Obstetrics: Pre eclampsia and hypertension

Question 1

Read this history

Answer 1

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

Question 2

What would you ask in history of presenting complaint?

Answer 2

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

Question 3

What should you ask for in the background history of this woman?

Answer 3

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.

Question 4

How does BP change during pregnancy?

Answer 4

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.

Question 5

How do you define HTN in pregnancy?

Answer 5

• Systolic >140 mmHg or diastolic >90 mmHg
• Any increase above booking readings of >30 mmHg systolic OR >15 mmHg diastolic

Question 6

What are the causes of HTN in pregnancy?

Answer 6

• Pre-existing hypertension (primary or secondary)
• Pregnancy-induced hypertension
• Pre-eclampsia

Question 7

What is pre-existing HTN?

Answer 7

• 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

Question 8

What changes would you make to medication if a woman had pre-existing hypertension?

Answer 8

• Stop ACE inhibitors, as they are teratogenic.
• Labetalol is first line, with nifedipine 2^nd line.
• Treat pregnancy as high risk and use uterine artery dopplers and additional antenatal visits

Question 9

What is pregnancy induced HTN? (PIH)

Answer 9

• 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.

Question 10

How would you define pre-eclampsia?

Answer 10

• 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.

Question 11

What are the features of pre-eclampsia?

Answer 11

• 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

Question 12

What are the epidemiology and pathophysiology of pre-eclampsia?

Answer 12

• 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

Question 13

List some risk factors for pre-eclampsia

Answer 13

• Nulliparity
• Previous hx
• FH
• Older maternal age
• Chronic htn o Diabetes
• Twin pregnancy
• Autoimmune disease
• Renal disease
• Obesity

Question 14

What Ix would you perform if you suspected pre-eclampsia?

Answer 14

• 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

Question 15

Would you admit this lady?

Answer 15

• 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.

Question 16

How would you manage this patient?

Answer 16

• 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

Question 17

What are the complications (maternal and fetal) of pre-eclampsia and how do you manage them?

Answer 17

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

Question 18

How do you screen and try and prevent pre-eclampsia?

Answer 18

• 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

Question 19

When you should delivery a woman with pre-eclampsia

Answer 19

• 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.

Question 20

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)

Answer 20

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