Hypertension in Pregnancy and Postpartum Flashcards
Chronic Hypertension and Pregnancy Summary
Measurement ‒
- Sitting
- DBP 4th Korotkoffsound
DBP <90mmHg from conception to 20/40 is strongly correlated with lower rates of pre-eclampsia
ACEI and ARB are relatively contraindicated from 6 weeks gestation and absolutely contraindicated from about 20 weeks.
ACEI are safe with breast feeding.
Metoprolol, oxprenolol and labetalol are associated with a better fetal outcome than other beta-blockers
Methydopa has a long record of safety in pregnancy
Dihydropyridine CCBs are very effective
Red Flags
New onset hypertension after 20 weeks
Severe HTN –
- SBP ≥ 160 mmHg
- or DBP ≥ 110 mmHg
Defined as
- SBP ≥ 140 mmHg
- DBP ≥ 90 mmHg
as measured on 2 or more consecutive occasions at least 4 hours apart.
Classifications
Eclampsia – new onset of seizures in association with pre-eclampsia.
Pre-eclampsia – new onset of hypertension after 20 weeks’ gestation or superimposed on pre-existing hypertension and one or more of the following develop as new conditions:
Proteinuria – protein:creatinine ratio ≥ 30 mg/mmol or 2+ on dipstick confirmed by protein:creatinine ratio test.
Other maternal organ dysfunction:
- Renal insufficiency
- Elevated ALT and AST
- Neurological complications e.g., hyperreflexia with clonus, severe headaches, persistent visual scotomata, altered mental status, blindness, stroke.
- Haematological complications (platelets
Uteroplacental dysfunction e.g., fetal growth restriction, abruption.
HELLP syndrome (Haemolysis, Elevated Liver enzymes, Low Platelet count) – a variant of pre-eclampsia
Women who have had pre-eclampsia are at increased risk of cardiovascular disease in later life.
Chronic or pre-existing hypertension:
is HTN that is confirmed before conception or before 20 weeks’ gestation, with or without known cause, as measured on 2 or more consecutive occasions at least 4 hours apart.
These women have a higher risk (20%) of pre-eclampsia
Associated increase risk of pre-term birth, fetal growth restriction, placental abruption
The main benefit of anti-hypertensive Rx is in decreasing maternal mortality from severe HTN such as stroke, heart failure, and renal failure.
Gestational hypertension:
New onset HTN (≥ 140/90) after 20 weeks’ gestation in a pt who had normal BP before 20 weeks’ gestation, in the absence of abnormalities that define pre-eclampsia, and the blood pressure returns to normal within 3 months after giving birth.
Requires close monitoring.
Assessment
Check for Hx of HTNin pregnancy, including eclampsia, pre-eclampsia, gestational HTN, and chronic HTN.
At the first antenatal appointment:
follow Antenatal – First Consult pathway.
check for HTN and risk factors for developing pre-eclampsia.
If HTN present, arrange bloods for creatinine, electrolytes, FBC, LFT, and AST, together with routine antenatal bloods.
perform urine dipstick test for protein. If +ve, send mid-stream urine for PCR and MSU.
At each antenatal visit:
Check for s/s of pre-eclampsia. Note that oedema is a common feature of normal pregnancy and is not included in the diagnostic features of pre-eclampsia.
check BP.
screen with MSU for proteinuria.
check fetal movements and growth.
if newly diagnosed HTN is suspected, assess as for any pt with HTN. If gestational HTN is diagnosed, check pre-eclampsia bloods.
Management
If pre-eclampsia, severe pre-eclampsia, or HELLP or eclampsia, manage as medical emergency.
If less acute presentation, manage as below:
- Pre-conception
- Pregnancy
- Postpartum
HTN control in pregnanacy reduces the risk of pre-eclampsia
If Pre-eclampsia, severe pre-eclampsia, or HELLP
Seek obstetric advice immediately.
Unless otherwise advised, give antihypertensive for acute lowering of BP, aiming for ≤ 140/100.
If severe pre-eclampsia and advised to do so by obstetrician, consider giving magnesium sulphate if available to prevent a primary seizure. Seek obstetric advice.
Request acute obstetric assessment and send the patient in by ambulance.
If Eclampsia
Immediate ABCDE management
Call ambulance via 111.
Seek obstetric advice if time allows.
If delay before ambulance arrival:
if required, give antihypertensive for acute lowering of blood pressure, aiming for ≤ 140/100.
give magnesium sulphate if available.
Request acute obstetric assessment. The obstetrician will advise where the patient should be sent.
If less acute presentation, manage Pre-conception HTN as:
If there is Hx of pre-eclampsia, HTNhypertension in pregnancy, or chronic (pre-existing) HTN, offer pre-conception counselling and non-acute obstetric assessment.
