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Induction of labour: Indications, Method, Management, Complications, Bishop score

Induction of labour is initiated using mechanical and pharmacological methods. The intervention is necessary when the well-being of the mother or baby may be at risk if the pregnancy is continued. The parents should be in agreement and fully informed of the procedures.

Indications of Labour

• Post-maturity. 

• PROM (>37 weeks). 

• PIH, pre-eclampsia. 

• APH. 

• Placental insufficiency and IUGR. 

• Large fetus, twins. 

• Diabetes, renal disease, or other underlying conditions. 

• IUD.

Method of induction  of Labour

A prostaglandin pessary is used to soften/ripen the cervix. When this is achieved, the membranes are ruptured (amniotomy) and an oxytocin infusion is commenced to stimulate regular uterine contractions and dilatation of the cervix. Most women are induced as inpatients; however, there is a move to provide an outpatient induction of labour service for low-risk women in some trusts. This should only take place where there is adequate support for the woman and the service is audited regularly.

Management of induction  of Labour

• If a consultant-booked woman requires induction of labour, always act under the instructions of the obstetric consultant or registrar.

• The obstetric consultant or registrar should authorize the induction and write the indication and method in the woman’s notes. 

• If a low-risk midwifery-led woman attends for induction of labour, transfer her care to the consultant on call for that day. 

• The woman will be admitted to the delivery suite or antenatal ward, depending on local guidance and the consultant management plan. 

• Carefully explain the length of time that induction may take and the procedures involved and possible outcomes. This will help to alleviate the prospective parents’ anxiety and enable them to make appropriate arrangements for hospital admission. 

• Before commencing the induction, ensure that:

  • The woman and her partner understand and consent. If induction fails, a Caesarean section is indicated.

             • The rationale for induction is documented and current. 

             • The estimated date of delivery is correct and, if possible, confirmed on an early pregnancy scan.

             • The presenting part is engaged (3/5 palpable abdominally).

             • The obstetric registrar has prescribed the treatment (if the woman is being induced purely for post-maturity, the trust may have a patient group directive (PGD), meaning that the midwife can write up the prostaglandin on the woman’s treatment card). 

             • The woman is comfortable and has passed urine. 

• Ensure that the woman’s dignity and privacy are preserved at all times.

HEART SOUNDS: S1, S2, S3, S4 and Heart Murmurs

Bishop score for induction  of Labour

You should be experienced in assessing the state of the cervix

• The Bishop score is a frequently used system of assessing the cervix which can give a clear indication of progress. The score should be recorded in the woman’s notes each time an assessment is made, i.e. at the time of administration of prostaglandin gel and amniotomy. 

• The higher the initial score, the more successful the induction. If the Bishop score is: 

• 0 to 6: the cervix is unfavourable for induction and a prostaglandin pessary will be necessary to soften the cervix 

• 6 and above: the cervix is very favourable and prostaglandin is not required. 

Variations on this scoring include one recommended in the NICE guidelines.

Modified Bishop (Calder) score

Score0123
Dilatation (cm)<11–22–45 or more
Cervical length (cm)5 or more2–41–2<1
Station above spines (cm)−3−2−1/0+1/+2
ConsistencyFirmAverageSoft
PositionPosteriorCentral/
anterior

Sweeping the membranes ( induction  of Labour )

When a woman’s care during pregnancy has been midwifery-led, induction of labour should be discussed by the midwife towards term. The community midwife may arrange with the delivery ward for the induction to be planned for a mutually convenient time. Prior to induction of labour in hospital, offer the woman a vaginal examination to assess the state of the cervix and to perform a sweeping of the membranes. This has been shown to increase the possibility of labour occurring naturally within the following 48h. Nulliparous women can be offered membrane sweeps at 40 and 41 weeks’ gestation; multiparous women are offered this at 41 weeks’ gestation. If the membrane sweep is discussed at a previous appointment, the woman has the opportunity to arrange support for the visit if she wishes.

This procedure may be performed in the woman’s home or at an antenatal clinic visit. It may be a preferable first step to stimulate labour and sometimes may pre-empt formal induction. 

• The pregnancy should be uncomplicated. 

• The gestational age should be term (40 or 41 weeks for nulliparous women and 41 weeks for multiparous women). 

• The membranes must be intact. 

• Warn the woman that she may experience some discomfort as a result of the procedure and that she may have a mucoid/bloodstained ‘show’ and should wear a light sanitary pad. 

• Reassure her that membrane sweeping is not associated with increased maternal or neonatal infection.

 • Auscultate the FHR and perform an abdominal palpation; record the information in the maternal notes. 

