The Specificity of Ultrasound in the Detection of Fetal Intracranial Tumors

Aims: To evaluate the specificity of ultrasound in identifying fetal brain neoplasms and its accuracy in the diagnosis of the tumor's histological type.

Methods: A retrospective evaluation of 7 cases of fetal brain tumors occurred at our unit in the period between January 92 and June 98 has been performed. All prenatal ultrasonographic diagnoses were compared with the postnatal findings on the aborted fetuses (post-mortem examination) or on the newborns (MRI or post-mortem examination).

Results: In 6 out of 7 cases the antenatal ultrasonographic diagnosis of brain tumor was confirmed postnatally, in one case a supratentorial arachnoid cyst was mistaken for a teratoma with cystic components (86% specificity in the diagnosis of congenital brain neoplasms). Out of the 6 cases of suspected teratomas, one revealed to be a glioblastoma, one an arachnoid cyst and one a primitive neuroectodermal tumor. The prenatal diagnosis was confirmed in the case of choroid plexus papilloma. Prenatal ultrasonography was accurate in identifying the tumor's histological type in the 57% of the cases. The diagnoses were not modified by the transvaginal scans performed in 2 cases.

Conclusions: Prenatal ultrasonography is a useful tool to identify any intracranial space-occupying lesion larger than 10 mm. In the present study it has shown an 86% specificity in the diagnosis of brain neoplasms. However the accuracy of ultrasound in diagnosing the tumor's histological type was limited (57%).