Cervical incompetence and cerclage in Denmark 1980-1990. A register based epidemiological survey.

OBJECTIVE To assess the incidence rate of cervical incompetence diagnoses in Denmark 1980-1990 according to maternal age, to analyse regional variations, to investigate how often cerclage is applied, and finally to estimate abortion rates among women with cervical incompetence with and without cerclage. DESIGN A register-based retrospective cross section study. SETTING All Danish gynecological departments. MATERIAL AND METHODS Since 1977, all hospitalized patients in Denmark have been centrally recorded by diagnosis according to the ICD classification and by operation codes in The National Patient Register. From this database, all women with cervical incompetence (CI) and cerclage in the period 1980-1990 were identified. From the same database all cases of spontaneous abortions were registered. RESULTS A total of 2756 cases of cervical incompetence were registered in the period 1980-1990, corresponding to an incidence rate of 4.6/1000 births. The risk of cervical incompetence increased from 2/1000 births among women 15-19 years old to 7.5/1000 births among women 35-39 years old. The incidence rate of the CI-diagnosis fell 44% from 1980 to 1990. The incidence rates in different counties ranged from 1.7/1000 births to 10.0/1000 births. The average length of stay in hospital among patients with cervical incompetence was three weeks. Among patients with cervical incompetence, 61% were treated with cerclage. This per cent increased from 29% among women 15-19 years old to 68% among women 35-39 years old. 13.5% of women with CI experienced spontaneous abortion. This percentage increased from 12% for women 15-19 years old to 17% among women 40-44 years old (p < 0.01). Among women with CI and cerclage, the abortion rate was 17.6%. CONCLUSION In the period 1980-1990 the incidence rate of cervical incompetence in Denmark was on the average 4.6/1000 births. The incidence rate of the CI-diagnoses has fallen significantly during the last decade, and it increases four-fold with increasing age. Six out of ten patients with cervical incompetence were treated with cerclage.