• Perform a vaginal examination and locate the cervix. A finger is inserted through the internal os, stretching the cervix slightly, and the membranes are palpated. Use a sweeping circular movement of the finger to separate the fetal membranes from the decidua/lower uterine segment. 

• There is potential for a natural rapid increase in prostaglandin production in late pregnancy. Sweeping of the membranes is a mechanical stimulant to tissue prostaglandin release in the cervix and lower segment. This, in turn, can initiate the onset of labour.

Prostaglandins for induction of labour 

Propess is a vaginal delivery system containing 10mg of dinoprostone. Propess is a sustained-release preparation delivering an active agent over 24h. Each maternity unit will have their own guidance on which prostaglandins are to be used in which circumstances; below is an example. 

• Obtain consent from the woman; perform abdominal palpation to assess the fetal lie, presentation, and size. Perform maternal baseline observations. Auscultate the FHR and record all findings. 

• Commence CTG for 30min prior to the administration of the prostaglandin.

• Perform a vaginal examination (with informed consent) and assess the cervix using the Bishop score. 

• If the woman’s cervix is not favourable (Bishop score <6), or the woman is a primigravida regardless of the Bishop score with no contractions, use the Propess vaginal delivery system to soften/ripen the cervix, as follows: 

• The Propess should be removed from the freezer 20min prior to insertion. It should then be positioned in the posterior fornix of the vagina using only a small amount of water-soluble lubrication 

• The Propess should lie transversely and after insertion the withdrawal tape should be cut to within 1–2 cm of the introitus. Ensure that there is sufficient tape outside the vagina to allow removal. The woman should be encouraged to remain resting on the bed for 30min after insertion. 

• Record the Bishop score and time of the procedure in the notes. 

• Encourage the woman to rest on the bed for an hour following the procedure, during which time the fetal heart is monitored continuously. If the recording is reassuring, the woman should mobilize and eat/drink as normal.

• Warn the woman that she may experience mild discomfort/soreness in the vagina as a result of prostaglandin, or painful uterine contractions caused by the prostaglandin prior to the onset of the regular contractions of labour. Oral or IM analgesics may be prescribed.

• Advise the woman to inform the midwife if contractions become regular (≥3 in 10min), she becomes uncomfortable and requires pain relief, or she experiences vaginal bleeding or SROM, or if the Propessfalls out or drops into the lower vagina.

• One hour following insertion:

     • Record maternal observations on MEOWS (PGE2 may cause mild pyrexia, due to its effect on cerebral thermoregulatory centres)

     • Auscultate the fetal heart and document

    • Determine uterine activity

    • Note and manage any adverse effects, i.e. nausea, vomiting, fever, vaginal irritation, abdominal pain, vaginal bleeding, hypertonic uterine activity, abnormal FHR.

• Performed as a minimum every 6h (in the absence of regular uterine activity or rupture of membranes):

     • Maternal observations

     • Auscultation of the fetal heart

    • Assessment of the strength and frequency of contractions

    • Assessment of vaginal loss

    • Monitor and discuss pain management.

• If there are no signs of labour commencing, Propess must be removed 24h after insertion. At this point, the woman should be assessed to see if an amniotomy is possible. If this is not possible, a review by an obstetrician must occur to decide on an appropriate management plan.

• A CTG should be performed if the woman is experiencing regular contractions (≥3 in 10min). Once the CTG is assessed as normal, it can be discontinued and intermittent auscultation can be used.

• Once labour is established, follow the process for normal labour. CTG is not indicated once the onset of labour occurs in low-risk women.

Arterial Cannulation: Indication, Equipment, Procedure, Complications

Contraindications for the use of dinoprostone 

• Allergy to prostaglandin.

• Labour is already established.

• Placenta praevia.

• Unexplained vaginal bleeding at the time of induction.

• Severe fetal growth restriction with abnormal Doppler studies.

• Parity—women with >3 full-term deliveries.

• Suspicious or pathological CTG.

• Oxytocic drugs are already being administered.

• Evidence of cephalopelvic disproportion.

• Fetal malpresentation.

• Pre-labour rupture of membranes at term.

Some women who are considered high risk can also be induced using Propess. In each case, a clear individualized management plan must be recorded in the antenatal notes. (An example of a high-risk management plan may be that a woman who has undergone a previous LSCS may have the Propess removed after 12h rather than the maximum 24h). All risks and possible outcomes should have been explained to the woman and her partner prior to admission to hospital. High-risk inductions should always occur on the labour ward.

