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Mrs. T.W. is a 23 year old primigravida at 38 weeks. During her routine OB check, she was noted to have an elevated blood pressure of 144/96 and 2+ proteinuria. She also had swollen hands, feet and face, and she noted a 6 pound weight gain since her last visit a week ago. Her peripheral reflexes are very brisk, but without any clonus. She has had no prenatal problems until now and no significant past medical history.
She is demonstrating the classical findings of pre-eclampsia, including hypertension, proteinuria, edema and increased reflexes. To make this diagnosis, it is not essential to see all of these, but persistent hypertension and proteinuria are necessary.
The 6 pound weight gain is best explained on the basis of fluid retention, since it really isn’t possible to excessively eat your way to a 6 pound weight gain in 1 week. Although she is retaining fluid, the fluid is not in her intravascular space, but rather in the periphery or 3rd space. This is because of the endothelial breaks present among pre-eclamptic women, that allow intravascular fluid/plasma to leak out into the surrounding connective tissue where it becomes trapped. The kidney, responding to the intravascular volume and the resulting increase in ADH, retains water which continues to leak out into the 3rd space.
I drew some blood tests and ran them immediately, finding:
• Hemoglobin = 13.6. This unusually high hemoglobin reflects the patient’s decreased blood plasma (It has leaked out into the periphery), with the same number of RBCs, which are too large to leak out through the damaged enothelium. So she has some degree of hemoconcentration, a finding common to pre-eclamptics.
• Platelets = 186,000. This normal finding is reassuring. Had the platelets been reduced to less than 100,000, then this patient would be re-classified as having severe pre-eclampsia, not mild pre-eclampsia.
• Uric Acid = 6.8. This abnormal elevation of uric acid is frequently seen in pre-eclampsia. I probably reflects some combination of increased production through breakdown of cells and their nuclei downstream from the microvascular vasospasm, and decreased renal clearance. There has been some recent evidence that elevation of uric acid, by itself, contributes to further vascular spasm and endothelial damage.
• BUN = 18. This elevation is consistent with the hemoconcentration we see in pre-eclampsia.
• SGOT and SGPT. These primarily liver enzymes were both normal. In the presence of severe pre-eclampsia or HELLP syndrome, they will frequently be elevated, and their elevation roughly reflects the severity of the disease.
• Bilirubin was normal, reflecting the absence of hemolysis. In the more severe forms of pre-eclampsia or HELLP syndrome, bilirubin will be elevated.
• Her urine dipstick confirmed the presence of 2+ protein. 1+ or greater is indicative of clinically significant proteinuria in pregnant women, although the gold standard is a 24 hour urine collection. Pregnant women can normally lose up to 200 mg of protein in the urine in 24 hours. If protein loss exceeds 300 mg in 24 hours, this is considered proteinuria. Urine dipstick analysis for protein measures only a single point in time and does not necessarily reflect protein loss over 24 hours. Nonetheless, assuming average urine production of about a liter a day, and consistent loss throughout the 24 hour period:
Based on the patient’s diagnosis of pre-eclampsia at 38 weeks (mild), I sent her to the hospital for induction of labor. Her cervix was favorable for induction, being 2 cm dilated, 80% effaced and 0 station, so we proceeded directly to Pitocin. I favored induction of labor because delivery is really the only cure for pre-eclampsia and at 38 weeks gestation, there was little to be gained by postponing delivery and much to be gained by getting her delivered.
While some physicians would favor starting this patient on magnesium sulfate to protect against seizures during the induction, I held off starting it. Magnesium sulfate is very useful in the management of pre-eclampsia, but it is somewhat dangerous, has a lot of side effects, makes people feel bad, and interferes to some extent with labor. If she had severe pre-eclampsia or even a worsening mild pre-eclampsia, I wouldn’t hesitate to start the magnesium. But for a simple, uncomplicated mild pre-eclampsia, I didn’t feel it was necessary to start the mag. I do think it’s important to be vigilant for evidence of worsening disease.
