Uterine atony is a loss of tone in the uterine

Uterus

The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

 musculature. Normally, contraction of the uterine muscle compresses the vessels and reduces flow. This increases the likelihood of coagulation and prevents bleeds. Thus, lack of uterine muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 contraction can cause an acute hemorrhage. Clinically, 75-80% of postpartum hemorrhages are due to uterine atony.

Risk factors

Many factors can contribute to the loss of uterine muscle tone, including:

- overdistention of the uterus

- multiple gestation

Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

s

- polyhydramnios

Polyhydramnios

Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in 0.2 to 1.6% of pregnancies,,...

- fetal macrosomia

- prolonged labor

Childbirth

Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

- oxytocin

Oxytocin

Oxytocin is a mammalian hormone that acts primarily as a neuromodulator in the brain.Oxytocin is best known for its roles in sexual reproduction, in particular during and after childbirth...

 augmentation of labor

- grand multiparity (having given birth 5 or more times)

- precipitous labor (labor lasting less than 3 hours)

- magnesium sulfate

Magnesium sulfate

Magnesium sulfate is a chemical compound containing magnesium, sulfur and oxygen, with the formula MgSO4. It is often encountered as the heptahydrate epsomite , commonly called Epsom salt, from the town of Epsom in Surrey, England, where the salt was distilled from the springs that arise where the...

 treatment of preeclampsia

- chorioamnionitis

Chorioamnionitis

Chorioamnionitis is an inflammation of the fetal membranes due to a bacterial infection. It typically results from bacteria ascending into the uterus from the vagina and is most often associated with prolonged labour...

- halogen

Halogen

The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...

ated anesthetics

- uterine leiomyomata

Treatment

Post-partum hemorrhage related with cesarean section should be treated by surgical tecniques such as the B-Lynch method.