Hypertension in Pregnancy

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Hypertension in Pregnancy
Faculty of Medicine Health Sciences
(FMHS) Obstetrics / Gynecology Rotation 2001/02

• Speaker
• Khalid A. Yarouf

. www.4MedStudents.com
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Outline

• Physiologic adaptations in normal pregnancy.
• Hypertension in Pregnancy
• Definition.
• Prevalence.
• Classification.
• Risk factors.
• Pathogenesis.
• Complications.
• Diagnosis Evaluation.
• Management.
• Self-assessment.

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Physiologic adaptations in normal pregnancy

• Blood changes
• ? Plasma volume by 40.
• Platelets count can ? below 200 X 109/L due to
  normal maternal blood-volume expansion.
• ? Coagulation factors (Fibrinogen, Factor VII).
• Cardiovascular changes
• Marked generalized vasodilation (? peripheral
  resistance)
• ? a/w arterial resistance to constrictor actions
  of Angiotensin II.
• ? CO Stroke volume.
• MAP ? by 10 mm Hg.

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Cont

• Renal changes
• Vasodilation ? ? Renal blood flow ? ? GFR (by
  50).
• ? in Creatinine clearance with a concomitant ? in
  S-Creatinine urea.
• ? Uric acid clearance Ca excretion.
• ? Glucosuria aminoaciduria.
• Respiratory changes.
• Endocrine changes
• e.g. parathyroid, adrenal, weight, GI changes.

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Hypertension in Pregnancy

• Definition
• Sustained ? BP _at_ bed rest on 2 occasions at
  least 6 hours apart.
• Prevalence 10 of all pregnancies.
• Classification
• Pre-eclampsia.
• Chronic hypertension (HTN).
• Transient HTN Gestational HTN.

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A. Pre-eclampsia

• Characteristic triad
• Sustained HTN Proteinuria Edema (not
  essential for Dx).
• Onset gt 20 weeks gestation.
• 50 of all HTN in pregnancies.
• Resolves after delivery.

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1. Mild pre-eclampsia

• Commonest entity ? has NO symptoms.
• Characteristics
• HTN BP 140 / 90 mm Hg OR
• ? sBP by 30 mm Hg above non-pregnant.
• ? dBP by 15 mm Hg above non-pregnant.
• Proteinuria (1-2 dipstick OR gt 300 mg / 24
  hr).
• Edema
• (non-dependent, hands / face, a/w excessive wt
  gain)

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2. Severe pre-eclampsia

• Less common.
• Can be diagnosed on basis of
• Severe HTN (BP 160 / 110 mm Hg). OR
• Severe proteinuria (3-4 dipstick OR gt 5 g / 24
  hr) alone without symptoms. OR
• Only mild HTN proteinuria if signs and symptoms
  are present

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Cont

• Resp Plum. Edema, cyanosis.
• Cardiac Congestive Cardiac Failure (CCF).
• Renal Proteinuria, ? Serum creatinine,
  oliguria.
• Hepatic ? LFTs, RUQ / epigastric pain.
• Neurologic visual disturbance (i.e. scotomas,
  loss of peripheral vision), headache,
  convulsions.
• GI severe nausea / vomiting.
• Hematologic
• thrombocytopenia, microangiopathic
  hemolysis.

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Cont

• HELLP syndrome
• Type of severe pre-eclampsia.
• Hemolysis Elevated Liver enzymes Low
  Platelets.

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3. Eclampsia

• Latin convulsions
• Unexplained tonic-clonic seizures Mild /
  severe pre-eclampsia.
• Most often occurs intra-partum (50), but can
  also occur ante-partum post-partum.

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B. Chronic HTN

• Pt may have any disease causing HTN
• e.g. essential HTN, A/c chronic GN, chronic
  pyelonephritis, SLE.
• Uncomplicated
• Definition
• Pre-existing HTN. OR
• HTN diagnosed 20 weeks. OR
• HTN persisting 6 weeks post-partum.
• NOT induced by pregnancy.

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Cont

• 2. Complicated by superimposed pre-eclampsia
• Isolated HTN without proteinuria.
• Characterized by worsening of HTN
  proteinuria severe PIH symptoms late in
  pregnancy.

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C. Transient HTN

• Late HTN Gestational HTN.
• Non-sustained (transient) ? BP without
  proteinuria / symptoms in last half of pregnancy.
• Has no impact on pregnancy outcome.

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Risk Factors of Pre-eclampsia

• Maternal Factors
• 1. Demographic criteria
• Primagravida ? commonest risk factor.
• Age extremes (lt20 years, gt 34 years).
• Medical complications
• DM Chronic HTN Pre-existing renal disease
  SLE.
• Past Hx or FHx of pregnancy-induced HTN.
• Fetal factors
• Hydatidiform mole, gt 1 fetus, fetal hydrops, IUGR.

