The clinical importance of intra-uterine rings complicating labor is not sufficiently appreciated. This condition, which causes dystocia, is chiefly functional and has been designated by at least twenty different terms. The assumption that intra-uterine rings are due solely to the contraction ring of Bandl, the contraction ring of Schroeder or the retraction ring of Barbour and Lusk is not tenable, in view of the different uterine levels at which they are found. The designation of this dystocia as a constriction ring dystocia is based on biologic grounds. A review of 350 cases collected from the literature and twenty-one cases in my experience demonstrates that a conservative management with delivery by vagina is the safest for the mother and child.
THE FORMATION OF INTRA-UTERINE RINGS
The physiologic division of the uterus into an upper and a lower uterine segment was definitely established by the second stage frozen section of Braune1
RUDOLPH L. CONSTRICTION RING DYSTOCIA. JAMA. 1937;108(7):532-538. doi:10.1001/jama.1937.02780070016005