Attempts to predict preeclampsia have met with poor results. Measurement of the ratio of uterine artery systolic to diastolic flow has not been informative in the general healthy population of pregnant women. Nor has uric acid determination been useful; it generally has very poor predictive value and should be interpreted with caution.
TABLE 2
13 criteria for establishing severe preeclampsia
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Hospitalization is essential for severe disease
Mild preeclampsia can be managed expectantly until fetal maturity or 37 weeks’ gestation. Severe preeclampsia can be managed expectantly in the mid trimester or early third trimester if both mother and fetus are stable, but hospitalization is necessary in a tertiary care facility that has critical-care OB expertise, an ICU facility, and a NICU facility and personnel on site.
Distinguish an existing condition from superimposed preeclampsia
One of the most difficult management challenges is the diagnosis of superimposed preeclampsia. Patients who have chronic hypertension often have underlying renal disease as well; in these patients, it may be difficult, if not impossible, to distinguish a worsening underlying medical condition from superimposed preeclampsia.
Our advice is not to agonize about this difference too much in the patient at or near term, as delivery may be indicated and the patient’s postpartum course may help resolve the question, with rapid resolution tending to favor a diagnosis of superimposed preeclampsia.
It also is important to note whether these patients are receiving antihypertensive therapy. If they are, hospitalization is recommended until delivery once the diagnosis of superimposed preeclampsia is made.
Given that the use of antihypertensive agents removes one of the major indicators of disease progression (i.e., rising BP), it is our practice to deliver these patients according to our severe preeclampsia management protocol and not to carry such pregnancies beyond 34 weeks. In carefully selected cases, the pregnancy can be continued to 37 weeks, but the decision to do so should be weighed carefully—ideally, with input from a maternal–fetal medicine specialist.
CHALLENGE NO. 2: Forgoing shortcuts
Evaluation and management of preeclampsia are relatively straightforward, but there are no shortcuts. Many patients who feel well initially may push for outpatient evaluation, but once a diagnosis of preeclampsia is established, in-hospital evaluation is preferable, at least until the degree of illness can be determined, fetal well-being can be established, and the patient’s candidacy for subsequent outpatient management can be more fully determined.
In-hospital management may be particularly useful for patients who have any of the risk factors for preeclampsia listed in TABLE 1.
Initial evaluation consists of:
- fetal nonstress testing
- amniotic fluid index
- serial BP determination
- 24-hour urine collection
- initial laboratory evaluation comprising a complete blood count with platelets and aspartate aminotransferase (AST), alanine aminotransferase (ALT), and creatinine levels.
If fetal and maternal evaluations are reassuring, and if the patient has remained stable, then outpatient management may be considered. In general, if proteinuria exceeds 1 g in 24 hours, in-hospital management is recommended, regardless of other parameters.
If outpatient management is considered, the level of care and surveillance must mirror what could be provided in the hospital. Hospitalization alone will not prevent all cases from progressing to severe preeclampsia or eclampsia, but daily and diligent observation and evaluation may minimize the risk.
CHALLENGE NO. 3: Treating the disease
Appropriate treatment of preeclampsia requires not only that the patient show up for prenatal care, but also that we:
- are certain of the diagnosis
- recognize the potential seriousness of the disease
- are thorough (remember, no shortcuts!).
Many experts in the field of preeclampsia have stated, on numerous occasions, that preeclampsia is more than simple hypertension. It is almost never advisable to initiate antihypertensive therapy for a patient in the third trimester when she was previously normotensive, because one runs the risk of masking a key clinical parameter used to assess disease progression.