Review
Obstetrics
Amniotic fluid embolism: an evidence-based review

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We conducted an evidence-based review of information about amniotic fluid embolism (AFE). The estimated incidence of AFE is 1:15,200 and 1:53,800 deliveries in North America and Europe, respectively. The case fatality rate and perinatal mortality associated with AFE are 13-30% and 9-44%, respectively. Risk factors associated with an increased risk of AFE include advanced maternal age, placental abnormalities, operative deliveries, eclampsia, polyhydramnios, cervical lacerations, and uterine rupture. The hemodynamic response in AFE is biphasic, with initial pulmonary hypertension and right ventricular failure, followed by left ventricular failure. Promising therapies include selective pulmonary vasodilators and recombinant activated factor VIIa. Important topics for future research are presented.

Section snippets

Materials and methods

We searched several databases (all from inception to March 31, 2009) with the terms “amniotic embolism” and “amniotic embolus.” We also searched references in retrieved articles, book chapters, review articles, and reports on maternal mortality from surveillance systems. Inclusion of individual articles was based on scientific merit and clinical relevance. The great majority of studies included were descriptive, mainly case reports and case series. We also included 2 population-based cohort

Incidence

In 1941, Steiner and Lushbaugh,2 based on the occurrence of 3 cases of fatal AFE in the first 24,200 deliveries at the New Chicago Lying-In Hospital, estimated the incidence of AFE to be about 1 in 8000 deliveries (maternal mortality ratio of 12.4 deaths per 100,000 deliveries), but they subsequently realized that this was an overestimation, since no more cases were observed in the next 26,000 deliveries (corrected maternal mortality ratio of 6.0 deaths per 100,000 deliveries).6 Forty studies2,

Diagnosis

The diagnosis of AFE is based on the clinical presentation and is essentially one of exclusion. Although wide consensus based on objective criteria is still to be achieved, the diagnosis is suspected in a woman experiencing several of the following features: hypotension (and/or cardiac arrest), respiratory distress, DIC, or coma and/or seizures during pregnancy or within 48 hours of delivery, in the absence of other medical condition or potential explanation for the symptoms and signs observed.

Treatment

The management of AFE is supportive and directed toward the maintenance of oxygenation, cardiac output and blood pressure, and correction of the coagulopathy. Treatment should take place in an intensive care unit, if possible. In the event of maternal cardiac arrest, cardiopulmonary resuscitation should be initiated immediately and, if the gestational age of an undelivered alive fetus is viable, cesarean section could be considered.126 Uterine evacuation after unsuccessful resuscitation may be

Recurrence

A total of 9 cases of successful pregnancy following AFE, with no instances of recurrent AFE, have been reported in the literature.21, 146, 147, 148, 149, 150, 151 Therefore, although the available information is limited, the current evidence suggests that AFE is not a recurrent disease.

Comment and conclusions

With the exception of research on risk factors and some diagnostic tests, the available literature on AFE is mainly based on case reports or case series. Thus, there is a need for future research to generate information based on a higher level of evidence, and observational studies are needed. For reliable evidence on rare entities such as AFE, we need systematic review of case reports and case series rather than a haphazard selection of them. Therefore, a worldwide registry of patients with

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    This study was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services.

    Reprints not available from the authors.

    Cite this article as: Conde-Agudelo A, Romero R. Amniotic fluid embolism: an evidence-based review. Am J Obstet Gynecol 2009;201:445.e1-13.

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