Hypertensive disorders in pregnancy Flashcards
Describe the normal pattern of changes to blood pressure in pregnancy
Normally in pregnancy blood pressure begins to fall in the first trimester, reaches its lowest point (DBP) in the second trimester and then rises towards preconception levels by term.
What is the definition of hypertension in pregnancy?
Systolic blood pressure greater than or equal to 140 mmHg and/or Diastolic blood pressure greater than or equal to 90 mmHg as confirmed with repeated readings over several hours
a rise of more than 30/15 mmHg above pre-pregnancy baseline may be significant for some women
What is the definition of severe hypertension in pregnancy?
Systolic blood pressure greater than or equal to 160 mmHg and/or Diastolic blood pressure greater than or equal to 110 mmHg
women > 170/110 require urgent treatment to prevent complications
List 4 factors are important to ensure you take an accurate blood pressure reading?
- positioning (comfortably seated, feet resting on a flat surface not crossed, arm supported at the level of her heart, not supine)
- equipment - manual rather than automatic assessment, correctly calibrated
- correct cuff size
- rate of deflation of cuff should be less than 2mm/sec
- if questioning check on opposite arm
What is preeclampsia?
is a multisystem disorder unique to human pregnancy, characterised by hypertension (usually developing >20/40 gestation) and involvement of one or more organ systems and/or the fetus
Which 6 body systems are often involved in diagnoses of preeclampsia?
- renal
- haematological
- liver
- neurological
- cardiac
- fetus
What 3 factors indicate renal involvement in diagnoses of preeclampsia?
- a spot protein/creatinine ratio (PCR) greater than or equal to 30mg/mmol showing proteinuria
- serum or plasma creatinine >90 umol/L
- oliguria
What factor indicates haematological involvement in diagnoses of preeclampsia?
- thrombocytopenia (low platelets)
What 2 factors indicate liver involvement in diagnoses of preeclampsia?
- raised serum transaminases
- severe epigastric and/or right upper quadrant pain
What 5 factors indicate neurological involvement in diagnoses of preeclampsia?
- convulsions (eclampsia)
- hypereflexia with sustained clonus
- headache
- visual disturbances (flashes, aura, blind spots, loss of vision)
- stroke
What factor indicates cardiac involvement in diagnoses of preeclampsia?
- pulmonary oedema
What factor shows the baby is impacted in diagnoses of preeclampsia?
- intrauterine growth restriction (IUGR)
What are the most important clinical features of severe preeclampsia?
- uncontrolled blood pressure
- HELLP syndrome
- impending eclampsia
- worsening thrombocytopenia
- worsening fetal growth restriction
Which circulating angiogenic factors may be useful in diagnosing preeclampsia?
- soluble fms like tyrosine kinase-1 (sFlt1)
- soluble endoglin
- reduced placental growth factor (PlGF)
What is the earliest gestation that preeclampsia would usually present at?
20 weeks gestation
rarely presents earlier but may in women with predisposing factors like hydatidiform mole, multiple pregnancy, fetal triploidy, severe renal disease or antiphospholipid antibody syndrome.
What level of proteinuria on dipstick is considered significant and an indication that further testing is required?
++, +++ or repeated +
What are the clinical features of HELLP syndrome?
- Haemolysis
- raised Liver enzymes (transaminases)
- Low Platelets
with or without other preeclamptic features, often only two of these features is recognisable
What is the definition of fetal growth restriction and what are three factors that are often associated with it?
- where a fetus fails to achieve its growth potential in utero
- often associated with small for gestational age fetus, abnormal umbilical artery dopplers or oligohydramnios in the absence of alternate reasons for these occuring.
What is superimposed preeclampsia?
- development of preeclampsia in women with chronic (i.e. prepregnancy or
what three clinical features may be indicative of superimposed preeclampsia?
- diagnosis of superimposed preeclampsia requires the presence of oligohydramnios, abnormal umbilical artery doppler flows or other evidence of maternal system involvement.
