Anaesthesia for Non-Obstetric Surgery in the Obstetric Patient

The Bottom Line: * Miscarriage is a complication but rarely due to anaesthesia * Principles of intrauterine resuscitation apply * General considerations for the obstetric patient apply * Consider antenatal steroids * Perioperative foetal monitoring required for all pregnancies, but intraoperative only if the pregnancy is viable and the operation could be paused to facilitate caesarian delivery

Approximately 2% of pregnant women will undergo surgery for non-obstetric indications. Key considerations are:

Preoperative

Assessment: * Indication for surgery and inherent risk to foetus
Most common including: * Appendicitis * Cholecystitis * Trauma * Maternal malignancy * Gestational age

Consultation: * Obstetric team * Paediatrician if pre-term labour anticipated

Optimisation: * Operation should occur at centre that is: * Capable of performing a delivery if delivery indicated * Capable of looking after child post-delivery (e.g. PICU/NICU, depending on gestational age)

Premedication: * Consideration of antenatal glucocorticoids if pre-term delivery likely

Explain/Consent: * Risk of miscarriage
↑ with lower gestational age and conditions associated with local inflammation. * Overall ~6%, though up to 10% in first trimester * Second trimester preferred for semi-elective surgery * Elective surgery should be postponed until postpartum * Pregnancy is never a contraindication to urgent surgery

Intraoperative

Preparation: * Regional anaesthesia preferred where feasible, though this lacks evidence * Minimises foetal drug exposure * Consideration of CTG monitoring * Should be considered in a viable pregnancy, i.e. if the use of the monitor would change management
Note that loss of foetal heart rate variability is normal in the context of anaesthesia. * Continuous monitoring preferable provided: * Technically possible with surgery * Surgery can be interrupted to deliver a distressed foetus * Prior to viability, doppler monitoring pre- and post-operatively can be used to confirm foetal wellbeing

Induction: * Use a wedge to prevent aorto-caval compression after 20 weeks
May be required earlier if polyhydramnios or multiple pregnancy. * Other obstetric considerations, depending on degree of gestation

Maintenance: * Drug considerations * N2O
Avoid in first trimester, may be teratogenic. * NSAIDs
Avoid after 28 weeks due to concern about premature ductus closure.

Postoperative

Referrals/Review: * Foetal monitoring must be performed in the recovery room: * Continuously for viable foetuses * Intermittently for non-viable foetuses

Thromboprophylaxis: * All pregnant patients are high risk and both mechanical and pharmacological prophylaxis should be employed

References

  1. Nejdlova M, Johnson T. Anaesthesia for non-obstetric procedures during pregnancy. Contin Educ Anaesth Crit Care Pain. 2012;12(4):203-206. doi:10.1093/bjaceaccp/mks022
  2. Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology. Anesthesiology 2016;124(2):270–300.
  3. Nonobstetric Surgery During Pregnancy – ACOG [Internet]. [cited 2019 Jul 18];Available from: https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Nonobstetric-Surgery-During-Pregnancy?IsMobileSet=false
  4. Tolcher MC, Fisher WE, Clark SL. Nonobstetric Surgery During Pregnancy. ObstetGynecol 2018;132(2):395–403.