Hypertensive Disorders of Pregnancy

1. Definition
   1. EPH gestosis: Edema, Proteinuria, Hypertension
2. Epidemiology
   1. Incidence
      1. All pregnancies: 6-8%
      2. Preterm births: 20%
   2. Mortality: 100,000 maternal deaths per year worldwide
      1. Accounts for 10-30% of all maternal deaths yearly
3. Pathophysiology
   1. Decreased Intravascular volume
      1. Hemoconcentrated
      2. Increased Hemoglobin
   2. Increased Vascular Resistance
   3. Endothelial Cell dysfunction
      1. Very active organ system (not just vessel lining)
      2. Surface Area >6300 square meters over 100g of tissue
      3. Associated findings
         1. Edema
         2. Proteinuria
   4. Coagulation abnormalities
   5. Multiple system effects by oxygen free radicals
      1. Perfusion and re-perfusion injury
      2. Lipid peroxidation
      3. Antioxidant mechanisms are protective
   6. Trophoblastic Invasion
      1. Two phases
         1. First: Decidua
         2. Second: 12-18 weeks gestation
      2. Effects of PIH are reversed with Trophoblast delivery
   7. Model System
      1. Pregnant ewes
      2. Used to study prostaglandin synthesis inhibitor
   8. Hypertension is a major mental roadblock
      1. Prevents understanding and treatment of toxemia
      2. Hypertension is an effect of PIH, not a cause
4. Classification
   1. Pregnancy Induced Hypertension (PIH)
      1. Hypertension without Proteinuria or pathologic edema (Gestational Hypertension)
      2. Preeclampsia with Proteinuria or pathologic edema
         1. Mild Preeclampsia
         2. Severe Preeclampsia
      3. Eclampsia
         1. Convulsions
         2. Proteinuria
         3. Edema
      4. HELLP Syndrome
         1. Hemolysis
         2. Elevated Liver Function Tests
         3. Low platelets
   2. Coincidental Hypertension
      1. See Chronic Hypertension in Pregnancy
      2. Pregnancy Aggravated Chronic Hypertension
         1. Superimposed Preeclampsia
         2. Superimposed Eclampsia
5. Risk Factors
   1. Primigravid or new paternity
   2. Family History of Preeclampsia (25%)
   3. Diabetes Mellitus
   4. Multiple Gestation
   5. Obesity
   6. Maternal age >40 years
   7. Preexisting Hypertension
   8. Angiotensin gene T235
   9. Antiphospholipid Syndrome
   10. Hydatiform mole
   11. Fetal hydrops
6. Symptoms: Onset after 20 weeks gestation
   1. Hand and face edema
      1. Least reliable PIH indicator
      2. Absent in 33% of PIH cases
      3. Often present in healthy third trimester pregnancies
   2. Headache
   3. Visual disturbance
   4. Epigastric Pain
7. Signs: General
   1. Excessive weight gain
   2. Hyperreflexia and Clonus
   3. Blood Pressure
      1. Assumes normal Blood Pressure before pregnancy
      2. Based on two supine Blood Pressures, 6 hours apart
      3. Mild Preeclampsia
         1. Blood Pressure exceeds 140/90
         2. Prior guideline: Relative BP increase 30/15
            1. NHLBI Working Group does not recommend using due to high false positive rate
            2. Use 140/90 cutoff for all pregnant patients
      4. Severe Preeclampsia
         1. Blood Pressure exceeds 160/110
8. Signs: Severe Preeclampsia
   1. Blood Pressure exceeds 160/110
   2. Proteinuria >5 grams per 24 hours (see labs below)
   3. Urine Output decreased
      1. Urine output less than 500 ml in 24 hours
   4. Increased Serum Creatinine
   5. Thrombocytopenia
   6. Pulmonary edema
9. Labs
   1. Proteinuria is not a useful screening measure
      1. Proteinuria is a late finding
