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3 Hypertensive disorders of pregnancy

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Contents

Objectives

When you have completed this unit you should be able to:

The hypertensive disorders of pregnancy

3-1 What is the normal blood pressure during pregnancy?

The normal systolic blood pressure is less than 140 mm Hg and the diastolic blood pressure is less than 90 mm Hg. During the second trimester both the systolic and diastolic blood pressures usually fall and then rise again toward the end of pregnancy. A mild rise in blood pressure early in the third trimester can therefore be normal.

3-2 What is hypertension during pregnancy?

Hypertension during pregnancy is defined as a diastolic blood pressure of 90 mm Hg or more and/or a systolic blood pressure of 140 mm Hg or more.

A diastolic blood pressure of 90 mm Hg or more or a systolic blood pressure of 140 mm hg or more during pregnancy is abnormal.

An abnormally high blood pressure during pregnancy is often accompanied by proteinuria.

3-3 What is proteinuria?

Proteinuria is defined as an excessive amount of protein in the urine. Normally the urine contains no protein or only a trace of protein. Therefore, just a trace of protein in the urine is not regarded as abnormal.

Proteinuria during pregnancy is diagnosed when either of the following is present:

  1. 0.3 g or more of protein in a 24-hour urine specimen.
  2. 1+ or more protein as measured with a reagent strip (e.g. Albustix, Labstix, Uristix, Multistix, Lenstrip, etc.).

Proteinuria during pregnancy may also be caused by:

  1. A urinary tract infection or renal disease.
  2. Contamination of the urine by a vaginal discharge or leucorrhoea.

Patients with proteinuria must be asked to collect a second sample, as a midstream specimen of urine (MSU). The correct method of collecting an MSU must be carefully explained to the patient. The amount of proteinuria present in the MSU will be the correct one and must, therefore, be recorded in the notes. The further management will be dictated by the amount of proteinuria in the MSU.

1+ or more protein in the urine is abnormal.

The classification of hypertension during pregnancy

3-4 How is hypertension during pregnancy classified?

The classification of hypertension during pregnancy depends on:

  1. Whether the hypertension started before or after the 20th week of pregnancy.
  2. Whether or not proteinuria is also present.

The classification of hypertension during pregnancy depends on the time of onset of the hypertension and the presence or absence of proteinuria.

Classifying hypertension is important, as the cause of the hypertension and the risk to the mother and fetus vary between the different groups.

The common forms of hypertension during pregnancy that will be discussed in this unit are:

  1. Pre-eclampsia (gestational proteinuric hypertension).
  2. Gestational hypertension.
  3. Chronic hypertension.
  4. Chronic hypertension with superimposed pre-eclampsia.
  5. Eclampsia.
Note
Based on the above criteria, hypertension during pregnancy is at present divided into the following conditions:
  • Gestational proteinuric hypertension (or pre-eclampsia).
  • Gestational hypertension.
  • Chronic hypertension and chronic renal disease with hypertension.
  • Chronic hypertension with superimposed gestational proteinuric hypertension (or pre-eclampsia).
  • Unclassified hypertension and unclassified proteinuric hypertension (if the patient is seen for the first time in the second half of pregnancy, with hypertension and/or proteinuric hypertension). The diagnosis is changed to pre-eclampsia if the blood pressure is normal and proteinuria absent six weeks postpartum.
  • Eclampsia.

3-5 What is pre-eclampsia?

Pre-eclampsia presents with hypertension and proteinuria which develop in the second half of pregnancy. Pre-eclampsia may present during pregnancy, labour, or the puerperium.

Pre-eclampsia is also called gestational (pregnancy-induced) proteinuric hypertension.

3-6 What is gestational hypertension?

In contrast to pre-eclampsia, gestational hypertension is not accompanied by proteinuria but also presents in the second half of pregnancy. Should proteinuria develop in a patient with gestational hypertension, the diagnosis must be changed to pre-eclampsia.

Pre-eclampsia presents with hypertension and proteinuria in the second half of pregnancy.

Note
The term pre-eclampsia (rather than gestational proteinuric hypertension) will be used, as it is still widely known as such.

3-7 What is chronic hypertension?

Chronic hypertension is hypertension, with or without proteinuria, that presents during the first half of pregnancy. There is usually a history of hypertension before the start of the pregnancy.

