The need for repeat angiography in subarachnoid haemorrhage.

This study was designed to assess the necessity for a second angiogram study in patients in whom initial angiography after primary subarachnoid haemorrhage (SAH) was negative. During a 12-year period, 122 of 694 patients (17.5%) had negative initial angiograms. CT, available for 98 patients, showed a preponderance of subarachnoid blood in the perimesencephalic cisterns in 50 of 73 patients (68.5%) in whom blood was visible on CT. Angiography, repeated in 67 patients, revealed an aneurysm in 4 (6%): 2 had an aneurysm of the anterior communicating artery, 1 of the posterior inferior cerebellar artery, and 1 of the P2 segment of the posterior cerebral artery. CT showed subarachnoid blood in the interpeduncular and ambient cisterns in this last case, and a preponderance of subarachnoid blood outside the perimesencephalic cisterns in the remaining 3 patients.