Obstetrics: Pre eclampsia and hypertension Flashcards
Read this history
This 32-week pregnant woman has been referred to the day assessment unit because of a BP of 150/100 on routine screening at the GP. She also has 2+ of proteinuria on dipstick, and ankle oedema
What would you ask in history of presenting complaint?
HoPC History of this pregnancy
- Any complications so far?
- Dates, multiple pregnancy, scans all normal?
- Did they say anything at the 20 week scan about an unusual flow of blood to the placenta? Any symptoms? (usually not)
- Headache, visual disturbance
- Drowsiness
- N+V
- Epigastric pain
What should you ask for in the background history of this woman?
Previous HTN PMHx:
- any chronic disease, especially renal problems, autoimmune disorders
- DM, epilepsy
POHx: previous pregnancies, complications
PGHx: operations, smears, infections
FHx: Any problems with high blood pressure in pregnancy
DHx: on any medications? Any allergies?
SHx – other children OK at home, need to make arrangements? Smoking, alcohol.
How does BP change during pregnancy?
BP falls in first trimester (esp diastolic) and continues to fall until 20-24 weeks.
After this time BP usually increases to Pre-pregnancy levels by term.
How do you define HTN in pregnancy?
- Systolic >140 mmHg or diastolic >90 mmHg
- Any increase above booking readings of >30 mmHg systolic OR >15 mmHg diastolic
What are the causes of HTN in pregnancy?
- Pre-existing hypertension (primary or secondary)
- Pregnancy-induced hypertension
- Pre-eclampsia
What is pre-existing HTN?
- Hx of HTN before pregnancy or elevated BP (over 140/90 mmHg before 20 weeks gestation)
- No proteinuria, no oedema
Occurs in 3-5% of pregnancies and is more common in older women
What changes would you make to medication if a woman had pre-existing hypertension?
- Stop ACE inhibitors, as they are teratogenic.
- Labetalol is first line, with nifedipine 2nd line.
- Treat pregnancy as high risk and use uterine artery dopplers and additional antenatal visits
What is pregnancy induced HTN? (PIH)
- HTN occurring in second half of pregnancy
- No proteinuria or oedema
- Resolves following birth (typically after 1/12) – women with PIH are at increased risk of future pre-eclampsia or HTN in later life.
How would you define pre-eclampsia?
- Systemic disorder characterised by widespread endothelial dysfunction as a result of abnormal development of the placental circulation early in pregnancy.
- Defined clinically by the presence of hypertension, proteinuria (>0.3g/24hrs) and oedema.
- Appears often in 2nd half of pregnancy.
- Cured only by delivery.
What are the features of pre-eclampsia?
- HTN: >170/110mmHg and proteinuria (2+)
- Headache/visual disturbance/papilloedema
- RUQ/epigastric pain
- Hyperreflexia
- Platelet count <100 x 10^6, abnormal liver enzymes or HELLP syndrome
What are the epidemiology and pathophysiology of pre-eclampsia?
- Affects 6% of nulliparous women, 15% recurrence rate
Pathophysiology of pre-eclampsia
- Stage 1 accounts for disease development, occurs before 20wks, causes no symptoms. Get incomplete invasion of spiral arterioles by trophoblast (?due to immune response) so less vasodilatation and reduced uteroplacental blood flow.
- Stage 2 is manifestation of disease- ischaemic placenta, via exaggerated maternal response, induces widespread endothelial damage, causing vasoconstriction (htn), increased vascular permeability (proteinuria) and clotting dysfunction
List some risk factors for pre-eclampsia
- Nulliparity
- Previous hx
- FH
- Older maternal age
- Chronic htn o Diabetes
- Twin pregnancy
- Autoimmune disease
- Renal disease
- Obesity
What Ix would you perform if you suspected pre-eclampsia?
- Examination- raised BP and/or epigastric tenderness suggests impending complications
- Repeat a urine dipstick, and send a sample for MC&S to exclude UTI.
- 24h urine collection to confirm the diagnosis OR single protein:creatinine ratio
- Tests for complications: FBC (platelets), U&S, LFTs, uric acid
- USS to assess foetal growth – repeat fortnightly
- Doppler or CTG to assess foetal wellbeing
Would you admit this lady?
- Women with 2+ or more of proteinuria or >0.3g/24hrs, or any signs of foetal distress, should be admitted, whatever their BP.
- If she had isolated hypertension, she should be admitted with a BP of 160/110 or higher.
How would you manage this patient?
- Consider anti-hypertensives if BP>160/110 – IV Labetolol for initial control (Nifedipine or hydralazine 2nd line), methyldopa for maintenance. Aim for a diastolic BP ~90mmHg.
- Give steroids for foetal maturity and anti-D.
- In severe disease, MgSO4 can be given to prevent eclampsia- increases cerebral perfusion.
- Test patellar reflexes to ensure pt not at toxic levels – must be continued for 24 hours after delivery/last seizure
- Maintain strict fluid balance + catheterisation
- Delivery is the cure
What are the complications (maternal and fetal) of pre-eclampsia and how do you manage them?
Maternal complications:
- Eclampsia – grand mal seizures, probably due to cerebrovascular vasospam – treat with MgSO4
- CVA – prevent by treating BP 170/110 (point when autoregulation begins to fail)
- HELLP – Haemolysis, elevated liver enzymes and low platelets.
- Renal failure – in severe cases may require haemodialysis
- Pulmonary oedema, risk of ARDS – O2, furosemide, assisted ventilation
Foetal complications: IUGR, prematurity, increased risk morbidity and mortality and placental abruption
How do you screen and try and prevent pre-eclampsia?
- Most accurate screening test is uterine artery Doppler at 23 weeks gestation.
- Urine dip and BP assessment at each point of contact
- Ask women about re-eclampsia symptoms (epigastric pain, migraines, limb swelling, changes in vision)
- Low dose aspirin (150mg) from 12 weeks modestly reduces risk- NICE recommend in at risk women
When you should delivery a woman with pre-eclampsia
- If purely htn: monitor and induce at 40 weeks
- Mild: deliver by 37 weeks
- Moderate: deliver by 34-36
- Severe: deliver when needed. If before 34 weeks, do c-section. Otherwise, induce and give epidural (lowers BP). Do not let mother push if BP at 160/110 due to rx of CVA.
Describe 3 different drugs from 3 different therapeutic groups that may be used to treat HTN in pregnancy (MoA, dosage regimens, route, CIs and SEs)
Labetolol: PO Beta blocker
- Usual starting dose is 100mg BD (can give up to 800mg in divided doses).
- Caution in patients with asthma/T1DM (lose warning signs of hypos), not effective in black, afro-Caribbean ladies.
- SE: GI disturbance, headaches, weakness, liver damage and scalp tingling
Nifedipine: PO CCB given in modified release format over 12-24 hours (pure nifedipine will cause big BP drop and disrupt placental blood flow).
- Dosing can be 10mg-20-40mg BD.
- SE: headaches, dizziness, fluid retention and inhibition of labour
Methyldopa: PO centrally acting anti-hypertensive.
- Dosing starts at 250mg TDS but can go up to 3g daily.
- Caution: should not be used post-natally or in patients with severe depression bc of association with PND (must be stopped within 2 days of delivery).
- SEs: depression, dry mouth, GI disturbance and tiredness
