Hypertension in pregnancy and pre-eclampsia

Hypertension in pregnancy and Pre-eclampsia

Introduction

Hypertension in pregnancy is common, complicating more than 10 percent of all
pregnancies.1 Hypertension can be a sign of preeclampsia, a multisystem disorder
specific to pregnancy also characterised by proteinuria; it affects about 4% of all
pregnancies, and can result in serious morbidity and mortality to both mother and fetus.
Pregnancy-induced hypertension (without proteinuria) maybe the first sign of pre-
eclampsia. Pre-existing hypertension can result in pregnancy complications such as fetal
growth restriction, even without pre-clampsia supervening.1,2 In the latest report on
Confidential Enquiries into Maternal and Child Health (CEMACH), there were 18 direct
deaths attributed to preeclampsia and eclampsia. The biggest impact pre-eclampsia has to
the baby is related to the need to deliver preterm, as this is the only cure.
Definitions of hypertension in pregnancy and preeclampsia
•
Hypertension: consecutive diastolic blood pressure readings of ≥90 mmHg on
more than one occasion at least 4 hours apart or a single DBP of ≥110 mmHg
Proteinuria: ≥300 mg excreted protein in a 24-hour collected urine or two clean-
catch urine specimens at least 4 hours apart with 2+ proteinuria by dipstick
Gestational hypertension/pregnancy-induced hypertension: hypertension after
the 20th week of pregnancy in a previously normotensive woman
Preeclampsia: hypertension with proteinuria
Risk factors which predispose women to developing preeclampsia

• ≥ 10 years since last baby • Aged ≥ 40 years • Raised body mass index before pregnancy and at booking • Family history of preeclampsia (mother or sister) • Booking DBP ≥ 80 mmHg • Multiple pregnancy • Underlying medical conditions ƒ Pre-existing hypertension, renal disease, diabetes, or anti-phospholipid
Diagnosis
Hypertension (BP ≥140/90 mmHg on at least 2 occasions or ≥160/110 mmHg on one
occasion) and proteinuria (>0.3 g/24h) are diagnostic.

Clinical Features
Preeclampsia is a pregnancy-specific multisystemic condition of unknown aetiology. Its
two cardinal features are the result of endothelial cell activation and subsequent
vasoconstriction resulting in hypertension and glomerular damage causing proteinuria.
It is important to remember that no single symptom or sign can be relied on to
diagnose the condition, and that its course and onset are variable and unpredictable,
affecting either the mother or baby predominantly.

Clinical symptoms, (may be absent even in severe disease), include:
• epigastric or right upper quadrant pain, • nausea or vomiting • oedema • epigastric or right upper quadrant tenderness

Complications
These include fetal growth restriction, placental abruption, disseminated intravascular
coagulopathy (DIC), HELLP syndrome (haemolysis, elevated liver enzymes and low
platelet count), liver rupture, pulmonary oedema, renal failure, eclampsia and cerebral
haemmorhage.



Management
Pre-conception

• Weight loss in overweight women should be encouraged prior to conception as there is an increase of both pre-eclampsia and gestational hypertension with increasing BMI.5 • Anti-hypertensive therapy in women with chronic hypertension should be reviewed; consideration should be given to stopping or changing therapy such as ACE inhibitors, diuretics and Beta blockers.6
Antenatal Visits

• Risk factors for pre-eclampsia which should be identified (see above.)
• Such women need early referral to the Obstetric team.
• Severe hypertension (systolic >160 mmHg) should be avoided and women should be informed that most therapy is not teratogenic or harmful. • At each antenatal visit with a healthcare professional, blood pressure and urinalysis should be performed to detect new hypertension and proteinuria • Pre-eclampsia should be considered if there are symptoms of headaches, visual disturbances, epigastric pain or vomiting. • Fetal compromise (reduced fetal movements, reduced symphisial fundal height) should be sought in all women where pre-eclampsia is considered. Investigations
Blood pressure, followed by urinalysis for proteinuria and liver function tests, are
the best clinically relevant test in predicting maternal and fetal complications of
preeclampsia.
If a woman is thought to be at risk of preeclampsia, uterine artery Doppler
ultrasonography performed at the same time as her anomaly scan at 20 weeks’ gestation
should be considered. Bilateral arterial notching with high resistant flow is associated
with severe early onset of the disease.8
Mercury sphygmomanometry is recommended for measuring blood pressure in
pregnancy and preeclampsia. Automated devices tend to underestimate readings in
women with preeclampsia. However, self-measurement automated devices such as the
Microlife 3BTO-A(2)9 and the Omron M710, and robust devices for hospital use such as
the Dinamap ProCare 40011 that have been assessed for accuracy in preeclampsia
specifically, may be used.
At each antenatal visit where a blood pressure is measured, a urinalysis should be
undertaken to test for proteinuria. An early morning or community sample of urine is the
most accurate for dipstick urinalysis. A 24-hour collection remains the best method to
confirm significant proteinuria, but PCR (protein creatinine ratios) are better then
dipstick as they control for urine concentration.

