ABSTRACT
In 1658 Riverius and colleagues1 described for the first time a late spontaneous abortion, whose cause was thought to be the ‘slackness’ of the uterine cervix. Two hundred years later, Gream2 speculated on the possibility that a ‘weakness’ in the cervical structures prevented them from supporting the weight of the pregnancy to term. It was not until 1947, however, that Danforth3 correctly described the musculofibrous sphincter mechanism of the internal cervical os of the uterine cervix. This detailed anatomical study enabled Lash and Lash4, in 1950, to define cervical incompetence, or insufficiency, as ‘the loss of structural or functional integrity in the sphincter mechanism of the internal cervical os, resulting in the effacement and dilatation of the uterine cervix and the subsequent interruption of the gestation at between 14 and 28 weeks’.