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Pathogenesis of Pre-eclampsia

• Pre-eclampsia / eclampsia is justly called a
  disease of theories. Despite extensive
  research, no definite cause has been identified.
  As the term toxemia indicates, the search for a
  toxin has been long, arduous, and fruitless.
• Because of the prompt resolution of disease
  following delivery, most attention has been
  focused on placenta its membranes and on fetus.
• Uteroplacental ischemia is postulated to be the
  center to the development of disease, which
  results in production of toxin that enters
  circulation and causes widespread endothelial
  dysfunction.

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Complications

• Maternal
• Cerebral hemorrhage (50 of deaths).
• LVF / Pulm. edema.
• Liver / renal dysfunction.
• Seizures.
• DIC.
• Abruptio placenta ante-partum painful vaginal
  bleeding.
• Fetal due to placental insufficiency
• Fetal loss.
• IUGR.
• Prematurity.

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Diagnosis Evaluation

• HTN is the most diagnostic sign. Because
  therere no specific diagnostic investigations,
  the initial Dx of pre-eclampsia remains clinical.
• Hx
• Previous HTN or proteinuria or both?
• Previous hypertensive pregnancies?
• P/E
• Vitals ? ? BP.
• In normal pregnancy, therere substantial CV
  changes with a 50 ? in CO blood volume, which
  is accompanied by a ? in BP due to peripheral
  vasodilation. The changes in pre-eclampsia tend
  to be the reverse.
• Edema.
• Funduscopic exam ? record baseline findings.

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Cont (Dx)

• For the purposes of clinical Dx further
  evaluation, pts may be divided into 2 working
  groups
• Chronic HTN
• Multiparous.
• Those with previous Hx of HTN.
• Those who developed HTN prior to 20wks gestation.
• Pre-eclampsia.
• 1st pregnancy develop syndrome after 20wks.

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Table 1. Initial lab evaluation of pt
with pre-eclampsia / eclampsia
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Notes

• Serum uric acid correlates with poorer outcome
  for the mother baby.
• Renal function is generally maintained in
  pre-eclampsia until late stage. If creatinine
  levels are high early in disease process,
  underlying renal disease should be suspected.
• In pre-eclampsia, Plt count ? due to increased
  consumption intravascular destruction. Also, ?
  Plts is part of HELLP synd.
• Maternal Hb can be ? due to hypovolemia, and its
  a/w IUGR.
• Liver involvement
• Inflammatory infiltrates obstructed blood flow
  in sinusoids ? local welling ? subcapsular
  hemorrhage ? upper epigastric pain.
• ? ALT AST leak across cell membranes (can also
  be a/w HELLP synd).
• Additional lab test for chronic HTN may include
  ANA (for SLE) and ECG.

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Management

• Outpatient observation
• Use only for transient HTN / uncomplicated
  chronic HTN.
• Specific guidelines
• Encourage left lateral rest
• ? to enhance placental perfusion.
• Serially monitor mother
• ? watching for progression to pre-eclampsia /
  superimposed pre- eclampsia.
• ? Check for BP, U-protein, headache, epigastric
  pain, scotomata.
• Serially monitor fetus
• Non-stress test (NST), Amniotic Fluid Index
  (AFI), Biophysical profile (BPP).

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Cont (Mx)

• Inpatient observation
• Use only for mild pre-eclampsia (lt 36 weeks
  gestation).
• Specific guidelines
• Encourage left lateral rest
• ? to enhance placental perfusion.
• Monitor mother fetus
• ? watching for progression to severe
  pre-eclampsia or eclampsia.
• Administer maternal steroids
• 2 doses of betamethasone IM 24 hours apart.

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Cont (Mx)

• Prompt delivery
• Use mild pre-eclampsia ( 36 weeks gestation),
  severe pre-eclampsia, eclampsia, chronic HTN with
  superimposed PIH, HELLP syndrome, or any evidence
  of maternal or fetal jeopardy.
• Specific guidelines
• Lower BP
• ? keep diastolic value between 90-100 mm Hg.
• Use IV Hydralazine / IV Labetalol.
• Prevent convulsions. Use IV MgSO4.
• Initiate delivery Attempt induction of labor
  vaginal delivery for 8-12 hours if mother fetus
  are stable. Otherwise, perform C-section.

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Self-assessment

• A 24-year-old gravida 1, para 0, at 37 weeks
  gestation was noted to have a 6-lb weight gain
  and an increase in blood pressure from 100/60 to
  130/80 in the past week. She also has 1
  proteinuria. The examination was repeated 6
  hours later and the same results were obtained.
  The best diagnosis is
• Normal pregnancy.
• Pre-eclampsia.
• Eclampsia.
• Chronic hypertension.
• Essential hypertension.

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Cont (test)

• The most common warning sign of pre-eclampsia is
• Proteinuria.
• Headache.
• Edema.
• Increased BP.
• Epigastric pain.

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Cont (test)

• The ultimate treatment for pre-eclampsia is
• Magnesium sulfate.
• Delivery.
• An antihypertensive drug.
• Renal dialysis.
• Bed rest.