Chapter 13 Common Medical Disorders Associated with Pregnancy

Cardiac disease

In most pregnancies, heart disease is diagnosed before pregnancy. There is, however, a small but significant group of women who will present at an antenatal clinic with an undiagnosed heart condition. Cardiac disease takes a variety of forms. Those more likely to be seen in pregnancy are:

rheumatic heart disease

congenital heart disease.

The most common congenital heart defects found in pregnancy are shown in Box 13.1. Some acquired heart conditions are listed in Box 13.2.

Box 13.1 Common congenital heart defects in pregnancy

• Atrial septal defect (ASD)

• Ventricular septal defect (VSD)

• Patent ductus arteriosus (PDA)

• Pulmonary stenosis

• Aortic stenosis

• Tetralogy of Fallot

• Eisenmenger syndrome

• Marfan syndrome

Box 13.2 Some acquired heart conditions

• Aortic dissection (acute)

• Rheumatic heart disease

• Ischaemic heart disease (IHD)

• Endocarditis

• Peripartum cardiomyopathy

Changes in cardiovascular dynamics during pregnancy

In normal pregnancy the haemodynamic profile alters in order to meet the increasing demands of the growing fetoplacental unit. Although this increases the workload of the heart quite significantly, normal, healthy pregnant women are able to adjust to these physiological changes easily. In women with coexisting heart disease, however, the added workload can precipitate complications.

The haemodynamic changes commence early in pregnancy and gradually reach their maximum effect between 28 and 32 weeks.

During labour there is a significant increase in cardiac output as a result of uterine contractions.

In the 12–24 hours following birth there is further alteration with the shift of blood (approximately 1 litre) from the uterine to the systemic circulation.

Diagnosis

The recognition of heart disease in pregnancy may be difficult, as many of the symptoms of normal pregnancy resemble those of heart disease. The signs and symptoms of cardiac compromise are listed in Box 13.3.

Box 13.3 Common signs and symptoms of cardiac compromise in pregnancy

• Fatigue

• Shortness of breath (dyspnoea)

• Difficulty in breathing unless upright (orthopnoea)

• Palpitations

• Bounding/collapsing pulse

• Chest pain

• Development of peripheral oedema

• Distended jugular veins

• Progressive limitation of physical activity

Laboratory tests can assist with the diagnosis of cardiac disease and determine the type of lesion, together with giving an assessment of current functional capacity. Tests include:

full blood count (FBC)

electrocardiography (ECG)

chest radiograph to assess cardiac size and outline, pulmonary vasculature and lung fields

clotting studies

echocardiography.

Risks to mother and fetus

The majority of pregnancies complicated by maternal heart disease can be expected to have a favourable outcome for both mother and fetus. The risk for morbidity and mortality depends on:

the nature of the cardiac lesion

its effect on the functional capacity of the heart

the development of pregnancy-related complications such as hypertensive disorders of pregnancy, infection, thrombosis and haemorrhage.

Preconception care

Women with known heart disease should seek advice from a cardiologist and an obstetrician before becoming pregnant, so that the risks of the condition can be discussed.

Antenatal care

The symptoms of normal pregnancy, together with the haemodynamic changes, can mimic the signs and symptoms of heart disease. Maternal investigations should be carried out prior to and at the onset of pregnancy in order to gain baseline referral points.

Management

All pregnant women with heart disease should be managed in obstetric units via a multidisciplinary approach involving midwives, obstetricians, cardiologists and anaesthetists. The aim is to maintain a steady haemodynamic state and prevent complications, as well as promote physical and psychological wellbeing. Visits to a joint clinic run by a cardiologist and obstetrician are usually made every 2 weeks until 30 weeks’ gestation and weekly thereafter until birth. At each visit functional grading is made according to the New York Heart Association classification and the severity of the heart lesion is assessed by clinical examination. Evaluation of fetal wellbeing will include:

ultrasound examination to confirm gestational age and congenital abnormality

assessment of fetal growth and amniotic fluid volume, both clinically and by ultrasound

monitoring the fetal heart rate by cardiotocography (CTG)

measurement of fetal and maternal placental blood flow indices by Doppler ultrasonography.

