Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
[36] Management of ectopic pregnancy and miscarriage: Practice Committee of American Society for Reproductive Medicine. Medical treatment of ectopic pregnancy: a committee opinion. Fertil Steril. 2013 Sep;100(3):638-44. https://www.ncbi.nlm.nih.gov/pubmed/23849842