Antenatal detection of a thyrocervical teratoma in the third trimester - A case report.

Introduction: Congenital teratomas are rare with less than 10% found in the cervical region. When they do occur in the neck, they are usually identified during the third trimester and, due to their location, they are associated with polyhydramnios.

Case Report: Cervical teratoma was identified at 32 weeks gestation during a routine scan of a 33-year-old female expecting dichorionic diamniotic twins. Only one twin was affected and referral to a specialist hospital allowed a care plan to be arranged to ensure safe delivery followed by immediate treatment and surgery. To date, both twins are thriving.

Discussion: Cervical teratomas usually occur in the third trimester and are not always detected prenatally. Although usually benign, their size and location may cause polyhydramnios as well as increasing the risk of neonatal asphyxiation and death. It is therefore essential to assess the foetal neck when polyhydramnios is noted at any third trimester scan, to maximise detection and ensure appropriate multidisciplinary healthcare can be organised to optimise postnatal survival.

Conclusion: Antenatal detection of a rare cervical teratoma was pivotal in the management and survival of this infant. Ultrasound practitioners must consider the possibility of a neck teratoma in the presence of third trimester polyhydramnios and therefore evaluate carefully foetal head, neck and chest anatomy as part of their examination.