There are four major hypertensive disorders related to pregnancy.
&bullPreeclampsia (formerly called pregnancy-induced hypertension) - refers to the new onset of hypertension and proteinuria after 20 weeks of gestation in a previously normotensive woman.
&bullChronic 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.
&bullPreeclampsia 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.
&bullGestational hypertension - Gestational hypertension refers to hypertension (usually mild) without proteinuria (or other signs of preeclampsia) developing in the latter part of pregnancy.
&bullPreeclampsia refers to the new onset of hypertension and proteinuria after 20 weeks of gestation in a previously normotensive woman.
&bullCRITERIA FOR DIAGNOSIS
&bullSystolic 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 ].
&bullProteinuria 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:

&bullThe 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.
&bullOxidative stress, inflammation, circulatory maladaptation, as well as humoral, mineral or metabolic abnormalities all appear to play a role in pathogenesis.
&bullNewer 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:

&bullHypertensive disorders complicate 10 to 20 percent of pregnancies.
&bullPreeclampsia occurs in approximately 3 to 14 percent of all pregnancies worldwide.
&bullPreexisting hypertension complicates about 3 percent of pregnancies.
&bullGestational hypertension occurs in about 6 percent of pregnancies.
&bullMore common in primiparas than in multiparas & age >40 years primigravidas.

Types of Pre Eclampsia:

Pre Eclampsia is classified as
&bullMild 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.
&bullSevere form:

Differental Diagnosis:

A variety of conditions can present with signs or symptoms similar to pre eclampsia, eclampsia, and HELLP syndrome:
&bullAcute fatty liver
&bullThrombotic thrombocytopenic purpura - hemolytic uremic syndrome
&bullExacerbation of SLE
&bullGestational thrombocytopenia and autoimmune thrombocytopenia.
&bullCerebral hemorrhage
&bullMigraine
&bullCholestasis
&bullPancreatitis

Investigations:

&bullUrine 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.
&bull3+ or greater or 5 g or more per day is a criterion of severe disease.
&bullHb/Hct & Platelet count - Hemolysis & dec. platelets.
&bullSerum Creatinine -- An elevated or rising level suggests severe disease
&bullALT/AST -- Elevated or rising levels suggest hepatic dysfunction indicative of severe disease.
&bullLDH -- Microangiopathic hemolysis is suggested by an elevated LDH level
&bullUA - Elevated but not diagnostic.
&bullFetal 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.
&bullCoagulation 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.