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a pathologic retraction ring at the juncture of the upper and lower segments of the uterus occurring at any stage of dysfunctional or obstructed labor. Normally, as contractions progress during labor the upper segment of the uterus becomes thicker and more active while the lower segment becomes thin-walled, supple, and passive. The boundary between the two points is marked by a normal physiologic retraction ring. In difficult labor the ring can become hardened and more prominent. The pathologic ring is observed as an indentation in the abdomen as the ring rises against the abdominal wall. The uterine wall below the pathologic ring becomes thin and distended as labor continues. If obstruction to the passage of the fetus and placenta is not relieved, the lower segment of the uterus may rupture.
1. any annular or circular organ, structure or area.
2. in chemistry, a collection of atoms united in a continuous or closed chain.
abdominal ring (external)
an opening in the aponeurosis of the external oblique muscle for the spermatic cord or round ligament. Called also external inguinal ring.
abdominal ring (internal)
an aperture in the transverse fascia for the spermatic cord or round ligament. Called also internal inguinal ring.
see bandl's rings.
an immature granulocyte, intermediate between the myelocyte and metamyelocyte, found in the bone marrow of rats. There is a 'hole' in the nucleus.
the posterior part of the ciliary body of the eye, a continuation of the choroid.
a ring at the junction of the conjunctiva and cornea.
a contracted area of the uterus, where the resistance of the uterine contents is slight, as over a depression in the contour of the fetus, or below the presenting part.
deep inguinal ring
an aperture in the transverse fascia for the spermatic cord or the round ligament.
the abdominal opening of the femoral canal through which the femoral nerve and blood vessels pass from the peritoneal cavity to the limb.
see abdominal ring (above).
the ring in the pancreas that accommodates the portal vein.
ring precipitin test
see precipitin reaction.
the rim of the external orifice of the prepuce proper, the internal prepuce, on the penis of the horse.
the demarcation between the upper, contracting portion of the uterus in normal parturition and the lower, dilating part.
retraction ring (pathological)
a complication of prolonged labor marked by failure of relaxation of the circular fibers at the internal opening of the cervix, obstructing delivery of the fetus.
see schwalbe's ring.
see ring of ossicles.
a rubber ring fitted over the glans penis of the stallion which discourages erection and masturbation.
superficial inguinal ring
a fissure-like opening in the aponeurosis of the external abdominal oblique muscle for the spermatic cord or the round ligament.
see ascoli test.
the bony ring forming part of the temporal bone at birth and developing into the tympanic plate.
the orifice in the abdominal wall of the fetus for transmission of the umbilical vein and arteries.
vaccination of all animals in a zone around an area in which the subject disease occurs. A preventive strategy that contains the infected population so that the eradication team has a finite target.
any of a number of congenital anomalies of the aortic arch and its branches, the vessels forming a ring about the trachea and esophagus that cause varying degrees of compression, vomiting and esophageal dilatation. See also persistent right aortic arch.