Introduction Modern CT angiography (CTA) has shown high sensitivity for detecting a ruptured aneurysm in the setting of acute subarachnoid hemorrhage (SAH). Patients with SAH and no aneurysm found on CTA pose a diagnostic dilemma for treating physicians. These patients traditionally undergo digital subtraction angiography (DSA) in search of an occult aneurysm; however, this practice has recently been called into question. We performed a meta-analysis of the current literature to assess the role of CTA in the diagnosis of non-aneurysmal SAH (NASAH).

Methods A systematic review of the literature was performed to find articles comparing the sensitivity of CTA to DSA for diagnosing aneurysms in the setting of acute SAH. Based on clinical relevance, only studies performed with 16-slice CT scanners or greater were included in the analysis. Data from these studies were combined with our own institutional data to create an overall 2×2 table, from which descriptive statistics were generated.

Results After an extensive literature review, 22 studies were included in the final analysis. The total number of true positive, false positive, true negative, and false negative CT angiograms were 3046, 7, 737, and 33, respectively. The overall sensitivity and specificity were 98.9% (98.4–99.2) and 99.1% (98.0–99), respectively. The positive and negative predictive values were 99.8% (99.5–99.9) and 95.7% (94.0–97.0), respectively. There was a trend toward higher sensitivity with 32- and 64-slice CT scanners when compared with 16-slice scanners, but this difference was not statistically significant.

Conclusions The results of this analysis demonstrate the high sensitivity of 16-slice or greater CTA in detecting aneurysms in acute SAH. Therefore, the vast majority of patients with negative CTA requires no further workup and needs not be subjected to the risks of DSA. DSA should be reserved only for patients exhibiting a clinical exam incongruent with NASAH, which has a typically benign course.

Competing interests None.