Histological differences in paired biopsies obtained by colposcopic directed punch biopsy and large loop excision of the transformation zone

SummaryHistological differences between biopsy specimens obtained by punch biopsy and large loop excision of the transformation zone were studied in 79 patients referred to our colposcopy clinic with abnormal cervical cytology. Cytological abnormalities included mild dyskaryosis (15), moderate dyskaryosis (38) and severe dyskaryosis (26). Patients were entered into the study if there was no cytologicical or colposcopic evidence of invasive disease, they were suitable for local destructive treatment, and were seen by one of three experienced colposcopists. Colposcopy, directed biopsy, and large loop excision of the transformation zone were performed at the same clinic visit. In 50 cases (64 per cent) there was agreement between loop excision and punch biopsy histology. In all cases of disagreement (36 per cent) the punch biopsy underestimated the severity of the lesion. One case of micro-invasive carcinoma was diagnosed by loop excision when, the punch biopsy had demonstrated only CIN III.