Case 93: Breathlessness in pregnancy

 CASE 93: BREATHLESSNESS IN PREGNANCY

History

A 42-year-old woman is referred by her general practitioner with breathlessness for the

past 3 days. She is 34 weeks pregnant in her third pregnancy. Prior to this she has had an

emergency caesarean section for abnormal cardiotocograph in labour, followed by a 7-week

miscarriage.

In this pregnancy she was seen by the obstetric consultant to discuss plans for delivery, and

is hoping for a vaginal delivery. Ultrasound scans and blood tests have been normal. Her

booking blood pressure was 138/80 mmHg and has remained stable during the pregnancy.

She describes her shortness of breath starting while she was at work and slightly worsening

since. She felt particularly breathless when she ran to catch a bus on her way home yesterday.

She has some left-sided chest pain on breathing in. There is no cough or haemoptysis. She

has had no previous episodes. She has not noticed any calf pain but has left leg swelling and

some back pain.

Examination

The body mass index is 28 kg/m2. The woman does not look obviously unwell. Blood pressure

is 127/78 mmHg and heart rate 98/min. Oxygen saturation is 96 per cent on air. On examination of the chest there is a systolic murmur and no added sounds. Chest expansion is normal

but the woman reports pain on taking a deep breath. The chest is resonant to percussion and

chest sounds are normal except for a pleural rub on the left. The left leg is generally swollen

but no redness or tenderness is apparent.

INVESTIGATIONS

Normal range for

pregnancy

Haemoglobin 12.0 g/dL 11–14 g/dL

White cell count 10.4×109/L 6–16×109/L

Platelets 302×109/L 346×109/L

Arterial blood gas (on air)

paO2 11.0 kPa 12–14 kPa

paCO2 5.3 kPa 5–6 kPa

D-dimer: positive

Electrocardiogram (ECG): sinus tachycardia 100/min, deep S wave in lead 1, Q wave in lead

3 and inverted T wave in lead 3

Chest X-ray: normal

Computerized tomography pulmonary angiogram (CTPA) is shown in Fig. 93.1.100 Cases in Obstetrics and Gynaecology

264

Questions

• What is the diagnosis?

• What further imaging is required?

• How would you manage this woman in the immediate term, during delivery and

postnatally?

Figure 93.1 Computed tomography pulmonary angiogram.Case 93: Breathlessness in pregnancy

265

ANSWER 93

The diagnosis is of pulmonary embolism (PE). The shortness of breath and pleuritic chest

pain are classic features, and the ECG and blood gas analysis support the diagnosis. D-dimer

is commonly raised in pregnancy but also supports the diagnosis. The CTPA demonstrates

a large filling defect within the right pulmonary artery and a smaller filling defect in the left

segmental pulmonary artery, consistent with blood clots (pulmonary embolism). These findings are illustrated by the arrows in Fig. 93.2.

Venous thromboembolism (VTE) is a leading cause of direct deaths in the Confidential

Enquiry into Maternal and Child Health, accounting for death in 1 per 100,000 maternities. Non-fatal VTE occurs in approximately 60 in 10,000 pregnancies, and there may

be many more unrecognized cases. Pregnancy itself is a risk factor because of the hyperoestrogenic state, the altered blood viscosity and obstruction to venous blood flow by the

gravid uterus.

Further imaging

There is no clinical evidence of ileofemoral deep vein thrombosis, but generalized leg swelling and back pain are suspicious of an ileofemoral thrombosis. If this is confirmed, which

may require Doppler ultrasound or magnetic resonance imaging (or if she develops recurrent

PE despite anticoagulation), then liaison with a vascular team should be considered regarding the possibility of insertion of a vena caval filter.

Management

As with non-pregnant patients, anticoagulation is the mainstay of treatment. Warfarin is

contraindicated in the first trimester of pregnancy but may safely be given from 12 to 36

weeks. However it can cause difficulties with excessive bleeding if it is not stopped early

enough before delivery and it can be difficult to achieve stable international normalized ratio

levels. Therefore low-molecular-weight heparin has become the treatment of choice in pregnancy as it is simple to administer, relatively easy to reverse in the emergency situation, does

not require monitoring, and is safe.

Figure 93.2 CT pulmonary angiogram demonstrating a large filling defect in the right main

pulmonary artery (large arrow) and smaller defect in a segmental branch of the left pulmonary artery (smaller arrow).100 Cases in Obstetrics and Gynaecology

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At delivery the heparin should ideally be discontinued 12 h before delivery and recommenced immediately following delivery. Similarly an epidural or spinal anaesthetic should

not be administered immediately after a heparin dose.

Postnatally some women change to warfarin, which is now known to be safe with breastfeeding, while others continue low-molecular-weight heparin.

A large proportion of VTE occurs postnatally, so anticoagulation should be continued for 6

weeks to 3 months in the puerperium.

Graduated elastic compression stocking should be worn from the time of diagnosis until at

least 6 weeks following delivery, to reduce the risk of the postthrombotic syndrome (chronic

leg pain, swelling and ulceration).

Postnatal investigation for inherited (e.g. protein C or S deficiency) or acquired (e.g. antiphospholipid syndrome) thrombophilia is appropriate, as is anticoagulation throughout any subsequent pregnancy.

KEY POINTS

• Thromboembolic disease is common in pregnancy and one should have a high

index of suspicion in making the diagnosis clinically.

• Therapeutic dose anticoagulation should be given while waiting for confirmation

of the diagnosis.