What clinical features are unreliable as criteria for diagnosing super-imposed preeclampsia?
- worsening hypertension
- small for gestation age
- proteinuria in women for whom this was preexisting
What is gestational hypertension?
- the new onset of hypertension after 20 weeks gestation without any maternal or fetal features of preeclampsia, followed by return to normal within 3 months postpartum.
- includes some women who will go on to develop preeclampsia or chronic hypertension (continuing after 3 months postpartum)
- often associated with adverse pregnancy outcomes particularly when it develops at earlier gestations or is more severe
What is chronic hypertension?
- hypertension before pregnancy or before 20 completed weeks gestation
- may be essential, secondary to another cause or white coat
What are important secondary causes of hypertension?
- kidney disease
- systemic disease with renal involvement e.g. diabetes mellitus or lupus
- endocrine disorders
What investigations are required for a woman who presents with new onset hypertension after 20 weeks gestation?
- assess for signs/symptoms of preeclampsia (severe hypertension, headache, epigastric pain, oliguria, nausea/vomiting, concerns about fetal wellbeing)
- spot urine PCR
- full blood count
- creatinine, electrolytes, urate
- liver function tests
- ultrasound to assess fetal growth, amniotic fluid volume and umbilical artery doppler assessment
- some facilities may measure PlGF and/or sFlt1
What ongoing assessments are important for women with pregnancy induced hypertension?
- urinalysis by dipstick followed by spot urine PCR if >1+ for proteinuria
(each visit for chronic hypertension, 1-2x weekly for gestational hypertension, daily for non-proteinuric women with developing preeclampsia) - preeclampsia bloods (FBC, Electrolytes, creatinine, LFT and coagulation studies if indicated)
(for chronic hypertension assessed if increase in BP or new proteinuria, weekly in gestational hypertension and twice weekly or more if unstable in women with signs of developing preeclampsia)
What is generally the recommendation for women who develop preeclampsia before 23-24 weeks gestation?
- high risk: high maternal morbidity and perinatal mortality
- depending on individual clinical situation, wishes of parents and institution may advise termination of pregnancy
- prolonging pregnancy means risk to mum, but improves prognosis for baby
What is key in terms of place of birth for women who develop preeclampsia between 24-36 weeks?
- tertiary hospital
- appropriate paediatric care (NICU)
What is expectant care for women with preeclampsia (usually 24-34 weeks)?
- prolong pregnancy where possible
- antenatal corticosteroids for lung maturation if possible
- magnesium sulphate for neuroprotection
- depends on maternal clinical condition, often not advisable
What health care providers are likely to be involved in the care of a woman with preeclampsia and her baby?
- obstetrician
- midwife
- neonatologist
- anaesthetist
- physician
What is the recommended blood pressure threshold for antihypertensive treatment?
systolic BP > 160mmHg and/or diastolic BP > 110mmHg the need for antihypertensive treatment is assessed on a case by case basis below this threshold
What are the 3 first line antihypertensive drugs?
- methyldopa
- labetalol
- oxprenolol
What are the 3 second line antihypertensive drugs?
- hydralazine
- nifedipine
- prazosin
What is a rare but significant risk for the baby associated with beginning antihypertensive therapy (particularly IV hydralazine? and what may be recommended in light of this?
- precipitous fall in blood pressure may lead to reduced placental perfusion and fetal distress
- small bolus of fluid e.g. 250mL normal saline
- continuous CTG monitoring
What major class of antihypertensive drugs are contraindicated in pregnancy?
- Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers
- use in third trimester has been associate with fetal death and neonatal renal failure
What 4 drugs are most likely to be used for acute blood pressure lowering for sever hypertension?
- labetalol
- nifedipine
- hydralazine
- diazoxide
Why should all preeclamptic women be assessed regarding the need for thromboprophylaxis?
