Colposcopy in a family planning clinic: a future model?

The first year''s experience of a satellite colposcopy clinic in the Glasgow Family Planning Centre was analysed. Establishment of the clinic was supervised by an experienced member of the colposcopy team at the department of gynaecology, Western Infirmary, Glasgow, who trained one of the family planning centre''s staff. Close links were thus maintained with the hospital clinic to which patients were referred for treatment. The policy at the new colposcopy clinic was to study prospectively all women in the hospital catchment area whose cervical smears were reported as abnormal. In 58 of 162 such patients there was at least moderate dyskaryosis and the cytologist''s recommendation had been referral for colposcopy. In 104 cases the changes were either atypia alone or mild dyskaryosis and a repeat smear was recommended within three to 12 months; 18 of these patients had grade II or III cervical intraepithelial neoplasia on biopsy, and relying on repeat smears would have resulted in an 11.7% false negative rate. If an atypical cytological picture is to be an indication for colposcopy clinics attached to family planning centres may have an important role, given satisfactory training and close links with central specialist colposcopy clinics.     

Liquid-based cytology and conventional smears compared over two 12-month periods.

BACKGROUND AND OBJECTIVE: Liquid based cytology (LBC) was introduced across the Scottish Cervical Screening Programme in 2003-2004. The objective of this study was to compare in a large cytopathology laboratory the results of cervical samples over two twelve-month periods, 2001-2002, when the great majority of smears were conventional, with 2003-2004, when all were LBC. METHODS: The results of smears in both periods were analysed to give overall reporting profiles, and correlated with results of cervical biopsies. The numbers of patients referred for colposcopy were compared. RESULTS: The percentage of unsatisfactory smears fell from 13.6% to 1.9%. Colposcopic referrals for repeated unsatisfactory smears fell from almost 25% to 0.5%. There was a decrease in overall smear numbers, but despite this there was an increase in the number of smears reported as showing dyskaryosis of any grade. There was an increase in positive predictive value for moderate dyskaryosis and above, from 79.5% to 86.1%. The outcome of biopsies from patients referred with mild dyskaryosis showed no decrease in accuracy of predicting a low grade histological lesion. Workload in the laboratory decreased, due to fewer smears received overall, more rapid primary screening times and fewer multi-slide cases. Primary screening backlogs all but disappeared, and reporting times greatly improved. CONCLUSIONS: Introduction of liquid based cytology led to improvements in unsatisfactory smear rates, with significant benefits to colposcopic referrals and laboratory turnaround times. Pick-up rates of dyskaryosis were maintained, and the positive predictive value of a dyskaryotic smear report was improved.     

The use of the 'borderline' category in the reporting of cervical cytopathology in the UK: results of a survey conducted under the aegis of the British Society for Clinical Cytology

Objective: To determine how the ‘borderline’ category was used by cytopathologists in the UK when reporting cervical smears. Methods: A questionnaire was sent by email to members of the British Society for Clinical Cytology. Results: There is wide variation in the use of the ‘borderline’ category in the UK but the majority of respondents (77.6%) used it when reporting smears that were either on the borderline between negative and low grade squamous dyskaryosis (‘borderline ?low grade’), or on the borderline between negative and high grade squamous dyskaryosis (‘borderline ?high grade’), or on the borderline between negative and glandular dyskaryosis ‘borderline ?glandular dyskaryosis’). A significant minority (15.7%), however, did not use ‘borderline’ when reporting smears that showed an abnormality that was possibly high grade squamous dyskaryosis. A majority (79.1%) of respondents thought that it would be useful to have separate reporting categories for ‘borderline ?low grade’ and ‘borderline ?high grade’. Conclusions: There is diversity in the use of the category ‘borderline’ in the UK. The proposed revised BSCC terminology with separate categories for borderline ?low grade, borderline ?high grades and borderline ? glandular dyskaryosis reflects the opinion of the majority of respondents to the questionnaire.     

A study of the effect of introducing a restrictive cervical screening policy on laboratory workload and cervical cancer detection rates

This study examines the effect of a change in screening policy on the detection rate of severe dyskaryosis. During 1987 a total of 423 cases of severe dyskaryosis were identified by the Avon Screening Programme. Eleven per cent of these abnormal smears were repeat smears taken without clinical indication within the recommended 5 year recall period (interval smears). In a comparable control group of negative smears 31% were interval smears. Twenty-five per cent of the dyskaryotic interval smears (3% of the total severely dyskaryotic smears) were taken within 3 years of the previous negative smear, compared with 50% of the control group. By discouraging opportunistic smears within 5 years of the previous smear, the laboratory workload could be reduced by 30%, or within 3 years of the previous smear by 15%. There is, however, a risk of 11% and 3% respectively of missing a significant lesion (severe dyskaryosis).     

