uterine segment


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segment

 [seg´ment]
a demarcated portion of a whole. adj., adj segmen´tal.
behavior segment the smallest descriptive unit of a response to a stimulus.
bronchopulmonary s's the smaller subdivisions of the lobe of a lung; each segment is separated from others by a connective tissue septum and supplied by its own branch of the bronchus leading to the particular lobe.
hepatic s's subdivisions of the hepatic lobes based on arterial and biliary supply and venous drainage.
renal s's subdivisions of the kidney that have independent blood supply from branches of the renal artery, including the superior, anterior superior, inferior, anterior inferior, and posterior segments.
uterine segment either of the two portions into which the uterus becomes differentiated early in labor; the upper contractile portion (corpus uteri) becomes thicker as labor approaches, and the lower noncontractile portion (the isthmus) is thin walled and passive in character.

uterine segment

One of the two functional divisions of the uterine musculature during labor. During labor the upper uterine segment forcibly contracts, becoming progressively shorter and thicker, exerting traction on the more passive lower segment, and increasing the hydrostatic pressure against the cervix. The combination of forces and traction gradually cause the lower segment to thin, resulting in cervical effacement and dilation. See: physiologic retraction ring
See also: segment
References in periodicals archive ?
Transmural extension through the wall of the right lower uterine segment and invasion of the upper endocervix were confirmed.
Therefore, the consensus and that of the authors of the current supplement is to perform routine diagnostic hysteroscopy before thermal balloon ablation as a conservative measure for a lower uterine segment condition.
In gravid patients, the largest cervical cup from a disassembled KOH colpotomizer is used to laparoscopically delineate the vaginal fornices and atraumatically manipulate the cervix and lower uterine segment by using two ring forceps secured opposite one another to the outer ring.
In the wedge technique, the cervix is bivalved in the anteroposterior plane to the level of the lower uterine segment.
Bipolar dissection and sharp dissection are used to mobilize the uterine arteries well off the lower uterine segment.
He says that when performing a cesarean section for arrest of descent with a well-engaged fetal head and no one available to lend "a vaginal hand," after making the uterine incision but before placing your hand in the incision, first cup the fetal head outside over the lower uterine segment and lift to disengage the head, breaking the vacuum and making delivery much easier.
This procedure releases local prostaglandins and inoculates the lower uterine segment with cervicovaginal microflora.
Three sonographic signs were found to predict placenta accreta: concomitant placenta previa; large or numerous placental venous "lakes"; and a remarkably thin, or even nonvisualized, lower uterine segment.