Vaginal Delivery
Stages of Labour
| Stage | NICE definition | |
|---|---|---|
| First stage | Latent | From:
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| Active (established labour) | From:
To: full dilation (10 cm) |
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| Second stage |
or starts when the baby is visible |
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| Third stage |
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Mechanisms of Normal Vaginal Delivery
The steps outlined in the table below assume vertex presentation, occiput-anterior position
The mechanism of vaginal delivery varies according to fetal presentation and position. Delivery in non-vertex presentations (e.g. breech, face, brow) and malpositions (e.g. occipito-posterior) follows different mechanisms and is considered specialist-level knowledge, therefore omitted.
| Stage | Movement | Description |
|---|---|---|
| 1 | Engagement | Widest diameter of fetal head enters the pelvic brim |
| 2 | Descent | Head descends through the pelvis |
| 3 | Flexion | Head flexes as it meets resistance of the pelvic floor |
| 4 | Internal rotation | Head rotates from transverse to anterior position, aligning with the anteroposterior diameter of the outlet |
| 5 | Extension | Head extends as it passes under the pubic symphysis |
| 6 | Restitution | Head returns to its natural alignment with the shoulders |
| 7 | External rotation | Shoulders rotate into the anteroposterior diameter of the outlet |
| 8 | Expulsion | Delivery of the anterior shoulder → posterior shoulder → rest of the body |
Assisted Vaginal Delivery
See the Assisted Vaginal Delivery article.
Caesarean Section
Types and Indications
Disclaimer:
The most important indications to learn for exam purposes are those for Category 1 and Category 4.
NICE NG25 does not provide specific clinical examples for Category 3, as indications at this level are highly variable and determined on an individual basis, this column has therefore been left blank.
| Classification | Description | Timing protocol | Indications (non-exhaustive) |
|---|---|---|---|
| Category 1 (Emergency / “Crash”) | Immediate threat to the life of the woman or fetus | Within 30 min of making the decision |
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| Category 2 (Emergency / Urgent) | Maternal or fetal compromise which is not immediately life-threatening | Within 75 min of making the decision |
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| Category 3 (Urgent / Early) | No maternal or fetal compromise but needs early birth | No strict time limit – scheduled at earliest convenience | |
| Category 4 (Planned / Elective) | Birth timed to suit the woman or healthcare provider |
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Pre-Operative Care
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Category
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Recommended actions
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Additional details
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|---|---|---|
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Blood Tests
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Perform:
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Do not routinely carry out cross-matching or clotting screen
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Gastric preparation
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Offer antacids and drugs (H2 antagonist or PPIProton pump inhibitor)
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This helps reduce gastric volumes and acidity before the caesarean birth to prevent Mendelson’s syndrome (chemical aspiration pneumonitis)
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Prophylactic antibiotics
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Offer prophylactic antibiotics before the skin incision
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BNF recommends single dose of IV cefuroxime
Do not use co-amoxiclav (due to increased risk of NECNecrotising enterocolitis)
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Thromboprophylaxis
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Offer thromboprophylaxis to women having a caesarean birth
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Base the method (e.g. graduated stockings, hydration, early mobilisation, low molecular weight heparin) on the risk of thromboembolic disease
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Bladder Care
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Give an indwelling urinary catheter
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This is indicated for women having regional anaesthesia to prevent over-distension of the bladder
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Pain relief during labour is covered in the Intrapartum Care article.
Do not routinely carry out a preoperative ultrasound for localisation of the placenta.
Types of Incision
Recommended incision: low, transverse, straight skin incision (Joel-Cohen technique)
- Incision made ~3cm above the pubic symphysis
- Subsequent tissue layers should be opened bluntly, and only extended using sharp dissection if necessary
- Associated with better outcomes compared to the Pfannenstiel technique: shorter operating time, less post-operative pain, reduced febrile morbidity, and shorter hospital stay
Alternative incisions:
- Pfannenstiel technique – curved, transverse incision, 2–3 cm above the symphysis pubis
- Uses sharp dissection of subsequent layers
- More commonly used in clinical practice despite being the non-recommended technique
- Preferred by some surgeons for cosmetic reasons
- Vertical midline (classical) – subumbilical midline incision
- Faster abdominal entry and less bleeding
- Used when rapid access is needed (e.g. some Category 1 emergencies) or when transverse incision is unsuitable
- Higher risk of wound dehiscence and incisional hernia
Disclaimer
NICE intentionally avoids using named techniques (such as Joel-Cohen and Pfannenstiel) in its formal recommendations, as the number of techniques and their modified variations may lead to confusion. However, familiarity with these named techniques remains important clinical knowledge and is likely to be encountered in practice.
Abdominal Wall Layers (Skin to Uterus)
This is the answer to the classic OSCE question of “what layers do you pass through in a C-section?”
Abdominal wall layers incised during Caesarean section (superficial to deep)
| Layer | Notes |
|---|---|
| Skin | See the ‘types of incision’ section above regarding how the skin is incised |
| Camper’s fascia | Loose, fatty adipose tissue |
| Scarpa’s fascia | Thin, membranous, fibrous layer |
| Rectus sheath (anterior layer) | Fibrous sheath enclosing the rectus abdominis muscle |
| Rectus abdominis muscle | Separated bluntly in the midline |
| Transversalis fascia | Often not distinctly identified or incised as a separate step in clinical practice, as it is very thin and closely adherent to the peritoneum |
| Parietal peritoneum | Outer layer of the peritoneum |
| Visceral peritoneum | Reflected downward to expose the lower uterine segment and displace the bladder inferiorly to protect it |
| Uterine wall (lower segment) | Incised to deliver the baby, either lower segment transverse (most common) or vertical (classical) |
Vertical (Classical) Uterine Incision
The classical uterine incision is a vertical incision through the upper uterine segment.
