Hypertensive Disorders in Pregnancy Flashcards
Describe the normal blood pressure changes in pregnancy
- BP falls to a minimum level in 2nd trimester due to reduced vascular resistance (by about 30/15mmHg)
- By term again rises to pre-pregnant levels
- Protein excretion increased in normal pregnancy (in absence of renal disease is <0.3g/24hrs)
Define pregnancy induced hypertension
- BP rises above 140/90mmHg after 20wks
- Due to either pre-eclampsia or transient HTN
Define pre-eclampsia
New HTN after 20wks with significant proteinuria (>0.3g/24hrs)
Define pre-existing HTN
BP>140/90mmHg before pregnancy or before 20wks, or the woman is already on antihypertensives
How is pre-eclampsia caused?
- Blood vessel endothelial cell damage leads to vasospasm, increased capillary permeability and clotting dysfunction
Describe the two phenotypes of pre-eclampsia
- Early onset:
- Causes complications before 34wks
- IUGR - Late onset:
- Later gestation
- No IUGR
Describe the pathophysiology of pre-eclampsia
- Poor placental perfusion:
- Incomplete trophoblastic invasion of spiral arterioles which causes oxidative stress
- High resistance to flow in uterine arteries - Oxidatively stressed placenta over-secretes proteins that regulate angiogenic balance:
- Widespread endothelial cell damage causing vasoconstriction, increased vascular permeability and clotting dysfunction
Define severe pre-eclampsia
Pre-eclampsia with severe HTN and/or with symptoms, and/or biochemical and/or haematological impairment
What are the degrees of HTN>
- Mild = 140/90 - 149/99 mmHg
- Moderate = 150/100 - 159/109mmHg
- Severe = >160/110mmHg
What are the risk factors that are indicative of high risk and require low dose aspirin from early pregnancy?
- Hypertensive disease during previous pregnancy
- Chronic kidney disease
- Autoimmune disease (e.g. SLE, antiphospholipid syndrome)
- Type I or II DM
- Chronic HTN
What are the risk factors that indicate moderate risk and require lose dose aspirin from early pregnancy if >1 of them is present?
- Nulliparous
- Age >/= 40
- Pregnancy interval >10yrs
- BMI >35 at booking
- Family hx pre-eclampsia
- Multiple pregnancy
How is urinary protein assessed?
- Dipstick - if +1 protein need to quantify amount with further investigations
- Protein:Creatinine ratio (PCR) - >30mg/mmol is confirmed significant proteinuria
- 24hr collection - >0.3g/24hrs is confirmed significant proteinuria
List the components of HELLP syndrome
H - haemolysis (dark urine, raised LDH, anaemia)
EL - elevated liver enzymes (epigastric pain, liver failure, abnormal clotting)
LP - low platelets
List the clinical features of pre-eclampsia
- Usually asymptomatic
- Headache
- Drowsiness
- Visual disturbances
- Nausea/vomiting
- Epigastric pain
List the signs of pre-eclampsia on examination
- HTN (usually 1st sign)
- Oedema (not postural or of sudden onset)
- Epigastric tenderness (impending complications)
- Proteinuria
List the maternal complications of pre-eclampsia
- Eclampsia
- Cerebrovascular haemorrhage
- HELLP syndrome
- Renal failure
- Pulmonary oedema
List the fetal complications of pre-eclampsia
- Increased perinatal morbidity and mortality
- IUGR
- Preterm delivery
- Placental abruption
What investigations are done for pre-eclampsia?
- Confirm diagnosis:
1. Urine PCR - Monitor maternal complications:
1. Blood tests (elevated uric acid)
2. FBC
3. LFTs
4. Renal function - Monitor fetal complications:
1. US
2. Umbilical artery Doppler
3. CTG
How can pre-eclampsia be prevented?
- Low dose aspirin (75mg) starting before 16wks to decrease risk
- High-dose vitamin D with calcium supplementation may also be effective
List the criteria for admission with a hypertensive disorder
- Symptoms
- Proteinuria with PCR >/= 30
- Severe HTN
- IUGR with abnormal umbilical artery Doppler or abnormal CTG
- Abnormal sFlt-1/PlGF assay
What drugs are use in management of pre-eclampsia?
- Antihypertensives:
- If BP >/= 150/100mmHg
- Labetalol for maintenance
- Target BP <140/90mmHg - Magnesium sulphate:
- Tx and prevention of eclampsia in severe disease
- IV loading dose followed by IV infusion
- Can have magnesium toxicity
- Dose decreased or stopped if renal impairment or anuria develops
- If magnesium required delivery is indicated - Steroids:
- If <34wks for fetal lung maturity
Discuss the timing of delivery in pre-eclampsia
- Delivered by 36wks
- Conservative management before 36wks
How is the baby delivered in pre-eclampsia?
- C-section before 34wks if IUGR
- IOL after 34wks
- Epidural (decreases BP)
- CTG monitoring
- BP and fluid balance observed
- Antihypertensives used in labour
- Avoid maternal pushing if BP >/= 160/110mmHg
- Oxytocin used for 3rd stage
List the general measures taken in severe pre-eclampsia
- One to one midwifery care
- IMEWS chart commenced
- Consultant obstetrician on duty informed
- Large bore IV cannula inserted