Anaesthetic considerations for impacted fetal head at caesarean delivery: a focused review

Impacted fetal head occurs when the fetal head is deeply engaged within the maternal pelvis and difficult to deliver during caesarean delivery. In order to deliver the fetal head, additional surgical manoeuvres and/or pharmacological tocolysis are needed. The aim of this focused review is to outline the incidence, risk factors, management and complications of this obstetric emergency from the perspective of the anaesthetist.

Databases were searched for free text headings and subject headings associated with different permutations of terms related to impacted fetal head and caesarean delivery.

Impacted fetal head has been estimated to occur in 1.5 % of elective caesarean deliveries and 2.9-18.4% of all emergency caesarean deliveries at any cervical dilatation. Risk factors include advanced cervical dilatation, labour augmentation with oxytocin, prolonged second stage of labour, fetal malposition and junior grade of operating obstetrician. If impacted fetal head occurs, the anaesthetist in conjunction with the multidisciplinary team should consider decreasing the height of the operating table, providing a step for the obstetrician to stand on, placing the patient in the head down position, providing pharmacological tocolysis with glyceryl trinitrate (or nitroglycerin), beta-2 adrenoreceptor agonists or volatile anaesthetic agents, and managing complications such as postpartum haemorrhage.

Impacted fetal head is an obstetric emergency that the anaesthetist should be familiar with and has a vital role in managing. We propose an algorithm for management that may serve as a clinical decision aid.