Regular audit of colposcopic biopsies from women with a mildly dyskaryotic or borderline cervical smear results in fewer cases of CINIII

Two years after introducing mandatory review of cases in which the cervical smear was discrepant with subsequent colposcopic or histological finding, the predictive accuracy of a first abnormal smear and the need for treatment were analysed. The results were compared with performance figures prior to this form of audit policy. Over 12 months 415 women referred for colposcopy were studied. Three per cent of patients with a single borderline smear and 6% with mild dyskaryosis had cervical intraepithelial neoplasia grade III (CINIII) revealed in histopathological examinations after colposcopy. Only 25% with a borderline smear and 33% with mild dyskaryosis required treatment. Of women with moderate dyskaryosis, 18% had a biopsy showing CINIII and 46% were treated. Of women with severe dyskaryosis in their cervical smear, 61% were shown to have CINIII or invasive cancer on biopsy and 90% were treated. Regular audit improved cytological prediction of grade of epithelial abnormality found on biopsy, allowing accurate, safe surveillance for minor smear abnormalities.     

Regular audit of colposcopic biopsies from women with a mildly dyskaryotic or borderline cervical smear results in fewer cases of CINIII

Two years after introducing mandatory review of cases in which the cervical smear was discrepant with subsequent colposcopic or histological finding, the predictive accuracy of a first abnormal smear and the need for treatment were analysed. The results were compared with performance figures prior to this form of audit policy. Over 12 months 415 women referred for colposcopy were studied. Three per cent of patients with a single borderline smear and 6% with mild dyskaryosis had cervical intraepithelial neoplasia grade III (CINIII) revealed in histopathological examinations after colposcopy. Only 25% with a borderline smear and 33% with mild dyskaryosis required treatment. Of women with moderate dyskaryosis, 18% had a biopsy showing CINIII and 46% were treated. Of women with severe dyskaryosis in their cervical smear, 61% were shown to have CINIII or invasive cancer on biopsy and 90% were treated. Regular audit improved cytological prediction of grade of epithelial abnormality found on biopsy, allowing accurate, safe surveillance for minor smear abnormalities.     

Management of women with mild and moderate cervical dyskaryosis.

OBJECTIVE--To compare the outcomes in women with mild and moderate dyskaryosis after increasing periods of surveillance and thereby to define a rational protocol for managing such women. DESIGN--Prospective study with randomisation of women to one of four treatment groups, each with a different period of surveillance; one group in which the women were given immediate treatment and three other groups in which the women were under surveillance for six, 12, and 24 months. SETTING--A dedicated colposcopy clinic in Aberdeen, Scotland. SUBJECTS--902 women who presented with a mildly or moderately dyskaryotic smear for the first time. INTERVENTIONS--Cytological and colposcopic examinations at intervals of six months until the allocated period of surveillance was completed, at which time biopsy was performed. Women with severe dyskaryosis were withdrawn from surveillance and a biopsy was performed. MAIN OUTCOME MEASURES--The histological findings after punch biopsy or large loop excision of the transformation zone, and the trends in cytological appearances of serial cervical smears. RESULTS--793 women completed the study. In all, 769 women had an adequate final smear, of which 197 were normal cytologically, 328 were still mildly or moderately dyskaryotic, and 244 were severely dyskaryotic. Seventeen of the 67 (25%) women with one repeat smear showing non-dyskaryosis had cervical intraepithelial neoplasia grade III compared with only one of the 31 (3%) women with no dyskaryosis in four repeat cervical smears (P < 0.0001). None of the women had invasive cancer. Of 158 women whose index smear showed mild dyskaryosis and who were allocated to the group under surveillance for two years, only 40 had not defaulted or still had dyskaryotic smears by the end of the two years. CONCLUSION--Cytological surveillance, although safe, is not an efficient strategy for managing women with mildly abnormal smears. Women with any degree of dyskaryosis in a smear should be referred for colposcopy.     

