Decision-making in the colposcopy clinic--a critical analysis. 
To consider the omission of several diagnostic steps from the management of patients with high-grade squamous intraepithelial lesion (SIL) by analyzing the role of each step on the choice of treatment.  Each diagnostic procedure was correlated to the treatment and outcome in 87 women with high-grade SIL.  Treatments considered were large loop excision of the transformation zone (LLETZ) cold knife conization, and CO2 laser vaporization.  Unsatisfactory colposcopy (P< or =0.01) and positive endocervical curettage (ECC) specimen (P< or =0.01) were essential for choice of treatment.  CIN2 diagnoses of the preoperative cervical biopsy were rediagnosed as CIN3 based on the surgical specimen in 57% of the cases.  The margins of 33 and 23% of surgical specimens removed by LLETZ or knife conization, respectively, displayed CIN involvement.  Forty and 47% of these patients, respectively, later developed recurrent CIN.  Omission of colposcopy and ECC could have resulted in sub-optimal treatment in many cases.  Excision by LLETZ or knife conization is recommended for cases of CIN2 and CIN3.  Follow up is imperative for patients with involvement of the margins.