Describe the approach to and management of caesarean section at full dilatation

In one line

Caesarean at full dilatation is a high-morbidity operation whose defining hazard is the impacted fetal head (IFH) — and the governing principle is to anticipate impaction before you cut, assemble the team, and disimpact by flexion-and-elevation rather than brute force, favouring a "pull" (reverse breech extraction) over an isolated "push" when standard cephalic delivery fails.

This chapter assumes the operative groundwork in safe caesarean technique basics and the second-stage judgement in prolonged-second-stage — it concentrates on the advanced layer: classifying the impaction subtype, the disimpaction-ladder judgement calls, and appraising a fragile, partly-retracted evidence base. Where a basic mechanism is mentioned it is stated in one line and linked down.

Assessment

The decision to operate at full dilatation is itself the first judgement, and at this level the question is why this woman is on the table at 10 cm — because that history predicts not just whether the head is impacted but which subtype of impaction you will face, and the two subtypes are managed by opposite manoeuvres.

Classify the impaction before you scrub — there are two mechanically distinct subtypes that the basic account does not separate:

• The deeply impacted (insinuated) head — the wedged, jammed head. Defined clinically by immobility of the cephalic pole on vaginal examination and the absence of any space between the fetal head and the pubic symphysis. The vertex sits at or below the spines with significant caput and moulding, often after a long active second stage or a failed instrumental attempt. The mechanical problem is that the head is deflexed and impacted behind the symphysis; the solution is to get below it, flex it, and elevate it — and if that fails, to reach past it for the feet (reverse breech extraction, a "pull"). This is the classic IFH.
• The floating / non-insinuated high head — the opposite problem, and the trap. Defined by a head at or above the De Lee −3 plane — most often an OT/deep-transverse arrest, abdomino-pelvic disproportion, or a CS in early labour where the head never engaged. Here a "push from below" is useless (there is nothing to push against) and reaching past the head for the feet is awkward because the head fills the upper segment. The correct manoeuvre is internal podalic version: a hand passes deep into the uterus, grasps one or both ankles, and the fetus is delivered as a breech while the head is guided up toward the fundus — essentially the second-twin manoeuvre applied through a hysterotomy. Misreading a floating head as a "deeply impacted" one and ordering a vaginal push is a setup for a long, traumatic extraction.

The governing link: station defines the subtype, and the subtype defines the manoeuvre. A head jammed below the spines → flex/elevate, then pull (RBE). A head floating above De Lee −3 → internal podalic version. Reaching to push the head up without first establishing where the head is skips the distinction that decides the operation.

• History that predicts impaction (and its severity): prolonged active second stage, oxytocin augmentation, malposition (OP/OT/deep transverse arrest), and — critically — a failed or abandoned assisted vaginal birth. More than half of IFH cases follow a failed instrumental attempt. Macrosomia and a deeply engaged head with significant caput/moulding compound the risk. A large registry cohort (Ammitzbøll et al., EJOGRB 2023; n=2332) quantified independent risk factors for difficult fetal extraction: deep descent (head at the spines aOR ≈ 2.5, at the pelvic floor aOR ≈ 3.1), high pre-pregnancy BMI (aOR ≈ 1.4), anterior placenta (aOR ≈ 1.4) and top-up epidural rather than spinal anaesthesia (aOR ≈ 1.4) — and difficult extraction roughly tripled–quadrupled the odds of cord pH ≤ 7.09 and of major maternal blood loss. The mechanism→consequence chain is: deep descent → impaction → forceful extraction → lower-segment laceration extending to the angles/broad ligament → torrential bleeding and a compressed, acidotic fetus.
• Examination at decision: abdominal fifths palpable, vaginal station, position and degree of moulding (3+ sagittal moulding signals cephalo-pelvic disproportion in SA NDoH/SASOG practice), and whether the head recedes on relaxation. A head that will not be displaced abdominally at the start of the case is the warning that you will need advanced manoeuvres — decide then, while the patient is calm and the team is assembling, not mid-laceration.
• Investigations: group-and-save with crossmatch availability (incision extension and atony drive blood loss), and confirm a neonatal resuscitation team and senior obstetric presence. IFH is unpredictable: the RCOG position is that no antenatal or intrapartum variable reliably forecasts it, so vigilance — not a score — is the safeguard. Interpret a "trial of instrumental in theatre" not as a soft option but as a setup that, if it fails, hands you a more impacted head than the one you started with.

