence.
The incidence in the overall population of 7 per 1000 is an underestimation of the prevalence of abruption, since vaginal bleeding prior to 20 weeks is far more common, and often the bleeding is due to abruption, in spite of lack of ultrasound evidence to back up the diagnosis. The ultrasound diagnosis of abruption involves the identification of an extra membranous clot. Rarely does one actually visualize a separation of the placenta from the underlying uterine wall. In about 50% of cases, when no ultrasound clues are present, the blood from the placenta tracks extra membranously to the cervix without stopping to form a clot.
This study, like others, once again shows a higher incidence of abruption among smokers. Also, there was a greater predisposition to abruption among pre-eclamptics. Other studies show a higher rate of abruption in patients with thrombophilia (Factor V Leiden, protein S deficiency, and Methylenetetrahydrofolate reductase [MTHFR] mutations). The common denominator in all of these relationships would be an interference with normal trophoblastic invasion of the spiral arteries in the second trimester.
Fortunately, this study should better allow us to counsel patients with abruption regarding future pregnancies.
John C. Hobbins, MD, Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver , is Associate Editor for OB/GYN Clinical Alert.