Loop excisions <10 mm for CIN do not raise the risk of recurrence in women aged 35 and under with high-grade disease, a study has found.

A total of 1,558 women with high-grade CIN undergoing loop excision of the cervix, over a six-year period, were studied. Patients were followed up for a median of 77 months (range 3-132 months).

Fifty-seven (3.7%) women had recurrence of high-grade disease; 16 (3.9%) >35 and 41 (3.6%) ≤ 35. In those >35 years of age, smaller loop excision size (<10 mm) was associated with a higher disease recurrence rate (7.5% vs 3.0%, p=0.05) as was disease involvement at the endocervical margin.

In women ≤ 35 years, recurrence rates were similar for those with loop depths <10 mm and > 10 mm, 4.3% vs 3.4% respectively. However, a smaller loop excision depth was associated with a greater chance of incomplete excision of the endocervical margin 24.4% vs 13.3%, odds ratio 1.83 (95% CI: 1.38-2.42, p<0.01).

The authors speculate that ball diathermy may have ablated residual disease.

Loop excision is quick, can be carried out at the patient's first attendance and generally allows reliable histological assessment of the sample. Deep loop excision may increase the risk of problems in subsequent pregnancies such as cervical stenosis and incompetence. Loop excisions in younger women therefore tend to be smaller, but this study suggests that this does not appear to increase the risk of recurrent disease.

Two anatomical features seem to have prognostic significance in CIN and its treatment. First, the maximum depth of cervical crypts on the transformation zone is 7.8 mm and almost all CIN-involved crypts lie within 4.8 mm of the surface. The second is that the endocervical upper limit of the transformation zone migrates caudally over the years making disease clearance in older women more difficult.

The upshot is that smaller loop excisions in potentially fertile women appear safe.

Dr Chris Barclay