Cytological screening

The ability to screen a predominantly negative cytology slide and notice occasional abnormalities among many thousands of cells requires specialist training, knowledge of the nature of normal and abnormal cells, and concentration and dedication.  Here we deal with sources of error in screening and how they can be avoided.   Sources of error                           Personal reasons […]

Processing the sample in the laboratory

Sources of error Procedures for processing cervical samples are described elsewhere. There are many diagnostic errors that can occur due to poor processing techniques in the laboratory:   Clerical procedures for receiving the samples Inconsistencies between information on the request form and sample. Misspelling of name or incorrect date of birth leading to screening history […]


Arbyn M, Anttila A, Jordan J et al. (Eds). (2008). European guidelines for quality assurance in cervical cancer screening, second edition. Chapter 3 pp.87-88. European Communities 2008. Available as Blanks RG, Kelly RS (2010). Comparison of cytology and histology results in English cervical screening laboratories before and after liquid-based cytology conversion: do the data […]

QA and QC of the complete cervical screening process

Protocols for quality control (QC) and quality assurance (QA) A pathology test that screens an entire healthy population to find the few with disease must have clearly defined protocols for QA and QC in order to become an acceptable and viable screening test.   The same protocols are required for cytology as a triage test […]

Processing cytology samples in the laboratory

Processing cytology samples involves reception of the specimen and request form, preparation of slides for microscopic examination, staining, screening and reporting the slides.  All these processes are subject to quality control and quality assurance measures.   Reception of specimen and request form Details on specimen and form are checked to make sure they match. Specimen […]


Arbyn M, Herbert A, Schenck U et al. European guidelines for quality assurance in cervical cancer screening: recommendations for collecting samples for conventional and liquid-based cytology. Cytopathology 2007;18:133-9. Arbyn M, Bergeron C, Klinkhamer P et al. Liquid compared with conventional cervical cytology: a systemic review and meta-analysis. Obstet Gynecol 2008;111:167-77. Davey E, Barratt A, Irwig […]

Avoidance of over-reporting of atypical/borderline cytology

Atypical squamous cells of undetermined significance (ASC-US) ASC-US (or borderline changes in squamous cells) border on LSIL and can largely be resolved by HPV triage.  HPV negativity would usually exclude minor changes in mature or intermediate squamous cells without koilocytosis (the only diagnostic feature of HPV infection).  Minor nuclear enlargement and hyperchromasia is frequent in […]

Criteria for adequacy of a cervical cytology sample

The European guidelines recommend TBS criteria to be used as a minimum:  “Recommendation As a minimum, TBS criteria for conventional smears and LBC should be used and, if a specimen is judged unsatisfactory, the reason for the quality judgement should be provided on the cytology report. Women with an unsatisfactory smear should be invited for […]

Potential false negatives

Most false negatives are well-recognised types of HSIL, which will not be missed if cytologists are familiar with them.     Small cell dyskaryosis Essentially, this is typical ‘carcinoma in situ’ (CIN3) but the cells may be deceptively small and little larger than neutrophils.   Attention to the nuclear chromatin pattern will allow this type of […]

Guidelines for reporting negative cytology

Negative for intraepithelial lesion or malignancy The Bethesda system links previous categories ‘normal and benign alterations’ as a single ‘negative’ category.  The EU guidelines support this opinion (Arbyn et al. 2008; Herbert et al. 2007).    Benign changes that need not be reported in a negative report Hormonal patterns (post-partum or atrophic) Repair changes Microglandular […]