Note
Chronic hypertension without proteinuria is usually due to essential hypertension. If the chronic hypertension is accompanied by proteinuria during the first half of pregnancy, then the hypertension is usually due to chronic renal disease.

3-8 What is chronic hypertension with superimposed pre-eclampsia?

This is hypertension presenting during the first half of pregnancy that is complicated by the appearance of proteinuria during the second half of pregnancy. In other words it is chronic hypertension that is complicated by the development of pre-eclampsia.

Note
Patients who book in the second half of pregnancy cannot be classified into any of the above types of hypertension, as it is not known whether the hypertension started in the first or second half of pregnancy. If a patient has hypertension without proteinuria when she books during the second half of pregnancy, she is said to have unclassified hypertension. However, if she has both hypertension and proteinuria when she books during the second half of pregnancy, she is said to have unclassified proteinuric hypertension. Most patients with unclassified hypertension probably have chronic hypertension, while most patients with unclassified proteinuric hypertension probably have pre-eclampsia.

3-9 What is eclampsia?

Eclampsia is a serious complication of pre-eclampsia that presents with convulsions during pregnancy, labour, or the first 7 days of the puerperium. Convulsions could also be the result of other causes such as epilepsy, but the possibility of eclampsia must be carefully ruled out whenever convulsions occur.

Pre-eclampsia

Pre-eclampsia is the hypertensive disorder of pregnancy which occurs most commonly and also causes the most problems for the mother and fetus.

Gestational proteinuric hypertension and chronic hypertension with superimposed pre-eclampsia will subsequently be discussed under the heading ‘pre-eclampsia’ because the management is similar.

3-10 How frequently does pre-eclampsia occur?

In the Western Cape 5–6% of all pregnant women develop pre-eclampsia.

3-11 Is pre-eclampsia a danger to the mother?

Yes, it is one of the most important causes of maternal death in most parts of southern Africa.

3-12 What are the maternal complications of pre-eclampsia?

The two most important complications of pre-eclampsia are also important causes of maternal death during pregnancy:

  1. Intracerebral haemorrhage.
  2. Eclampsia.
Note
Other, less common, complications of pre-eclampsia are pulmonary oedema and the HELLP (Haemolysis, Elevated Liver enzymes, and a Low Platelet count) syndrome. Rupture of the liver, renal failure, the adult respiratory distress syndrome, and a generalised disorder of blood coagulation may also occur, but fortunately, those are rare complications.

3-13 Which patients are at an increased risk of intracerebral haemorrhage?

The risk of intracerebral haemorrhage is especially high if the diastolic blood pressure is 110 mm Hg or more and/or a systolic blood pressure of 160 mm Hg or more.

3-14 Does eclampsia only occur at a very high diastolic blood pressure?

No, eclampsia can occur at a much lower blood pressure, especially in young patients.

3-15 Why is pre-eclampsia a danger to the fetus and newborn infant?

Pre-eclampsia is an important cause of perinatal death because:

  1. Preterm delivery is often necessary because of a deterioration in the maternal condition or the development of fetal distress.
  2. Abruptio placentae is more common in patients with pre-eclampsia and often results in an intra-uterine death.
  3. Pre-eclampsia is associated with decreased placental blood flow. As a result of decreased placental blood flow the fetus may suffer from:
    • Intra-uterine growth restriction or wasting.
    • Fetal distress.

Pre-eclampsia may result in intra-uterine growth restriction, fetal distress, preterm delivery and intra-uterine death.

3-16 How can the severity of pre-eclampsia be graded?

The severity of pre-eclampsia can be graded by:

  1. The diastolic and/or systolic blood pressure.
  2. The amount of proteinuria.
  3. Signs and symptoms of imminent eclampsia.
  4. The presence of convulsions.

Patients with pre-eclampsia can be divided into four grades of severity:

  1. Pre-eclampsia: A diastolic blood pressure of 90–109 mm Hg and/or a systolic blood pressure of 140–159 mm Hg and proteinuria.
  2. Severe pre-eclampsia: Any of the following:
    • A diastolic blood pressure of 110 mm Hg or more and/or a systolic blood pressure of 160 mm Hg or more on two occasions, 4 hours apart.
    • A diastolic blood pressure of 120 mm Hg or more, and/or a systolic blood pressure of 170 mm Hg or more, on one occasion, and proteinuria.
  3. Imminent eclampsia: These patients have symptoms and/or signs that indicate that they are at extremely high risk of developing eclampsia at any moment. The diagnosis does not depend on the degree of hypertension or the amount of proteinuria present.
  4. Eclampsia: Eclampsia is diagnosed when a patient with any of the grades of pre-eclampsia has a convulsion.

