Principles of Caesarean Section
This covers general principles of caesarian section. Particulars of caesarian section performed under general or regional anaesthesia are covered elsewhere.
Time: 45 to 90 minutes
Pain: Significant opioid requirement post-operatively
Position: Supine.
Blood loss: G+H required. Typically 500-100, but can be substantial.
Special Drugs: Uterotonics.
Caesarian section is delivery of a foetus through an abdominal incision. A caesarian section can be performed:
- At different degrees of urgency
Divided into 4 categories:- Cat 1
Imminent threat to life of mother or foetus.- Objective is to deliver baby as rapidly as possible whilst being safe
Epidural top-up (if available) or GA otherwise. Spinal is associated with ~8-10 minute additional anaesthetic time.
- Objective is to deliver baby as rapidly as possible whilst being safe
- Cat 2
Maternal or foetal compromise that is not imminently life threatening. - Cat 3
No compromise, but requires early delivery. - Cat 4
No compromise, delivery timed to suit the mother and the hospital.
- Cat 1
- With different techniques:
- General Anaesthesia
- Quick to perform and reliable
- Allows fastest delivery of baby
- Generally ↑ risk of complications
- Indications:
- Maternal request
- Cat 1 CS without pre-existing epidural
- Contraindication to regional technique
- Failure of regional technique
May be:- Prior to incision
- After incision
Limited consent and preparation time.
- Expected massive haemorrhage
- Regional
- Preferred method in absence of contraindications
- Includes:
- Spinal
- CSE
- Epidural top-up
- General Anaesthesia
Considerations
Indication:
Expected duration
Combined surgery
e.g. With salpingectomy or hysterectomy.A
- Probably higher risk of difficult airway
- Mallampati score ↑ both during pregnancy and during labour
- Higher risk of aspiration
- Probably higher risk of difficult airway
B
- Reduced FRC and ↑ VO2 in pregnancy lead to faster desaturation
- Respiratory function may be compromised with regional techniques
C
- HDx state may be compromised with regional techniques
Avoid if significant antepartum blood loss.
- HDx state may be compromised with regional techniques
D
- Consent
Depth of consent will be tailored to clinical urgency. - Anxiety
- Often first exposure many people have to the hospital system
Aim to make it a positive one. - Regional and neuraxial anaesthesia are anxiety-inducing
- Often first exposure many people have to the hospital system
- Consent
G
- Antacid prophylaxis
H
- Group and Hold
There is always a risk of massive haemorrhage with obstetric cases.
- Group and Hold
O
- Placenta position
Low-lying anterior placenta greatly ↑ risk of major haemorrhage, especially if there is a scar from previous CS. - Obstetric history
- Key questions:
- Previous gestations
- Previous caesarians
- Issues with current pregnancy
- Key obstetric factors:
- Pre-eclampsia
Generally, early epidural prior to thrombocytopenia is preferred. - Prematurity
Generally, regional techniques reduce foetal morbidity. - Post-dates
- Often require LUSCS
- Regional techniques generally preferred
- Breech presentation
- Elective LUSCS improves neonatal outcomes
- Regional preferred in elective LUSCS
- Multiple Gestation
- Early epidural provides route enables quick conversion to LUSCS in second-twin distress
- GA for cat 1 LUSCS
- Placenta praevia
Requires caesarian, cannot undergo spontaneous labour. - Placental adhesive disorders
High risk of haemorrhage and requirement for hysterectomy.
- Pre-eclampsia
- Key questions:
- Placenta position
Preparation
- Give antacid prophylaxis
- Ranitidine 150mg PO
2 hours prior to surgery. - 30ml sodium citrate
Immediately prior.
- Ranitidine 150mg PO
- Standard ANZCA monitoring
Cycle BP cuff minutely from induction until delivery.- Treat hypotension aggressively with vasopressor
Treat nausea aggressively with vasopressor, as this is often a sign of hypotension.