      2. Rely on BP and other measures for screening
      3. Proteinuria assesses degree of pre-Eclampsia
   2. Urine Protein and 24 Hour Urine Protein
      1. Non-proteinuric Hypertension in Pregnancy
         1. Trace or no Urine Protein present
      2. Mild Preeclampsia
         1. Urine chemstrip exceeds 1+ protein (>0.3 g/liter)
            1. Based on 2 random urines >6 hours apart
         2. Urine Protein exceeds 300 mg in 24 hours
      3. Severe Preeclampsia
         1. Urine chemstrip exceeds 3+ protein
            1. Based on 2 random urines >6 hours apart
         2. Urine Protein exceeds 5 grams in 24 hours
   3. Urine for single Specimen protein to Creatinine ratio
      1. Correlates with 24 Hour Urine Protein
      2. PIH unlikely if protein to Creatinine ratio < 0.21
         1. Negative Predictive Value: 83%
      3. Confirm abnormal tests with 24 hour urine
      4. References
         1. Wheeler (2007) Am J Obstet Gynecol 196(5): 465
         2. Young (1996) J Fam Pract 42:385-9
   4. Complete Blood Count with platelets
      1. Thrombocytopenia seen in Severe Preeclampsia
   5. Serum Electrolytes
   6. Serum Creatinine (>0.9 in Severe Preeclampsia)
   7. Uric Acid
   8. Liver Function Tests
      1. Aspartate Aminotransferase
      2. Alanine Aminotransferase
      3. Serum Bilirubin
      4. Serum Albumin
      5. Lactic Acid dehydrogenase
   9. Coagulation Studies for Severe Preeclampsia or HELLP
      1. ProTime (PT)
      2. Partial Thromboplastin Time (aPTT)
      3. Fibrin split products (Fibrin Degradation Products)
      4. Fibrinogen
10. Diagnostic studies: fetus
    1. Fetal Nonstress Test
    2. Obstetric Ultrasound
       1. Biophysical Profile
       2. Amniocentesis for Fetal Lung Maturity when indicated
11. Monitoring
    1. See Gestational Hypertension (chronic Hypertension)
    2. See Mild Preeclampsia
    3. See Severe Preeclampsia
    4. See HELLP Syndrome
12. Management
    1. See Delivery Indications in PIH
    2. See Gestational Hypertension Management
    3. See Mild PIH Management
    4. See Severe PIH Management
    5. See Eclampsia
    6. See HELLP Syndrome
    7. See PIH Blood Pressure Management
    8. See PIH Seizure Prophylaxis
13. Prevention
    1. See PIH Prophylaxis
14. Complications: Maternal
    1. Eclampsia
15. Complications: Fetus
    1. Neonatal Asphyxia
    2. Neonatal Hypoglycemia
    3. Intrauterine Growth Retardation
16. Course: Postpartum
    1. Most PIH cases improve in first 1-2 days after delivery
       1. Blood Pressure decreases
       2. Diuresis
    2. Eclampsia may occur after delivery (usually <24 hours)
       1. Consider continuing Magnesium Sulfate for 24 hours
       2. Continue to follow Blood Pressure and urine output
       3. Observe for signs of HELLP Syndrome
    3. Hypertension remits by 6-12 weeks postpartum
17. Prognosis
    1. Isolated Preeclampsia risks outside of pregnancy
       1. Confers future risk of Hypertension, vascular disease
       2. Wilson (2003) BMJ 326:845-9
    2. Increased risk of Preeclampsia in future pregnancies
       1. All women with history of Preeclampsia
       2. Onset before 30 weeks gestation (40% recurrence risk)
       3. Black race
       4. Different father than prior gestation
       5. Preeclampsia previously in multiparous patient
18. References
    1. (2000) Am J Obstet Gynecol 183(1):S1-22
    2. Leeman (2008) Am Fam Physician 78:93-100
    3. Sibai (2003) Obstet Gynecol 102:181-92
    4. Zamorski (2001) Am Fam Physician 64(2): 263-70