If there is any doubt about the grade of pre-eclampsia, the patient should always be placed in the more severe grade.

Patients who improve on bed rest should be kept in the grade of pre-eclampsia which they were given at the initial evaluation on admission. Further management should be in accordance with this grade.

3-17 What are the symptoms and signs of imminent eclampsia?

The symptoms are:

  1. Headache.
  2. Visual disturbances or flashes of light seen in front of the eyes.
  3. Upper abdominal pain, in the epigastrium and/or over the liver.
  4. Shortness of breath.

The signs are:

  1. Tenderness over the liver.
  2. Increased tendon reflexes, e.g. knee reflexes.
  3. Tachypneoa (respiration rate >20/minute).

The diagnosis of imminent eclampsia is made even if only one of the symptoms or signs is present, irrespective of the blood pressure or the amount of proteinuria.

3-18 How common is eclampsia?

In the Western Cape, the incidence of eclampsia is 1 per 1000 pregnancies.

Patients at increased risk of pre-eclampsia

3-19 Which patients are at an increased risk of pre-eclampsia?

  1. Primigravidas.
  2. Patients with chronic hypertension.
  3. Patients over 34 years of age.
  4. Patients with a multiple pregnancy.
  5. Diabetics.
  6. Patients with a past history of a pregnancy complicated by pre-eclampsia, especially if the pre-eclampsia developed during the late 2nd or early 3rd trimester.
  7. Patients who develop generalised oedema, especially facial oedema.

3-20 What advice should be given to patients at an increased risk of pre-eclampsia?

They must be told about the symptoms of imminent eclampsia, and advised to contact the clinic or hospital immediately, if these symptoms appear.

3-21 What special care should be given to patients at an increased risk of pre-eclampsia?

In the second half of pregnancy, the following must be carefully watched for:

  1. A rise in diastolic and/or systolic blood pressure.
  2. Proteinuria.
  3. Symptoms and signs of imminent eclampsia.

Patients with an obstetric history of pre-eclampsia that developed late in the second trimester or early in the third trimester, must receive 75 mg aspirin (a quarter Disprin) daily from a gestational age of 14 weeks. This will reduce the risk that pre-eclampsia may develop.

3-22 What should you do if a patient develops generalised oedema, but remains normotensive and does not have proteinuria?

  1. She should rest as much as possible.
  2. She must contact the clinic or hospital immediately if she has any symptoms of imminent eclampsia.
  3. She should be followed up weekly at the antenatal clinic and carefully checked for the development of hypertension and proteinuria.
  4. She should carefully monitor the fetal movements.

The management of pre-eclampsia

3-23 What should you do if a patient develops pre-eclampsia?

  1. A patient with pre-eclampsia must be admitted to hospital. Such a patient may be safely cared for in a level 1 hospital.
  2. Methyldopa (Aldomet) must be prescribed to control the blood pressure.
Note
High doses of methyldopa (Aldomet), e.g. 500 mg 8-hourly, must be given.

All patients with pre-eclampsia must be admitted to hospital, irrespective of the level of their blood pressure.

3-24 How should you monitor the fetus to ensure fetal wellbeing?

Patients with pre-eclampsia often have placental insufficiency, associated with intra-uterine growth restriction. Fetal distress, therefore, occurs commonly. If this is not diagnosed, and the fetus is not delivered soon, intra-uterine death will result. These patients are also at high risk of abruptio placentae, followed by fetal distress and frequently also intra-uterine death. The fetal condition must, therefore, be carefully monitored in all patients with pre-eclampsia.

Fetal movements must be counted and recorded by the patient twice a day.

Note
In level 2 and 3 hospitals antenatal fetal heart rate monitoring (CTG) for fetal distress must be done at least daily.

Patients with pre-eclampsia are at high risk of developing fetal distress. They must, therefore, be carefully monitored for fetal distress.

3-25 When should you deliver a patient with pre-eclampsia?

Patients who have a gestational age of 36 weeks or more should have their labour induced on the day that the diagnosis is made. If the patient has a favourable (‘ripe’) cervix, a surgical induction can be done.

