Proteinuria, or elevated protein in the urine, should no longer be considered the signature criterion besides new-onset hypertension in diagnosing preeclampsia, says the American College of Obstetricians and Gynecologists.
In exhaustive new clinical guidelines on hypertension in pregnancy, ACOG says that equal weight should be given to reduced platelet counts, renal insufficiency, severe headache, heart-lung compromise, and impaired liver function. Any one of these concurrent with new-onset hypertension at 20 weeks of pregnancy or beyond is enough to establish preeclampsia, even in the absence of proteinuria.
"Clinicians like hard numbers," said Dr. James N. Martin, chief of the division of maternal-fetal medicine at the University of Mississippi Medical Center in Jackson, a past ACOG president, and an author of the guidelines. "But sometimes we can be misled by them." Reviews of maternal mortality data have shown that waiting for proteinuria to present can result in delayed intervention or missed diagnosis, as not all women with preeclampsia will develop proteinuria.
The new guidelines replace recommendations from a 2002 ACOG Practice Bulletin (Obstet. Gynecol. 2002;99:159-67). In addition to the revised diagnostic recommendations and precisely defined measures to determine severity of disease, they address several important management challenges: preeclampsia on top of an existing hypertensive disorder; timing of induction for preeclampsia with and without severe symptoms; use of corticosteroids; and recognizing and managing preeclampsia in the postpartum period.
The guidelines do emphasize one hard number that should be useful to clinicians: Delivery at 37 weeks is advised for women with preeclampsia without severe features.
Dr. Martin said that the 37-week delivery recommendation was based largely on results from a 2009 trial in Holland in which 756 women were randomized to induction at the 36- to 37-week point or expectant monitoring to await labor; induction at 37 weeks was associated with poor outcomes in only 31% of subjects, compared with 44% of those receiving expectant monitoring.
The guidelines distinguish extensively between preeclampsia with and without severe features, but discourage the use of the phrase "mild preeclampsia," considering it misleading. "Preeclampsia in any form should never be minimized as ‘mild,’ " Dr. Martin said.
Proteinuria, in addition to being downgraded as the signature diagnostic finding in preeclampsia, should no longer be considered as useful in classifying preeclampsia as severe or in deciding whether to induce, the guidelines say, because the amount of protein in the urine has not been shown to predict either maternal or fetal outcomes.
Fetal growth restriction, once considered a major criterion to make the diagnosis of severe preeclampsia, is now to be used not for diagnosis of preeclampsia, but for indicated delivery in a patient with preeclampsia who also has an extremely small fetus (less than 5th centile) that is associated with abnormal blood flow findings in the umbilical cord connecting the fetus to the placenta.
The guidelines emphasize that preeclampsia can appear for the first time following delivery, or worsen rather than improve during in the postnatal period. It is advisable that all postpartum patients become educated about symptoms suggestive of new or worsening preeclampsia after leaving the hospital so that the patient’s doctors can be alerted and treatment begun in time to prevent problems.
On the prevention front, the guidelines have less to recommend. The use of vitamins C and E is not advised in preventing preeclampsia. Low-dose aspirin, however, is recommended starting late in the first trimester for patients who experience preterm severe preeclampsia.
"What we really need are biomarkers," Dr. Martin said, adding that despite encouraging science on placental growth factor and other potential early markers, none is yet ready for routine clinical use.
Some of the guidelines’ coauthors reported financial relationships or potential conflicts of interest. Dr. George Bakris disclosed associations with Takeda, CVRx, and other companies. Dr. John Barton disclosed relationships with Alere and Beckman Coulter. Dr. Ananth Karumanchi disclosed relationships with Beckman Coulter, Roche, and others. Dr. Baha Sibai disclosed a relationship with Alere. The remaining task force members said they had no relevant financial disclosures.