Commentary

A new paradigm for preeclampsia


 

That preeclampsia is a growing problem, and one of the most significant causes of maternal-fetal morbidity and mortality today, is what drove the American College of Obstetricians and Gynecologists (ACOG) to convene a task force on hypertension in pregnancy in 2011. Indeed, the incidence of preeclampsia has increased approximately 10% over the last 3 decades in the United States, such that approximately 5%-7% of all pregnant women will develop the disorder.

The specific etiology of preeclampsia remains unclear, but the reasons for the increased incidence likely include the rise in delayed childbearing, the increased use of assisted reproductive technology, a rise in the number of twins, and the obesity pandemic.

Epidemiologically, older women with their first pregnancy are at higher risk of developing preeclampsia, whether or not they use assisted reproductive technology (ART). The not-infrequent use of ART among older women, namely IVF, has a compounding effect. So too, does the incidence of twinning. While we fortunately are seeing a lower rate of higher-order multiple gestations associated with IVF than we did in the 1990s, the incidence of twinning has increased dramatically. Women with multiple gestations of any order are at higher risk of developing preeclampsia.

Dr. John T. Repke

The obesity pandemic is widely believed to be the most modifiable risk factor for preeclampsia. If we can help women to achieve a body mass index (BMI) that is as close to optimal as possible prior to conception, we will likely see significant reductions in the incidence of hypertensive disorders.

Prompt diagnosis of preeclampsia is critical, and on this front, ACOG\'s Task Force on Hypertension in Pregnancy report of 2013 sets forth an important new paradigm for thinking about the disorder and establishing its presence.

Managing preeclampsia remains challenging, however, as there are many areas in which evidence for guiding therapy and management is still insufficient. ACOG’s task force set out to review available data and to attempt to provide clarity on the management of preeclampsia as well as its diagnosis. This was no easy task, and in their culminating report, which lists 60 distinct recommendations, the task force clearly acknowledges the weak evidence base, giving relatively few of their recommendations top marks for both the quality of evidence and their strength of recommendation.

The report appropriately reminds us that there are few if any prescriptions or protocols when it comes to managing preeclampsia. My main concern with the task force’s coverage of management involves their recommendations that magnesium sulfate be used to treat patients with eclampsia and those with preeclampsia with severe features, but not necessarily those without severe features. Patients can progress so rapidly that unless every woman with preeclampsia is vigilantly scrutinized during labor and post delivery – a difficult, if not impossible, task – the window of opportunity to prevent convulsions through the use of magnesium sulfate may well be missed.

ACOG’s new terminology, definitions

Importantly, ACOG’s Task Force on Hypertension in Pregnancy report emphasizes that preeclampsia is an evolving, dynamic, and multisystemic process. It recommends elimination of the terms "mild" and "severe" preeclampsia and encourages the use of new terminology, pushing us to think instead of preeclampsia as being a disorder with or without "severe features." According to the report, a diagnosis of "mild preeclampsia" applies only at the moment at which the diagnosis is established, making the phrase misleading.

Physicians and other providers who have long been in practice will have a hard time ridding their vocabulary of the terms mild and severe preeclampsia, but the intent of the recommendation – to foster appreciation of preeclampsia as an evolving disease – is important and should become entrenched in our approach to hypertension in pregnancy.

The report also downgrades the role of proteinuria in the diagnosis of preeclampsia. Proteinuria is defined as the excretion of 300 mg or more of protein in a 24-hour urine collection or a urine protein/creatinine ratio of at least 0.3 mg/dL. Although proteinuria may indeed be a primary diagnostic finding, it should not be required in order to make the diagnosis of preeclampsia if other severe features are present.

As described in the report, severe features of preeclampsia may include thrombocytopenia (platelet count less than 100,000/microliter), impaired liver function, a rise in serum creatinine indicating progressive renal insufficiency (a serum creatinine concentration greater than 1.1 mg/dL or a doubling of the serum creatinine concentration in the absence of other renal disease), central nervous system disturbances, pulmonary edema, and persistently high elevations in blood pressure (a systolic blood pressure of 160 mm Hg or higher or a diastolic reading of 110 mm Hg or higher on two occasions at least 4 hours apart).

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