| 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 |
[38] Methotrexate, IM: Ectopic pregnancy and miscarriage: diagnosis and initial management in early pregnancy of ectopic pregnancy and miscarriage. National Guideline Clearinghouse [Internet]. [cited 2017 Jun 8]. Available from: https://guideline.gov/summaries/summary/39274/ectopic-pregnancy-and-miscarriage-diagnosis-and-initial-management-in-early-pregnancy-of-ectopic-pregnancy-and-miscarriage?q=ectopic+pregnancy.
Methotrexate, IM: Diagnosis and Management of Ectopic Pregnancy [Internet]. Royal College of Obstetricians & Gynaecologists. [cited 2017 Jun 8]. Available from: https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg21/
Renner R-M, Nichols MD, Jensen JT, Li H, Edelman AB. Paracervical block for pain control in first-trimester surgical abortion: a randomized controlled trial. Obstet Gynecol. 2012 May;119(5):1030–7. https://www.ncbi.nlm.nih.gov/pubmed/22525915