Case 94: Blood pressure and pregnancy

 CASE 94: BLOOD PRESSURE AND PREGNANCY

History

A woman was admitted from the antenatal clinic 2 days ago at 38 weeks’ gestation. She is 42

years old and this is her second pregnancy. Her first child was born by spontaneous vaginal delivery 13 years ago. She has subsequently remarried. Her booking blood pressure was

138/70 mmHg at 13 weeks. Her booking blood tests were unremarkable. At her 36-week midwife appointment 2 weeks ago, her blood pressure was 140/85 mmHg and the urinalysis was

normal. The blood pressure was repeated 2 days later and was 140/82 mmHg. Two days ago

she saw her midwife for a further appointment and her blood pressure was 148/101 mmHg.

Urinalysis showed protein +.

She feels well in herself except for swollen legs. She denies any headache or blurring of vision.

Examination

She has oedema to the midcalves and her fingers are swollen such that she cannot remove her

rings. Abdominal palpation is non-tender and the symphysiofundal height is 39 cm. Reflexes

are normal.

INVESTIGATIONS

Normal range for

pregnancy

Haemoglobin 12.4 g/dL 11–14 g/dL

White cell count 8×109/L 6–16×109/L

Packed cell volume 34% 31–38%

Platelets 210×109/L 150–400×109/L

Sodium 137 mmol/L 130–140 mmol/L

Potassium 3.9 mmol/L 3.3–4.1 mmol/L

Urea 2.5 mmol/L 2.4–4.3 mmol/L

Creatinine 80 mmol/L 34–82 mmol/L

Alanine transaminase 37 IU/L 6–32 IU/L

Alkaline phosphatase 98 IU/L 30–300 IU/L

Bilirubin 10 mmol/L (3–14 micromol/L)

Gamma glutamyl transaminase 32 IU/L 5–43 IU/L

Urate 43 mmol/L (0.14–0.38 mmol/L)

24 h urinary protein collection: volume 1.8 L; total protein 2.16 g; protein per litre 1.2 g

Questions

• How would you interpret the investigations?

• What further investigations are needed and how should she be managed?100 Cases in Obstetrics and Gynaecology

268

ANSWER 94

Results interpretation

The haemoglobin and packed cell volume suggest mild haemoconcentration. The platelet

count is normal for pregnancy, though low for a non-pregnant person. Electrolytes are within

the normal range but the creatinine is higher than normal for pregnancy. Alkaline phosphatase is always raised in pregnancy due to its production by the placenta. However the alanine

transaminase is abnormal.

A normal urate value correlates with gestational age (the urate level should not be more than

the number of weeks gestation) and therefore the level of 43 mmol/L is high. Finally, the 24 h

urinary protein measurement, performed to quantify the degree of proteinuria, has shown a

significantly raised result (>0.3 g/24 h).

This woman thus has pregnancy-induced hypertension (PIH) with proteinuria, abnormal

liver function and raised serum creatinine and urate. This is known as pre-eclampsia. The

condition commonly occurs in asymptomatic women and the severity of symptoms often

does not correlate with the disease severity.

No further maternal investigations are needed but fetal wellbeing needs to be assessed by

cardiotocograph and ultrasound assessment for fetal growth and liquor volume in view of the

association between pre-eclampsia and intrauterine growth restriction.

Induction of labour as soon as possible is indicated, as the fetus is beyond 37 weeks and

delay might increase the likelihood of fulminating pre-eclampsia in the mother or fetal

compromise, including placental abruption. There is no indication for caesarean section

unless induction is unsuccessful or fetal compromise occurs before or during labour. Close

monitoring of blood pressure is imperative during and after labour, as many eclamptic fits

occur postnatally.

In this case the woman agreed to induction of labour and started contracting after the first

dose of intravaginal prostaglandin gel. The labour progressed rapidly with subsequent normal delivery. However the blood pressure increased in labour to 155/110 mmHg. An epidural

was sited to help reduce the blood pressure. Blood pressure increased further and a hydralazine infusion was required.

She remained in hospital for 5 days postpartum for blood pressure monitoring, during which

time her blood results returned to normal. Postnatally she was converted to oral labetalol for

6 weeks, after which blood pressure was normal, and treatment discontinued.

KEY POINTS

• Pre-eclampsia is common and is associated with significant maternal morbidity

and mortality.

• Proteinuria should be quantified with analysis of a 24 h urine collection.