A patient with an unfavourable (‘unripe’) cervix must be referred to a level 2 hospital. There, labour is induced by first ‘ripening’ the cervix with a very low dose of oral misoprostol (Cytotec) or prostaglandin E2, after which the membranes are ruptured. A patient must always be carefully monitored for an hour after oral misoprostol or the insertion of the prostaglandin, because overstimulation of the uterus may cause fetal distress.

Patients with a gestation of less than 36 weeks must be managed as described in sections 3-23 and 3-24.

3-26 What should you do if a patient with pre-eclampsia develops severe pre-eclampsia?

  1. If the patient is 34 weeks pregnant or more, labour must be induced.
  2. If she is less than 34 weeks pregnant, she must be managed as indicated in section 3-37.

The management of pre-eclampsia is bed rest and careful monitoring, to detect a worsening of the pre-eclampsia or the development of fetal distress.

3-27 What special investigations are indicated in pre-eclampsia?

  1. An MSU must be sent to the laboratory for culture, as a urinary tract infection may be responsible for the proteinuria.
  2. A platelet count must be done, if a laboratory is available. A platelet count of less than 100 000 is an indication for referral of the patient to a level 2 hospital.

A urinary tract infection must be excluded in all patients with proteinuria in pregnancy.

The emergency management of severe pre-eclampsia and imminent eclampsia

The management of patients with severe pre-eclampsia and imminent eclampsia is the same and consists of stabilising the patient, followed by referral to a level 2 or 3 hospital.

3-28 What are the greatest dangers to a patient with severe pre-eclampsia?

The two greatest dangers which are a threat to the patient’s life are eclampsia and an intracerebral haemorrhage.

3-29 How should you manage a patient with severe pre-eclampsia or imminent eclampsia?

The main aims of management are to:

  1. Prevent eclampsia by giving magnesium sulphate.
  2. Prevent intracerebral haemorrhage by decreasing the blood pressure with parenteral oral nifedipine capsules (Adalat) or dihydralazine (Nepresol).

The initial management of severe pre-eclampsia and imminent eclampsia is aimed at the prevention of eclampsia and intracerebral haemorrhage.

The steps in the management of severe pre-eclampsia are:

Step 1: An intravenous infusion is started (Plasmalyte B or Ringer’s lactate) and magnesium sulphate is administered as follows:

  1. Give 4 g slowly intravenously over 10 minutes. Prepare the 4 g by adding 8 ml 50% magnesium sulphate (i.e. 2 ampoules) to 12 ml sterile water.
  2. Then give 5 g (i.e. 10 ml 50% magnesium sulphate) by deep intramuscular injection into each buttock.

A total of 14 g of magnesium sulphate is given.

Note
300 ml of the intravenous infusion is given rapidly over half an hour. Thereafter, the infusion is given slowly, at a rate of 80 ml per hour.

Step 2: After the magnesium sulphate has been administered, a Foley catheter is inserted into the patient’s bladder to monitor the urinary output.

Step 3: After giving the magnesium sulphate, the blood pressure must be measured again. If the diastolic blood pressure is still 110 mg Hg or more and/or the systolic blood pressure 160 mm Hg or more, oral nifedipine (Adalat) or dihydralazine (Nepresol) is given as follows:

Or

Note
If dihydralazine is not available, labetalol (Trandate) 20 mg is given intravenously. If a decline in blood pressure does not occur after 10 minutes a further 40 mg is given intravenously.

Step 4: When the blood pressure is controlled, the patient is transferred to a level 2 or 3 hospital.

Patients with severe pre-eclampsia or imminent eclampsia must always be stabilised before they are transferred, or until further management is decided upon.

3-30 What can be done to ensure maximal safety for the patient during her transfer to hospital?