Borderline Nuclear Abnormality In Cervical Smears: A Cytological Review of 200 Cases With Histological Correlation

The cervical cytology and histology specimens from 200 patients referred to colposcopy with borderline nuclear abnormality were reviewed. Human papillomavirus (HPV)-associated changes were identified in 103 of 200 (53%) referral smears and in 139 of 150 (91%) biopsy specimens. Cervical intraepithelial neoplasia (CIN) was less frequently diagnosed on review compared with the original histopathology reports (30.7%vs 45.4%); the discrepancy was largely attributable to a lower incidence of CINI. There was agreement in the grading of borderline nuclear abnormality in 161 of 200 referral smears following review. Twenty-three smears were upgraded to mild dyskaryosis, whereas 16 were reclassified as negative.     

Improving the NHS cervical screening laboratory performance indicators by making allowance for population age, risk and screening interval

OBJECTIVE: One of the key performance measures in the monitoring of the NHS cervical screening programme is the targeting of laboratories with very high or low percentages (outside the 10th-90th percentile) of adequate smears that have moderate dyskaryosis or worse. These laboratories are assumed to include those laboratories that may have extremes of sensitivity and specificity. A clear limitation with this methodology is that laboratories do not examine smears from women with the same underlying risk, age distribution or screening interval and adjustment for these factors should considerably improve the method. METHODS: This paper describes a method that allows for these confounding variables and a new age-risk-interval adjusted moderate dyskaryosis or worse rate (ARI-adjusted mod+ rate) can be calculated. The adjusted rate is the rate of moderate or worse dyskaryotic smears that the laboratory would have detected had it been screening women with an English 'average' age-risk-interval. All laboratories can therefore be compared using this method. RESULTS: The methodology is illustrated using data from the NHSCSP South West Region. The particularly low percentage of moderate or worse smears detected by one or two laboratories can be shown to be due to a local screened population with a very low risk because of a high mean age, relatively short screening interval and census variables associated with a low risk, rather than any under-calling by the associated laboratories. CONCLUSIONS: The ARI-adjusted mod+ rate requires to be calculated for all laboratories in England if it is to be used as a primary performance indicator. Alternatively, it can be used to further examine laboratories that are deemed to be outliers using the current methodology.     

Long term follow up of women with borderline cervical smear test results: effects of age and viral infection on progression to high grade dyskaryosis.

OBJECTIVE--To follow up and assess the significance of borderline change in cervical smears. DESIGN--Retrospective study of women undergoing routine cervical cytological screening in 1981. SETTING--Avon Cervical Screening Programme, covering 250,000 women in Bristol and Weston super Mare. SUBJECTS--437 women showing borderline cervical changes in 1981 and 437 age matched controls with normal results in 1981. MAIN OUTCOME MEASURES--Cytological progression to high grade dyskaryosis (cervical intraepithelial neoplasia grade III or invasive carcinoma). RESULTS--During follow up ranging from 13 to 106 months 98 of the 437 women (22.4%) with borderline cytological changes on routine cervical cytology screening had a subsequent smear test showing high grade dyskaryosis compared with three of the 437 women (0.9%) in the control group. The risk of progression was greater in women aged 20 to 39 than in those aged 40 and over. Human papillomavirus infection had initially been diagnosed cytologically in 101 of the 437 (23%) women with borderline results. Significantly fewer of these women developed high grade dyskaryosis (13/98 (13%) v 88/339 (26%), p less than 0.05). CONCLUSIONS--Women with borderline smear test results are at increased risk of developing high grade dyskaryosis, particularly if the borderline changes occur without cytological features of human papillomavirus infection. Progression occurs within three years in 50% of cases, although a linearly increasing risk was sustained over the nine years of follow up and was greatest in women aged 20 to 39. Careful follow up of these women is indicated.     

Five-year follow-up of women with borderline and mildly dyskaryotic cervical smears

This study investigated the 5-year follow-up status of women with cervical smears showing borderline nuclear changes (BNC) or mild dyskaryosis and the effect of koilocytosis on the outcome. Thirteen per cent of women with cervical smears showing BNC had high-grade cervical intraepithelial neoplasia (CIN). In contrast, 28% of women with cervical smears showing mild dyskaryosis had high-grade CIN. The presence of koilocytosis (24% for borderline smears and 34% for mild dyskaryotic smears) did not appear to influence the risk of developing high-grade CIN. Our results suggest that the simultaneous implementation of the British Society for Clinical Cytology proposed terminology and the colposcopy guidelines from the British Society for Colposcopy and Cervical Pathology could have an impact on colposcopy services.     

The inadequate smear: does it matter?