Women suspected to have preeclampsia by their healthcare professional should be
referred for urgent obstetric review. Measurement of platelets, aspartate
aminotransferase (AST), (or alanine aminotransferase (ALT)) and serum creatinine at the
initial assessment, establish a baseline and monitor disease progression and in established
disease will diagnose HELLP syndrome.12-13 A raised serum uric acid in women with
hypertension is associated with superimposed preeclampsia and poor fetal outcome.
Monitoring of fetal growth may be done on a two- to four-week basis depending on the
level of suspicion. Umbilical artery Doppler ultrasonography is the best test for
predicting an at-risk fetus in women with preterm new hypertension and once abnormal is
usually done on a one- to two-weekly basis. The use of umbilical artery Doppler for fetal
assessment is associated with a trend towards a reduction in perinatal death, fewer
inductions and fewer admissions to hospital.14


Prophylactic strategies
Antiplatelet agents, particularly low-dose aspirin, has been shown to reduce the risk of
both preeclampsia and serious adverse outcomes by 10%.15 Calcium (1 gram per day) is
sometimes prescribed in high risk women as some studies have shown a 50% decrease in
the rates of pre-eclampsia.16

Antenatal management of hypertension

Antihypertensive therapy does not alter the progression of preeclampsia but may prevent
cerebrovascular haemorrhage, which remains the leading cause of death associated with
preeclampsia and eclampsia in the UK.17 CEMACH recommends treating systolic
hypertension of ≥160 mmHg with antihypertensives.17 Clinicians usually aim for blood
pressure to be maintained between 140-150 mmHg systolic and 90-100 mmHg diastolic.
Methyldopa, labetolol and nifedipine are the medications of choice.
A medical review on a Day Assessment Unit is recommended with a named obstetric
consultant in women with abnormal bloods, Dopplers, and new hypertension without
proteinuria. Women with new hypertension or new proteinuria benefit from weekly
follow-up to monitor disease progression and ensure blood tests and/or Dopplers are not
becoming abnormal. Serial assessment of the fetus with ultrasound measurements of
fetal size, umbilical artery Doppler and liquor volume is also important.18
Intrapartum Managament

Delivery is the treatment for preeclampsia but the decision to do is a careful balance of
maternal wellbeing and fetal maturity at gestations of under 34 weeks.
Blood pressure should be checked every 15 minutes until the woman is stabilized and
blood sent for full blood count, liver and renal function tests; clotting studies are not
usually necessary if the platelet count is over 100x106/L.19. An in-dwelling catheter and
intravenous fluid may facilitate close fluid balance, limiting intake to 80 ml/hour thus
reducing the likelihood of pulmonary oedema.20 Women in labour require continuous
electronic fetal monitoring. Oral or intravenous labetolol, oral nifedipine (not sublingual)
or intravenous hydralazine may be used for acute management of hypertension.19
Magnesium sulphate is recommended for eclampsia, and in cases of severe pre-eclampsia
(eg with symptoms, severe hypertension or abnormal blood tests). Its increased use is
associated with a decrease in deaths from eclampsia in the UK.21
In the third stage, it is advisable to avoid ergometrine as it may increase blood pressure
and it should be managed with syntocinon. A vaginal delivery is safer then a Caeserean
Section if it can be achieved. A regional block is preferred to a general anaesthetic.

Postpartum Management
Pre-eclampsia may occur for the first time after delivery. Up to 44% of eclampsia occur
in the postpartum period, and women with pre-eclampsia should be closely monitored for
48 hours following delivery.22.
Postpartum hypertension may be managed by using beta-blockers, calcium channel
antagonists or ACE inhibitors; methyldopa is avoided because it causes depression and
possible psychosis in the postnatal period. Blood pressure increases up to 4 days
postpartum.
Community review by a healthcare professional is recommended within the first two
weeks following discharge, and women with severe hypertension (SBP > 160 mmHg)
should be treated urgently.23 At the 6-week postnatal visit, women should have a blood
pressure and urinalysis measurement. The majority will have their medication tailored
off by this time as their blood pressure returns to the pre-pregnancy state. However,
hypertension in women with severe preeclampsia may take up to six months to resolve.
Women with pre-eclampsia have a higher risk of cardiovascular disease in later life.