If the pt has pre-existing HTN already on Rx:
- control HTN before conception, if possible.
- ensure that current antihypertensive considered safe in pregnancy, or switch to one that is.
Alternatively, if the current antihypertensive agent is an ACE inhibitor, an angiotension II receptor blocker (ARB), a diuretic, or atenolol, consider discontinuing the medication as soon as there is a positive pregnancy test and observing blood pressure.
- BP tends to drop in early pregnancy and it may not be necessary to add back safer agents.
- aim for BMI in the normal range to improve pregnancy outcomes.
- advise pt on the risk of pre-eclampsia, which is around 20% for women with pre-existing HTN.
Request preconception non-acute obstetric assessment for pts:
- with complicated pre-existing HTN.
- on more than one antihypertensive agent.
- with history of severe pre-eclampsia.
If endocrine causes suspected, seek endocrinology advice.
If less acute presentation, manage Pregannacy HTN as:
If severe pre-eclampsia in a previous pregnancy and not referred pre-conception, request non-acute obstetric assessment.
If high risk of pre-eclampsia, commence:
Aspirin 100 mg at night from 12 weeks’ gestation.
- Continue until the pt gives birth.
- NNT to prevent 1 case of pre-eclampsia = 56.
Calcium. Offer along with dietary advice to achieve 1 g elemental intake per day
- Continue from booking until birth.
- NNT to prevent 1 case of pre-eclampsia = 7.
If not high risk of pre-eclampsia but the pt has multiple lower risk factors, seek obstetric advice as to whether aspirin is indicated.
If otherwise unsure about starting aspirin or calcium, seek obstetric advice.
Manage according to presentation:
- severe hypertension
- pre-existing or chronic hypertension
- gestational hypertension
- pre-eclampsia, severe pre-eclampsia, or HELLP
- eclampsia
If BP does not meet criteria for referral relating to HTN but urine protein:creatinine ratio (PCR) > 30 mg/mmol, or any significant abnormalities in bloods, request non-acute obstetric assessment.
If unsure whether referral is required or how urgent referral should be, seek obstetric advice.
Pts are managed by secondary and tertiary services for ongoing needs, and lead maternity carer (LMC) for ongoing primary care needs.
Advise pts to contact their LMC urgently if they experience signs and symptoms of pre-eclampsia.
If less acute presentation, manage Postpartum HTN as:
Pts are usually managed by the LMC and obstetric team until 6 weeks postpartum. Thereafter the GP takes over the care.
ACE I, beta blockers, and calcium channel blockers are all considered safe to prescribe in breastfeeding. Avoid methyldopa unless advised to use by specialist, as other agents are more effective.
Continue anti-hypertensive Rx as dictated by the BP. If reducing medication, do so gradually.
Discuss risk of developing future conditions following gestational HTN or pre-eclampsia.
Discuss lifestyle factors to reduce BP.
Consider investigations to assess long-term CVR via the HTN pathway. Schedule cardiovascular risk assessment for 3 to 6 months postpartum.
For advice, contact Maternal Fetal Medicine Unit or seek obstetric advice.
Seek nephrology advice if:
- HTN and proteinuria persist at 6 weeks postpartum.
- RA stenosis or other cause is suspected.
If endocrine causes suspected, seek endocrinology advice.
Antihypertensive for acute lowering of BP
Nifedipine
- 10 mg conventional release tablet
- Oral
- Onset: 30 to 45 minutes
- Repeat after 30 to 45 minutes (if needed)
- Maximum: 80 mg per day
- Also used but infrequently available in primary care
Labetalol
- Initially 20 mg intravenous bolus over 2 minutes
- Repeat with 40 to 80 mg
- Onset: 5 minutes
- Repeat with 40 to 80 mg
- Repeat every 10 minutes
- Maximum: 300 mg
Hydralazine
- 5 to 10 mg (5 mg if fetal compromise)
- IV bolus over 3 to 10 min
- Onset: 20 min
- Repeat every 20 min
- Max: 30 mg (consider IV bolus of crystalloid fluid before or when administering first IV hydralazine dose, usually 200 to 300 mL)
Magnesium sulphate
Indicated to minimise risk of eclamptic seizures in severe unstable eclampsia and to prevent further seizures in eclampsia.
Administer loading dose only: 4 mg of 50% IM into each buttock.
Suitable regime for pts being transferred to hospital immediately.
IV Mg is an alternative if there may be delay in transporting the pt. Seek obstetric advice and see the Ministry of Health clinical practice guideline (pages 21 to 24) for detailed instructions.
