Fetus in fetu: use of intraoperative ultrasound for safe excision of a rare entity

A prenatally diagnosed abdominal mass at 36 weeks and 0 days was further characterised by postnatal ultrasound and MRI to be likely a rare case of fetus in fetu in an otherwise healthy male. Due to close proximity to both the coeliac axis and superior mesenteric artery (SMA), surgical excision was delayed for several months. Interim CT with intravenous contrast performed at 2 months of age demonstrated the SMA travelling through the posterior aspect of the mass. Surgery proceeded at 2 months of age. Intraoperative ultrasound was used to definitively identify both the coeliac axis and SMA in order to facilitate a safe excision. The patient recovered well with an uneventful discharge to home on postoperative day 8. Pathology confirmed the diagnosis of fetus in fetu.