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Pre-eclampsia

From Mediwikis
Preeclampsia.nih.jpg

Pre-eclampsia is a state characterised by:

  • Proteinuria
  • Rising blood pressure
  • Edema

during pregnancy. Typically asymptomatic, preeclampsia usually occurs after 20 weeks, and very rarely before 32 weeks. Pre-eclampsia occurring before 32 weeks is associated with a worse prognosis. It is a major cause of IUGR and perinatal mortality, most common cause of iatrogenic prematurity.

Risk Factors

  • Primgravida - or first pregnancy with a new partner
  • Family history of pre-eclampsia
  • Obesity
  • Previous pre-eclampsia
  • <155 cm maternal height
  • Existing hypertension
  • Existing renal disease
  • PMH of migraine
  • Change of sexual partner (thought to be an immunological bases of the condition)
  • Age <20 or >35 years
  • Diabetes
  • Multiple pregnancy
  • SLE
  • Thrombophilic disease
  • Hydatidiform mole

Note: Smoking reduces the risk of pre-eclampsia unless it's a high risk pregnancy (multiples or preexisting diabetes/hypertension)

Maternal risk if developing pre-eclampsia is determine by the number of risk factors the mother possesses:

  • Low risk (1:1000) if no risk factors
  • Medium risk (1:10) if primigravida or other singular risk factors
  • High risk (1:5) if multiple risk factors

High risk women, if identified by screening BP, urine samples, or indeed risk factors, can be offered low dose prophylactic aspirin to reduce the risk of pre-eclampsia.

Pathology

Poor placental perfusion causes the release of blood borne products from the fetoplacental unit, which invade maternal tissue. This alters the mother's endothelial contractility leading to increased sensitivity to normal circulating pressor agents, increased intracellular coagulation and increased fluid loss from the intravascular compartment. This leads to the rise in blood pressure. Causes of poorly perfused placenta:

  • Abnormal trophoblast implantation and spiral artery atherosis
  • Microvascular disease – pre-existing hypertension, diabetes, vascular diseases
  • Large placenta – multiple pregnancy, hydatidiform mole, a fetus with a hydropic placenta

Clinical Features

Generally asymptomatic and can only be detected by routine screening. Most common symptoms (if any) are:

  • Headache
  • Visual disturbance (commonly ‘flashing lights’
  • Epigastric pain
  • Vomiting
  • Oedema (particularly facial oedema)

If a woman presents with any of these symptoms and has a raised blood pressure then an immediate referral for an obstetric review is needed. There are additional signs which are not strictly of pre-eclampsia but do help to identify the condition:

  • Excessive weight gain (>1 kg per week)
  • Ascites
  • Hyperuricaemia
  • Hypocalciruria
  • Thrombocytopenia
  • Increased blood concentration of liver enzymes

IUGR and intrauterine hypoxaemia are fetal signs of pre-eclampsia

Diagnosis

The diagnosis of pre-eclampsia can be made by fitting the following NICE criteria:

  • BP ≥140 mmHg systolic and/or ≥90 mmHg diastolic, based on at least 2 measurements taken at least 4 hours apart

AND

  • proteinuria ≥0.3 g protein in 24 hours

Whilst not diagnostic, it is important to follow up on women with a rise of >30 mmHg systolic or >15 mmHg diastolic from baseline rates taken at booking visit.

Management

Following diagnosis, a multi-disciplinary team approach must be undertaken, including obstetric team, anaesthetics and haematology in hospital, and the wider general practice team outside of hospital for regular checks on hypertension status. The only cure for pre-eclampsia is early delivery, or termination of pregnancy. This isn’t considered in the cases of fetal immaturity unless absolutely required, so the following areas are important:

  • Screening (BP and urine dipstick) and early diagnosis
  • Hospital admission
  • Timing of delivery - – induced early labour vs. keeping baby to grow in potentially hostile environment. Give steroid to help fetal lung maturation if planned early labour.
  • Manage and control with antihypertensives and anticonvulsants. Medications "safe" to use in pregnancy include, labetolol, nifedipine and hydralazine.
  • Disease prevention and risk factor management – e.g. aspirin and diet

Severe pre-eclampsia can be managed with:

  • Hydralazine Iv 5 mg/20 mins until 20 mg given
  • Prophylactic H2 agonists until after delivery
  • Catheterise and measure urine output
  • Restrict fluid intake to 80 ml/hour (unless haemorrhaging)
  • Avoid diuretics at all costs due to reduction of plasma volume
  • Seizures can be prevented with magnesium sulphate 4g IV, if risk of eclampsia suspected.
  • Following third stage of delivery, give 5U oxytocin IM/IV.

Complications

Complications of pre-eclampsia include:

  • Eclampsia
  • HELLP Syndrome
  • DIC
  • Renal Failure
  • Cerebral haemorrhage
  • Cortical blindness
  • Liver failure
  • Pulmonary oedema
  • Abruptio placentae
  • Fetal death
  • Fetal hypoxia
  • Iatrogenic immaturity


HELLP Syndrome is associated with Haemolysis, Elevated Liver enzymes and Low Platelets. It occurs in 5-10% of severe pre-eclampsia cases and is more common in multiparous women.

NICE recommendation

  • Blood pressure measurement and urinalysis for protein should be performed at each ante-natal visits
  • At the booking appointment the following risk factors should be determined:
    • Age >40 years
    • Nulliparity
    • Pregnancy interval of >10 years
    • FH or PMH of pre-eclampsia
    • BMI >30
    • Pre existing vascular disease, hypertension, diabetes or renal disease
    • Multiple pregnancy
  • More frequent blood pressure measurements should be considered for pregnant women who have any of the above risk factors
  • The presence of hypertension of proteinuria alone should lead to increased surveillance
  • Systolic BP >160mmHg on two consecutive reading at least 4hrs apart treatment should be considered (with or without proteinuria)
  • Pregnant women should be advised that they should seek immediate advice from HCPs if they experience ANY symptoms of pre-eclampsia.