Intrapartum care

The first stage of labour

Vaginal birth is preferred unless there is an obstetric indication for caesarean section. Optimal management involves monitoring the maternal condition closely. This will include the measurement of:

temperature

pulse

respiration

blood pressure

urine output.

Pulse oximetry, insertion of a central venous pressure (CVP) catheter and electrocardiogram (ECG) monitoring may be utilised.

Fluid balance

Women with significant heart disease require care to be taken concerning fluid balance in labour. Indiscriminate use of intravenous crystalloid fluids will lead to an increase in circulating blood volume, which women with heart disease will find difficult to cope with and they may easily develop pulmonary oedema.

Pain relief

It is important to consult a doctor before administering any form of pain-relieving drug to a woman with a heart condition. In the majority, an epidural would be the analgesia of choice.

Positioning

Cardiac output is influenced by the position of the labouring woman. It is preferable for an upright or left lateral position to be adopted.

Preterm labour

If a woman with heart disease should go into labour prematurely, then beta-sympathomimetic drugs are contraindicated.

Induction

The least stressful labour for a woman with cardiac disease will be spontaneous in onset; induction is considered safe only if the benefits outweigh the disadvantages.

The second stage of labour

This should be short without undue exertion on the part of the mother.

The midwife should encourage the woman to breathe normally and follow her natural desire to push, giving several short pushes during each contraction.

Forceps or ventouse may be used to shorten the second stage if the maternal condition deteriorates.

Care should be taken when the woman is in the lithotomy position, as this produces a sudden increase in venous return to the heart, which may result in heart failure.

The third stage of labour

This is usually actively managed owing to the increased risk of postpartum haemorrhage (PPH).

Oxytocin is the drug of choice but its use in the prevention of PPH must be balanced against the risk of oxytocin-induced hypotension and tachycardia in women with cardiovascular compromise.

Ergot-containing preparations such as ergometrine are contraindicated.

Postnatal care

During the first 48 hours following birth the heart must cope with the extra blood from the uterine circulation. Close observation should identify early signs of infection, thrombosis or pulmonary oedema.

Breastfeeding is not contraindicated.

Discharge planning is particularly important for women with heart disease. The woman and her partner will need to discuss the implications of a future pregnancy with the cardiologist and obstetrician.

Respiratory disorders

Asthma

Pregnancy does not consistently affect the maternal asthmatic status; some women experience no change in symptoms whereas others have a distinct worsening of the disease.

Antenatal care

The main anxiety for women and those providing care is generated by the use of medication and the fear that this may harm the fetus.

To date all medications commonly used in the treatment of asthma, including systemic steroids, are considered safe and it is crucial that therapy is maintained during pregnancy in order to prevent deterioration of the condition and precipitation of adverse pregnancy events.

The lynchpin of management is the use of peak expiratory flow rates (PEFR) to monitor the level of resistance in the airways caused by inflammation or bronchospasm, or both.

Intrapartum care

If an asthma attack does occur, it should be treated with the same rapidity and medication as an attack outside of pregnancy.

Intravenous, intra-amniotic and transcervical prostaglandins should be avoided in pregnancy and labour because of their bronchospasmic action.

Any woman who has received corticosteroids in pregnancy should have increased doses for the stress of labour.

Postnatal care

Breastfeeding should be encouraged, particularly as it may protect infants from developing certain allergic conditions.

Cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder affecting the exocrine glands that causes production of excess secretions with abnormal electrolyte concentrations, resulting in the obstruction of the ducts and glands.

Prepregnancy care

When planning a pregnancy, a woman with CF and her partner should have genetic counselling.

Although pregnancy appears to be well tolerated in women with pre-existing mild pulmonary dysfunction, morbidity and mortality are increased in women with pancreatic insufficiency or moderate to severe lung disease, or both.

Antenatal care

Once pregnancy is confirmed, a multidisciplinary approach combining midwifery, obstetric, dietetic, medical, nursing and physiotherapy expertise is essential.

Intrapartum care

During labour close monitoring of cardiorespiratory function will be required and an anaesthetist should be involved at an early stage.

Fluid and electrolyte management requires careful attention, as women with CF may easily become hypovolaemic from the loss of large quantities of sodium in sweat.

Epidural analgesia is the recommended form of pain relief in labour and general anaesthesia should be avoided.

