Hypertensive disorders in pregnancy

Intravenous: bolus dose 50 mg given slowly followed by continuous infusion up to 160 mg/hBradycardia
Bronchospasm
Scalp tinglingAsthma
PhaeochromocytomaNifedipineCalcium channel antagonistOral:10 mg bd to 20 mg qdsHeadache
Flushing
Tachycardia
Oedema
LethargyAortic stenosis
Liver disease
Avoid before 20 weeks gestation (NICE 2010)1MethyldopaCentral actionOral: 250 mg tds to 1 g tdsTiredness
Postural hypotension
Depression
Headaches
Dry mouth
Gastrointestinal disturbancesPhaeochromocytoma
Liver disease
Depression
Avoid postpartumHydralazineVasodilatorOral: 25mg tds to 75mg qds
Intravenous: bolus 5–10 mg in sodium chloride administered slowly over 10–20 minutes followed by a continuous infusion of 5–20 mg/hTachycardia
Palpitations
Flushing
Fluid retention


Labetalol is the only antihypertensive agent licensed for treatment in pregnancy, although the other drugs listed have been used extensively in pregnancy and appear to be safe for mother and fetus. Beta-blockers such as atenolol are relatively contraindicated in pregnancy due to their association with fetal growth restriction. Methyldopa should be avoided postpartum because of its association with depression.



Antihypertensive medication and breastfeeding


Labetalol, nifedipine, enalapril, captopril, atenolol and metoprolol have no known adverse effects on breastfed babies. Postnatally, women with chronic hypertension usually revert to their pre-pregnancy medication.




Outpatient management of hypertensive disorders in pregnancy


Outpatient management of women with mild or moderate hypertension was introduced in the early 1980s.6 Obstetric day-care units provide a comprehensive assessment of maternal and fetal wellbeing with senior clinician review. They offer safe, effective and economically sound management when appropriately targeted.7,8 Furthermore women prefer outpatient care to hospital admission. The frequency of day-care appointments will depend on the woman’s medical/obstetric history, results of recent maternal/fetal monitoring and gestation.


APEC (Action on Pre-eclampsia charity, action-on-pre-eclampsia.org.uk), the Royal College of Obstetricians and Gynaecologists (RCOG) and NICE have collaborated to provide the PRECOG guidelines for community midwives to detect early signs of pre-eclampsia and refer to day-care or hospital admission.9


These guidelines advise hospital referral if:




  • Diastolic blood pressure 90 mmHg or systolic blood pressure is  160 mmHg.



  • 2+ or more proteinuria on dipstick or  1+ on dipstick with significant symptoms.



  • Epigastric pain even if BP is < 90 mmHg and trace or no proteinuria.


The urgency of hospital referral depends on the blood pressure level, degree of proteinuria and presence/absence of symptoms.


Immediate hospital admission is advised if:




  • Diastolic blood pressure is 110 mmHg and new proteinuria 1+ on dipstick.



  • Diastolic blood pressure is 90 mmHg and new proteinuria 1+ on dipstick with significant symptoms (including epigastric pain, vomiting, headache, visual disturbances, reduced fetal movements, small-for-gestational-age fetus).



  • Systolic blood pressure is  170 mmHg.


In 2009 PRECOG2 was published.9 This guideline is for midwives working in day-care units and advises on how to care for women diagnosed with pre-eclampsia.



Management of chronic hypertension


Women with chronic hypertension should be advised to have their blood pressure control and medication reviewed before they conceive. Once pregnant, the need for antihypertensive medication should be reassessed. These women often exhibit the same fall in blood pressure as seen in normal pregnancy, and they may not require therapy until the second or third trimester.


Hypertension presenting for the first time in early pregnancy should not be assumed to be essential until secondary causes such as renal, adrenal and cardiac have been excluded.


There is no drug of preference for the management of chronic hypertension in pregnancy. However, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers and chlorothiazide are associated with a risk of congenital anomalies and should be avoided. Women planning to conceive and taking any of these agents should be advised to change to medications such as methyldopa or labetalol prior to conception.


For women with uncomplicated chronic hypertension, the aim is to keep blood pressure less than 150 mmHg systolic and between 80 and 100 mmHg diastolic.


If there is target-organ damage due to hypertension (e.g. kidney disease), systolic blood pressure should be kept below 140 mmHg and diastolic between 80 and 90 mmHg.


Women with secondary chronic hypertension should be managed in conjunction with their physician.