  1. A doctor or registered nurse or midwife should accompany the patient.
  2. Resuscitation equipment, together with magnesium sulphate, calcium gluconate and dihydralazine or nifedipine, must be available in the ambulance. Respiration may be depressed if a large dose of magnesium sulphate is given too rapidly. Calcium gluconate is the antidote to be given in the event of an overdose of magnesium sulphate.
  3. Convulsions must be watched for and the patient’s blood pressure must also be carefully observed.
  4. If the patient begins to convulse in the ambulance, she must be given a further 2 g of magnesium sulphate intravenously. The dose may, if required, be repeated once. (Make up the solution beforehand and keep it ready in a 20 ml syringe). Further maintenance doses of magnesium sulphate must be given if more than 4 hours pass after the loading dose.
  5. If the blood pressure again rises to 110 mm Hg and/or the systolic blood pressure 160 mm Hg or more while the patient is being transported, you should give a second dose of 10 mg nifedipine orally or 6.25 mg dihydralazine intramuscularly. Remember that with every administration of dihydralazine there is a danger that the patient may become hypotensive. Another side effect is tachycardia, and if the pulse rate rises to 120 beats per minute or above, further administration of dihydralazine must be stopped.

3-31 How and when should you give maintenance doses of magnesium sulphate?

After the initial loading dose of magnesium sulphate, the patient will need regular maintenance doses until 24 hours after delivery. Magnesium sulphate 5 g is given every 4 hours by deep intramuscular injection into alternate buttocks. The injections are less painful if the magnesium sulphate is injected together with 1 ml 1% lignocaine.

3-32 What are the adverse effects of an overdose of magnesium sulphate and how can they be prevented?

An overdose of magnesium sulphate causes respiratory and cardiac depression. Here, the patellar reflex acts as a convenient warning. If the reflex is present, the drug may safely be given, as there is no danger of overdosage. If the reflex is absent or very reduced, there is a danger of overdosage and the next dose must not be given.

Magnesium sulphate is excreted by the kidneys. If the urinary output is less than 30 ml per hour, follow-up doses must only be given if there is a definite patellar reflex present.

3-33 What should you do if the patient develops the effects of an overdose of magnesium sulphate?

This is a life-threatening emergency and the following steps must be taken immediately:

  1. The patient must be intubated and ventilated or else temporarily ventilated with a bag and face mask. External cardiac massage may also be needed.
  2. Give 10 ml of 10% calcium gluconate slowly intravenously. This is an antidote for magnesium sulphate poisoning.

The management of eclampsia

3-34 What is your immediate management if a patient convulses?

The management of eclampsia is as follows:

Step 1: Prevent aspiration of the stomach contents by:

Step 2: Stop the convulsion and prevent further convulsions by putting up an intravenous infusion of Balsol or Ringer’s lactate and giving magnesium sulphate as described in 3-30.

Step 3: After the magnesium sulphate has been given, insert a Foley catheter to monitor the urinary output.

Step 4: If the diastolic blood pressure is 110 mm Hg and/or the systolic blood pressure 160 mm Hg or more, it must be reduced with dihydralazine (Nepresol). Oral nifedipine can be used if the patient is fully conscious after the convulsion, as described in 3-29.

Step 5: The patient must now be urgently transferred to a level 2 or 3 hospital.

Eclampsia is a life-threatening condition for both the mother and the fetus. Immediate management is therefore needed.

3-35 What should you do if the patient convulses again?

If the patient convulses again, after the initial loading dose of 14 g of magnesium sulphate has controlled the first convulsion, a further 2 g of magnesium sulphate should be administered intravenously. This dose can be repeated once more in the unlikely event of the patient having yet another convulsion.

The following management is not essential knowledge, but should be read by medical and nursing staff working in level 2 or 3 hospitals.

The further management of severe pre-eclampsia and imminent eclampsia at the referral hospital

3-36 How should you manage the patient further in a level 2 or 3 hospital?

Further management consists of either delivery or conservative treatment, depending on:

  1. The degree to which the patient’s condition stabilises, i.e. the diastolic blood pressure remains below 110 mm Hg and/or the systolic blood pressure below 160 mm Hg, and there are no symptoms or signs of imminent eclampsia. (Oral anti-hypertensive drugs must be given to control the blood pressure, if it is decided to continue conservative management).
  2. The duration of the pregnancy.
  3. The condition of the fetus.

The patient must be delivered if any of the following apply:

  1. The patient’s condition does not stabilise.
  2. The fetus is not nearing viability (it is less than 26 weeks).
  3. The duration of pregnancy is 34 or more weeks.
  4. There is fetal distress.

If none of the above apply then the patient can be managed conservatively until 34 weeks gestation or until the maternal condition deteriorates or fetal distress develops.

The maternal condition must always be stabilised first. Thereafter, the condition of the fetus and the duration of the pregnancy must be taken into consideration in planning the further management of the patient.