Artificial rupture of the membranes ( induction  of Labour )

• If the cervix is favourable (i.e. Bishop score >6), then it may be possible to perform an amniotomy for induction of labour. 

• Amniotomy may be performed if:    

• The senior registrar authorizes/performs the procedure in the high-risk client    

• The woman understands the procedure and consents    

• The fetal head is engaged or 3/5 palpable abdominally    

•The CTG is reassuring.

Management 


• The woman may value the support of a partner/friend. She should understand that she can withdraw consent to the procedure at any point if she so wishes. 

• The procedure is performed using sterile pack, gloves, lubricant, amnihook, protection for couch, and clothing. 

• Monitor the fetal heart continuously.

 • Entonox® should be available in case the woman experiences discomfort. 

• The woman should pass urine prior to the procedure. 

• Perform a vaginal examination; assess the Bishop score; insert a finger through the internal os and palpate the membranes and forewaters. Introduce the amnihook along the examining fingers and perform the amniotomy. 

• Address the woman’s hygiene needs. 

• Document the Bishop score, time of amniotomy, and colour and volume of the liquor.

• Monitor the fetal heart: 

• Continuously following the procedure 

• For 60min when the induction is in a low-risk woman; thereafter the fetal heart should be monitored intermittently (each 15min) until contractions occur regularly or IV oxytocin is commenced. 

• If the woman is not experiencing regular contractions, administer an oxytocin regimen: 

• Immediately after ARM for all primigravidae and multigravidae with an urgent indication for induction such as pre-eclampsia 

• 2h after ARM if regular contractions have not commenced and if multiparous and a non-urgent indication for delivery.


Complications 

• Prolapsed cord may occur if the fetal head is not engaged when the membranes are ruptured or if it has not been recognized that the cord is presenting prior to the procedure. 

• Non-reassuring fetal heart pattern may occur following ARM. This may be due to compression of the fetal head or placenta. It should settle to normal soon after. 

• Increased infection risk once the membranes have been ruptured. It is important that effective progress in labour is achieved.

Intravenous oxytocin for induction  of Labour


• Syntocinon® is a synthetic oxytocin. It is effective in stimulating uterine activity and promoting dilatation of the cervix. 

• Before commencing oxytocin, ensure that: 

• The drug is prescribed by the registrar 

• The woman understands the procedure for administration, the restriction it will place on her mobility, and the analgesia available 

• 6h have elapsed if Prostin® vaginal tablets have been administered rather than Propess®

• SROM is certain or that ARM has been performed 

• You are fully conversant with the client’s obstetric history, since extreme caution is indicated in clients with a uterine scar or grand multiparty 

• You are aware of the current state of maternal observations, contractions, and cervical dilatation as a baseline 

• The fetal heart is monitored continuously and is reassuring. 

• Siting of an IV cannula is a good time to take FBC/platelets and G&S in case of later need. 

• Check the medication with a colleague—it can be given via IV infusion using a pump or a syringe driver. An example of the dilution of the oxytocin can be: 5IU of oxytocin in 50mL of 0.9% sodium chloride; this would be administered via a syringe driver at a starting rate of 4 milliunits per hour (2.4mL/h). This can then be increased every 30min by 4 milliunits, up to 12 milliunits, until there are effective uterine contractions. 

• Titrate the dose against uterine activity. 

• The aim is to achieve three or four regular contractions in 10min. There should be 1min relaxation between each contraction. To achieve this, the dose may be increased every 30min.

• Further increases should be discussed with the obstetric registrar.

Oxytocin regime

2.4mL/h4 milliunits
4.8mL/h8 milliunits
7.2mL/h12 milliunits
Seek advice from the registrar/consultant before
increasing above 12 milliunits

Risks/complications of oxytocin administration 


You should remain in attendance, ensuring the safety of the mother and fetus, and observe for the following.


 • The uterus may be hyperstimulated. This may cause FHR irregularities. Stop the infusion temporarily and observe the FHR. If the abnormality persists, inform the registrar who may perform FBS. If the FHR becomes reassuring, the oxytocin may be restarted at half the preceding rate.

• Hyperstimulation of the uterus could cause rupture. This rarely happens in primigravidae, but care is needed in multiparous women. 

• PPH is more common following induction. 

• Oxytocin may be ineffective on the cervical dilatation so that labour does not progress. A Caesarean section may be necessary. 

• Oxytocin tends to encourage water retention. This is minimized by diluting it in normal saline. Care should be taken to monitor IV fluids infused and assess maternal observations. 

• Amniotic fluid embolism is not now thought to be precipitated by oxytocin induction.