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Cervical biopsies not reliable in ruling out high-grade CIN

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Cervical biopsies guided by colposcopy are accurate in confirming suspected cases of high-grade cervical intraepithelial neoplasia (CIN), but the negative predictive value is low, Austrian investigators report.

“Clinicians should be aware of the limited accuracy of guided cervical biopsies,” Dr. Christian Zuchna of Paracelsus Medical University, Salzburg, and colleagues advise in a July 14 online issue of the American Journal of Obstetrics & Gynecology.

The authors note that conization to diagnose the grade of CIN imparts risk of pregnancy-related morbidity, and that colposcopically directed biopsies are widely used instead. However, while an early study showed good agreement between biopsy results and findings from cone or hysterectomy specimens, several recent studies have found only a moderate correlation.

To investigate further, Dr. Zuchna’s group analyzed findings in 244 women with cervical lesions who underwent up to three colposcopically guided cervical biopsies followed by conization of the same area, in a single procedure.

With the excisional specimen as the reference, the sensitivity and specificity of guided cervical biopsies were 66.2% and 95.0%, respectively. While the positive predictive value was 98.5%, however, the negative predictive value was only 35.5%, the team reports.

They conclude that the results highlight the shortcomings of colposcopically direct cervical biopsies.

“Most doctors would regard cervical biopsy results as an accurate histologic diagnosis; this is not the case, as we showed in our study,” Dr. Zuchna commented by email. “We found underestimation in almost 50% of cases.”

For example, the investigators report in their paper, “Of 107 patients with CIN 0,1 on biopsies, almost 65% had CIN 2,3 on cone specimens at the same time.”

Dr. Zuchna advised, “Probably three or more biopsies are needed to receive a reliable result, which again highlights the limitation of this diagnostic test. Two biopsies should be the minimum.”

In summary, “Cervical biopsy results should not be considered an accurate histologic diagnosis, but as part of a patient’s individual risk assessment.”

Reference:

Diagnostic accuracy of guided cervical biopsies: a prospective multicenter study comparing the histopathology of simultaneous biopsy and cone specimen

Am J Obstet Gynecol 2010;203.