Induction of labour
- Induction if labour is the stimulation of the uterine contractions before the onset of spontaneous labour. It is an obstetric intervention that should be used when elective birth will be beneficial to mother and baby. The purpose of induction is to affect the birth of baby, thereby ending the pregnancy. Successful induction depends on adequate contractions which are effective in bringing about progressive dilation of the cervix. The procedure is more likely to be successful when the cervix is said to be ripe, it has undergone structural changes to produce softening, dilation, and effacement.
- Parents should be partners in the decision making process, giving their consent based on full information about the alternative.
Indication for induction
Induction is indicated when the benefits to the mother or the fetus outweigh those of continuing the pregnancy and it is associated with the following maternal and fetal factors.
- Prolonged labour or post-term pregnancy. This is the main indication for induction of labour.
- Hypertension, including pre-eclampsia. The timing of induction depends on the severity of the symptoms, and the possible consequences on maternal and fetal mortality and morbidity.
- Medical problems. Woman with current renal, respiratory or cardiac disease may require induction of labour.
- Placental abruption. Indication may be considered in cases of severe or moderate abruption after the condition of the mother has been stabilised. Caesarean suction is more common.
- Obstetric history, such as previous stillbirth
- Unstable lie. If placenta praevia and pelvic abnormalities have been excluded, induction may be offered. The lie is corrected to longitudinal but as there remains a possibility of cord prolapse, caesarean suction may be preferred.
- Prelabour rupture of membranes. When rupture occurs at term, spontaneous labour can be anticipated for 60% of mothers within 24 hours and for 90% labour will commence within 72 hours .delay increases the morbidity to mother and fetus from infection developing.
- Maternal request. Some women may request to be induced citing social or psychological reasons.
- Suspected fetal compromise. Evidence of intrauterine growth retardation, diminished fetal movements or abnormal umbilical artery blood flow detected with Doppler ultrasound may provide indication for induction of labour.
- Intrauterine death.
Contraindications to induction of labour
- Placental praevia
- Transverse or compound fetal presentation
- Cord presentation or cord prolapse
- Cephalopelvic disproportionSever fetal compromise
Methods of inducing labour
– Prostaglandin and induction
- In order to decide in method of induction, assessment of the cervix is required. Prior to prescribing the prostaglandin, the Bishop’s score is measured .this is an objective method of assessing whether the cervix is favorable for induction of labour. The five different features are considered and each is awarded a score of between 0 and 3. When a total of 6 or over is reached the prognosis for induction is good.
- Prostaglandin is most commonly administered by intravaginal route, although oral preparations are available. Prostaglandin E2 administered locally to the cervix is absorbed, resulting in changes which can be assessed on vaginal examination, increasing the Bishop’s score.
- Prostaglandin produces frequent, but low intensity, contractions of the uterus. Fetal heart rate and uterine contractions should be monitored continuously for 30 – 60 minutes. The mother should remain recumbent or resting for 1 hour.
– Sweeping or stripping of membranes
Sweeping the membranes is though to be an effective method of inducing labour, where there is an uncomplicated pregnancy .prostaglandin are rapidly produced as the fetal membranes are detached from the decidua. In order to carry out the procedure, a vaginal examination with stretching is needed. This provides additional stimulus for prostaglandin release.
- Is the artificial rupture of the fetal membranes resulting in drainage of liquor. It is commonly abbreviated to ARM.
- ARM is performed to induce labour when the cervix is favourable or during labour to augment contractions. A well-fitting presenting part is essential, to prevent cord prolapse. ARM may also be carried out to visualize the colour of the liquor or to attach a fetal scalp electrode for the purpose of continuous electronic monitoring of the fetal heart rate. These reasons are not sufficient indications on their own to require ARM.
- Rupture of the membranes allow the presenting part to descend, with improved application to the cervical. This increased stimulation result in stronger contractions, as levels of prostaglandin rise.
- ARM is carried out during a vaginal examination using an amnihook, a tool with a small hook at one end, or an amnicot, a glove with a small hook on one finger. Informed maternal consent should be given and reason for the amniotomy clearly started in the records.
- Amniotomy may be used on its own or in association with oxytocin and my be either low , involving rupture of the forewaters , or less commonly , high which require the hindwaters to be ruptured . The letter uses a curved Drew-Symthe catheter and should be reserved for cases of polyhydramnios with a firm indication for induction.
Hazards of ARM:
- Intrauterine infection, particularly iatrogenic from digital or instrumental contamination.
- Early decelerations of the fetal heart.
- Cord prolapse
- Bleeding from the following sources: fetal vessels in the membranes (vasa praevia); the friable vessels in the cervix; or a low-lying placental site (placental praevia).
