Preeclampsia & Eclampsia
Definition
- Hypertension in pregnancy: (CPG HTN pg82)
- SBP ≥140 mmHg and/or DBP ≥90 mmHg
- Significant proteinuria: (CPG HTN pg82)
2. 24hr urine protein: ≥300 mg/24hr
3. Spot UPCR: ≥30 mg/mmol
4. Dipstick: 2+ (approx. ≥300 mg/day)
5. (Training Manual pg16)
- Edema: (Training Manual pg16)
- Endothelial damage resulting in accumulation of fluid evidenced by pitting oedema following 12 hours of recumbant bedrest.
- Weight gain ≥1 kg/week + proteinuria = increasing severity of PIH
- Edema is common in pregnancy & may not be usual sign for early detection of PIH
Classification
Classification of HTN in Pregnancy (by Training Manual)
1. Pregnancy Induced Hypertension (PIH)
Definition: Hypertension after the 20th week of pregnancy in a previously normotensive woman. It may be associated with proteinuria. The condition is expected to return to normal after pueperium.
- Gestational Hypertension (GH)—PIH without proteinuria
- Pre-eclampsia (PE)—PIH with proteinuria
- Eclampsia—PIH with convulsions
- HELLP syndrome is a severe form of PE manifested by Haemolysis, Elevated Liver Enzymes and Low Platelets.
2. Chronic Hypertension in Pregnancy
Definition: Presence of hypertension of at least 140/90 mmHg before 20 weeks of pregnancy OR beyond 6 weeks postpartum.
i. Essential HTN
ii. Secondary HTN
3. Chronic Hypertension with Superimposed PE
Definition: PE in women who have pre-existing hypertension.
- Criteria used should include worsening hypertension, proteinuria and non-dependent oedema.
Classification of HTN in Pregnancy (by ISSHP)
1. Preeclampsia
- Followed by normalisation of the BP by three months postpartum.
- Oedema is no longer part of the definition of PE.
- Excessive weight gain or failure to gain weight in pregnancy may indicate the onset of PE.
1. De novo PE (new HTN)
Definition: diagnosed after 20w with one or more of the following:
- Significant proteinuria
- Renal insufficiency: serum creatinine ≥90 micromol/l or oliguria
- Liver disease: raised transaminases and/or severe right upper quadrant or epigastric pain
- Neurological problems: convulsions (eclampsia), hyperreflexia with clonus or severe headaches, persistent visual disturbances (scotoma)
- Haematological disturbances: thrombocytopenia, coagulopathy, haemolysis
- Fetal growth restriction
2. Chronic HTN with Superimposed PE
Definition: diagnosed in woman with chronic HTN with the presence any of the following:
- De novo proteinuria after 20 weeks gestation
- A sudden increase in the severity of hypertension
- Appearance of features of PE-eclampsia
- Worsening proteinuria in a woman with pre-existing proteinuria early in gestation
3. Gestational HTN
Definition: Hypertension detected for the first time after 20 weeks gestation.
- Progress to PE in 25% of cases
4. Isolated office hypertension
Definition: elevated BP of 140/90 mmHg only in the clinic with normal BP demonstrated by ambulatory BP monitoring (ABPM) either awake or during sleep.
- Progress to GH in 50% cases or PE in 8% cases
5. Chronic HTN
Definition: HTN diagnosed before 20 weeks gestation or presence of HTN preconception, or de novo hypertension in late gestation that fails to resolve three months postpartum.
Preeclampsia
Definition
- potentially life-threatening HTN disorder in pregnancy
- characterized by vascular dysfunction and systemic inflammation involving brain, kidney, liver of mother
- Definition & Criteria
Pathogenesis
Training Manual
- Impaired trophoblastic invasion or maternal spiral arteries
- Poor trophoblastic perfusion
- Endothelial injury
- Altered endothelial permeability
- Utero-placental ischemia
- Results in activation of coagulation
Blueprints
Abnormal development of placental vasculature and maternal systemic endothelial dysfunction.
- Placental under perfusion -> growth restriction & hypoxia
- Endothelial dysfunction (primarily by circulating antiangiogenic factors) -> increase vascular permeability, activation of coagulation cascade, microangiopathic hemolysis, vasoconstriction -> clinically hypertensive & proteinuric
Gabbe
1. Uterine vascular changes
- Migratory interstitial & endovascular trophoblasts -> modify spiral arterioles -> develop uteroplacental arteries -> low resistance, low pressure, high flow system
- Stage 1: first trimester, conversion of decidual segments of spiral arterioles by endovascular trophoblast migration
- Stage 2: second trimester,conversion of myometrial segments by second wave of trophoblasts
- Extensive fibrinoid formation & degeneration of muscular layer in arterial wall
- Modification of of spiral arterioles into distended, tortuous, funnel-shaped vessels
- Abnormal in PE: inhibition of second wave of endovascular trophoblast migration, usually occur in >18w gestation
- vascular changes only found in the decidual segments of uteroplacental artery
- the myometrial segments of spiral arterioles continue to exhibit their musculoelastic architecture
2. Vascular endothelial activation & inflammation
- Placental factors i.e. soluble fms-like tyrosine kinase 1 (sFlt-1) bind to VEGF (vascular endothelial growth factor) & PLGF (placental-like growth factor) -> reduced levels of free VEGF & PLGF -> endothelial dysfunction
- PLGF is angiogenic growth factors
- The angiogenic imbalance results in manifestations of endothelial cell permeability and increased platelet aggregation
Risk Factors
Risk for PIH (Training Manual)
- Maternal age <20y/o and >35y/o
- Primigravida
- History of PIH
- Multiple gestation
- Polyhydramnios
- Non-immune fetal hydrops
- Underlying renal disease
- Chronic HTN
- DM
- Gestational trophoblastic disease (molar pregnancy)
- Low socio-economic group
- Pregnancies with different partners
- Excessive weight gain
- Rh incompatibility
Risk for PE (Blueprints)
Risk for PE (Gabbe’s)
Clinical Risk Factor for PE (ISSHP)
Complications
Blueprints
1. Maternal
2. Fetal
Training Manual
Clinical Presentation
Blueprint
1. Gestational hypertension
2. Preeclampsia without severe features
3. Preeclampsia with severe features
4. HELLP Syndrome
5. Acute Fatty Liver of Pregnancy
Gabbe’s
Interactive Graph