Summary
The hallmarks of management of hypertensive disorders of pregnancy in the antenatal
period are close surveillance and timely delivery. Very high-risk women will benefit
from prophylactic aspirin. Accurate measurement of blood pressure and proteinuria, and
the judicious use of antihypertensive therapy are essential to reduce morbidity and
mortality. Urgent referral should be made in any suspected cases, even if not typical.
References

1. Brown MA, Mangos G, Davis G, et al. The natural history of white coat hypertension during pregnancy. BJOG 2005; 112:601-6.
2. World Health Organization. Make every mother and child count. World Health 3. Brown MA, Lindheimer MD, de Swiet M, et al. The classification and diagnosis of the hypertensive disorders of pregnancy: a statement from the International
Society for the Study of Hypertension in Pregnancy (ISSHP). Hypert Preg 2001;
20: ix-xiv.
4. Duckitt K, Harrington D. Risk factors for preeclampsia at antenatal booking: systematic review of controlled studies. BJOG 2005; 330:549-50.
5. Bhattacharya S, Campbell DM, Liston WA, et al. Effect of body mass index on pregnancy outcomes in nulliparous women delivering singleton babies. BMC
Public Health 2007; 7:168
6. Cooper WO, Hernandez-Diaz S, Arbogast PG, et al. Major congenital malformations after first-trimester exposure to ACE inhibitors. N Engl J Med
2006; 354:2443-51.
7. Thangaratinam S, Ismail K. Sharp S, et al. Prioritisation of tests for the prediction of preeclampsia complications: a Delphi survey. Hypertens
Pregnancy 2007; 26: 131-8.
8. Shennan AH. Preeclampsia and non-proteinuric pregnancy-induced hypertension. In: Luesley DM, Baker PN, eds. Obstetrics and gynaecology. London: Arnold, 2004. 9. Reinders A, Cuckson AC, Lee JTM, et al. An accurate automated blood pressure device for use in pregnancy and preeclampsia: the Microlife 3BTO-A.
BJOG 2005; 112: 1-6.
10. De Greeff A, Beg Z, Ganghi Z, et al. Accuracy of inflationary vs. deflationary oscillometry in pregnancy and preeclampsia: Omron MIT vs. Omron M7. Blood Pressure Monitoring 2009; in press. 11. De Greeff A, Ghosh D, Anthony J, et al. Accuracy assessment of the Dinamap ProCare 400 in pregnancy and preeclampsia. Hypertens Pregnancy 2009; in press. 12. Martin JN Jr, May WL, Magann EF, et al. Early risk assessment of severe preeclampsia: Admission battery of symptoms and laboratory tests to predict
likelihood of subsequent significant maternal morbidity. Am J Obstet Gynecol
1999; 180: 1407-12.
13. Martin JN Jr, Rinehart BK, May WL, et al. The spectrum of severe preeclampsia: comparative analysis by HELLP (haemolysis, elevated liver
enzyme levels and low platelet count) syndrome classification. Am J Obstet
Gynecol 1999; 180: 1373-84.
14. Neilson JP, Alfirevic Z. Doppler ultrasound for fetal assessment in high risk pregnancies. Cochrane Database of Syst Rev 1996; Issue 2.
15. Askie LM, Duley L, Henderson-Smart D, et al. Antiplatelet agents for prevention of preeclampsia: a meta-analysis of individual patient data. Lancet
2007; 369: 1791-8.
16. Hofmeyr GJ, Duley L, Atallah A. Dietary calcium supplementation for prevention of preeclampsia and related problems: a systematic review and
commentary. BJOG 2007; 114: 933-43.
17. Lewis G, ed. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer 2003-2005. The Seventh Report of Confidential Enquiries into Maternal Deaths in the United Kingdom. London: CEMACH; 2007. 18. Action of Preeclampsia. PRECOG 2: Day Assessment Unit Guidelines. 19. Tuffnell DJ, Shennan AH, Waugh JJS, et al. The management of severe preeclampsia/eclampsia. Guideline no. 10(A). London: RCOG Press; 2006. 20. Tuffnell DJ, Jankowich D, Lindow SW, et al. Outcomes of severe preeclampsia/eclampsia in Yorkshire 1999-2003. BJOG 2005; 112: 875-80.
21. Knight M. Eclampsia in the United Kingdom 2005. BJOG 2007; 114: 1072-8.
22. Douglas KA, Redman CWG. Eclampsia in the United Kingdom. BMJ 1994;
309: 1395-400.
23. Tan L, de Swiet M. The management of postpartum hypertension. BJOG 2002; 109: 733-6.

Source: http://www.feedingforlifehcp.ie/fileadmin/images/milks/Hypertension_in_Pregnancy___Pre-eclampsia.pdf