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← Obstetrics and gynaecology indexChapter sections
Purpose and principlesIndications, selection and cautionsAssessment before treatmentTreatment approachRegimens, contraindications and interactionsComplications, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Assisted vaginal birth

Obstetrics and gynaecology · UK scope · Sources checked 7 Sept 2026 · Clinical review pending

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An unsuccessful or unsafe instrumental attempt

Failure of the head to descend, difficulty applying forceps, difficult rotation or repeated vacuum detachment requires the attempt to stop and the plan to be reassessed. Greater traction is not a substitute for understanding why progress has failed.

Action: Stop the attempt, call an experienced obstetrician and reassess position, station, application, fetal condition and possible disproportion. Decide promptly whether another carefully justified approach or caesarean birth is safer. Inform neonatal colleagues about failed attempts, detachments or sequential instruments so that the baby receives appropriate assessment.

Purpose and principles

Assess when forceps or vacuum assistance may provide a safe route to birth, explain the alternatives, and recognise prerequisites, stopping points and postnatal complications.

Assisted vaginal birth uses forceps or a vacuum cup to help the baby through the final part of the birth canal. The purpose is to complete a birth that is already sufficiently advanced for a safe vaginal attempt. It may be quicker and less invasive than caesarean birth in an appropriate situation, but the comparison changes if the head is high, its position is uncertain or rotation is difficult. The decision therefore rests on a skilled examination and an honest assessment of likely success.

Forceps and vacuum have different trade-offs. Forceps are generally more likely to complete birth with the first instrument but are associated with more maternal perineal trauma. Vacuum tends to cause less maternal trauma but may fail or cause scalp injury. Neither is uniformly preferable. Explain why assistance is being advised, the proposed instrument, likely discomfort, possible episiotomy and the alternative of caesarean birth where feasible. Even in urgent care, use clear language and check consent rather than assuming that the urgency removes the patient's involvement.

Key points

Indications, selection and cautions

Indication and urgency

Clarify whether the aim is to address fetal concern, lack of progress, exhaustion or a medical reason to reduce prolonged pushing. Assess the degree of urgency alongside what can realistically be achieved. A low straightforward birth and a difficult rotational attempt are not equivalent choices in an emergency.

Prerequisites for an attempt

Confirm full dilatation, ruptured membranes, an engaged head and an accurately identified presentation and position. Assess station from the bony skull rather than caput, and consider pelvic adequacy and moulding. Check that the bladder is empty and analgesia is sufficient before instrument application.

Selecting the instrument

Gestation, fetal condition, position, station and anticipated rotation influence choice. RCOG advises avoiding vacuum below 32 weeks and using caution from 32+0 to 36+0 weeks. Suspected fetal bleeding or bone disorders require particular consideration; routine vacuum use is also inappropriate for a face presentation.

Likelihood of difficulty

A high station, uncertain position, marked caput or moulding, suspected large baby and rotational requirements can lower success. When difficulty is anticipated, choose a setting with immediate access to caesarean birth and the appropriate anaesthetic and neonatal team.

Red flags requiring action

  • No progressive descent with correctly applied moderate traction requires abandonment or expert reassessment.
  • Two vacuum cup detachments require vacuum-assisted birth to be discontinued.

Assessment before treatment

  1. 01
    Abdominal and vaginal assessmentFirst step
    Why
    Establish whether the anatomical conditions permit a safe attempt.
    Interpretation and limitations
    Assess engagement, position, station, caput, moulding and pelvic findings after confirming full dilatation. Findings should be recorded before application. If the examination cannot establish position reliably, further assessment is preferable to proceeding on an assumption.
  2. 02
    Intrapartum ultrasound when appropriate
    Why
    Clarify fetal head position before an uncertain or rotational procedure.
    Interpretation and limitations
    Ultrasound is more reliable than clinical examination for defining occiput position and is advisable before Kielland's rotational forceps. It is not mandated before every assisted birth, and interpretation still requires an operator able to connect the finding to the proposed procedure.
  3. 03
    Current fetal heart assessment
    Why
    Determine urgency and monitor the baby's response to the attempt.
    Interpretation and limitations
    Review the trace and preceding events rather than relying on an earlier reassuring assessment. Persistent fetal compromise may shorten the time available for an attempt, while failure to progress requires prompt reconsideration of the safest route.
  4. 04
    Maternal and neonatal examination after birth
    Why
    Detect trauma and physiological complications requiring treatment or observation.

