Induction of labour and operative vaginal delivery

• Induction of labour is a planned medical intervention that starts labour when continuing the pregnancy is riskier, or when the woman asks for it after informed discussion.
• Whether the cervix is ready is judged with the Bishop score. A score of more than 8 generally means a favourable cervix; 6 or less means cervical ripening is needed first.^[1][7]
• For a favourable cervix, NICE recommends amniotomy plus an intravenous oxytocin infusion. For an unfavourable cervix, a prostaglandin (dinoprostone or low-dose oral misoprostol), or a mechanical method such as a balloon catheter, is used.^[1]
• Operative vaginal delivery (forceps or vacuum) is used in the second stage to shorten labour for maternal or fetal reasons, when the prerequisites for safe instrumental birth are met.^[4][5]
• Perineal tearing is repaired by degree: first and second degrees with layered closure; third and fourth degrees (OASIS) need operating-theatre repair of the sphincter.^[3][6]

By the end of this page you should be able to:

1. State the main indications and contraindications for induction of labour, and the circumstances in which it is deferred or declined.
2. Interpret a Bishop score and choose between pharmacological and mechanical methods of cervical ripening.
3. Explain how dinoprostone, misoprostol and oxytocin are used, and how hyperstimulation is recognised and treated.
4. List the prerequisites, indications, classification and complications of forceps and vacuum extraction.
5. Classify a perineal tear on the Sultan scale and describe the repair of second-, third- and fourth-degree tears.
6. Describe aftercare, complications and low-resource adaptations for induction, operative vaginal birth and perineal repair.

This is a procedure page. It brings together three parts of intrapartum care that a student meets in the same patient journey: getting labour started (induction), helping a birth that has already reached the second stage (operative vaginal delivery), and repairing the perineum afterwards. Each part has its own indications, its own risks and its own aftercare, and the decision to move from one to the next changes the risk-benefit balance. Throughout, treat the woman's preferences as central and document every discussion.^[1]

Cervical readiness is described by the Bishop score, a score from 0 to 13. It awards points for cervical dilation, effacement, position and consistency, and for the station of the fetal head relative to the ischial spines.^[7] Dilation, effacement and station score 0 to 3 points each; position and consistency score 0 to 2 points each.^[7] A score of more than 8 usually means a favourable cervix, particularly in multiparous women at term.^{[7] [4]}

Labour ward language uses three levels of fetal station. Outlet means the fetal head is on the perineum. Low means the head is at station plus 2 or lower but not on the perineum. Mid means the head is engaged but above station plus 2.^[4][5] These stations decide whether an instrumental delivery is safe and how likely it is to succeed.

Induction is offered when continuing the pregnancy carries more risk than being born, or when the woman chooses it after discussing the options. NICE NG207 (published 2021, minor changes May 2026) covers the circumstances, methods, monitoring and complications of induction.^[1]

Common indications include:

• Pregnancy lasting longer than 41 weeks: from 41 weeks onward the risks of caesarean birth, admission to neonatal intensive care and stillbirth or neonatal death may rise, and induction can reduce them.^[1]
• Prelabour rupture of membranes at term: offer a choice of expectant management for up to 24 hours or induction as soon as possible, and offer induction at about 24 hours if labour has not started. If she had a positive group B streptococcus test in this pregnancy, offer immediate induction or caesarean birth.^[1]
• Preterm prelabour rupture of membranes: do not induce before 34 weeks unless there are added indications such as infection or fetal compromise; offer expectant management until 37 weeks. Between 34 and 37 weeks, discuss expectant management to 37 weeks versus induction.^[1]
• Suspected fetal macrosomia in a woman without diabetes: discuss induction, expectant management and caesarean birth; shoulder dystocia is reduced and third- or fourth-degree tears are increased with induction.^[1]
• Intrauterine fetal death: with an intact uterus and no urgency, discuss expectant management, induction or caesarean birth. With ruptured membranes, infection or bleeding, offer immediate induction or caesarean birth.^[1]
• Maternal request, after discussion of benefits and risks.^[1]