Severity stratification and the judgement call. There is no validated numerical IFH severity score. What you do stratify on is a triad: station/subtype (above De Lee −3 vs jammed below the spines), the preceding insult (virgin uterus vs failed Kielland's/ventouse with a battered lower segment), and the field you are operating in (a thinned, ballooned lower segment after prolonged obstructed labour, possibly with a Bandl's ring, tears far more readily). A deeply-impacted head after a failed instrumental in a Bandl-ringed obstructed labour is the highest-acuity version — assemble maximal seniority and have the disimpaction ladder rehearsed before the knife touches skin.

Management

Management runs immediate (pre-incision preparation) → intra-operative (the disimpaction ladder) → ongoing/long-term (complications and the next pregnancy).

Immediate — before the knife. Declare the anticipated difficulty in the WHO safety brief and name it: "anticipated impacted fetal head, I want a second obstetrician, neonatal team, and an assistant gowned for a vaginal manoeuvre." Stop any oxytocin infusion. Have GTN drawn up (the consultant dose, below), a step for the operator, and a trained assistant gowned and ready to assist vaginally. Position matters: reposition the legs in semi-lithotomy (knees flexed, thighs abducted) so a whole hand can reach the head from below — the act of repositioning sometimes releases the impaction itself. Choose the abdominal incision deliberately: a thinned, over-distended lower segment after obstructed labour tears unpredictably, so plan the uterine entry high enough to avoid extending into a Bandl's ring or the cervix.

Intra-operative — the disimpaction ladder (escalate like a shoulder-dystocia drill; there is no single mandated technique). Note that steps 3–5 are subtype-specific, not a fixed sequence — pick the limb that matches the impaction you classified at assessment:

Throughout, flexion is the mechanical principle for the impacted head — a deflexed head jammed behind the symphysis is the commonest reason elevation fails. The errors SIP No. 73 explicitly cautions against are a single forceps blade or the ventouse applied abdominally, and bladder filling to "float" the head — none are evidence-supported, and the forceps-blade/fingertip techniques are linked to fetal skull fracture.

After delivery, actively anticipate uterine incision extension, atony and PPH (build on PPH basics); have uterotonics and a postpartum-haemorrhage plan ready, and inspect systematically for bladder and ureteric injury — run the lower segment angles, check the bladder with methylene blue if in doubt, and identify the ureters before closing an extension that has tracked laterally.

Ongoing / long-term. Document the diagnosis, the subtype (impacted vs floating), the sequence of manoeuvres, incision type and findings contemporaneously — inadequate notes are the recurring medico-legal failure, and "impacted head, delivered with difficulty" is not a record. Examine the neonate for head/facial trauma, long-bone (femur/humerus) and brachial-plexus injury and HIE; have the neonatologist present. Counsel on the operative findings and their bearing on the next birth: a lower-segment T/J extension or classical extension changes future delivery advice (it argues against a trial of labour next time) and contraceptive counselling (postpartum contraception basics; intra-Final, contraception-in-high-risk-women). A psychological debrief matters — a traumatic, prolonged extraction is a recognised driver of birth-related PTSD and of declining future pregnancy.

The evidence & the controversy

The current authority is RCOG Scientific Impact Paper No. 73, 2nd edition (Cornthwaite et al., BJOG 2026) — note the first (2023) edition was retracted and replaced after data-integrity concerns in the underlying device literature, so the 2023 SIP no longer stands as a citation. The epidemiology: IFH complicates up to 1 in 10 unplanned caesareans (~1.5% of all births) and 16–32% of second-stage caesareans, with roughly 2 in 100 affected babies dying or seriously injured.

On technique, the best synthesis is the commissioned systematic review (Peak, Barwise & Walker, EJOGRB 2023; 16 studies, 3344 women). Compared with reverse breech extraction, the push method carried significantly higher risk of uterine incision extension (pooled OR ≈ 3.4, 95% CI ≈ 2.6–4.5), blood transfusion (RR ≈ 2.75), PPH (RR ≈ 2.2) and increased blood loss/operative time, with equivocal neonatal differences. That looks decisive — but the certainty is very low (GRADE): trials are small, poorly defined, at serious risk of bias, and crucially do not report operator training. The honest position is therefore that pull methods are associated with better maternal outcomes, but the evidence cannot establish superiority of any single technique; competence and case-specifics should drive the choice.

