Table 2: The classification systems of included studies.

American Fertility Society (AFS), 1988 Stage I, stage II, stage III

European Society of Hysteroscopy (ESH), 1989Stage I, stage II, IIa, or III, stage IIIa, IIIb, or IV
European Society of Gynecological Endoscopy (ESGE), 1995 Stage I, stage II, IIa, or III stage IV, Va, or Vb
March, 1978Mild, moderate, severe