Before any induction, abdominal palpation checks the level and stability of the fetal head at the brim, an ultrasound excludes malpresentation if suspected, the Bishop score is recorded, and a normal fetal heart rate pattern is confirmed by cardiotocography. Facilities for cardiotocography must be available wherever induction is started.^[1]

• Induction is not generally recommended for a breech presentation.^[1]
• Do not induce if there is fetal growth restriction with confirmed fetal compromise; offer caesarean birth instead.^[1]
• Induction is not routinely offered to women with a history of precipitate labour simply to avoid an unattended birth.^[1]
• Careful discussion is needed after a previous caesarean birth: induction can increase emergency caesarean and uterine rupture; dinoprostone and misoprostol are contraindicated by their marketing authorisations for women with a uterine scar. Mechanical methods remain an option.^[1]

Induction changes the birthing options. Women should be told before induction that vaginal examination is needed, place of birth may be limited, a birthing pool may not be available, assisted vaginal birth may be needed (with its increased risk of anal sphincter injury), induced labour may be more painful, and the hospital stay may be longer.^[1] Uncomplicated pregnancies should be given every opportunity to go into spontaneous labour.^{[1] [7]}

After 39 weeks, offer a vaginal examination for membrane sweeping if the woman wants it, with verbal consent. It may make spontaneous labour more likely and avoids pharmacological or mechanical methods in some women. Pain, discomfort and vaginal bleeding can occur. Do not perform it if there is a low-lying placenta.^[1]

Dinoprostone is prostaglandin E2. NICE recommends that for a Bishop score of 6 or less, induction should be offered with dinoprostone as a vaginal tablet, gel or controlled-release vaginal delivery system.^[1] It can be managed as an outpatient in selected low-risk women.^[1] Follow the manufacturer's guidance for each preparation, including when to remove a controlled-release system.^[1]

Low-dose (25 microgram) oral misoprostol tablets are the other pharmacological option where the Bishop score is 6 or less.^[1] Hyperstimulation from misoprostol may be harder to reverse than from dinoprostone, so use with care.^[1]

Where the Bishop score is more than 6, offer an amniotomy plus an intravenous oxytocin infusion.^[1] Women may still choose not to have oxytocin, or to delay it, accepting that labour may take longer and neonatal infection risk may be higher.^[1] Oxytocin alone is not supported for induction.^[1]

For a Bishop score of 6 or less, a mechanical method (balloon catheter or osmotic cervical dilator) is considered when pharmacological methods are unsuitable, such as after a previous caesarean birth or where hyperstimulation risk is higher, or when the woman prefers it.^[1] Mechanical methods are less likely to cause hyperstimulation than pharmacological ones.^[1]

When contractions begin after a prostaglandin, assess fetal wellbeing and contractions with cardiotocography. If the trace is normal and risk is low, intermittent auscultation may be used. If the fetal heart rate is abnormal or contractions are excessive: continue or restart continuous monitoring, stop further doses, and remove any vaginal product if possible.^[1] Facilities for continuous monitoring must exist wherever induction starts.^[1]

Hyperstimulation is overactivity of the uterus from induction. It is defined as tachysystole (5 or more contractions per 10 minutes for at least 20 minutes) or hypertonicity (a contraction lasting at least 2 minutes), with or without changes in the fetal heart rate.^[1] If it occurs: carry out a fetal assessment, give no further doses and remove any retained vaginal product if possible, and consider tocolysis.^[1]

Unsuccessful induction means labour has not started after one cycle of treatment. It calls for support, full reassessment of the woman and pregnancy, and fetal assessment by cardiotocography, then an agreed plan: rest and reassess, expectant management, further induction attempts, or caesarean birth.^[1]

