Hypertension in pregnancy (04/11/2021) Flashcards
What is the incidence of hypertension in pregnancy and who is it more likely to effect?
10%. Pre-eclampsia 5% more likely in sub saharan African women
Why did the rates fall from 1950-70
Wider provision and access to AN care. Improved nutrition post war national milk and vitamin schemes so calcium intake
Improvement since 80-90s?
Improvements in the organisation of care/clinical management
Why did rates steeply fall in 2010?
Publication of NICE guidance
Hypertension
A blood pressure of 140 systolic or higher, and diastolic of 90 or higher
Chronic hypertension
Hypertension that is present at booking or before 20 weeks or if it is already present before pregnancy. Can be primary or secondary.
Gestational hypertension
New hypertension presenting after 20 weeks of pregnancy without significant proteinuria
Severe hypertension
Blood pressure over 160 systolic or 110 diastolic
Eclampsia
A convulsive condition with pre-eclampsia
Pre-eclampsia
New onset of hypertension after 20 weeks of pregnancy and the coexistence of 1 or more of proteinuria, renal insufficiency, liverinvolvement, neurological complications, haematological complications and uteroplacental dysfunction.
Proteinuria
-Urine protein creatinine ratio of 30mm or more or albumin creatinine ratio of 8mg or more.
Renal Insufficiency
Creatinine level 90micromol/litre or more.
Liver involvement
Elevated transaminases (alanine aminotransferase or aspartate aminotransferase over 40IU/Litre) with or without right upper quadrant or epigastric abdominal pain.
Neurological complications
Eclampsia, altered mental status, blindness, stroke, clonus, severe headaches, or persistent visual scotomata.
Haemotological complications
Thrombocytopenia (Platelet count below 150,000/microletre) disseminated intravascular coagulation or haemolysis.
Uteroplacental Dysfunction
Such as fetal growth restriction, abnormal umbilical artery doppler waveform analysis, or still birth.
Describe the pathophysiology of hypertension
- Trophoblast go into decide and myometrium and strip away muscle from spiral arteries into low resistance vessels from high resistance vessels.
- The trophoblast cells don’t remodel the spiral arteries in the same way in a woman with hypertension. The spiral arteries remain more narrow, and highly resistant. Reduced blood flow to the placenta.
What factors pre-implantation can influence hypertension?
- Inflammation/metabolic disorder
- Genetics
- Abnormal Angiotensin 2 response
- Fetal genetics
What is stage one of hypertension in pregnancy and at what gestation?
Deflective trophoblast invasion following implantation before 12 weeks
What occurs due to deflective trophoblast invasion, what phase?
Stage 2, 28 weeks, a stressed placenta due to reduced uteroplacental blood flow releasing factors triggering endothelial dysfunction.
What is stage 3, what is it caused by?
Manifestation of maternal syndrome, signs and symptoms of pre-eclampsia post 28 weeks. leaky glomeruli in the kidneys so protein in the urine. Coagulation at the blood-brain barrier causing seizures.
What are the systemic effects of pre-eclampsia?
High level of pro-inflammatory cytokines
- increased capillary permeability
- Endothelial dysfunction
- Release of vasoconstrictors
- Decrease in prostacyclin synthesis
- Leading to platelet activation, vasoconstriction and microvascular damage.
- hypertension and organ damage
What are the two placental factors on a blood test associated with PE?
Increased Sflt-1 and Endoglin compared to normal pregnancy.
Describe the angiogenic factors in PE?
Sflt-1 binds proangiogenic factors VEGF and PIGF. Endoglin antiangiogenic glycoprotein endometrium and syncytiotrophoblast.
Are GH and PE the same disorder in terms of pathophysiology?
NO
Describe the differences between GH and PE?
Studies suggest distinct differences in the pathophysiology between gestation hypertension and pre-eclampsia. GH is less evident for systemic cardiovascular maladaptation and abnormality in anti-angiogenic markers.
How can we reduce risk antenatally?
-At booking assess risk factors, refer for early obstetric opinion. Anti-platelet agents (aspirin 75-150mg from 12 weeks to birth).
How can we reduce risk pre-conception?
- Reduce BMI if overweight or obese
- Stop smoking
Describe the assessment of someone with new hypertension?
- Assess risk factors and gestational age
- Do blood pressure. Is the systemic BP more than 140 and diastolic BP more than 90 twice 4 hours apart. Or is there one single reading of a BP 160 or more over 110 or more.
- Avoid morning sample, but is there proteinuria in the urine.
- Assess symptoms
- Sflt-1/PIGF testing recommended to help ‘rule in’ PE for women with gestational hypertension between 20-35 weeks.
- Fetal assessments associated with placental insufficiency, FGR, still birth. Assess growth, chat, activity, USS fetal growth, amniotic fluid volume, umbilical artery doppler.
What is the treatment of hypertension?
- first line is labetalol, a beta blocker contraindicated by pregnancy.
- Next line is nifedipine if labetalol not suitable
- Methyldopa if others not suitable
- Amlodipine can replace nifedipine and doxazosin is useful when stuck
- IV drugs may be needed if severe hypertension and critical care need labetalol or hydralazine
When does hypertension become severe?
it becomes severe pre-eclampsia when unresponsive to treatment or associated with symptoms.
Consider magsulf to prevent eclamptic seizures and fetal neuroprotection >30 weeks. Loading dose 4g over 5-15 minutes, 1g/ hour 24 hours.
-Antenatal corticosteroids (24 to 35+6 weeks).