A worked appraisal of the only dedicated RCT, Nooh 2017 (n=192). Incision extension was 18.8% with RBE vs 47.9% with push. That is an absolute risk reduction of 47.9 − 18.8 = 29.1 percentage points (ARR ≈ 0.29), so the number-needed-to-treat to prevent one incision extension is 1 ÷ 0.291 ≈ 3.4 — i.e. roughly one extension avoided for every 3–4 women delivered by RBE rather than push, in this single small single-centre trial. The relative risk of extension is 18.8 ÷ 47.9 ≈ 0.39 (a ~61% relative reduction). The arithmetic comes with a hard caveat — n=192, one centre, unblinded, no training data — so the effect must be both quantified and discounted.

On Patwardhan and internal podalic version, the data are thinner still: small series suggest the Patwardhan ("pull"-family) method has fewer incision extensions than push and no clear difference from RBE, so it sits with RBE as a reasonable maternal-sparing option where the operator is trained. The defensible position is that all the "pull"-family manoeuvres (RBE, Patwardhan, internal podalic version) share the maternal-morbidity advantage over an isolated abdominovaginal push, and the choice between them is dictated by the impaction subtype and the operator's competence, not by trial superiority.

The Fetal Pillow is the controversy that separates current from outdated practice. The device is a disposable balloon inflated with ~180 mL saline that elevates the head 2–3 cm before incision. The 2014/2016 RCT and a later non-randomised study were retracted (2023–2024); SIP No. 73's own meta-analysis of remaining studies found no significant difference in incision extension (RR 0.90, 0.67–1.23) or PPH versus no pillow, and concluded the device should not be used outside research trials pending high-quality evaluation. The Tydeman tube and C-snorkel remain unproven. Recommending the Fetal Pillow as routine prevention misreads the current evidence. This is also a clean critical-appraisal worked example (statistics basics; intra-Final, maternity-statistics-critical-appraisal): a retracted positive trial, predatory-journal sensitivity analyses, and confidence intervals crossing 1.

Where genuine uncertainty remains. No technique is proven superior; there is no validated severity score; the role of preventive devices is unresolved; and the field still lacks the definitive RCT — the MIDAS scoping study calculated it would need 754 women per arm, which is why every current recommendation is "reasonable practice," not Grade-A evidence.

Landmark trials & key evidence

These are the studies to cite by name. The evidence base is dominated by small observational studies and one modest RCT, and that fragility — the certainty, not just the direction of effect — matters as much as the headline finding.

A defensible summary: "Reverse breech extraction is consistently associated with less maternal morbidity than the push method across one RCT and several meta-analyses — in Nooh the NNT to prevent one incision extension was about 3 to 4 — but every synthesis rates the certainty very low; no technique is proven superior, so the choice is individualised by impaction subtype and operator competence, and the Fetal Pillow is not adopted outside a trial given the retracted RCT and the negative real-world cohort."

Screening, prevention & system design

There is no antenatal screening test for IFH — RCOG is explicit that no antenatal or intrapartum variable reliably forecasts it. The "screening" that matters is therefore intrapartum recognition and system design:

• Decide instrumental-vs-caesarean honestly and early. The single most modifiable upstream factor is the failed assisted vaginal birth — more than half of IFH follows one. A senior, accurate assessment of the likelihood of vaginal delivery (station, position, caput/moulding, pelvic adequacy) before attempting instruments prevents the impacted-head CS that a failed forceps creates. A "trial in theatre" with the team prepared for immediate CS is reasonable; an optimistic instrumental attempt on the labour ward that fails and is then transferred to theatre is the worst pathway.
• Anticipate and brief. Where IFH is suspected, the maternity theatre team should be alerted pre-operatively in the standard WHO safety briefing and a senior obstetrician informed — this is the one process intervention with consensus support.
• Train the team. Because the evidence cannot crown a single technique, competence in more than one (RBE and at least recognition of when to use internal podalic version) is the realistic safeguard, drilled in skills-and-drills alongside shoulder dystocia and PPH.
• SA system reality: in district practice the failure mode is a junior operator meeting an impacted head from prolonged obstructed labour with no one more senior on site. The system answer is the NDoH referral framework — anticipate at the decision-for-CS, and where time and the fetal condition allow, the most senior available obstetrician should be present or the patient managed at a unit that can provide that.