Chronic hypertension is associated with a risk of superimposed pre-eclampsia, fetal growth restriction and placental abruption. An individual plan should be made for the frequency of antenatal assessments depending on medical and obstetric history and any additional risk factors for adverse outcome. Measurement of blood pressure and urinalysis should be every 2–4 weeks from 20 weeks onwards. At 28–30 weeks and 32–34 weeks ultrasound measurements of fetal growth and amniotic fluid volume and umbilical artery Doppler should be undertaken. If the results are normal, further ultrasound assessment is not indicated unless the clinical situation deteriorates. Fetal cardiotocography should be carried out if there are concerns about fetal activity. If blood pressure can be maintained below 160/110 mmHg and there is no evidence of fetal compromise or superimposed pre-eclampsia, then pregnancy can be prolonged to at least 37 weeks.


During labour, antenatal antihypertensive treatment should be continued, with the aim of keeping systolic pressure less than 150 mmHg. If blood pressure is stable and less than 150/100 mmHg then it is not necessary to limit the duration of second stage. Continuous fetal heart rate monitoring is recommended. After birth, ergometrine, including Syntometrine (Alliance), should be avoided, as these drugs can further increase the blood pressure.


After birth, maternal blood pressure should be measured daily for the first 2 days and at least once between the third and fifth postnatal day, with the aim of keeping the level below 140/90 mmHg. If antihypertensive medication is required, methyldopa should be avoided because of its association with depression. Alternative agents include labetalol, nifedipine, atenolol and enalapril. Blood pressure control should be reviewed 6–8 weeks postpartum by the woman’s general practitioner.



Management of gestational hypertension



Antepartum care


Women with mild or moderate hypertension (blood pressure < 160/110 mmHg) can be safely managed as outpatients. At each antenatal visit, urine should be tested for proteinuria with either an automated reagent-strip reading device or urinary PCR. Moderate hypertension (150/100 mmHg to 159/109 mmHg) should be treated to maintain systolic pressure below 150 mmHg and diastolic pressure 80–100 mmHg. Once treatment has been initiated, blood pressure should be measured at least twice a week.


Women with moderate hypertension should have blood tests for renal function, electrolytes, full blood count, transaminases and bilirubin at initial diagnosis. Repeat testing is not required unless proteinuria develops.


In the event of severe hypertension, the woman should be admitted to hospital and started on antihypertensive medication (or medication increased) to maintain systolic pressure below 150 mmHg and diastolic pressure 80–100 mmHg. Blood pressure should be measured at least four times a day and urine tested for protein daily with either an automated reagent-strip reading device or urinary PCR. Blood tests for renal function, electrolytes, full blood count, transaminases and bilirubin should be taken at admission and weekly thereafter. Once severe gestational hypertension has been controlled, outpatient management can be instituted with twice-weekly blood pressure and urine testing and weekly blood tests.


Women who present before 32 weeks with mild hypertension or who are high risk for pre-eclampsia should be advised to have their blood pressure measured and urine tested twice weekly.


There are no studies of fetal surveillance in populations that include only women with gestational hypertension. An individual plan for fetal monitoring should be made depending on gestation at diagnosis, severity of hypertension and any previous history of pre-eclampsia, stillbirth or a small-for-dates baby. Ultrasound examinations for fetal growth, amniotic fluid assessment and umbilical artery Doppler velocimetry should not normally be repeated more frequently than every two weeks unless the clinical situation changes or the results are abnormal. For women with mild or moderate gestational hypertension fetal cardiotocography is only indicated if fetal activity is abnormal. If hypertension is severe and conservative management is planned, then fetal cardiotocography should be at least once a week, and more often if the clinical situation changes.



Timing of delivery


Pregnancy can be prolonged to reach fetal maturity at 37 weeks if blood pressure is less than 160/110 mmHg with or without treatment and there are no concerns about fetal wellbeing. After 37 weeks, the woman can be offered induction of labour. The HYPITAT trial demonstrated that induction of labour in women with gestational hypertension or pre-eclampsia at term resulted in less progression to severe disease, without a higher caesarean section rate.10



Care in labour


Blood pressure should be measured hourly if hypertension is mild or moderate, and continually if severe. Antihypertensive medication should be continued. It is not necessary to limit the duration of second stage unless hypertension is severe and unresponsive to treatment. Oxytocin should be administered for active management of third stage. Ergometrine/Syntometrine are contraindicated, as these agents can produce an acute rise in blood pressure.



Postnatal care


Blood pressure should be recorded daily for the first 2 days and at least once between 3 and 5 days after birth. Before discharge to community care, blood pressure should be stable below 150/100 mmHg. On transfer to community care, a plan of management should be documented including frequency of blood pressure monitoring and when to reduce/stop antihypertensive treatment. Antihypertensive medication can be reduced once blood pressure falls below 130/80 mmHg. Women who did not require treatment for hypertension before birth will require medication postpartum if their blood pressure rises above 149/99 mmHg.


