Hypertensive Disorders in Pregnancy - By: Dr. D.S. Merchant

There are four major hypertensive disorders related to pregnancy.
• Preeclampsia (formerly called pregnancy-induced hypertension) — refers to the new onset of hypertension and proteinuria after 20 weeks of gestation in a previously normotensive woman.
• Chronic hypertension — (or preexisting hypertension) is defined as systolic pressure >140 mmHg, diastolic pressure >90 mmHg, or both, that antedates pregnancy, is present before the 20th week of pregnancy, or persists longer than 12 weeks postpartum.
• Preeclampsia superimposed upon chronic hypertension — Superimposed preeclampsia is diagnosed when a woman with preexisting hypertension develops new onset proteinuria after 20 weeks of gestation. Women with both preexisting hypertension and proteinuria are considered preeclamptic if there is an exacerbation of blood pressure to the severe range (systolic 160 mmHg or diastolic 110 mmHg) in the last half of pregnancy, especially if accompanied by symptoms or increased liver enzymes or thrombocytopenia.
• Gestational hypertension — Gestational hypertension refers to hypertension (usually mild) without proteinuria (or other signs of preeclampsia) developing in the latter part of pregnancy.
• Preeclampsia refers to the new onset of hypertension and proteinuria after 20 weeks of gestation in a previously normotensive woman.
• CRITERIA FOR DIAGNOSIS
• Systolic blood pressure >140 mm Hg or Diastolic blood pressure >90 mmHg. [ The elevation in blood pressure should be sustained, which is generally regarded as two measurements at least six hours, but no more than seven days, apart ].
• Proteinuria of 0.3 g or greater in a 24-hour urine specimen. [ Random urine protein determination of 30 mg/dL or 1+ on dipstick is suggestive ].

Pathogenesis of Pre Eclampsia:

• The pathogenesis of pre-eclampsia is incompletely understood, but the disorder is clearly initiated by the presence of the defective trophoblast, and impaired placental angiogenesis plays an important role.
• Oxidative stress, inflammation, circulatory maladaptation, as well as humoral, mineral or metabolic abnormalities all appear to play a role in pathogenesis.
• Newer evidence suggests that placental release of circulating factors that interfere with the action of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) plays a central role

Incidence of Pre Eclampsia:

• Hypertensive disorders complicate 10 to 20 percent of pregnancies.
• Preeclampsia occurs in approximately 3 to 14 percent of all pregnancies worldwide.
• Preexisting hypertension complicates about 3 percent of pregnancies.
• Gestational hypertension occurs in about 6 percent of pregnancies.
• More common in primiparas than in multiparas & age >40 years primigravidas.

Types of Pre Eclampsia:

Pre Eclampsia is classified as
• Mild form:
Hypertension.
Proteinuria.
Hyperuricemia and hypocalciuria.
Edema.
Thrombocytopenia-due to formation of microthrombi and increased platelets turnover.
Microangiopathic hemolysis may also occur with schistocytes & helmet cells or elevation in the serum lactate dehydrogenase concentration.
• Severe form:

Differental Diagnosis:

A variety of conditions can present with signs or symptoms similar to pre eclampsia, eclampsia, and HELLP syndrome:
• Acute fatty liver
• Thrombotic thrombocytopenic purpura - hemolytic uremic syndrome
• Exacerbation of SLE
• Gestational thrombocytopenia and autoimmune thrombocytopenia.
• Cerebral hemorrhage
• Migraine
• Cholestasis
• Pancreatitis

Investigations:

• Urine D/R – Quantification of protein excretion, Excretion of 300 mg or more in 24 hours is necessary for diagnosis or at least 1+ protein on dipstick of two urine specimens collected at least four hours apart.
• 3+ or greater or 5 g or more per day is a criterion of severe disease.
• Hb/Hct & Platelet count – Hemolysis & dec. platelets.
• Serum Creatinine -- An elevated or rising level suggests severe disease
• ALT/AST -- Elevated or rising levels suggest hepatic dysfunction indicative of severe disease.
• LDH -- Microangiopathic hemolysis is suggested by an elevated LDH level
• UA – Elevated but not diagnostic.
• Fetal well-being is evaluated by a non-stress test or biophysical profile. In addition, the fetus is examined by ultrasound to evaluate growth and amniotic fluid volume.
• Coagulation function tests (eg, PT, APTT & fibrinogen concentration) are usually normal if there is no thrombocytopenia or liver dysfunction, and therefore do not need to be monitored routinely.

About the Author

Dr. Syed Mujtaba H. Bilgrami Resident Family Medicine (AKUH). He has written on a range of related issues as pregnancy planning, pre pregnancy checklist, Hypertensive Disorders in Pregnancy and pre pregnancy stage.

Article Directory Source: http://www.articlerich.com/profile/Dr--D-S--Merchant/9723

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