Non-contrast computed tomography for the diagnosis of non-traumatic subarachnoid hemorrhage

Subarachnoid hemorrhage is a neurosurgical emergency that requires timely diagnosis due to its severity and the existence of therapeutic measures that are effective when carried out in time. The most used diagnostic sequence to rule it out is computed tomography without contrast which, if negative, is followed by lumbar puncture. However, it has been suggested that a negative non-contrast computed tomography (without blood) may rule out the diagnosis.

To answer this question we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach.

We identified three systematic reviews including nine studies. We concluded the diagnostic accuracy of non-contrast computed tomography is probably very high, but the clinical impact of relying only on this test has not yet been evaluated.