Prenatal care always has been in part about identifying women with medical complications including preeclampsia. We have long measured blood pressure, checked the urine for high levels of protein, and monitored weight gain. We still do.
Dr. Baha Sibai
However, over the years, the diagnostic criteria for preeclampsia have evolved, first with the exclusion of edema and more recently with the exclusion of proteinuria as a necessary element of the diagnosis. The American College of Obstetricians and Gynecologists’ Task Force Report, Hypertension in Pregnancy, published in 2013, concluded that while preeclampsia may still be defined by the occurrence of hypertension with proteinuria, it also may be diagnosed when hypertension occurs in association with other multisystemic signs indicative of disease severity. The change came based on evidence that some women develop eclampsia, HELLP syndrome, and other serious complications in the absence of proteinuria.
The 2013 document also attempted to review and clarify various issues relating to the classifications, diagnosis, prediction and prevention, and management of hypertension during pregnancy, including the postpartum period. In many respects, it was successful in doing so. However, there is still much confusion regarding the diagnosis of certain categories of hypertensive disorders – particularly preeclampsia with severe features and superimposed preeclampsia with or without severe features.
While it is difficult to establish precise definitions given the often insidious nature of preeclampsia, it still is important to achieve a higher level of clarity with respect to these categories. Overdiagnosis may be preferable. However, improper classification also may influence management decisions that could prove detrimental to the fetus.
Severe gestational hypertension
ACOG’s 2013 Report on Hypertension in Pregnancy classifies hypertensive disorders of pregnancy into these categories: Gestational hypertension (GHTN), preeclampsia, preeclampsia with severe features (this includes HELLP), chronic hypertension (CHTN), superimposed preeclampsia with or without severe features, and eclampsia.
Some of the definitions and diagnostic criteria are clear. For instance, GHTN is defined as the new onset of hypertension after 20 weeks’ gestation in the absence of proteinuria or systemic findings such as thrombocytopenia or impaired liver function. CHTN is defined as hypertension that predates conception or is detected before 20 weeks’ gestation. In both cases there should be elevated blood pressure on two occasions at least 4 hours apart.
A major omission is the lack of a definition for severe GHTN. Removal of this previously well-understood classification category combined with unclear statements regarding preeclampsia with or without severe features has made it difficult for physicians to know in some cases of severe hypertension only what diagnosis a woman should receive and how she should be managed.
I recommend that we maintain the category of severe GHTN, and that it be defined as a systolic blood pressure (BP) greater than or equal to 160 mm Hg and/or diastolic BP greater than or equal to 110 mm Hg on at least two occasions at least 4 hours apart when antihypertensive medications have not been initiated. There should be no proteinuria or severe features such as thrombocytopenia or impaired liver function.
The physician may elect in these cases to administer antihypertensive medication and observe the patient in the hospital. An individualized decision can then be made regarding how the patient should be managed, including whether she should be admitted and whether the pregnancy should continue beyond 34 weeks. Blood pressure, gestational age at diagnosis, the presence or absence of symptoms, and laboratory tests all should be taken into consideration.