• Intrauterine fetal death: if the woman chooses induction, offer oral mifepristone 200 mg followed by vaginal dinoprostone or oral or vaginal misoprostol, or a mechanical method; base dose and drug on clinical circumstances and national protocols; with a uterine scar discuss risks and alternatives.^[1]
• PROM or hyperemesis management in labour follows the same pain-relief principles as spontaneous labour, with referral to intrapartum guidance.^[1]
• Pain relief should be discussed, and can include simple analgesia, labour in water and epidural analgesia; induced labour may be more painful than spontaneous labour.^[1]

Operative vaginal delivery uses forceps or a vacuum extractor to expedite birth for maternal or fetal reasons in the second stage. Common indications include a non-reassuring fetal heart rate tracing, maternal exhaustion, a prolonged second stage, or maternal conditions in which prolonged pushing is unwise, such as certain cardiac or neurological disease.^[4][5] No single situation makes it absolutely mandatory; the decision weighs its risks against caesarean birth.^[5]

ACOG defines a prolonged second stage as 3 or more hours for a first vaginal birth with regional anaesthesia, or 2 or more hours of pushing without it; for multiparous women, 2 hours without regional anaesthesia or 1 hour with it.^[5]

Before either instrument, RCOG and ACOG prerequisites must be met: the cervix fully dilated, membranes ruptured, fetal head engaged with the station at or below the ischial spines, position known, fetal size estimated, maternal pelvis considered adequate, adequate anaesthesia given, a full bladder emptied, consent obtained with risks explained, and a backup plan (usually caesarean birth) in place with an operating theatre, facilities and trained staff available.^{[2][5] [4]}

Operative vaginal birth is classified by the station and rotation required, and risk falls as the head descends:

• Outlet: scalp at the introitus without separating the labia, skull on the pelvic floor, sagittal suture in anterior-posterior or oblique anterior position, head on the perineum, rotation of no more than 45 degrees.^[4][5]
• Low: leading point at station plus 2 or more, not on the pelvic floor; with or without rotation.^[4][5]
• Mid: head engaged but above station plus 2.^[4][5]
• High: head not engaged; rarely performed because of higher complication rates, and caesarean birth is preferred instead.^[5]

Forceps application uses the cephalic curve to fit the fetal head and the pelvic curve to fit the birth canal. Outlet and low applications handle most cases. Mid and rotational forceps carry higher risk. Keilland forceps have a sliding lock and minimal pelvic curve, making them useful for rotation, but their misuse can cause serious complications.^[5]

RCOG's June 2023 reminder states that rotational Kielland births should only be performed by experienced operators or under their direct supervision, the fetal head position and occiput should be identified correctly (ultrasound is more reliable than clinical examination), and the procedure stopped if gentle rotation does not succeed.^[2] Ultrasound is not mandatory before every assisted birth, but inaccurate assessment of position has led to serious incidents.^[2]

Technique principles: traction follows the pelvic curve in line with the Saxtorph-Pajot manoeuvre, applied during contractions, with an early right mediolateral episiotomy only when space is needed. Most deliveries complete with one or two pulls, and no more than three or four; emphasis is now on gentle, controlled traction and stopping if there is no progress.^[5]

Vacuum extraction pulls the fetal head with a cup placed over the pivot point, about 2 cm anterior to the posterior fontanelle. Soft cups detach more often but cause fewer scalp injuries than metal cups.^[4]

A vacuum is discouraged before 34 weeks of gestation.^[4] Hard prerequisites match operative delivery in general: full dilation, ruptured membranes, engaged head, known position, estimated weight, adequate pelvis, anaesthesia, empty bladder and consent, with a caesarean birth backup.^[4]

Operational limits: manufacturers discourage more than two to three cup detachments (pop-offs); successful delivery is aimed for within three sets of pulls and within 20 to 30 minutes of vacuum application. Rocking and torque should be avoided. Sequential use of vacuum and forceps (or vice versa) is discouraged because of higher fetal and maternal injury risk.^{[4] [5]}

