General anaesthesia for operative obstetrics

Abstract

In the UK, general anaesthesia for elective obstetric surgery is uncommon. This article concentrates on general anaesthesia for caesarean section, however, many principles apply for antepartum and postpartum surgery such as cervical cerclage, manual removal of retained placenta, and repair of genital tract trauma. Regional anaesthesia for caesarean section is encouraged, but there are absolute and relative indications for general anaesthesia. If a woman refuses regional anaesthesia, her concerns and discussion of risk and benefits should be documented. Immediate delivery for fetal survival (e.g. cord prolapse) does not necessarily mandate general anaesthesia. Even if the anaesthetist is presented with an unknown patient with a fetus in extremis, there must be a focused preoperative assessment. Essential aspects of the practical conduct of general anaesthesia for caesarean section are antacid prophylaxis, patient positioning with left uterine displacement to prevent aortocaval compression, preoxygenation and a rapid-sequence induction with cricoid pressure. Overpressure of the volatile agent rapidly increases the end-tidal concentration to over 0.75 MAC. After delivery, oxytocin, opioids and prophylactic antibiotics are given. The patient is extubated awake, in a head-down, left-lateral position. NSAIDs, paracetamol and opioids provide postoperative analgesia. Thromboprophylaxis includes early mobilization, leg stockings and heparin until discharge if there are additional risk factors. Potential complications are hypoxia, pulmonary aspiration of gastric contents, a hypertensive response to intubation, maternal awareness, transient neonatal depression, and haemorrhage.