A general practitioner review should be advised for women who require antihypertensive medication at two weeks post birth. Women with gestational hypertension should be offered a medical review 6–8 weeks postpartum. This is an opportunity to review blood pressure control, and to discuss contraception and the implications of gestational hypertension for future pregnancies and long-term health (Table 4.2). Women with persistent hypertension requiring medication eight weeks postpartum should be referred to a specialist for investigation.



Table 4.2 Long-term health risks (NICE 2010)1









































Future risk Hypertensive disorder
Gestational hypertension Pre-eclampsia Severe pre-eclampsia, HELLP syndrome or eclampsia
Gestational hypertension in future pregnancy Risk ranges from about 1 in 6 (16%) to about 1 in 2 (47%) Risk ranges from about 1 in 8 (13%) to about 1 in 2 (53%)
Pre-eclampsia in future pregnancy Risk ranges from 1 in 50 (2%) to about 1 in 14 (7%). Risk up to about 1 in 6 (16%)
No additional risk if interval before next pregnancy < 10 years
If birth was needed before 34 weeks risk is about 1 in 4 (25%)
If birth was needed before 28 weeks risk is about 1 in 2 (55%)
Cardiovascular disease Increased risk of hypertension and its complications Increased risk of hypertension and its complications Increased risk of hypertension and its complications
End-stage kidney disease If no proteinuria and no hypertension at 6–8 week postnatal review, relative risk increased but absolute risk low. No follow-up needed
Thrombophilia Routine screening not needed


Long-term significance of hypertension in pregnancy


Pregnancy may be considered as a vascular stress test. Women who develop gestational hypertension or pre-eclampsia are at increased risk of developing hypertension and its complications in later life. Women should be informed of the risk of recurrent hypertensive disease in pregnancy and lifetime risk of cardiovascular and kidney disease (Table 4.2).


There is an association between pre-eclampsia and maternal thrombophilia. However, there is insufficient evidence of benefit to recommend routine screening for thrombophilia in women who have had pre-eclampsia.



Pre-eclampsia



Aetiology and pathogenesis


Although advances have been made in understanding the pathophysiology of pre-eclampsia, the initiating event(s) is unknown.11 The pathophysiological features of pre-eclampsia include systemic inflammation, oxidative stress, altered levels of angiogenic factors, increased vascular reactivity, endothelial dysfunction and activation, insulin resistance and dyslipidaemia. Many of these changes are seen in normal pregnancy but to a lesser degree.


Crucial to the syndrome of pre-eclampsia is impaired placentation with deficient remodelling of the spiral arteries in early pregnancy. As a result placental blood flow is reduced. In recent years two theories of pathogenesis have been described. The two-stage process proposes that intermittent perfusion of the intervillous space results in periods of hypoxia which cause factors to be released into the circulation. These factors damage the vascular endothelium triggering a multisystem disorder with protein and fluid leaking into the intravascular space. The continuum theory suggests that pre-eclampsia is an increased maternal immune response to trophoblastic debris. The abnormal response may be due to the presence of increased amounts of debris (owing to impaired placental perfusion or a large placenta) or normal amounts of debris but abnormal maternal susceptibility.


To explain the different presentations of hypertensive diseases in pregnancy, it is proposed that some women will tolerate the physiological adaptations to pregnancy even if placentation is abnormal while others fail to tolerate the adaptations to a greater or lesser degree and develop gestational hypertension or pre-eclampsia.



Prediction of pre-eclampsia


Predicting who will develop pre-eclampsia has exercised the minds of researchers for many years. A clinically useful predictive test should be reliable, valid and efficient when performed early in pregnancy. If such a test became available, maternal and fetal monitoring could be directed to women considered to be at high risk. Moreover, such women could be offered interventions with the aim of reducing risk or ameliorating the condition.


The simplest method of prediction is to identify risk factors from the clinical history (Table 4.3). Unfortunately such factors have a relatively low predictive value even in combination. More sophisticated methods include Doppler ultrasound assessment of the uteroplacental circulation and the measurement of angiogenic factors in the maternal circulation. A meta-analysis of 74 studies (79,547 women) found that elevated second-trimester uterine artery pulsatility index with notching predicted pre-eclampsia with a positive likelihood ratio of 21 among high-risk women and 7.5 among low-risk women.12 The same meta-analysis found uterine artery Doppler to be more predictive when performed in the second trimester than in the first.



Table 4.3 Risk factors for pre-eclampsia



Family history of pre-eclampsia



Primigravida



Multiple pregnancy



Assisted conception



Previous pre-eclampsia/eclampsia/HELLP syndrome



Extremes of reproductive age

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Jan 31, 2017 | Posted by in GYNECOLOGY | Comments Off on Hypertensive disorders in pregnancy

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