5. Limitations
There are several limitations in our study. First, studies enrolled in
this meta-analysis are nonrandomized, observational design, thus
selection bias is impossible to avoid. Second, the sample size included
in the study is small which may affect the stability of the result
indicators, reduce the efficiency of the test, and may bias the research
results. Third, different studies were followed with different tests,
which led to biased follow-up. In addition, clinical studies did not
have uniform definitions of procedural success and procedure-related
complications.