Preeclampsia: Pathogenesis and Evaluation
Preeclampsia
New-onset hypertension is defined as the development of hypertension (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg on two occasions 4 hours apart) in a woman whose blood pressure readings were previously normal, after the 20th week of pregnancy.
New-onset proteinuria is defined as ≥0.3 g of protein in a timed 24-hour urine collection or a protein/creatinine ratio ≥0.3 after the 20th week of gestation.
160 is pre-eclampsia, even if there is no proteinuria
Proteinuria Assessment
- Urine dipstick readings are not preferred, but if no other method is available, +1 or greater indicates proteinuria.
- Protein levels are not predictive of how the disease will progress.
- Edema is no longer considered a diagnostic criterion.
Eclampsia
Eclampsia is the presence of new-onset grand mal seizures in a woman with preeclampsia that cannot be attributed to other causes.
HELLP Syndrome
- Hemolysis
- Elevated liver enzymes (ALT/AST if amount is double in this case)
- Low platelets- <100k
Need all three to diagnose HELLP syndrome; however, any one of them is diagnostic of preeclampsia with severe features when elevated BP is present.
Chronic HTN with Superimposed Preeclampsia
Women with chronic hypertension who develop new-onset proteinuria (≥0.3 g in a 24-hour collection) after the 20th week of gestation. In pregnant women with preexisting hypertension and proteinuria, the diagnosis of superimposed preeclampsia should be considered if they experience sudden significant increases in blood pressure or proteinuria or the new onset of any of the other signs and symptoms of severe preeclampsia.
Criteria for Severe Preeclampsia
BOX 14-1
- Severe hypertension (systolic BP ≥160 mm Hg or diastolic BP ≥110 mm Hg) at rest on two occasions at least 4 hr apart*
- Renal insufficiency (serum Cr >1.1 mg/dL or doubling of baseline values)
- Cerebral or visual disturbances
- Pulmonary edema
- Epigastric or right upper quadrant pain
- Elevated liver enzymes (AST or ALT at least two times normal level)
- Thrombocytopenia (platelet count <100,000/µL)
ALT, Serum alanine aminotransferase; AST, serum aspartate aminotransferase; BP, blood pressure; Cr, creatinine. *4-hr delay not required if antihypertensive therapy is initiated.
Preeclampsia as a Multisystem Disorder
Pathogenesis of Preeclampsia
It is a multisystem disorder.
Inadequate uteroplacental perfusion leading to placental ischemia, which leads to oxidative and inflammatory stress, with the involvement of secondary mediators leading to endothelial dysfunction, vasospasm, and activation of the coagulation system.
When preeclampsia arises in Treatment :
- the early second trimester (14 to 20 weeks),
- Admission
- Hydration
- a hydatidiform mole or choriocarcinoma should be considered.
Risk Factors for Preeclampsia
- Nulliparity
- First-degree relative with a history of preeclampsia
- Previous preeclamptic pregnancy
- Chronic HTN
- Obesity
- Chronic renal disease
- Multiple-gestation pregnancy
- Diabetes
- Systemic lupus erythematosus
- Maternal age >40 years
Evaluation
The evaluation should focus on whether there is any past history of elevated blood pressure or renal disease, either before pregnancy or during previous pregnancies. The patient should be questioned carefully regarding symptoms of severe preeclampsia or its complications, ICU admission.
- Outcome of her pregnancy and NICU admission.
- Mode of delivery and at which GA.
- Follow-up after delivery.
Physical Examination
The physical examination should be focused on the assessment of blood pressure, weight gain, edema, fundal height, and reflexes, as well as on a qualitative assessment of urinary protein excretion with a dipstick. In addition, findings consistent with severe preeclampsia, such as epigastric or right upper quadrant tenderness, and signs of pulmonary edema, should be sought. If there is severe headache or visual symptoms, an ophthalmic examination may be indicated.
Initial Laboratory Evaluation for a Patient with Preeclampsia
- CBC, platelet count, LDH: if abnormal, order D-dimers, coagulation panel, and smear
- Renal studies: serum BUN creatinine and uric acid, urinalysis, 24-hr urine for protein and creatinine, or protein/creatinine ratio
- Liver function tests: AST, ALT, and bilirubin
ALT, Serum alanine aminotransferase; AST, serum aspartate aminotransferase; BUN, blood urea nitrogen; CBC, complete blood count; LDH, lactate dehydrogenase.
Fetal Assessment
Fetal ultrasound should be performed to evaluate fetal growth, amniotic fluid index, and the umbilical artery Doppler resistance index or systolic/diastolic ratio. A nonstress test (NST) should also be done to determine if there is evidence of acute fetal compromise.