Indications:
- Preterm labour with poorly formed lower uterine segment
- Placenta praevia / placenta accreta spectrum – to avoid cutting directly through the placenta, thus massive haemorrhage
- Transverse fetal lie – as a lower segment transverse incision does NOT provide adequate room or access to deliver a transversely lying fetus safely
- Some Category 1 emergencies – to gain rapid uterine access
It is avoided where possible, as a scar at the upper uterine segment (the contractile portion of the uterus) is under significantly greater mechanical stress during future labours, resulting in a higher risk of uterine rupture.
A previous classical uterine incision is an absolute contraindication to vaginal birth after caesarean (VBAC) – see the Birth After Previous Caesarean Birth article for more information.
Mode of Delivery Indications (Vaginal Delivery vs Caesarean Section)
Information regarding delivery setting is discussed in the Intrapartum Care article.
Clinical Indications for Mode of Delivery
The 2 most important indications for elective Caesarean section (category 4) are:
- Placenta praevia (see the Placenta Praevia article)
- Placenta accreta spectrum (see the Placenta Accreta Spectrum article)
Assuming they are uncomplicated…
IMPORTANT: the following are indications for category 1 (emergency / “crash”) Caesarean section:
- Placental abruption (with maternal and/or fetal compromise)
- Umbilical cord prolapse (esp. with abnormal fetal heart rate)
- Placenta previa with spontaneous labour (esp. with maternal and/or fetal compromise)
- Suspected uterine rupture
- Fetal hypoxia
- Persistent fetal bradycardia
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Clinical Scenario / Condition
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Indicated Mode of Birth
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|---|---|
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Low-risk, uncomplicated pregnancy
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Vaginal birth is generally planned, as it is very safe for the woman and baby
Patient may also request Caesarean section – see the Caesarean Section on Maternal Request section below
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Placenta praevia
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Planned caesarean birth
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Placenta accreta spectrum
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Planned caesarean birth
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Breech presentation (uncomplicated)
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Discuss the following 3 options:
See the Breech Presentation article for more information
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Hepatitis B virus
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Vaginal birth (A planned caesarean birth should not be offered for this reason alone, as vaccination and immunoglobulin reduce transmission)
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Hepatitis C virus (without HIV)
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Vaginal birth (A planned caesarean birth should not be offered for this reason alone)
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Hepatitis C and HIV co-infection
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Planned caesarean birth is offered to reduce mother-to-baby transmission
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Primary genital herpes (in the third trimester or 6 weeks before delivery)
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Planned caesarean birth is offered to decrease the risk of neonatal infection
See the Genital Herpes in Pregnancy article for more information
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Recurrent genital herpes
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Vaginal birth (A planned caesarean birth should not routinely be offered)
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High BMI
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Vaginal birth (A BMI of over 50 kg/m2 alone should not be used as an indication for a planned caesarean birth)
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Predicted cephalopelvic disproportion
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Vaginal birth (Estimations of fetal size, maternal height, or maternal shoe size do not accurately predict disproportion and should not be used for decision making about a caesarean birth)
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Caesarean Section on Maternal Request
Vaginal birth is the standard planned mode of delivery for women at low risk of complications, and is generally very safe for both the mother and baby.
However, women have the right to choose their mode of birth. If a woman requests a caesarean birth without a medical or obstetric indication (listed above), including cases of tokophobia (a severe, pathological fear of childbirth) or personal preference, her choice should be supported following an informed discussion about the benefits and risks of each mode of delivery
This discussion should include the comparative outcomes and complications of caesarean section versus vaginal birth, outlined in the table below. In clinical practice, this conversation is supported by a formal consent form with numerical estimates of risks (RCOG version), therefore specific risk figures are omitted here.
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Outcome / Complication
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Key Takeaway and Risk Difference
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|---|---|
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MATERNAL OUTCOMES: Increased Risk with Caesarean section (CS)
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Maternal Death
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Rare but increased maternal death in CS
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Peripartum Hysterectomy
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Increased risk of peripartum hysterectomy in CS
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Hospital Stay
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Longer hospital stay and recovery in CS (4 days vs 2.5 days)
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Uterine Rupture (Future Pregnancies)
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Significant future risk of uterine rupture
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Placenta Accreta (Future Pregnancies)
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Significant future risk of placenta accreta spectrum
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MATERNAL OUTCOMES: Increased Risk with Vaginal Birth (VB)
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Vaginal Tear
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Exclusive to vaginal birth (CS does NOT cause vaginal tear)
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Urinary Incontinence (>1 year after birth)
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Increased risk of urinary incontinence in VB
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Faecal Incontinence (>1 year after birth)
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Increased risk of faecal incontinence in assisted VB (forceps / ventouse)
However, there is no difference in risk between CS and unassisted vaginal birth
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Pain (During and after birth)
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More pain in VB
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NEONATAL/CHILDHOOD OUTCOMES
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Neonatal Mortality
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Rare but elevated in CS
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Childhood Asthma
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Elevated in CS
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The following outcomes are likely to be similar for CS and VB:
- Maternal outcomes
- Thromboembolic disease
- Major obstetric haemorrhage
- Postnatal depression
- Neonatal / childhood outcomes
- Admission to neonatal unit
- Infection
- Persistent verbal delay
- Infant mortality (up to 1 year)
Birth After Previous Caesarean Section
See the Birth After Previous Caesarean Birth article.
References
NICE guideline Caesarean birth
NICE guideline Caesarean birth Appendix A - Benefits and risk of vaginal and caesarean birth