Background: Evidence-based medicine is defined as the link between good scientific research and clinical practice and it uses existing and available scientific evidence, with good internal and external validity, to apply its results in clinical practice. Systematic reviews are criticized for frequently offering inconsistent evidences and absence of straightforward recommendations. Their value seems to be depreciated when the conclusions are uncertain or based on less than the highest grading of evidence.

Objectives: To describe a method of evaluating case series studies in health care when there is absence of clinical trials.

Methods: We provide illustrations from recent experiences and discuss the impact of the level of evidence in the clinical practice.

Results: As demonstrated by the example, this method is an alternative design to provide some evidence of the intervention under evaluation and plotting all available case series.

Conclusions: We describe a new method to evaluate case series in health care reviews which we propose to call meta-analysis of case series studies. Thismethod is extended to be used in the absence of clinical trials, mainly, for surgical procedures. The use of this method leads to substantial gains in the scientific community as it supports the clinicians and surgeons in their clinical practice until higher-quality primary studies are conducted, although we cannot ruled out the possibility of clinical and methodology heterogeneity due to the nature of this type of studies.