Abstract of review: Cervical smear collection devices: how effective are they at detecting endocervical cells and dyskaryosis?

Objectives: 1. To assess the effectiveness of different cervical sampling devices for the collection of endocervical cells
2. To assess the effectiveness of these devices for detecting atypical cells
3. To assess the ability of these devices to produce adequate smears.
4. To obtain information on the relevance of endocervical cell status to the detection of atypical cells.

Search strategy: A computerised Medline search and manual literature search of 16 relevant journals was conducted to identify all registered randomised trials comparing cervical smear collection devices before July 1997.

Selection criteria: Studies: Randomised or quasi-randomised trials.

Participants: Women attending for primary screening, colposcopy following an abnormal smear or colposcopy after treatment.

Interventions: Different Designs of Cervical Smear Collection Devices
Outcome measures: Presence of Endocervical Cells, Detection of Cervical Cytological Abnormality, Blood Contamination, Inadequate Smears

Data collection and analysis: Data were extracted independently by two reviewers, and any discrepancies resolved by discussion.

Main results: Thirty-four randomised controlled trials investigating cervical smear collection devices were identified prior to July 1997. All RCTs compared the ability of different devices to collect endocervical cells while nineteen RCTs compared the ability of different collection devices to detect dyskaryosis. Meta-analysis demonstrated that:
1. compared to other collection devices, the Ayre spatula is an ineffective device for collecting endocervical cells
2. the Ayre spatula also gives a lower yield of dyskaryosis
3. the Ayre spatula also reduces the number of adequate smears
4. a) devices that collect a higher proportion of endocervical cells also detect a higher proportion of abnormal cytology
b) smears that contain endocervical cells are more likely (compared to those that do not have endocervical cells) to detect abnormal cytology and this is particularly so when dyskaryosis is severe.

Conclusions: The widely used Ayre spatula is the least effective device for cervical sampling and should thus be superseded by the Aylesbury spatula for primary screening and evaluating women prior to and after treatment for cervical intraepithelial neoplasia. Detection rates of endocervical cells appear to be a valid and convenient surrogate for the ability to detect dyskaryosis.

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