The RCOG view is that obstetricians should be competent in both instruments for non-rotational births and at least one rotational technique, with intrapartum ultrasound support.^[2]

Maternal complications of operative vaginal birth include higher rates of perineal and vaginal lacerations, haematomas and anal sphincter injury (forceps more than vacuum), postpartum haemorrhage, pain and pelvic floor dysfunction in later life.^[5][4] Neonatal complications with vacuum include intracranial haemorrhage at an estimated rate of 1 in 650 to 850 live births, cephalohematoma and hyperbilirubinaemia; with forceps, transient facial nerve palsy, bruising and, rarely, skull fracture or ocular trauma occur.^[4][5] Most neonatal injuries are mild and temporary.^[5]

After any instrumental birth, examine the perineum carefully including a rectal examination, check the baby for scalp or facial injury, plan thromboprophylaxis, antibiotics and analgesia as indicated, and document the procedure, station and pulls. A mediolateral episiotomy is repaired in layers.^[5][6]

Perineal tears are classified by depth:

• First degree: skin and/or vaginal mucosa.^[6]
• Second degree: first degree plus the perineal muscles.^[6]
• Third degree: second degree with anal sphincter involvement, subdivided into 3a (less than 50% of the external anal sphincter), 3b (more than 50% of the external anal sphincter) and 3c (external and internal sphincters torn).^[6]
• Fourth degree: tear involving the sphincter complex and rectal mucosa.^[6]

Third- and fourth-degree tears (obstetric anal sphincter injuries, OASIS) complicate roughly 4 to 11% of vaginal deliveries in the United States, and the UK incidence is about 2.9% (range 0 to 8%), higher in first births (about 6.1%) than later births (about 1.7%).^[3][6] Nine of 10 women have some perineal trauma, of which 60 to 70% need repair.^[6]

Repair of severe tears should be by an appropriately trained clinician or a supervised trainee, in an operating theatre, under regional or general anaesthesia, with good lighting and equipment.^[3] Before repair of OASIS, insert a Foley catheter, give prophylactic antibiotics (commonly a second-generation cephalosporin) and use regional or general anaesthesia.^[6]

First-degree tears often need no suturing unless bleeding or distortion. For second-degree tears, continuous (running) closure is preferred over interrupted, using 2-0 or 3-0 polyglactin. Close vaginal mucosa and muscle to the hymenal ring, then perineal muscles and subcuticular skin, and finish with a rectal check.^[6]

Repair is more complex. Anchor 3-0 or 4-0 delayed absorbable suture distal to the apex and embed the knot in the anorectal lumen; close the anorectal mucosa in a running, non-locked fashion about 5 mm past the anal verge; then add a second layer using the rectovaginal fascia. Repair a torn internal sphincter end-to-end with interrupted 3-0 polyglactin or polydioxanone sutures. For the external sphincter: ^[6]

• partial tear (less than 50%): end-to-end interrupted sutures, tied posteriorly, inferiorly, superiorly and anteriorly.^[6]
• complete tear: overlapping technique, dissecting about 1.5 cm of each end, overlapping about 1 cm, and suturing with interrupted or mattress sutures.^[6]

Bury the knots behind the superficial perineal muscles, close the rest as a second-degree tear, and finish with a rectal examination. Keep the Foley catheter in overnight.^[6]

Remove the Foley on postoperative day 1 with a voiding trial. Use cool packs, topical anaesthetic, sitz baths, paracetamol and non-steroidal analgesics; avoid opiates. Prescribe stool softeners and oral laxatives twice daily for 6 weeks to reduce constipation and wound dehiscence. About a quarter of OASIS repairs dehisce within 6 weeks and a fifth become infected.^[6]

Routine episiotomy is not supported by WHO and ACOG; its restricted use is advised. Midline episiotomy is associated with more severe tears; mediolateral episiotomy is harder to repair but reduces severe tears.^[6]

