Case 75: Labour

 CASE 75: LABOUR

History

You are on the labour ward and called to see a 33-year-old woman in labour as the midwife is

concerned about the cardiotocograph (CTG).

She is 41 weeks 2 days’ gestation and this is her first baby. The pregnancy was uncomplicated until 2 days ago when she developed mild hypertension, without proteinuria. In view

of the gestational age a decision was made for induction of labour yesterday. She had 2 mg

prostaglandin gel administered into the vagina at 6 pm last night and again at 6 am this

morning. Spontaneous rupture of membranes occurred at 10 am today after which contractions commenced.

Examination

Blood pressure is 135/68 mmHg, heart rate 90/min, and temperature is 37.1°C.

On abdominal palpation the fetus is cephalic, 1/5 palpable, and strong contractions are felt.

Vaginally the cervix is fully effaced and 6 cm dilated. The fetus is cephalic at ischial spines

with mild caput but no moulding. Grade 1 meconium is noted.

INVESTIGATIONS

The CTG, as shown in Fig. 75.1, has demonstrated a similar pattern for approximately

50 min.

A decision is made for fetal blood sampling and the result is as follows:

pH: 7.10

Base excess: –7.9 mmol/L

Questions

• How would you interpret the CTG and fetal blood sample result?

• How would you manage the patient?

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Figure 75.1 Cardiotocograph.100 Cases in Obstetrics and Gynaecology

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ANSWER 75

The CTG shows a baseline of 155/min with reduced variability (<5/min) and atypical variable decelerations with over 50 per cent of contractions. No accelerations are seen. The CTG

is therefore classified as pathological (one non-reassuring feature and one abnormal feature, according to National Institute for Health and Clinical Excellence (NICE) guidance).

Contractions are 5 in 10.

The classification system for CTG interpretation is outlined in case 79.

The fetal pH should normally be between 7.25 and 7.35. This fetal blood sample suggests an

acidotic baby (low pH and high negative base excess).

In cases of an abnormal CTG, the fetus may not be compromised, and it is therefore

important to assess the fetal wellbeing with a fetal blood sample before progressing to

operative intervention (unless fetal blood sampling is contraindicated or in cases of persistent fetal bradycardia). In this case the fetal blood sample confirmed that the fetus was

significantly compromised.

The meconium-stained liquor may be a sign of fetal compromise, but at 41 weeks’ gestation

meconium may be an incidental finding and is therefore difficult to interpret.

Management

If the cervix were fully dilated and the head below the ischial spines then instrumental delivery, by ventouse or forceps, would be appropriate. As this is not the case, then immediate

delivery by caesarean section is essential. The important points for an emergency caesarean

section are:

• the midwife in charge, theatre staff, obstetric consultant, specialist registrar, anaesthetist and paediatrician should be informed

• the reasons for the proposed procedure should be explained to the woman and

informed consent obtained

• metoclopramide and ranitidine should be given in case of the need for general anaesthetic

• intravenous access is needed with full blood count and group and save sent

• a urethral catheter should be inserted

• the baby should be delivered within a maximum 30 min after the decision.

KEY POINTS

• Atypical variable decelerations with more than 50 per cent of contractions or a

single prolonged deceleration for more than 3 min are suggestive of a pathological CTG, and fetal blood sampling or immediate delivery in such cases should be

considered urgently.

• Except in the cases of prolonged deceleration/bradycardia, operative delivery for

abnormal CTG should only be performed after confirmation of fetal compromise

by fetal blood sampling.

• CTG interpretation guidelines are published by the National Institute for Health

and Clinical Excellence (NICE) and should be integrated into all obstetric care