HTN in pregnancy Flashcards
high risk groups for pre-eclampsia?
hypertensive disease in a previous pregnancy
chronic HTN
type 1 or 2 DM
CKD
AI disorders e.g. SLE and antiphospholipid syndrome
NICE guidance for medication in pregnant women who are deemed high risk of pre-eclampsia?
aspirin 75mg OD from 12 weeks until birth of the baby
define chronic HTN in pregnancy?
HTN present at booking visit or before 20 weeks or already taking antihypertensivie medication before r/f to maternity services.
can be primary or secondary
what is eclampsia?
convulsive condition associated with pre-eclampsia
can explain convulsions during pregnancy, labour or up to 7 days post partum, that are not caused by epilepsy or another neurological disorder.
44% of seizures occur postnatally
what is gestational HTN?
new HTN presenting after 20 wks without significant proteinuria
symptoms patients should be made aware of to seek immediate medical advice as symptoms of pre-eclampsia?
severe headache
visual problems-blurring, flashing before eyes
severe abdo pain just below ribs-*liver subcapsular haematomas
vomiting
sudden swelling of face, hands or feet
normal variation of BP with gestation?
BP decreases until after 20 weeks gestation when there is a slow increase in BP which does not reach hypertensive levels
occurs due to physiological vasodilatory effect of pregnancy-progesterone causes smooth muscle relaxation hence vasodilation that reduces TPR, which is reduced to a greater extent than the increase in CO. Increase in blood volume and CO then exceeds decrease in TPR in later pregnancy to allow the slow rise in BP back to the patient’s norm.
pathogenesis of pre-eclampsia?
failure of trophoblast to invade maternal spiral arterioles means that they retain their smooth muscle and so inability to create a low resistance circulation through arterial dilation. There is reduction in endothelial vasodilators e.g. PGI2 and NO, and maternal plasma volume fails to expand. Endothelial damage causes inflammation and activation and impairment of the coagulation system that can lead to DIC, and systemic effects including fibrin deposition in hepatic sinusoids and thrombosis and fibrinoid necrosis of cerebral arterioles.
endothelial damage also causes oxidative stress
what defines HTN in pregnancy?
BP of 140/90 or higher on 2 occasions more than 4hr apart or single diastolic reading of greater than 110.
or increase in systolic from booking by 30 or more, or diastolic by 15 or more
gold standard measurement technique for proteinuria in pregnancy?
24 hr urine collection
but acceptable 1st line investigation=PCR-30mg/mmol or more should prompt a 24hr urine collection.
what result is abnormal for proteinuria on 24hr urine collection?
300mg or more in 24hrs
what proportion of patients with pre-eclampsia will develop eclampsia?
2%
fetal complications of pre-eclampsia?
fetal death, still birth-HTN and/or proteinuria=highest single RF for stillbirth (20% of cases), stillbirth complicates 7% of cases
fetal growth restriction
those resulting from necessary intervention: prematurity
cerebral haemorrhage
pneumothorax
ventilation
related to both the disease and intervention: cerebral palsy
what preventative medication for eclampsia is given?
magnesium sulfate
define severe pre-eclampsia?
diastolic BP of at least 110 or systolic of at least 160 and/or symptoms and/or biochemical and/or haematological impairment.
biochemical derangement may include raised LFTs, raised urate (breakdown product of purines)-due to reduced renal perfusion or increased production by poorly perfused tissue, raised U+Es
RFs that put a women at moderate risk of developing pre-eclampsia?
age 40 or over 1st pregnancy more than 10 years since last pregnancy multiple pregnancy FH of pre-eclampsia BMI 35 or more at presentation
note smoking reduces the risk-been found that heme oxygenase 1 and its metabolite CO have a protective role.
NICE guidance on pharmacological management of women with moderate risk of pre-eclampsia?
if more than 1 moderate RF take aspirin 75mg OD from 12 weeks of pregnancy and continue until birth.
define pre-eclampsia
new onset HTN in pregnancy after 20 wks, with BP greater than 140/90 and proteinuria (more than 300mg/24hr), multisystem disorder in the 2nd half of pregnancy which resolves after delivery (post placenta delivery) (although can persist up to 3 wks afterwards, perisistence post partum most likely up to 7days).
can be just HTN or proteinuria, but with other features.
NICE definition=new onset HTN in pregnancy after 20 weeks with significant proteinuria
maternal complications of pre-eclampsia?
intracranial haemorrhage and cortical blindness-?secondary to fibrinoid necrosis, MAP 125mmHg
renal tubular and cortical necrosis
pulmonary oedema-reduced plasma protein and capillary leakage
liver-subcapsular haematomas, hepatic rupture, HELLP syndrome-haemolysis, elevated LFTs and low PLT
microangipathic haemolysis, DIC-increased risk with placental abruption (placenta partially or completely separates from uterus before birth)
placental infarction
signs on examination of patient with pre-eclampsia?
hyperreflexia
clonus
oedema
epigastric tenderness
what measurement is indicative of fetal risk in pre-eclampsia?
proteinuria
so fetal growth must be monitored when proteinuria is present in pregnancy even if maternal BP us normal
indications for admission to hospital in pre-eclampsia?
BP persistent over 170/110
or
persistent over 140/90 plus proteinuria or significant symptoms
how is risk to fetus in pre-eclampsia assessed?
fetal movements
CTG-cardiotocography-montior fetal heart and uterine contractions
umbilical doppler
US-fetal size, liquor (AF) volume
management principles for admitted pt with pre-eclampsia?
-minimum 4hrly monitoring
-eclampsia prevention-Mg sulfate-IV Mg sulfate loading dose 4g over 5min, followed by infusion of 1g/hr maintained for 24hrs, is indicated for severe pre-eclampsia in critical care setting if birth is planned within 24hr. severe pre-eclampsia= severe HTN and proteinuria OR mild/mod HTN and proteinuria with 1 or more symptoms-severe headache, visual disturbance, severe upper abdo pain, liver tenderness, papilloedema, 3 or more beats of clonus, HELLP syndrome, falling PLTs to below 100, abnormal liver enzymes-ALT/AST rising to above 70.
aim to prolong pregnancy if baby well on admission and mother is stable.