Treatment approach

01Before assistanceAgree a feasible birth planFirst stepA maternal or fetal indication for assistance has been identified during second stage.+
  1. 1Explain why assistance is advised and discuss the proposed instrument, expected benefit, trauma risks, possible failure and feasible alternatives.
  2. 2Confirm the prerequisites and document position and station, with ultrasound when uncertainty or rotational planning makes it useful.
  3. 3Ensure a suitably experienced operator, adequate analgesia, an emptied bladder and access to appropriate assistance and resuscitation.
  4. 4Choose the location according to anticipated difficulty, including theatre when an immediate caesarean may be needed, and state the stopping and backup plan.
02During the attemptRequire progress and stop when safety limits are reachedForceps or vacuum assistance has begun after assessment and consent.+

Regimens, contraindications and interactions

Reduces maternal infection following forceps or ventouse birth.

Co-amoxiclav after assisted vaginal birth

Use a single intravenous dose of co-amoxiclav 1.2 g, containing amoxicillin 1 g and clavulanic acid 200 mg, as soon as practicable and within six hours after cord clamping when suitable. This is the regimen studied in the UK ANODE trial supporting prophylaxis.

Check penicillin allergy, previous co-amoxiclav-associated liver injury and concurrent treatment. NICE permits a locally agreed alternative for allergy; established sepsis or major contaminated trauma requires its own treatment assessment rather than prophylaxis alone.

Provides adequate comfort and operating conditions for a safe birth attempt.

Analgesia and anaesthesia for assistance

The anaesthetist or trained operator selects an epidural top-up, spinal technique, pudendal block or local infiltration according to the procedure and existing analgesia. Drug, concentration and volume depend on the block already present, patient factors and anticipated manipulation.

Do not proceed through pain because an instrument has already been selected. Rotational or potentially difficult procedures generally require more substantial anaesthesia, and all additional local anaesthetic doses must account for cumulative exposure.

Complications, monitoring and follow-up

  • Observe maternal bleeding, haemodynamics and perineal pain after birth, with examination for a concealed haematoma when pain or instability is disproportionate.
  • Monitor bladder sensation and voiding, particularly after epidural, prolonged labour or significant trauma; urinary retention needs timely assessment.
  • Ensure the neonatal team evaluates concerning scalp swelling, altered behaviour, feeding difficulty, pallor or poor perfusion, especially after a difficult vacuum attempt.
  • Arrange appropriate review for suspected sphincter injury, persistent urinary or faecal symptoms, wound problems or ongoing severe pain.
  • Document the procedure and provide a balanced explanation of implications for a future pregnancy; one assisted birth does not automatically require another.

Special situations

A detachment is a warning

Vacuum cup detachment should prompt reassessment of application, traction and the mechanical situation. It is not a protective event that allows repeated attempts without consequence.

Pull counts require clinical judgement

RCOG expects most vacuum births to bring the head to the perineum within three pulls; up to three additional gentle pulls may be used to ease the head out once it reaches the perineum. Lack of descent requires stopping or reassessment earlier, rather than using the full count.

Sequential instruments change neonatal assessment

Using forceps after a failed vacuum may occasionally avoid a difficult caesarean, but increases traumatic risk. The senior decision and neonatal handover should make that extra exposure explicit.

Episiotomy is a procedure-specific decision

Discuss the likely need and use a mediolateral technique when indicated, considering an angle of 60 degrees from the midline at a distended perineum. Adequate analgesia and careful examination afterwards remain necessary.

Common pitfalls

  1. 01

    Attempting assistance when fetal head position or engagement has not been established.

  2. 02

    Mistaking caput for a low bony station and overestimating the likelihood of success.

  3. 03

    Continuing traction despite absent descent because the fetal heart makes birth urgent.