3-37 What is the conservative management of severe pre-eclampsia?

  1. Magnesium sulphate must be stopped.
  2. The patient must be hospitalised for bed rest in a level 2 or 3 hospital.
  3. The fetal movements must be monitored daily.
  4. Antenatal cardiotocography (CTG) is very useful and if possible must be done twice or more daily. This is because of the risk of fetal distress, as a result of placental insufficiency or abruptio placentae.
  5. Urinary tract infection must be excluded.
  6. A platelet count and renal function tests (urea and creatinine) must be done twice a week. If the platelet count is less than 100 000, liver function tests should be done. Poor renal function, raised liver enzymes or a platelet count that falls further are indications for delivery.
  7. An ultrasound examination is of value to assess fetal weight, and to assess fetal viability. Remember that a patient with a viable, growth-restricted fetus can present with a fundal height of 24, or even 22 weeks gestation. Fetal growth must also be monitored.
  8. Because of the danger of hyaline membrane disease in a newborn infant who, though viable, has a gestational age of less than 34 weeks, steroids (betamethasone 12 mg, Celestone-Soluspan) must be given intramuscularly to the patient, to enhance fetal lung maturity. A second dose must be repeated 24 hours later.
  9. If the duration of the pregnancy is unknown, and the clinical assessment or ultrasound size suggests a pregnancy of 34 weeks or more, the fetus must be delivered.
  10. If there is no fetal distress and the presentation is cephalic, a medical or surgical induction of labour must be done at 34 weeks gestation.
  11. If fetal distress is present, or the presentation is abnormal, a Caesarean section must be done.
  12. A patient whose condition becomes well stabilised, must be placed on an oral antihypertensive drug. Alpha methyldopa is the drug of choice. A high dosage (such as 500 mg 8-hourly that can be increased to 750 mg 8-hourly) must be used. If the diastolic blood pressure remains at 110 mm Hg and/or the systolic blood pressure 160 mm Hg or higher, a second or even a third antihypertensive drug is added.
Note
Long acting nifedipine (Adalat XL) is the drug of choice if a second antihypertensive drug is required. Labetalol (Trandate) may be added if a third drug is required. This form of management must take place in a level 3 hospital.

If the decision is taken to manage the patient conservatively, the danger of prematurity (if the fetus is delivered) must continually be weighed against the danger of fetal distress or abruptio placentae (which could result in an intra-uterine death).

Gestational hypertension

3-38 What should you do if a patient develops gestational hypertension?

A patient with a slightly elevated blood pressure (a diastolic blood pressure of 90 to 95 mm Hg), which develops in the second half of pregnancy, in the absence of proteinuria, may be managed in a level 1 hospital or clinic. If the home circumstances are poor, she must be admitted to hospital for bed rest. Where the home circumstances are good, the patient is allowed bed rest at home, under the following conditions:

  1. The patient must be told about the symptoms of imminent eclampsia. Should any of these occur, she must contact or attend the hospital or clinic immediately.
  2. The patient must be seen weekly at a high-risk antenatal clinic. In addition, she must be seen once between visits, to check her blood pressure and test her urine for protein.
  3. If the patient cannot be seen more frequently, she must be given urinary reagent strips to take home. She must then test her urine daily and go to the clinic, should there be 1+ proteinuria or more.
  4. No special investigations are indicated.
  5. Alpha methyldopa (Aldomet) must be prescribed to control her blood pressure. The initial dosage of alpha methyldopa (Aldomet) is 500 mg 8-hourly. The dose could be increased to a maximum of 750 mg 8-hourly.
  6. If a second drug is needed, long acting nifedipine (Adalat XL) is used, starting with 30 mg daily.

Patients with a diastolic blood pressure of 100 mm Hg and/or a systolic blood pressure 150 mm Hg or higher must be admitted to hospital and alpha methyldopa (Aldomet) must be prescribed. Once the diastolic blood pressure has dropped below 100 mm Hg and the systolic blood pressure to below 150 mm Hg, they are managed as indicated above.

3-39 How should you monitor the fetus in order to ensure fetal wellbeing?

Fetal movements must be counted and recorded twice daily.

3-40 When should you deliver a patient with gestational hypertension?

If the blood pressure remains well controlled, no proteinuria develops, and the fetal condition remains good, the pregnancy must be allowed to continue until 40 weeks when labour must be induced.

