INVESTIGATION OF 100 CONSECUTIVE NEGATIVE CONE BIOPSIES

Objective To investigate the reasons for cone biopsies reported as not containing intraepithelial or invasive malignancy and thereby find wa ys to decrease their incidence. Design One hundred cone biopsies repor ted as negative were identified out of a total of 436 consecutive cone biopsies. The patients' cytology, colposcopy and histology reports an d cytology and histology slides were reviewed. Further opinions in cas es of doubt were obtained in cytology and histology. In cone biopsies still considered negative after reviews, deeper levels were cut, exhau sting all paraffin blocks. Follow up cytology, colposcopy and histolog y were reviewed. Setting Gynaecological oncology unit in a university teaching hospital. Results After re-evaluation the final diagnoses of cone biopsies initially reported as negative were positive (n = 21), u nsatisfactory (n = 27) and true negative (n = 51), with one case exclu ded because of insufficient material for review. The positive cases we re diagnosed on review (n = 11) or extra levels (n = 10). The unsatisf actory cases were all due to denudation. The 51 true negative cases we re divided into those which never had had histologic confirmation by p unch biopsy or endocervical curettage (n = 47) and those with a previo usly confirmed histological abnormality (n = 4). Conclusions The numbe r of negative cone biopsies can be reduced by: 1. taking Pap smears af ter correction of atrophy and inflammation; 2. more scrupulous colposc opy aimed at reducing the number of unsatisfactory colposcopies or mis interpreted colposcopic findings; this thorough examination should inc lude the vagina and vulva; 3. confirmation of smear and colposcopic fi ndings by biopsy prior to cold-knife conisation and performing a large loop excision of the transformation zone (LLETZ) for cases where ther e is a discrepancy between the smear abnormality and colposcopy/biopsy findings; 4. good quality cone biopsies using a technique that does n ot handle the mucosa and is performed after the mucosa has had time to regenerate following the colposcopic investigations; and 5. exhaustin g all blocks with multiple levels before reporting a cone biopsy as ne gative.