  4. 04

    Treating repeated vacuum detachments as an acceptable routine feature of the device.

  5. 05

    Changing instruments without senior reassessment and a documented comparison with caesarean birth.

  6. 06

    Omitting antibiotic prophylaxis or postnatal examination because the birth was completed quickly.

Practice

Two practice questions

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Question 1 of 2
0 correct
Obstetrics and gynaecologyOriginal SBA

Apply vacuum detachment limits

A maternity team is reviewing the stopping rules for vacuum-assisted birth. Apart from other reasons to stop earlier, which combination correctly states RCOG's detachment limit and the point when a less experienced operator should seek senior support?

Choose one answer, then submit
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Sources and review status5 sources · checked 7 Sept 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 7 Sept 2026; clinical approval remains outstanding.

  • RCOG Green-top 26 assisted vaginal birth and safety update
  • RCOG assisted vaginal birth full guideline
  • NICE NG235 assisted birth and antibiotic recommendations
  • NIHR ANODE trial antibiotic regimen and findings
  • RCOG patient information on ventouse and forceps

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Assisted vaginal birth may be appropriate for fetal concern, prolonged second stage, maternal need to limit pushing or a request for assistance.
  • The cervix must be fully dilated, membranes ruptured and the head engaged, with presentation, position and station established.
  • Adequate analgesia, consent, an emptied bladder, a competent operator and a realistic backup plan are essential.
  • The instrument and setting depend on urgency, fetal position and station, gestation and the operator's expertise.
  • Rotational forceps require experienced practice or direct supervision; ultrasound confirmation of position is advisable for Kielland's rotational forceps.
  • A successful low assisted birth can avoid the difficulties of a second-stage caesarean, but a prolonged unsuccessful attempt adds risk.
  • After forceps or ventouse birth, offer a single intravenous prophylactic antibiotic dose within six hours of cord clamping.
    • Forceps that do not apply or approximate easily, or rotation that requires more than gentle pressure, must not be forced.
  • A deteriorating fetal heart pattern requires an updated urgent birth decision, including whether the proposed vaginal attempt remains achievable.
  • Increasing neonatal scalp swelling, pallor, tachycardia or poor perfusion after vacuum birth requires urgent assessment for significant bleeding.
    • Interpretation and limitations
    Assess blood loss and examine the genital tract, including assessment for anal sphincter injury with consent and adequate analgesia. Examine the baby and communicate the instrument, difficulty, number of pulls and detachments, because some traumatic complications develop after an initially reassuring appearance.
    1. 1Continue fetal assessment and ensure the patient understands what is happening, including the role of pushing and any need for an episiotomy.
    2. 2Require progressive descent with appropriate moderate traction; lack of progress prompts reassessment of application, position and possible disproportion.
    3. 3For vacuum, discontinue after two detachments; a less experienced operator should seek senior support after the first. Minimal descent with the first two pulls also warrants reassessment.
    4. 4For forceps, stop if application or handle approximation is difficult, rotation is not easily achieved with gentle pressure, or birth is not imminent after three pulls by an experienced operator.
    5. 5If the attempt is abandoned, reassess urgently with senior help. Sequential instruments require a deliberate risk comparison with caesarean birth rather than being an automatic next step.
    03After birthPrevent infection and identify traumaThe baby has been born after a completed or attempted assisted vaginal procedure.+
    1. 1Assess maternal condition, quantify bleeding and examine for perineal, vaginal and anal sphincter trauma with appropriate explanation and analgesia.
    2. 2Offer the indicated single intravenous prophylactic antibiotic within six hours of cord clamping, accounting for allergy and any existing antibiotic treatment.
    3. 3Provide neonatal assessment and explicitly communicate failed attempts, repeated detachments, sequential instruments or suspected traumatic injury.
    4. 4Plan analgesia, bladder monitoring, thrombosis assessment and pelvic floor advice according to the actual injuries and recovery.
    5. 5Explain the events and reasons for decisions before discharge, offer an opportunity for questions and arrange follow-up for persistent pain, continence problems or psychological distress.