Chronic hypertension

These patients have hypertension in the first half of pregnancy, or are known to have had hypertension before the start of pregnancy.

3-41 Which patients with chronic hypertension should be referred to a level 2 or 3 hospital?

A good prognosis can be expected if:

  1. Renal function is normal (there is a normal serum creatinine concentration).
  2. Pre-eclampsia is not superimposed on the chronic hypertension.
  3. The blood pressure is well controlled (a diastolic blood pressure of 90 mm Hg and/or the systolic blood pressure 140 mm Hg or less) from early in pregnancy.

These women can be managed at a level 1 hospital. However, women with chronic hypertension should be referred to a level 2 or 3 hospital for further management if:

  1. Renal function is abnormal (serum creatinine more than 120 mmol/l).
  2. Proteinuria develops.
  3. The diastolic blood pressure is 110 mm Hg and/or the systolic blood pressure 160 mm Hg or higher.
  4. There is intra-uterine growth restriction.
  5. More than 1 drug is required to control the blood pressure.

3-42 Will you adjust the medication of a patient with chronic hypertension when she becomes pregnant?

Yes, she must change to alpha methyldopa (Aldomet) 500 mg 8-hourly. Other antihypertensives (i.e. diuretics, beta blockers and ACE inhibitors) must be stopped.

Note
In pregnancy, beta-blockers are not completely safe for the fetus, while diuretics reduce the intravascular fluid compartment, with adverse effects on placental and renal perfusion. An ACE inhibitor, such as captopril (Capoten and enalapril (Renitec)), is completely contraindicated in pregnancy, as intra-uterine deaths have occurred in patients on this drug.

3-43 What special care is needed for a patient with chronic hypertension during pregnancy?

  1. Any rise in the blood pressure or the development of proteinuria must be carefully looked for, as they indicate an urgent need for referral.
  2. A Doppler measurement of the blood flow in the umbilical artery should be done to determine placental function.
  3. Postpartum sterilisation must be discussed with the patient, and is recommended when the patient is a multigravida.

3-44 When should you deliver a patient with chronic hypertension?

The management is the same as that for gestational hypertension.

Postpartum hypertension

3-45 When does the blood pressure return to normal following pregnancy?

  1. With pre-eclampsia and pregnancy-induced hypertension, the blood pressure usually settles within three days. A diastolic blood pressure of 110 mm Hg or more and/or a systolic blood pressure of 160 mm Hg or more requires treatment. Nifedipine 10 mg orally can be given and maintenance therapy with an ACE inhibitor could be started. Commence with enalapril (Ciplatec) 5 mg daily, increasing to 20 mg daily as necessary.
  2. With chronic hypertension the patient could be changed back to the maintenance therapy she used prior to her pregnancy.

Case study 1

A 21-year-old primigravida patient is attending the antenatal clinic. Her pregnancy progresses normally to 33 weeks. At the next visit at 35 weeks, the patient complains that her hands and feet have started to swell over the past week. On examining her, you notice that her face is also slightly swollen. Her blood pressure at present is 120/80, which is the same as at her previous visit, and she has no proteinuria. She reports that her fetus moves frequently.

1. Why is this patient at high risk of developing pre-eclampsia?

Because she is a primigravida and has developed generalised oedema over the past week.

2. How should this patient be managed further?

She should rest a lot. She should also be seen at the antenatal clinic again in a week when she must be carefully examined for a rise in blood pressure or the presence of proteinuria.

3. What advice should this patient be given?

She should be told about the symptoms of imminent eclampsia, i.e. headache, flashes of light before the eyes, upper abdominal pain and shortness of breath. She should also be asked to count and record fetal movements twice a day. If any of the above-mentioned symptoms are experienced, or if fetal movements decrease, she must immediately report to the clinic or hospital.

4. When you see the patient a week later she has a diastolic blood pressure of 90 mm Hg, but there is still no proteinuria. How should she be managed further?

The patient has pregnancy-induced hypertension. If the home conditions are satisfactory, she can be managed with bed rest at home. The hypertension must be controlled with alpha methyldopa (Aldomet). She must be seen twice a week and carefully monitored to detect a rise in her blood pressure and the possible development of proteinuria. If her blood pressure rises and/or proteinuria develops, she must be admitted to hospital. If the home conditions are poor, she should be admitted to hospital for bed rest.