Exam traps & red flags

• Failing to classify the subtype. Pushing a floating head (nothing to push against) or attempting internal podalic version on a head jammed below the spines wastes the minutes that matter. Establish the station first; let the subtype pick the manoeuvre.
• Treating a failed instrumental as the "safe" route. A failed forceps/ventouse pushes the head deeper; the resulting CS is more impacted, not less. Decide instrumental-vs-caesarean honestly at the outset.
• Pushing with fingertips. One or two fingers on the vertex is linked to skull fracture; the correct technique is a whole cupped hand with even pressure and flexion. Do not let an untrained assistant improvise.
• Brute abdominal force / repeated hand-jamming. Causes trauma and extension toward the angles, broad ligament, cervix and vagina. Pause, flex, consider tocolysis, then escalate the ladder.
• Rough reverse breech extraction. Excessive traction on the femur/humerus causes iatrogenic long-bone fracture — RBE's maternal advantage is real but not a licence for force; deliver the breech with controlled, Løvset-disciplined traction.
• Forgetting the cascade after delivery. Incision extension → atony → PPH, plus bladder/ureteric injury — anticipate and check actively (inspect the angles, methylene blue if unsure, identify the ureters before closing a lateral extension), do not discover them in recovery.
• Citing retracted evidence. The retracted 2023 SIP and retracted Fetal Pillow trials; recommending the Fetal Pillow, a single forceps blade/ventouse abdominally, or bladder filling for disimpaction (all explicitly cautioned against) reads as out-of-date.
• SA-context miss: the realistic district answer is anticipate at the decision-for-CS, call for the most senior obstetrician available, and be trained in reverse breech extraction — a "pull" technique well suited to lower-resource settings where impaction from prolonged obstructed labour is common — rather than relying on a device. The SA stakes are stark: in the Saving Mothers data the case-fatality rate for caesarean was 18.9 per 10 000 versus 6.7 per 10 000 for vaginal birth (2.8× higher), with 5.5 haemorrhage deaths per 10 000 caesareans — a difficult full-dilatation CS sits at the dangerous end of that distribution.

Worked viva — how to structure the answer

A typical stem: "You are called to theatre for a primigravida at full dilatation; a failed mid-cavity ventouse for OP position, the registrar cannot deliver the head. How do you proceed?" A high-scoring answer runs:

1. Frame it and classify — "This is an anticipated impacted fetal head after a failed instrumental — the highest-risk scenario. My first move is to establish which impaction this is: a head jammed below the spines, or a high/floating head — because that decides the manoeuvre."
2. Prepare before extending the difficulty — stop oxytocin, declare it in the safety brief, call a second obstetrician and the neonatal team, reposition to semi-lithotomy, draw up GTN, gown an assistant for a vaginal manoeuvre, ensure blood is available.
3. Run the ladder, subtype-led — "For a deeply impacted head I flex and elevate abdominally; if that fails I consider tocolysis with IV GTN, then a controlled vaginal push with a whole cupped hand, escalating to reverse breech extraction. For a floating head I would perform internal podalic version. I would not use a single forceps blade, a ventouse abdominally, or bladder filling."
4. Anticipate the cascade — "I expect incision extension, atony and PPH, and I actively inspect for bladder and ureteric injury before closing."
5. Justify from evidence honestly — "Pull methods are associated with less maternal morbidity than push — in the only RCT the NNT for incision extension was about 3 to 4 — but the certainty is very low and no technique is proven superior; the Fetal Pillow trials were retracted, so I individualise by subtype and competence."
6. Close the loop — contemporaneous documentation of subtype and manoeuvres, neonatal examination for trauma, debrief, and counselling that a lower-segment extension changes the plan for the next birth.