- increased risk of DVT
What is the lower limit of the normal platelet count in pregnancy?
and what is the cut off for abnormal platelet count (thrombocytopenia) in preeclampsia?
at what level are peripartum bleeding complications a significant concern (particularly re anaesthetics)?
lower limit in pregnancy: 140x10^9/L
abnormal cut off in preeclampsia: 100x10^9/L
requires serial monitoring
significant risk of bleeding: 50x10^9/L
What is the key treatment for severe thrombocytopaenia, particularly at the time of surgery or bleeding?
- platelet transfusion
- fresh frozen plasma may also be required for management of coagulopathy
What are the 4 main aspects to care of the woman who has an eclamptic seizure?
- resuscitation (assure patent airway, oxygen by mask, IV access), IV diazepam or clonazepam may be given if seizure is prolonged while preparing MgSO
- prevention of further seizures with magnesium sulphate for 24 hours after seizure (monitor BP, RR, output, O2 sats, reflexes)
- control of hypertension to below 160/100
- close fetal monitoring and arrangements for birth
What is the usual protocol for IV administration of magnesium sulphate for a woman with eclampsia?
- magnesium sulphate should be available prediluted as 4g in 100ml normal saline
- loading dose 4g (100ml), given over 15-20 mins
- then infusion of 1-2g (25-50ml) per hour for 24 hours
in the event of a further seizure a further 2-4g should be given over 10 mins - caution vital in women with oliguria or renal impairment
What is the protocol for prevention of eclampsia with magnesium sulphate (variable between units)?
- magnesium sulphate should be available prediluted as 4g in 100ml normal saline
- loading dose 4g (100ml), given over 15-20 mins
- infusion of 1g per hour
indications may include a combination of persistant headache, hypereflexia with clonus, evidence of liver involvement, severe hypertension
What is generally the protocol for AN fetal surveillance in women with chronic hypertension?
- first trimester early dating ultrasound
- 3rd trimester USS for fetal growth, AFV, Doppler repeat as indicated
What is generally the protocol for AN fetal surveillance in women with gestational hypertension?
- USS for fetal growth, AFV, Doppler at time of diagnosis and 3-4 weekly
What is generally the protocol for AN fetal surveillance in women with preeclampsia?
- USS for fetal growth, AFV, Doppler at time of diagnosis and 2-3 weekly, weekly or more if signs of FGR or abnormal doppler or AFV
- CTG twice weekly or more frequently if indicated
What are the benefits of administration of antenatal corticosteroids in the preterm infant?
reduced risk of:
- neonatal death
- respiratory distress syndrome
- cerebrovascular haemorrhage
- nectrotizing enterocolitis
- need for respiratory support and NICU admission
Up to what gestation are antenatal corticosteroids considered beneficial?
- generally up to 34 weeks
- may have benefit beyond 34 weeks, assessed on a case by case basis, but not usually justification for delaying urgent birth
- repeat courses may be considered but remain controversial due to limited evidence base
What drug is recommended for fetal neuroprotection in preterm birth? What gestation is this generally recommended up to?
- magnesium sulphate
- prior to 30 weeks
- less evidence but potentially beyond 30 weeks
What is the main patient advocacy body for women who have had preeclampsia or gestational hypertension?
- AAPEC Australian Action on Preeclampsia
What usually happens to effects of preeclampsia after birth?
- all features recover to normal, but often delayed for several days or longer
- first day or two liver enzyme elevations and thrombocytopenia often worsen
- hypertension may persist and requires monitoring, medication may need to be adjusted
What important class of drugs are contraindicated in women with resolving preeclampsia and gestational hypertension in the early postpartum period as they may adversely effect hypertension, renal function and platelet function?
- NSAIDS
What is an important element of postnatal care for women with preeclampsia that is often overlooked?