Case study 2

At an antenatal clinic you see a patient who is 39 weeks pregnant. Up until now she has had a normal pregnancy. On examination, you find that her diastolic blood pressure is 95 mm Hg and that she has 2+ proteinuria.

1. How should this patient be managed?

She should be admitted to hospital as all patients with 2+ proteinuria must be hospitalised. She should also be delivered, as she is more than 38 weeks pregnant.

2. On examining this patient you observe that she has increased patellar reflexes i.e. brisk knee jerks. How should this observation alter her management?

Increased tendon reflexes are a sign of imminent eclampsia. The diagnosis must be made, irrespective of the degree of hypertension or the amount of proteinuria. To prevent the development of eclampsia, the patient must be given magnesium sulphate.

3. What is the danger to this patient’s health?

The patient has severe pre-eclampsia. Therefore, the immediate danger to her life is the development of eclampsia or an intracerebral haemorrhage.

4. How should this patient be managed?

Her clinical condition must first be stabilised. An intravenous infusion should be started and a loading dose of 14 g magnesium sulphate must be given. This should prevent the development of eclampsia. A Foley catheter must be inserted in her bladder.

5. Is a loading dose of magnesium sulphate also adequate to control the high blood pressure?

No. Sometimes with severe pre-eclampsia, the blood pressure will drop to below 160/110 mm Hg after the loading dose of magnesium sulphate has been given. In that case, no further management is needed for the hypertension. However, if the patient’s blood pressure does not drop after administering the magnesium sulphate, 10 mg (1 capsule) oral nifedipine (Adalat) or intramuscular dihydralazine (Nepresol) 6.25 mg should be given.

Case study 3

While working at a level 1 hospital you admit a patient with a blood pressure of 170/120 mm Hg and 3+ proteinuria. She is 32 weeks pregnant. On further questioning and examination, she has no symptoms or signs of imminent eclampsia.

1. What is the danger to this patient’s health?

The patient has severe pre-eclampsia. Therefore, the immediate danger to her life is the development of eclampsia or an intracerebral haemorrhage.

2. How should this patient be managed?

Her clinical condition must first be stabilised. An intravenous infusion should be started and a loading dose of 14 g magnesium sulphate must be given. This should prevent the development of eclampsia. A Foley catheter must be inserted in her bladder.

3. Following the administration of magnesium sulphate, the blood pressure is 160/110 mm Hg. What should the further management be?

Her blood pressure needs to be lowered. 10 mg (1 capsule) oral nifedipine (Adalat) or intramuscular dihydralazine (Nepresol) 6.25 mg should be given. If the diastolic blood pressure remains 110 mm Hg and/or the systolic blood pressure 160 mm Hg or more after 30 minutes, patients who received 10 mg nifedipine orally can be given a second dose of 10 mg nifedipine orally. If dihydralazine was used, an ampoule of dihydralazine (25 mg) should be mixed with 20 ml of sterile water. A bolus doses of 2 ml (2.5 mg) should be given slowly intravenously.

4. Should you continue to manage this patient at a level 1 hospital?

No. The patient should be transferred to a level 2 or 3 hospital for further management.

Case study 4

A 37-year-old gravida 4, para 3 patient books for antenatal care. She has chronic hypertension and is managed with a diuretic. By dates and examination she is 14 weeks pregnant.

1. Should the management of the patient’s hypertension be changed during the pregnancy?

Yes. The diuretic should be stopped, as these drugs are not completely safe during pregnancy. Instead, the patient should be treated with alpha methyldopa (Aldomet).

2. What factors indicate a good prognosis for a patient with chronic hypertension during pregnancy?

Normal renal function, no superimposed pre-eclampsia and good control of the blood pressure during pregnancy.

3. How can superimposed pre-eclampsia be diagnosed during pregnancy?

The patient will develop proteinuria and/or a rise in blood pressure during the second half of pregnancy.

4. Why is it important to detect superimposed pre-eclampsia in a patient with chronic hypertension?

Because the risk of complications increases and as a result, a preterm delivery may be necessary. The patient should, therefore, be transferred to a level 2 or 3 hospital if superimposed pre-eclampsia develops.

A postpartum sterilisation. Postpartum sterilisation should be discussed with the patient during the pregnancy. Postpartum sterilisation is particularly important as the patient is a 37-year-old multipara.

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