Dilatation of the parous non-pregnant cervix

In vitro cervical dilatations were carried out on 33 uteri removed by hysterectomy for conditions not involving the cervix from parous women in their reproductive span of life. A specially designed force measuring dilator was used for all the tests. The analysis of the results involved the application of a thick-walled cylindrical stress determination technique. Using this approach it was possible to calculate quasi-elastic moduli for different degrees of dilatation and obtain theoretical distributions of radial and circumferential stress across the cervical wall. These results indicated a yielding of the cervical tissue at about 9 to 11 mm. dilatation in a significant number of cases.