- Treat hypotension aggressively with vasopressor
- Give supplemental oxygen if < 95% on air
- Wedge
Under right hip to displace the gravid uterus off the IVC, and ensure venous return. - Large IVC
16G or bigger ideal, 18G acceptable. - Start phenylephrine infusion on commencement of anaesthesia, aiming to preserve the baseline BP
Generally 30-60ml/hr of 100ug/ml of phenylephrine.- Adjust infusion rate each minute depending on the blood pressure
25-50% increments are reasonable. - Phenylephrine is the preferred agent as it does not constrict the spiral arteries
- 100μg bolus can be used to treat hypotension
- Adjust infusion rate each minute depending on the blood pressure
- Ensure uterotonics available
- Prophylactic antibiotics
Should be given prior to skin incision.
Intraoperative
This section is divided into:
- Surgical stages
- General complications of CS
- Complications of regional techniques in CS
- Complications of GA in CS
Surgical Stages
- Test block (if regional)
- Transverse laparotomy
Generally little muscle relaxation is required. - Peritoneal retraction
- Uterine incision
If amnion is intact then amniotic fluid will enter abdominal cavity. - Delivery
Provision of routine uterotonics after delivery. - Uterine closure and haemostasis
Uterotonics
Uterotonics are routinely given to reduce PPH risk. General recommendations:
- Oxytocin or carbetocin should be given immediately following delivery
Inadvertent administration prior to delivery may be catastrophic. - Second-line agents should be considered early
- IM is a reasonable alternative to IV infusions in resource-limited settings
- Dose requirements for intrapartum caesarian are ↑ compared to elective caesarian
Dosing of first line agents:
- Oxytocin 5 IU IV and then an infusion 10 IU/hr
- Recommendations for dosing vary widely between official bodies, from 1-10U IV, with infusions from at 2.5-15 IU/hr
- Oxytocin should be given slowly to avoid adverse effects
- Recommendations for dosing vary widely between official bodies, from 1-10U IV, with infusions from at 2.5-15 IU/hr
- Carbetocin 100μg slow IV
Dosing of second line agents:
- Ergometrine 200-500μg
- Contraindicated in pre-eclampsia
- Can give half IV, half IM
- Contraindicated in pre-eclampsia
- Carboprost 250μg IM
- Contraindicated IV
- Contraindicated in asthma
- Can be given every 15 minutes up to 8 doses.
- Sulprostone 500μg; given at 100μg/hr.
General Complications of CS
- Massive haemorrhage
- Amniotic fluid embolism
- Post-partum haemorrhage
Typically due to poor tone.- Uterine massage
- Oxytocin
Postoperative
Most departments have a standard post-operative analgesia management protocol. Consider:
- Paracetamol 1g QID
- Ibuprofen 400mg TDS
- Tramadol 50-100mg IV/PO QID
- Ondansetron 4-8mg IV/SL TDS
If intrathecal morphine given:
- Naloxone 40μg SC Q1H
For itch. - Naloxone 100μg IV Q5 min
For RR ⩽8.
If no intrathecal morphine given:
- Oxycontin 20mg SR BD (wean in 1-2/7)
References
- Maronge, L., & Bogod, D. (2018). Complications in obstetric anaesthesia. Anaesthesia.
- Aberdeen Maternity Hospital Anaesthetic Guidelines. Management of Blood Pressure during Caesarean Sections under Spinal Anaesthesia. 2009.
- Nixon H, Leffert L. Anesthesia for cesarian delivery. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com
- Rollins M, Lucero J. Overview of anesthetic considerations for Cesarean delivery. Br Med Bull. 2012;101:105-25. doi: 10.1093/bmb/ldr050. Epub 2012 Jan 4.
- McGlennan A, Mustafa A. General anaesthesia for Caesarean section. Continuing Education in Anaesthesia Critical Care & Pain, Volume 9, Issue 5, 1 October 2009, Pages 148–151.
- Heesen M, Carvalho B, Carvalho JCA, et al. International consensus statement on the use of uterotonic agents during caesarean section. Anaesthesia. 2019;74(10):1305-1319. doi:10.1111/anae.14757