Cervical intraepithelial neoplasia (CIN) has been shown to progress to invasive cervical cancer in a proportion of cases cases, with the more severe the abnormality, the greater the risk of malignant progression.1 The detection of cytological abnormalities through screening has resulted in a fall in the incidence of cervical cancer because of treatment of these pre-invasive lesions.2 Colposcopic examination of the cervix allows assessment of the abnormality before it is treated, either by excision or ablation.3–5 The colposcopically directed punch biopsy is a cornerstone of colposcopic practice because it allows a small piece of cervical tissue, typically <5 mm in diameter, to be taken to confirm the clinical impression because colposcopy alone is known to miss approximately one-third of high-grade CIN.6–8
In the management of CIN2+ the punch biopsy is primarily used to confirm the diagnosis of a high-grade abnormality, thereby reducing the number of unnecessary treatments and the associated morbidity.9,10 The punch biopsy also plays a role in the management of women undergoing ablative treatment for CIN because pretreatment biopsies are required to exclude invasive disease.11,12
Despite its widespread use, there is increasing concern over the accuracy of the colposcopically directed punch biopsy to diagnose the presence or absence of high-grade CIN. A Norwegian study has recently shown that of 520 women whose colposcopy-directed biopsies were reported as negative, 78 women (23.8%) were found to have CIN2+ in a follow up biopsy.13 Many studies over the past five decades have been performed attempting to compare the histological diagnosis obtained from a punch biopsy with a reference standard diagnosis obtained from an excisional biopsy. Results were highly variable. Recent reports have revealed a lower sensitivity of colposcopy and colposcopy-based biopsies than was generally expected previously and have raised considerable concerns about the probability of missed CIN2+.14 Various reasons have been proposed to explain this low sensitivity, including insufficient experience of the colposcopist, inability to target the abnormal area with the biopsy forceps and the occurrence of lesions not being visible on colposcopy. To quantify the ability of colposcopy-based punch biopsies to diagnose the presence or absence of cervical precancer, a systematic review and meta-analysis was conducted.