Labour outcomes in siblings with channelopathy associated insensitivity to pain due to bi-alleleic SCN9A mutations.

The gene SCN9A encodes for the voltage-gated sodium channel Nav1.7, which is highly expressed in pain sensing neurons. Bi-allelic 'loss of function' mutations result in a channelopathy associated with insensitivity to pain and anosmia. This is the first report of the labour and postpartum outcomes of two sisters who belong to a non-consanguineous Caucasian family with homozygous SCN9A mutations. Neither sister experienced pain during labour; this had major implications for the staff titrating the syntocinon for labour augmentation and contributed towards their ultimate delivery by caesarean section. During the postpartum period, one of the sisters developed lower limb sensory loss and investigations revealed a spinal haematoma and unrecognized bilateral pelvic fractures. The other sister had an uneventful recovery and both babies are well. These case histories underline the importance of pain in labour management and its function in alerting patients and staff to problems during the puerperium.