7.4.1 Indications
– Induction of labour.
– Correction of a dynamic dystocia: delayed dilation in a woman in active phase of labour, with arrest for more than 4 hours, due to inadequate uterine contractions. The membranes must have been ruptured.
– Contractions fail to resume 15 minutes after the birth of a first twin.
7.4.2 Risks of using oxytocin during labour
– Maternal risk: uterine rupture, especially in a scarred uterus, but in a unscarred uterus as well, particularly if it is overdistended [multiparity, polyhydramnios, multiple pregnancy] or if there is major foeto-pelvic disproportion.
– Foetal risk: foetal distress due to uterine hypertony [uterine contraction without relaxation].
7.4.3 Contra-indications to the use of oxytocin during labour
– Obvious foeto-pelvic disproportion, including malpresentation [brow, transverse, etc.].
– Complete placenta praevia.
– Spontaneous uterine hypertony.
– Foetal distress.
– Two or more prior caesarean sections.
– Prior classical caesarean section [vertical uterine incision].
– Absence of indication.
7.4.4 Situations requiring special precautions
– Prior single low transverse caesarean section.
– Grand multiparity [5 deliveries or more].
– Overdistended uterus.
These factors increase the risk of uterine rupture. Oxytocin may be used provided the following precautions are respected:
1. maximum infusion rate of
30 drops/minute for 5 IU in 500 ml [i.e. 15 milli-units per minute];
2. assess maternal and foetal status before every dosage increase;
3. interval of at least 30 minutes between dose increases;
4. do not increase dosage [possibly even decrease dosage] if satisfactory uterine contractions and progress of cervical dilation.
7.4.5 Conditions for oxytocin use
– Given
the risk to both mother and foetus, use of oxytocin during labour requires:
• close maternal monitoring [check for hyperstimulation, dystocia and imminent rupture at least every 30 minutes];
• close foetal monitoring [check for decelerations in heart rate at least every 30 minutes];
• proximity to an operating theatre, in order to perform prompt caesarean section if needed.
– Position the patient on her left side.
In the event of foetal distress, uterine
hyperkinesia [more than 5 contractions in 10 minutes] or uterine hypertony [absence of uterine relaxation]: stop the oxytocin.
After delivery, however, there is no risk of uterine rupture or foetal distress, and oxytocin can be used more readily.
Table 7.2 - Use of oxytocin
During labour | |||
Labour induction | • On vaginal exam, assess cervical dilation and effacement, and engagement [Bishop score ≥ 6, Table 7.1]. |
| • Appearance and quality of contractions, uterine relaxation. Rupture the membranes as soon as possible. |
Correction of dynamic dystocia | • Cervix at least 5 cm on vaginal exam. | As for labour induction. | • Resumption or augmentation of contractions, uterine relaxation. |
No contractions 15 minutes after the birth of first twin | Verify that presentation is vertical [not transverse]. | • Start or resume oxytocin infusion. | • Resumption or augmentation of contractions, uterine relaxation. |
Note: outside of labour, oxytocin is use as below | |||
Haemorrhage due to uterine atony | • First, manually remove the placenta, if needed. | IV infusion over 2 hours of 20 IU in 1 litre of Ringer lactate or 0.9% sodium chloride [160 drops/minute]. At the same time, give 5 to 10 IU by slow IV injection; repeat if necessary until the uterus becomes firm and contracted [max. 60 IU total dose]. | • Heart rate, blood pressure, blood loss. |
After caesarean section | 10 IU by slow IV injection after clamping the cord then IV infusion over 2 hours of 20 IU in 1 litre of Ringer lactate or 0.9% sodium chloride [160 drops/minute]. | Uterine retraction. | |
Prevention of postpartum haemorrhage | Verify that there is no second twin. | 5 to 10 IU by slow IV or IM injection, before or after the third stage, depending on staff expertise. |