False positive cervical smears
The audit of cervical cytology in Leicestershire, summarised by Annabel Ferriman, focusses yet again on the alleged adverse clinical outcomes as a result of false negative smears.By contrast, there appears to be comparative silence on the harmful effects to women as a consequence of false positive reports.The lay public generally believe that a smear result is either negative or positive, without being fully informed about the range of cytological abnormalities.These vary from borderline (nearly normal)categories through to severe dyskaryosis or possible invasive change. Traditionally, about 5% of smears were quoted as being false positive,but this figure is outdated due to the great increase in borderline smear reports in recent years. Referral for colposcopy has increased as well as the number of women receiving cervical biopsies for histology. The increased biopsy rate also reflects the modern trend for target setting, rigid guidelines and doubtless,some defensive medical practise.But the clinical management of an individual woman should not be based on the smear test result alone.Many other factors such as age,concurrent genital tract infection,reproductive potential and the asymptomatic state have to be balanced against the morbidities of surgical techniques, diagnostic or therapeutic. Even with moderate or severe dyskaryotic change,there has to be the same balanced approach to what is considered to be a risk of invasive disease, either imminent or more distant in time.
The science of cervical cytology is imprecise in predictive terms and carcinoma in situ has variable biological behaviour. Consequently, many more women are overinvestigated or overtreated compared to the number that may benefit from screening.
The surgical morbidities of various types of cervical biopsy include pain or discomfort, haemorrhage, secondary sepsis and sometimes distorted cervical anatomy. These side effects are particularly regrettable when histology reveals no abnormality and anxious women are not easily reassured.
There is understandable concern when mortality occurs, despite cervical cytology screening, but precise data on the mortality of the screening process itself is sadly lacking, given that any screening process must lead to intervention in many cases. On the technique of cone biopsy alone, one leading text book states 'cone biopsy is not free from risks and hazards and fatalities are reported.'
Neville Goodman's account of smear tests and seat belts should remind all concerned of Aristotle's famous dictum 'primum non nocere'- the first duty is to do no harm.
Competing interests: No competing interests