Oxytocin is a hormone released from the posterior pituitary gland. It acts, at cell level, on smooth muscle and is released in a pulsed manner in response to stimulation. Receptors to oxytocin are found in myometrium and increase in number towards term and throughout labour.
Oxytocin is used in conjunction with amniotomy and may be commenced at the same time as ARM or after a delay of several hours. Less analgesia was required and the rate of postpartum hemorrhage was reduced.
Administration of oxytocin to induce labour
Local policies and protocols should be followed for the administration of oxytocin. Variations occur in the initial dose and the rate of incrementation of oxytocin used for induction of labour .oxytocin is used intravenously, diluted in an isotonic solution such as normal saline. Dextrose solutions used over long periods, in conjunction with oxytocin, can alter the electrolyte balance because of the mild antiduretic effect of the hormone. The infusion should be controlled through a pump to enable accurate assessment of volume and rate. Dosages should be recorded in minutes per minute. The rate of infusion must be titrated against the assessment of strength and frequency of uterine contraction. The nurse should aim to administer the lowest dose required to maintain effective, well-spaced uterine contractions, typically occurring ever 3 minute, lasting 45-50 seconds.
Care of mother for induction of labour
If the reason for induction allows, planning may include a visit to the delivery suite and special care unit. Communication should be clear between personnel with good liaison between nurse and obstetric and medical terms and pediatric services to ensure that support and care are available as needed. Mothers and their birth partners should be given factual and unbiased information about induction of labour. Written opportunity to discuss issues relating to induction with both medical and nursing staff.
Care in labour
- As with spontaneous labour, all maternal and fetal observations are recorded as contemporaneously as possible on the partogram .a record of discussion and information given during labour is also documented in the mother’s notes, with each entry signed and time of entry noted.
- Maternal well-being. Observations of maternal pulse rate, blood pressure and temperature are made recorded on the partogram.
- Uterine contractions. Uterine contractions can be felt on palpation and their frequency, duration and strength should be recorded on the partogram every 15-30 minute. Continuous tocography may be used, in conjunction with monitoring of the fetal heart. The nurse should remain in constant attendance while the rate of oxytocin is increasing, and be able to assess uterine tone both during and after contractions using fingertip palpation.
- Fetal well-being. Continuous monitoring is used in conjunction with oxytocin, using an abdominal ultrasound transducer or by applying a fetal scalp electrode.
- Assessment of pain. The nurse should not’s the mother reaction to pain caused by the contractions. With an oxytocin infusion the build-up in frequency and strength of the contractions may be difficult for the woman to cope with. The nurse should be able to give support and encouragement to the woman to help her cope with the contractions, and appropriate pain relief should be available if it is required.
- Assessment of progress. Before commencing the oxytocin infusion the position of the fetus and relationship of the presenting part to the pelvic brim is assessed by abdominal palpation. A vaginal examination will be performed to assess the length, consistency, position and dilation of the cervix. Position and station of the presenting part will also be noted and these observations act as a baseline for assessing progress of the labour. Vaginal examinations are usually carried out 4 hourly, but this may very if progress is slow, or may be dependent on local policies. If high doses of oxytocin are used, examination may also be requested more frequently.
- When a woman’s labour is induced or augmented with oxytocin and there is a previous history of caesarean suction, the nurse should be aware of the risk of uterine rupture associated with excessive use of oxytocin. The rate of oxytocin administration should be closely monitored to ensure uterine activity that is adequate to maintain progress in labour.
Augmentation of Labour
Augmentation of labour occurs to correct slow progress in labour. Correction of ineffective uterine contractions includes amniotomy, amniotomy and administration of oxytocin, or administration oxytocin in the presence of the previously ruptured membrane. When labour is induced or augmented with oxytocin, the nurse must be vigilant and aware of the risk of hyperstimulation of the uterus.
Active management of Labour
The use of active management in preventing prolonged labour and reducing the caesarean section rate is controversial. Analysis of trials shows that augmentation with amniotomy and early oxytocin does not improve the caesarean section rates.
Incoordinate uterine activity
This may be hypertonic and also inefficient .Lacking fundal dominance, the contraction begins and lasts longest in the lower segment. Polarity is reversed. The resting tone of the uterus is raised, the uterus feeling tense on palpation. Pain is intense but out of proportion with the effect on the cervix, this pattern of activity is typically found in association with malposition of the occiput and minor degrees of disproportion.
Where coordination of the contraction is completely lacking, different areas of the uterus contract independently. This is so –called “colicky” uterus. The mother suffers severe generalized pain, as the resting tone of the uterus is raised. Fetal distress may be the result of diminished placental perfusion.
Constriction ring dystocia
This is a localized spasm of a ring of muscle fibers which occurs at the junction of the upper and lower segment of the uterus. It is rare, affecting less than 1 in 1000 labours and may arise at any stage; it is associated with the use of oxytocin.