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Pre-term uterine constriction rings and their consequences

Thickenings in uterine muscle are described as retraction or constriction rings. The term retraction (Bandl’s) ring is used generically to describe several different patterns of ring (Johnson 1946). It refers to a thickening in the uterine musculature between the upper and lower uterine segments that develops during prolonged labours and causes difficulty with delivery. Constriction rings are different. Their aetiology is not known, although they may cause considerable difficulty for mother, baby and obstetrician (Donald 1955; Rudolph 1935; Turrentine and Andres 1997).