The objective of this study was to quantify the incidence of underlying cervical intraepithelial neoplasia (CIN) among women referred for colposcopy with three consecutive inadequate smears. The design was a retrospective cohort study analysing data from a regional colposcopy database at Cervical Screening Wales. Women who were referred to all the colposcopy clinics in Wales with three consecutive inadequate smears, the third inadequate smear being taken between 1 April 2001 and 31 March 2002 constituted the study population. The results of the fourth smear taken at the colposcopy clinic after three consecutive inadequate smears, the worst biopsy results from any of the subsequent colposcopies and the relationship between the result of the fourth smear taken at colposcopy clinic and any histology result were the main outcome measures. The accuracy of the colposcopic opinion was also examined. Of the 433 women identified as having been referred because of three consecutive inadequate smears, 302 were linked to either a subsequent smear and/or a biopsy result. An adequate smear result was available for 85% of these women when the smear was taken in the colposcopy clinic; 77% were reported as negative and 8% were abnormal. Of the 347 women seen in the colposcopy clinic, high-grade CIN was seen in 3% and low-grade lesion in 8%. The sensitivity and specificity of the fourth inadequate smear test in predicting underlying CIN were 15% and 84% respectively, with a positive predictive value of 8%. The sensitivity and specificity of colposcopy in predicting histological CIN among patients with three inadequate smears was 70% and 49%, respectively, and the positive predictive value was 44%. This study raises the question as to whether three consecutive inadequate smears should be considered as an indication for colposcopy, or merely for a further smear to be taken in circumstances where there is a greater likelihood getting an adequate result.     

Posters. P11 Positive predictive values for high and low‐grade cytological abnormalities as surrogates for specificity and sensitivity

Introduction Positive predictive value (PPV), measuring the percentage of moderate dyskaryosis or worse confirmed as CIN2 or worse, is used as a measure of accuracy in cervical screening. However, it relates more to specificity than sensitivity because the denominator includes false positives rather than false negatives. Low values reflect over‐reporting of high‐grade dyskaryosis but high values may reflect under‐reporting. Sensitivity is impossible to measure from correlation of cytology with outcome because women with negative cytology are rarely referred for colposcopy. Rates of CIN3 resulting from referrals for low‐grade cytology may be used as a surrogate for sensitivity, as high values may reflect under‐reporting (ref). Study design Outcome of colposcopy referrals was monitored during a period of 4 years, using a fail‐safe database. Results PPV at Guy's & St Thomas rose from 54% in 1998/1999 to 69% in 2001/2002. The former was below the NHSCSP recommended range. During the same period of time CIN1 rates for moderate dyskaryosis fell from 37% to 24%, reflecting the main source of discrepancy. While specificity increased (as reflected by increasing PPV) sensitivity remained constant in that CIN3 rates for mild dyskaryosis and borderline remained below 6%: average rates in England have fallen over the last 3 years and were 7.4% in 2000/2001 (ref). CIN2 rates for mild dyskaryosis also remained constant at 11% to 12%. Conclusion Correlation of biopsy results with high‐ and low‐grade cytological abnormalities is a useful method of monitoring accuracy of cytology reporting, and can be used to measure over‐ and under‐reporting as surrogates for specificity and sensitivity.     

Assessment of the Accuracy of Cytology In Women Referred For Colposcopy and Biopsy: the Results of a 1 Year Audit

The results of weekly colposcopy review meetings have been audited for 1 year and cases where there was a discrepancy between the referral cervical smear and the initial colposcopy biopsy have been analysed. New referrals (n = 476) for colposcopy were studied. In the final outcome 80% of 326 women referred for moderate or severe dyskaryosis were found to have cervical intraepithelial neoplasia (CIN) grade II or III or invasive carcinoma. Three women found to have invasive carcinoma had been referred for severely dyskaryotic smears. Twenty women were referred for smears with cell changes suggesting glandular neoplasia: five were found to have adenocarcinoma in situ, whereas eight had CIN and seven had negative biopsies. The results justify the referral policy and demonstrate the need for further investigation when initial colposcopic biopsies are negative.     