• Uterine hyperstimulation is treated by fetal assessment, no further doses, removal of retained prostaglandin and consideration of tocolysis.^[1]
• Cord prolapse can be triggered by induction: assess fetal head engagement before induction, avoid dislodging the head on vaginal examination, and use continuous cardiotocography after rupture of membranes if the head is not well applied.^[1]
• Uterine rupture, suspected during induced labour, is an immediate indication for category-1 caesarean birth.^[1]
• Placenta and membrane checks: ensure no low-lying placenta on previous scans before membrane sweeping or induction.^[1]

• If a balloon catheter or osmotic dilator is unavailable, use dinoprostone or misoprostol protocols that suit the local formulary; always have cardiotocography or intermittent auscultation and a plan for emergency caesarean birth.^[1]
• Operative vaginal birth requires a skilled operator, functional instruments, anaesthesia and a theatre ready for immediate caesarean birth. If these are unavailable, transfer early rather than attempt a difficult instrumentation.^[2][4][5]
• Rectal examination and attention to sphincter trauma during repair are essential everywhere; where operating-theatre access is limited, stabilise and transfer an OASIS repair.^[3][6]
• Respect a woman's decision not to be induced, and offer monitoring or expedited caesarean birth as clinically appropriate.^[1]

• Induction is a medical intervention offered after discussion of reasons, timing, place, methods, pain relief, alternatives and risks; uncomplicated pregnancies should be encouraged to start labour spontaneously.^[1]
• Bishop score of more than 8 is generally favourable; 6 or less needs ripening.^[1][7]
• Favourable cervix: amniotomy plus intravenous oxytocin. Unfavourable cervix: dinoprostone or low-dose oral misoprostol 25 micrograms, or a mechanical method.^[1]
• Membrane sweeping from 39 weeks may reduce the need for pharmacological or mechanical induction.^[1]
• hyperstimulation is defined as uterine tachysystole (5 or more contractions in 10 minutes for at least 20 minutes) or hypertonicity (a contraction of at least 2 minutes).^[1]
• Maternal and fetal safety checks (engagement, normal cardiotocography, no low-lying placenta) precede every induction.^[1]
• Operative vaginal birth works best when prerequisites are met; forceps and vacuum each have distinct risks and advantages.^[2][4][5]
• Use outlet, low, mid and high station terminology; high forceps is outdated.^[4][5]
• vacuum extraction is discouraged before 34 weeks.^[4]
• Limit vacuum to three sets of pulls, two to three pop-offs and 20 to 30 minutes of application.^[4]
• Sequential vacuum and forceps is discouraged.^[4][5]
• Rotational Kielland forceps require an experienced operator, accurate position assessment with ultrasound preferred, and stopping if rotation is not easy.^[2]
• Perineal trauma is almost universal; classify by the Sultan scale and repair OASIS in theatre by trained clinicians.^[3][6]
• OASIS incidence is higher in first births than in later births.^[3][6]
• Continuous closure is preferred for second-degree tears; third- and fourth-degree repairs restore mucosa, internal sphincter and external sphincter separately.^[6]
• Treat severe perineal repairs with antibiotics, catheter care, laxatives and close follow-up.^[6]
• Respect informed choice; record every discussion.^[1]

Related practices include antepartum fetal surveillance, normal labour and delivery, labour stages and failure to progress, obstetric analgesia and anaesthesia, obstetric examination and fetal heart rate monitoring, postpartum haemorrhage, postpartum infection, pre-eclampsia and eclampsia, and prematurity. These topics are not linked individually until they are verified in the library.

Guidelines named are NICE NG207 (published 4 November 2021, minor changes May 2026), RCOG Green-top Guideline No. 26 (2020, 4th edition extended to 2026), RCOG Green-top Guideline No. 29 (3rd edition, June 2015, 4th in development), StatPearls reviews (2023 to 2025). ^[2][3]