LabMed

Eclampsia

At a Glance

Eclampsia is defined as the occurrence of 1 or more generalized convulsions and/or unexplained coma during pregnancy or postpartum in women with signs and symptoms of preeclampsia (hypertension and proteinuria). The reported incidence of eclampsia ranges from 4 to 6 cases per 10,000 pregnancies in developed countries and higher in developing countries.

Rather than a separate disease, eclamptic seizures are considered 1 of several clinical complications of severe preeclampsia. Preeclampsia occurs in about 5-8% of pregnancies after 20 weeks’ gestation in the United States and 3-14% of all pregnancies globally. Eclampsia occurs in about 0.5% of mild preeclampsia and 2-3% of severe preeclampsia. Ninety-one percent of cases of eclampsia develop at or beyond 28 weeks. The remaining cases occur between 21 and 27 weeks of gestation, with the onset of eclampsia at or prior to 20 weeks of gestation being rare (1.5%).

Eclampsia is characterized by generalized, tonic-clonic seizures, which are almost always self-limiting and usually last 60-75 seconds. Symptoms that may occur before or after the onset of seizure include persistent frontal or occipital headaches, visual changes, photophobia, right upper quadrant or epigastric pain, and altered mental status.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

The diagnosis of eclampsia is based on evidence of new-onset tonic-clonic seizures and/or coma in a woman with preeclampsia.(Table 1)

Table 1.

ACOG Recommendations for the Diagnosis of Preeclampsia
Blood Pressure Proteinuria
Preeclampsia 140 mm Hg systolic or higher or/ 90 mm Hg diastolic or higher ≥0.3 g protein in a 24-hour urine specimen or/ persistent 1+ (30 mg/dL) on dipstick

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

False-positive dipstick urine protein may be due to contamination of urine with other sources of protein, such as blood, semen, or vaginal secretions. The specimen for protein urine testing should be obtained before pelvic examination to minimize the chance of contamination from vaginal secretions. False-positive tests may also occur in the presence of highly alkaline urine, quaternary ammonium compounds, detergents and disinfectants, drugs, radio-contrast agents, and high specific gravity. False-negative tests can occur with low specific gravity, high salt concentration, and highly acidic urine. Urine dipstick results can be greatly affected by hydration status, as urine dipstick reflects protein concentration, but not an absolute value.

What Lab Results Are Absolutely Confirmatory?

The diagnosis of eclampsia is secure in the presence of hypertension, proteinuria, and seizures. Screening for proteinuria is commonly performed by a semi-quantitative dipstick test. If slight to moderate amounts of protein are detected, then a repeat dipstick protein may be performed at a later time. If there is a large amount of protein on the first test and/or the protein persists in the second specimen, then quantitative 24-hour urine protein measurement should be performed as a confirmatory test.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Since mild gestational hypertension occurring in the first half of pregnancy may, subsequently, develop into preeclampsia/eclampsia, close clinical follow-up is essential for pregnant women with hypertension and characteristic signs and symptoms, even if proteinuria is absent. This recommendation is also supported by the observations that proteinuria is absent in 10% of women with preeclampsia and 20% of women with eclampsia.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

Drug interference in 24-hour urine protein assays has been widely reported, and different urine protein assays vary in response to different drugs. For instance, acetazolamide may produce false-positive results with the sulfosalicylic acid (SSA) assay because of alkalinization of urine. Aminoglycoside interference has been reported in the Pyrogallol Red–Molybdate (PRM) assay. The benzethonium chloride (BEC) assay is less prone to interference from aminoglycosides; however, therapeutic concentrations of Ca-dobesilate, levodopa, and phenazopyridine interfere with the BEC assay.

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