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 ?
CD for placenta previa is associated with an increased risk of postpartum hemorrhage, with bleeding from the lower uterine segment greatly contributing to total blood loss.
Key imaging findings include an empty uterine cavity and cervix, gestational sac in the low anterior uterine segment, and thinned or absent overlying myometrium; MRI may provide useful anatomic information in equivocal cases or for surgical planning.
Therefore, we believe that if the abdominal aorta is blocked before the delivery, a transverse incision of the lower uterine segment is the best choice.
Accreta also can occur if the placenta implants over a submucosal fibroid located in the lower uterine segment, near the rudimentary uterine horn or near the uterine cornu.
These findings were confirmed by the Department of Radiology which described an anterior placenta extending along the lower uterine segment with multiple retro-placental vessels invading the myometrial wall and placenta extending into the posterior wall crossing over the internal cervical os.
The definitive resection specimen consisted of a uterus measuring 110 x 87 x 68 mm and weighing 290 g, with a tumor originating in the right lower uterine segment. The collective volume of the tumor tissue was 145 x 135 x 30 mm.
Sweeping involved separating the membranes from the lower uterine segment as far as possible with a finger inserted into the internal os.
Moreover, as mentioned by the readers, the effect of uterine contractions on the lower uterine segment is not determined yet, and still need further investigation.
Arising from the posterior aspect of the uterine fundus, body, and lower uterine segment is a fibroid that measures 9.7 x 15.5 x 18.9 cm.
Lower uterine segment pregnancy with placenta increta complicating first trimester induced abortion: diagnosis and conservative management.
This incision site appears hypoechoic relative to the myometrium on US, shows as an oval hypodense area on CT, and has higher signal intensity relative to muscles in the myometrium of the anterior lower uterine segment on T1- and T2-weighted images (4, 8).
reported the first case of bilateral uterine artery embolization at 20 weeks of gestation in 2009 for treatment of an 8 cm lower uterine segment arteriovenous malformation with a successful pregnancy outcome [8].