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Circular uterine dystopia (contracture ring)
Last reviewed: 04.07.2025
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Circular dystopia of the uterus (contraction ring) is a pathology caused by contractions of a section of circular muscle fibers at various levels of the uterus (except for the cervix). Circular dystocia of the uterus occurs during protracted labor with long-standing amniotic fluid leakage. In this case, the uterus wraps around the fetus around the neck or abdomen. The cause may be increased excitability of the uterus. This pathological condition occurs both in the first and second stages of labor.
Symptoms. Women in labor usually complain of severe pain in the uterus, localized in the area of the contraction ring and above it. Visually, a constriction on the uterus in the area of the contraction ring can be seen. Palpation reveals an annular retraction on the uterus. During contractions, the fetal head can be easily moved from side to side. The opening of the cervix is slow or stops. Premature rupture of membranes is common. Labor becomes protracted, and the fetus suffers.
During vaginal examination, the presenting part of the fetus does not make any forward movement during the contraction (in the absence of signs of discrepancy). The part of the uterus between the external os and the contraction ring is passive during the contraction. The diagnosis of this pathology can be confirmed by examining the uterus during a cesarean section - constriction on the uterus. An ultrasound examination can undoubtedly help in diagnosing this anomaly of labor.
Differential diagnosis should be made primarily with the discrepancy between the fetal head and the pelvis of the mother in labor, with secondary weakness of labor, and with cervical dystocia. Cervical dystocia should be classified as anomalies of the soft birth canal, and not as anomalies of labor. The presence of cervical dystocia usually leads to anomalies of labor.
In the absence of a threatening condition on the part of the mother and fetus, tocolysis with beta-adrenergic agonists (partusisten, brikanil, ritodrine, etc.) and administration of antispasmodics (no-shpa 2 ml, baralgin 2 ml, etc.) are indicated. A 25% solution of magnesium sulfate 10 ml can be administered intramuscularly, pantopon (2% solution - 1 ml), promedol (1% solution - 1 ml), seduxen (10 mg) can be administered subcutaneously. If the effect cannot be achieved, deep anesthesia with ether or fluorothane should be used to eliminate the contraction ring.
Obstetric forceps can be applied only under deep ether or fluorothane anesthesia and if there are conditions for their application. In the case of a dead fetus, a feto-destroying operation is performed, sometimes it is necessary to resort to a cesarean section. A cesarean section operation is the method of choice in the absence of success from drug therapy, including deep anesthesia. In order to carefully extract the child, it is advisable to make a longitudinal incision on the uterus.
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