P‐26CONVENTIONAL V THIN LAYER TECHNIQUES: A COMPARATIVE STUDY OF BRONCHIAL SPECIMENS USING CONVENTIONAL AND TWO LBC METHODS,THINPREP AND SUREPATH

Introduction: There is ongoing debate about the terminology used in the classification of dyskaryosis, including whether BNA smears should be classified according to whether koilocytes are present or not. We explored the effect of koilocytosis in the management experiences and clinical outcomes of women with a single BNA smear. Methods: This study includes 410 women aged 20–59 years, resident in Tayside who had an ‘baseline’ BNA smear between 31/10/1999 and 31/10/2002 who were eligible for the TOMBOLA trial but who did not participate. Recommended follow‐up for these women was a repeat smear in six months. Up to three‐years follow‐up data was collected on subsequent cytological smears, colposcopy examinations and any related histology. The baseline smear was re‐read for the presence or absence of koilocytes. Women were classified according to their clinical outcomes during their three years. Results: 47% (192/410) of women were classified as having koilocytosis at baseline. The mean age was lower among these women (25 years) compared to those without koilocytosis (35 years). 55% (105/192) of women with koilocytosis at baseline had one or more negative smears and no further abnormal smears, compared to 63% (137/218) of those without koilocytosis, the difference was not statistically significant. 28% (53/192) of women with koilocytosis at baseline were referred to colposcopy after subsequent low‐grade or high‐grade smears compared to 19% (42/218) of those without koilocytosis; the difference was statistically significant. 14% (27/192) of women with koilocytosis at baseline were diagnosed with CIN2/3 or worse during follow‐up compared to 10% (21/218) of women without koilocytosis; the difference was not statistically significant. Discussion: Our results suggest that the presence or absence of koilocytosis has little impact on the clinical outcomes of women with a BNA smear.     

Inter‐ and intra‐observer variation in the reporting of cervical smears: specialist cytopathologists versus histopathologists

One hundred and ten cervical smears were circulated to five specialist consultant cytopathologists and five consultant histopathologists. Of these smears, 100 were randomized and re‐circulated. The cytopathologists reported endocervical cells and wart virus infection more frequently than the histopathologists, although neither group showed good inter‐observer agreement for either assessment. Apart from smear adequacy and the presence of endocervical cells, both groups showed good intra‐observer agreement in all the parameters measured. This suggests that overall individuals were applying their own personal criteria with consistency over time, although a previous study had shown considerable lack of inter‐observer agreement among the histopathologists on the grade of dyskaryosis and the management recommendation. The results indicate that specialist cytopathologists bring a different viewpoint to the reporting of cervical smears than histopathologists. They also show a lack of standardization in the reporting of smears despite the guidelines issued by the British Society for Clinical Cytology.     

Follow up of women with a history of mildly abnormal cervical smears which have returned to normal without treatment

The progress of 124 women with at least two negative cervical smears following a history of mildly abnormal smears for which no treatment had been given was compared with 106 women with negative smears and a clinical history of genital warts or herpes virus infection and 460 age-matched controls. After 4 years, excluding those for whom there was no follow up, 5.8% of those with a history of abnormal smears, none of those with a clinical history of genital warts or herpes virus and 1.1% of controls had developed histological evidence of at least cervical intraepithelial neoplasia grade III (CINIII) when referred for investigation of subsequent abnormal smears; one woman, from the control group, had developed invasive cervical cancer. Women with two negative smears after a history of abnormal smears who subsequently developed CINIII were more likely to have had a previous smear reported as moderate or mild-moderate dyskaryosis (2/6) compared with those whose follow up was negative (2/89). the results suggest that two negative cervical smears may not necessarily indicate that a lesion has regressed, but that a clinical history of genital warts or herpes virus infection should not be an indication for increased surveillance.     

The use of screening episodes linked to CIN3 and invasive cancer registrations to study outcomes from the NHS Cervical Screening Programme

