4. Unsatisfactory cervical screening results

HPV tests can be unsatisfactory because of the effects of inhibition or, in the case of some tests, because the internal control failed to demonstrate the presence of human DNA in the sample. If the HPV test cannot be performed, then the screening episode should be classified and reported as ‘Unsatisfactory’.

The Bethesda System 2014 (TBS 2014)[1] defines an unsatisfactory LBC preparation as one with fewer than 5000 well-visualised, well-preserved squamous or squamous metaplastic cells. TBS 2014 provides extensive practical guidance for laboratories.[1]

When reflex LBC is unsatisfactory in a case where it was required to determine whether the woman should be referred for colposcopic assessment or should have a repeat test in 12 months, then the screening episode should be classified as ‘Unsatisfactory’ and retesting in 6 weeks should be recommended.

At retesting, the repeat sample should not be tested for HPV. The laboratory should undertake LBC and then prepare a cervical screening report combining the results of the original HPV test and the repeat LBC (see Preparation of cervical screening reports in Chapter 3. Terminology). It is anticipated that the support of the NCSR will be critical in this circumstance.

When reflex LBC is unsatisfactory, but the woman requires colposcopic referral regardless of the LBC result, then the screening episode should be reported as ‘Higher risk for significant cervical abnormality’. LBC should then be performed at the time of colposcopy.

The laboratory should state why the screening sample is unsatisfactory: either because the HPV test or the LBC could not be completed. In the case of unsatisfactory LBC, the laboratory should report why the sample is unsatisfactory.