Examining the Evidence
When is endocervical curettage informative in cervical cancer screening?
Although more than 400 studies have explored the use of ECC in cervical cancer screening, the practice remains controversial. Because this procedure most commonly involves circumferential scraping of the endocervical canal using a curette to obtain a specimen, the procedure can be painful, and some women may be reluctant afterward to continue follow-up. In addition, inadequate sampling is a frequent problem, making the specimen difficult or impossible to interpret. Furthermore, an ectocervical lesion that happens to get sampled inadvertently may contaminate the endocervical specimen, leading to potential diagnostic inaccuracy.
Despite these disadvantages, ECC remains fairly widely used. Proponents of ECC contend that ECC may be the only indicator of serious cervical lesions and, therefore, should be performed routinely. Alternatively, some colposcopists perform an ECC only when there is a specific indication, such as a high-grade squamous intraepithelial lesion (HSIL) on cervical cytology, or in the setting of an inadequate colposcopic examination.
Large data set is a strength
Gage and coworkers are authors of the latest ECC investigation, a data analysis from a regional health system in Canada that performs colposcopically guided biopsy and ECC on all outpatients undergoing colposcopy examination. A strength of their study is the large data set they used, which also allowed for analysis of subgroups to determine whether any subset of women may benefit from ECC. Indeed, the investigators did identify women who would be more likely to benefit from ECC: those 46 years or older who are referred for colposcopy after a high-grade cytology report. However, these same women are also likely to have an indication for an excisional procedure, obviating the need for ECC.
Gage and colleagues also reported the number needed to treat to identify one case of high-grade cytology that otherwise would have been missed: 99. This figure is a valuable aid in interpreting the significance of the results of this study as well as in counseling patients.
Keep the findings in context
Because the authors analyzed only cases in which both ECC and colposcopically directed biopsy were available for review, we cannot extrapolate these findings to cases in which only ECC is performed.
Also, keep in mind that use of a cyto-brush may boost sensitivity and adequacy of the specimen, in comparison with a curette, but may reduce specificity unless a sleeved brush is used. Gage and coworkers do not specify the technique utilized during ECC. They do remark on the pain associated with ECC, however, suggesting that the ECC procedures were performed using a curette.
Last, in regard to the difficulty encountered in the interpretation of some ECC specimens, it is important to recognize that, in contrast to reproducibility data available for cervical biopsy specimens, there is essentially no published reproducibility data on ECC specimens.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
This large study bolsters the “con” side of the ECC debate and is consistent with other investigations demonstrating minimal utility of the procedure. At this time, ECC is not recommended for routine use.
This study found that the diagnostic yield of ECC was lowest among women who had a fully visible transformation zone and who:
- were younger than 46 years
- used an oral contraceptive
- were premenopausal
- had fewer than 4 live births.
Diagnostic yield also was low among women of all ages who were referred for low-grade cytology.
ECC appears to have the greatest utility among women 46 years and older who are referred for high-grade CIN, HSIL, or more ominous cytologic findings and who have had four or more live births. However, many of these same women will also likely have an indication for an excisional procedure regardless of the ECC results, which may limit the utility of the procedure. —COL. CHRISTOPHER M. ZAHN, MD
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