Objective: To examine how NHS cervical screening data can be collected and analysed in order to evaluate women’s screening histories as episodes rather than as individual smears. Design: Analysis of routine cervical screening data grouped into screening episodes for a cohort of women regarding episodes starting in a given year. Setting: NHS Cervical Screening Programme. Population: Data from four Health Authorities (now eight Primary Care Trusts) from the NHS Cervical Screening Programme with primary smears (first in an episode) taken between 1 April 1999 and 31 March 2000. Methods: Cytology information obtained from the call/recall (‘Exeter’) computer system was linked to cervical intraepithelial neoplasia (CIN) 3 and invasive cancer outcome information obtained from cancer registries. Screening histories were divided into episodes, each starting with a primary smear that was followed up to episode closure or, for episodes still open followed for an average 4.25 years, from the primary smear. The episode was divided into two parts (up to referral to colposcopy and following the referral). The outcomes of the episodes are described including referral rate to colposcopy and CIN3 and invasive cancer rates by factors such as age. Main outcome measures: Episode histories and rates of referral to colposcopy, CIN3 and invasive cancer. Results: There were 176 923 episodes from 176 319 women (1.003 episodes per woman) followed up to March 2004, the date at which the first phase of information accrual ceased. Of these episodes, 172 100 (97.3%) were closed either by a negative smear referring the woman back to routine recall or by default (defined as no smear recorded within 21 months following a smear requiring an action of repeat or refer to colposcopy). The remaining 4823 (2.7%) of episodes were still open, of which in 3121 (1.8%) the woman had been referred to colposcopy and in 1702 (1.0%) no referral decision had been made. Referral rates to colposcopy varied by age from 5.7% in women aged 20–24 years down to 0.9% in women aged 60–64 years. The overall efficiency of screening was highest for woman aged about 30 years, with a CIN3 detection rate of eight per 1000 women and a positive predictive value (for CIN3 or worse) of referral to colposcopy of 21%. Conclusion: The study has shown that routinely collected NHS cervical screening data can be combined to give information on complete episodes, allowing important performance measures to be studied. We suggest that in future information in the NHS screening system should be structured to facilitate such analysis and to allow cytology and histology information to be readily linked.     

Prevalence of high-grade CIN following mild dyskaryotic smears in different age groups

OBJECTIVE: The new guidelines of the British Society of Colposcopy and Cervical Pathology suggest that women should be offered colposcopy after only one mildly dyskaryotic smear. This is expected to generate increased workload for the colposcopy clinics, at least in the short term. The main objective of this study was to estimate the incidence of high-grade cervical intraepithelial neoplasia (CIN) in women with mildly dyskaryotic smears and investigate whether there is any variation in different age groups. The rationale was to determine whether we could reduce the burden on colposcopy services by prioritizing the mild dyskaryotic referrals by age, as we hypothesized that high-grade CIN is less frequent in younger women. METHODS: The study sample included all women who were referred for colposcopy with a cervical smear suggesting mild dyskaryosis (with or without koilocytosis) from April 2000 to March 2003. RESULTS: We studied 510 women. They were divided into three age groups (<20, 20-25 and >25 years). The overall prevalence of high-grade CIN (CIN II and III) was 28.7%.The positive predictive value of a mildly dyskaryotic smear for high-grade CIN was similar in all groups. CONCLUSIONS: Our results show that we are not in a position to prioritize our referrals by age group and reduce the initial pressure for colposcopies. We are also concerned that with the implementation of the new guidelines, a significant number of women <25 years will be carrying high-grade CIN for more than 5 years before they are first screened.     

Six years' audit of laboratory workload and rates of referral for colposcopy in a cervical screening programme in three districts.

OBJECTIVE--To determine laboratory workload and rates of referral for colposcopy in a three district cervical screening programme during 1983-9 to assess the feasibility of accommodating call up of all women at risk, recall at three year intervals (now five year intervals), and investigation of women with all degrees of abnormality. DESIGN--Analysis of computerised screening histories dating back to 1977 of women screened in the Avon cervical screening programme. SETTING--Three district health authorities covering the population of Bristol and Weston-super-Mare, comprising 800,000 people, of whom 250,000 were female residents aged 20 to 64. SUBJECTS--196,977 Women aged 20 to 64 screened in cervical screening programme since 1983. RESULTS--Laboratory workload devoted to follow up of women with abnormalities increased sharply between 1987-8 and 1988-9, with increases of 54% (from 2075 to 3196) in the number of smears for follow up of severe dyskaryosis and invasive cancer, 40% (from 1925 to 2695) for mild and moderate dyskaryosis, and 49% (from 1793 to 2677) for borderline change. The increases were partly explained by the introduction in April 1988 of protocols for follow up and investigation based on guidance in an intercollegiate working party report. The proportion of women with mild and moderate dyskaryosis who were recommended for referral for colposcopy increased steadily from 9.9% in 1983-4 to 79.9% in 1988-9, and for borderline change the proportions were 3.5% and 13.6% respectively. Of all women tested in 1988-9, referral for colposcopy was recommended in 3%. CONCLUSIONS--The increase in laboratory follow up work identified, if it continued, could result in half of existing laboratory capacity in Avon being devoted to follow up work by 1993, with little prospect of maintaining call, recall, and quality control. Investigation of all women with minor cytological abnormalities is neither justifiable nor sustainable and will undermine the benefits of screening by increasing the rate of false positive results and the financial costs.