Blood pressure, edema and proteinuria criteria in pregnancy
THE CONTEXT
The passage describes blood pressure thresholds and measurement technique, along with edema and proteinuria findings relevant to pre-eclampsia.
Blood pressure thresholds and confirmation
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When previous blood pressure is unknown, an absolute level of at least 140/90 mm Hg is commonly considered. The passage describes this threshold as arbitrary and associates higher levels with more complications.
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A systolic rise of at least 30 mm Hg or a diastolic rise of at least 15 mm Hg above a known previous blood pressure was also taken as pregnancy-induced hypertension.
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Mean arterial pressure is calculated as [systolic blood pressure + (2 × diastolic blood pressure)] ÷ 3.
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A rise in mean arterial pressure of 20 mm Hg above the previous reading, or a mean arterial pressure of at least 105 mm Hg, is considered significant in the passage.
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The rise in blood pressure should be evident on at least two occasions at least four hours apart.
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Some women with a rise in blood pressure that remains below 140/90 mm Hg, termed delta hypertension, develop overt pre-eclampsia, eclampsia or HELLP syndrome.
Blood pressure measurement
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Diastolic blood pressure is recorded at disappearance of the sounds, corresponding to Korotkoff phase V.
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The cuff length should be 1.5 times the upper arm circumference, and its bladder should encircle at least 80% of the arm.
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Measure blood pressure after at least 10 minutes of rest, with the patient upright, sitting or in the left lateral position.
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Keep the occluded brachial artery at heart level.
Edema and weight gain
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Pitting ankle edema after 12 hours of bed rest or weight gain exceeding 4 lb per week in the later months of pregnancy may be the earliest evidence of pre-eclampsia.
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Some edema is physiological in normal pregnancy.
Significant proteinuria
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Significant proteinuria includes total urinary protein of at least 0.3 g in 24 hours or a urine protein-to-creatinine ratio greater than 0.3.
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Persistent urine protein of 30 mg/dL in at least two random clean-catch samples collected four hours apart is also described as significant in the absence of urinary tract infection.