Evidence anchors

• Management of Impacted Fetal Head at Caesarean Birth — RCOG Scientific Impact Paper No. 73 (2nd edition; Cornthwaite et al., BJOG 2026) — definition, incidence, technique ladder, Fetal Pillow caution. RCOG landing page: SIP No. 73
• Peak AGq, Barwise E, Walker KF. Techniques for managing an impacted fetal head at caesarean section: a systematic review. Eur J Obstet Gynecol Reprod Biol 2023;281:12–22 — 16 studies/3344 women; push vs reverse breech extraction; push significantly worse for extension (pooled OR ≈ 3.4), transfusion, bladder injury, PPH, NICU admission, Apgar <7.
• Jeve YB, Navti OB, Konje JC. Comparison of techniques used to deliver a deeply impacted fetal head at full dilation: a systematic review and meta-analysis. BJOG 2016;123(3):337–45 — earlier synthesis (12 studies) favouring reverse breech extraction.
• Berhan Y, Berhan A. A meta-analysis of reverse breech extraction to deliver a deeply impacted head during cesarean delivery. Int J Gynaecol Obstet 2014;124(2):99–105 — uterine extension >8× higher with the push method.
• Nooh AM, Abdeldayem HM, Ben-Affan O. Reverse breech extraction versus the standard approach of pushing the impacted fetal head up through the vagina in caesarean section for obstructed labour: a randomised controlled trial. J Obstet Gynaecol 2017;37(4):459–63 — the only dedicated RCT (n=192); RBE 18.8% vs push 47.9% incision extension (ARR 29.1%, NNT ≈ 3.4).
• Seal SL, Dey A, Barman SC, et al. (RETRACTED) Randomized controlled trial of elevation of the fetal head with a fetal pillow during cesarean delivery at full cervical dilatation. Int J Gynaecol Obstet 2016;133(2):178–82 — reported RR 0.23 for major extension; subsequently retracted — do not cite as live evidence.
• Sacre H, Bird A, Clement-Jones M, Sharp A. Effectiveness of the fetal pillow to prevent adverse maternal and fetal outcomes at full dilatation cesarean section in routine practice. Acta Obstet Gynecol Scand 2020;100(5):949–54 — largest cohort (n=391); no significant maternal or fetal benefit.
• Lassey SC, Little SE, Saadeh M, et al. Cephalic Elevation Device for Second-Stage Cesarean Delivery: a randomized controlled trial. Obstet Gynecol 2020;135(4):879–84 — CED RCT (n=60): 23-second faster delivery, no significant reduction in incision extension (underpowered).
• Ammitzbøll ILA, Andersen BR, Lange KHW, Clausen T, Løkkegaard ECL. Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. Eur J Obstet Gynecol Reprod Biol 2023;283:74–80 — registry cohort (n=2332): deep descent, BMI, anterior placenta and top-up epidural predict difficult extraction.
• MIDAS scoping study — Walker KF, Mitchell EJ, Ayers S, et al. Feasibility of a RCT of techniques for managing an impacted fetal head during emergency caesarean section. Health Technol Assess 2023;27(6):1–87 — IFH in 16% of second-stage CS; 41% maternal, 3.5% neonatal complications; a definitive trial needs 754 women/arm. PMC full text
• Difficult fetal extraction in cesarean section (review). Obstet Gynecol Sci / PMC 2024 — defines the deeply-impacted vs floating (De Lee −3) subtypes, internal podalic version for the floating head, and the IV nitroglycerin tocolysis dose (50 µg, repeatable).
• Young C et al. Maternal and perinatal outcomes of prolonged second stage of labour: a historical cohort study of over 51,000 women. BMC Pregnancy Childbirth 2023 — rising PPH/OASI with second-stage duration that drives full-dilatation CS.
• Gebhardt GS et al. Maternal death and caesarean section in South Africa: 2011–2013 Saving Mothers report. SAMJ 2015 — CS case-fatality 18.9 vs 6.7 per 10 000 (2.8× higher than vaginal birth); 5.5 haemorrhage deaths per 10 000 CS — the SA stakes behind a difficult full-dilatation caesarean.
• SASOG BetterObs guide to best practice for management of labour — SA second-stage time limits (active pushing: Para 0 ≤ 45 min, multipara ≤ 30 min; refer on 3+ sagittal moulding/CPD). PDF
• SA NDoH National Integrated Maternal and Perinatal Care Guideline (2024) — national referral/level-of-care framework for second-stage decisions.