- often a distressing experience
- psychological and family support
What investigations are important antenatally for women with pre-existing chronic hypertension? (ideally investigated prepregnancy)
- detailed history
- urinalysis (dipstick, PCR, MSU culture and microscopy)
- blood tests ( serum electrolytes, creatinine, uric acid, FBE, fasting blood glucose)
- ECG
- medical assessment of pre-existing organ damage
- assessment for features of preeclampsia at every visit after 20/40
- assessment of fetal growth and wellbeing
- admission if condition deteriorating
- possible antihypertensive treatment
What non-pharmacological treatments may be considered for women with chronic hypertension?
- many lack evidence
- salt restriction
- calorie restriction in obese women
- heart healthy diets
- exercise
- stress reduction (e.g. meditation)
- workload reduction
- bed rest
What is the risk of perinatal death for women with preexisting hypertension during pregnancy compared with singleton normotensive pregnancies?
- 3 times higher risk of perinatal death
- highest from 39 weeks
Which antihypertensive drugs are considered to be compatible with breastfeeding?
- methyldopa
- labetalol
- oxprenolol
- nifedipine
- prazosin
- hydralazine
- enalapril
- captopril
- quinapril
- clonidine (but may accumulate, significance unknown)
What drug used to control PPH should be avoided for women with severe preeclampsia?
- ergometrine
What kind of anaesthesia is preferred for caesarian birth in women with severe preeclampsia?
- regional spinal, epidural or combined spinal-epidural are preferred to GA
What are the main risk factors associated with preeclampsia?
- nulliparity
- multiple pregnancy
- previous history of preeclampsia
- family history of preeclampsia
- Overweight BMI 25-29.9
- Obese BMI>30
- Maternal age > or = 40
- BP> 130/80mmHg 10 years
- fetal hydrops
- fetoplacental triploidy
- gestational trophoblastic disease
- own birthweight
What factors may be protective against preeclampsia?
- miscarriage with the same partner in nulliparous women
- high fruit intake (Vit C supplementation not recommended)
- taking greater than 12 months to conceive
What are the risks of gestational hypertension and preeclampsia in women who have had previous gestational hypertension?
16-47% develop gestational hypertension
2-7% develop preeclampsia
What are the risks for women who have had previous proteinuric preeclampsia of developing gestational hypertension and preeclampsia?
13-53% develop gestational hypertension
16% develop preeclampsia
What preventative care may be considered for women at risk of developing preeclampsia?
- low dose aspirin (usually 50-150mg/day) ideally commenced before 16 weeks may reduce risk of developing PE, stillbirth, neonatal or infant death, SGA
- calcium supplements (1.5g/day) reduce parathyroid hormone release and intracellular calcium, so reduces smooth muscle contractility, also increases magnesium levels, increases uteroplacental blood flow, reduced risk of hypertension and preterm birth, no difference in fetal growth
- possibly heparin (5000IU/day dalteparin)
- possibly folic acid
What recommendations may improve long term health outcomes for women who have had preeclampsia?
- avoiding smoking
- maintaining healthy weight
- exercising regularly
- eating a healthy diet
- annual blood pressure check
- 5 yearly or more frequent assessment of CVD risk factors including serum lipids and blood glucose
- awareness of increased risk of DVT, renal disease, type II diabetes and hypothyroidism
What is the key guideline for management of hypertensive disorders of pregnancy?
Lowe et al. SOMANZ Guideline (2014)
What factors influence blood pressure in pregnancy?
- blood volume
- heart rate
- age
- diurnal variations, higher in evening
- weight
- alcohol
- smoking
- eating
- stress, fear, anxiety
- exercise
- distended bladder
- hereditary
- disease (peripheral resistance, renal disease)
What is the trade name of Labetalol?
Trandate
What is the trade name of Nifedipine?
Adalat
What is the trade name of Methyldopa?
Aldomet
What is the mode of action of magnesium sulphate?
- unclear
- important cation in neural conduction, believed to have a neuromuscular blocking action
- relaxes smooth muscles
- reduces calcium influx