Postnatal care

Women should be cared for in a high-dependency unit and should be closely monitored, as studies have highlighted that cardiorespiratory function often deteriorates following birth.

Breastfeeding is not contraindicated; however, in order for this to be successful, women need to be well nourished and maintain an adequate calorie intake.

Pulmonary tuberculosis

Tuberculosis (TB) is caused by the tubercle bacillus, Myobacterium tuberculosis. The lungs are the organ most commonly affected, although the disease may involve any organ.

Management

Standard antituberculous therapy should be used to treat TB in pregnancy. TB is treated in two phases:

In the first phase, rifampicin, isoniazid and pyrazinamide are given daily for the first 2 months.

In the second (continuation) phase, rifampicin and isoniazid are taken for a further 4 months.

These drugs are considered to be safe and are not associated with human fetal malformations. Attention should also be given to rest, good nutrition and education with regard to preventing the spread of the disease. TB is usually rendered non-infectious after 2 weeks of treatment.

Postnatal care

Babies born to mothers with infectious TB should be protected from the disease by the prophylactic use of isoniazid syrup 5 mg/kg/day for 6 weeks and should then be tuberculin tested.

If the tuberculin test is negative, bacille Calmette–Guérin (BCG) vaccination should be given and drug therapy discontinued.

If the test is positive, the baby should be assessed for congenital or perinatal infection, and drug therapy should be continued if these are excluded.

Breastfeeding is contraindicated only if the mother has active TB.

It is advisable for a woman with TB to avoid further pregnancies until the disease has been quiescent for at least 2 years. The woman needs to be aware that rifampicin reduces the effectiveness of oral contraception.

Renal disease

Asymptomatic bacteriuria

A diagnosis of asymptomatic bacteriuria (ASB) is made when there are more than 100 000 bacteria per millilitre of urine. All women should be screened for bacteriuria using a clean voided specimen of urine at their first antenatal visit.

If ASB is not identified and treated with antibiotics, 20–30% of affected women will develop a symptomatic urinary tract infection such as cystitis or pyelonephritis. These infections represent a significant risk for both mother and fetus and there is evidence to suggest that they may play a role in the onset of preterm labour.

Pyelonephritis

Clinical presentation

See Box 13.4.

Box 13.4 Clinical presentation of pyelonephritis

• Pyrexia, rigors and tachycardia

• Nausea and vomiting; dehydration

• Pain and tenderness over the loin area; muscle guarding

• Urine cloudy; infecting organism often found to be Escherichia coli

Management

Refer to a doctor; admit to hospital.

Obtain a midstream specimen of urine (MSU) to test for culture and sensitivity.

Give intravenous antibiotics followed by oral antibiotics once the pyrexia has settled.

Record fluid balance; intravenous fluids may be required.

Maintain 4-hourly observation of temperature and pulse.

Monitor uterine activity.

Prevent complications of immobility, e.g. deep vein thrombosis.

Repeat cultures 2 weeks after completion of antibiotics and monthly until birth.

Chronic renal disease

In order to determine the impact of pregnancy on a woman with chronic renal disease, the following factors need to be considered:

Type of pre-existing renal disease.

General health status of the woman.

Presence or absence of hypertension.

Current renal function.

Prepregnancy drug therapy.

If renal disease is under control, the maternal and fetal outcome is usually good. In some instances renal function may deteriorate and the chance of pregnancy complications subsequently rises.

Care and management

The aim of pregnancy care is to prevent deterioration in renal function. This will necessitate more frequent attendance for antenatal care and close liaison between the midwife, obstetrician and nephrologist.

Renal function is assessed on a regular basis by measuring serum urate levels, serum electrolyte and urea, 24-hour creatinine clearance and serum creatinine.

Screen for glycosuria, proteinuria, haematuria, urinary tract infection and anaemia.

Monitor for the emergence and severity of hypertension and pre-eclampsia.

Fetal surveillance includes fortnightly ultrasound scans from 24 weeks, Doppler flow studies and daily fetal activity charts.

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Related

Related posts:

1. The Placenta
2. Prolonged Pregnancy and Disorders of Uterine Action
3. The Third Stage of Labour
4. Antenatal Care

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