In medicine, atony (; also "atonia") is a condition in which a muscle has lost its strength. It is frequently associated with the conditions atonic seizure, atonic colon, uterine atony, gastrointestinal atony (occurs postoperatively) and choreatic atonia.

Atony can also refer to the paralyzed or extremely relaxed state of skeletal muscles in rapid eye movement sleep (REM sleep) in most warm-blooded animals.

The term "atony" comes from the Ancient Greek ἀτονία ("atonia"), "slackness, debility".

A boggy uterus is a finding upon physical examination where the uterus is more flaccid than would be expected.

It can be associated with uterine atony.

It may also be associated with adenomyosis.

Uterine atony is a loss of tone in the uterine musculature. Normally, contraction of the uterine muscles during labor compresses the blood vessels and reduces flow, thereby increasing the likelihood of coagulation and preventing hemorrhage. A lack of uterine muscle contraction, however, can lead to an acute hemorrhage, as the uterine blood vessels are not sufficiently compressed. Clinically, 75-80% of postpartum hemorrhages are due to uterine atony.

Precipitate delivery refers to a delivery which results after an unusually rapid labor (combined 1st stage and second stage duration is <2hrs) and culminates in the rapid, spontaneous expulsion of the infant. Delivery often occurs without the benefit of asepsis.

There are common factors which may cause a woman to deliver rapidly. These factors include:

1. A multipara with relaxed pelvic or perineal floor muscles may have an extremely short period of expulsion.

2. A multipara with unusually strong, forceful contractions. Two to three powerful contractions may cause the baby to appear with considerable rapidity.

3. Inadequate warning of imminent birth due to absence of painful sensations during labor.

Bloody show is the passage of a small amount of blood or blood-tinged mucus through the vagina near the end of pregnancy. It can occur just before labor or in early labor as the cervix changes shape, freeing mucus and blood that occupied the cervical glands or cervical os. Bloody show is a relatively common feature of pregnancy, and it does not signify increased risk to the mother or baby . A larger amount of bleeding, however, may signify a more dangerous, abnormal complication of pregnancy, such as placental abruption or placenta previa. Large amounts of bleeding during or after childbirth itself may come from uterine atony or laceration of the cervix, vagina, or perineum.

Three common signs of the onset of labor are:

1. A bloody show

2. Rupture of membranes ("Water breaking")

3. Onset of tightenings or contractions

However, these may occur at any time and in any order. Some women neither experience a bloody show nor have their "water break" until well into advanced labor. Therefore, neither bloody show nor rupture of membranes are required to establish labor.

Symptoms of ileus include, but are not limited to:

- moderate, diffuse abdominal discomfort

- constipation

- abdominal distension

- nausea/vomiting, especially after meals

- vomiting of bilious fluid

- lack of bowel movement and/or flatulence

- excessive belching

Decreased propulsive ability may be broadly classified as caused either by bowel obstruction or intestinal atony or paralysis. However, instances with symptoms and signs of a bowel obstruction occur, but with the absence of a mechanical obstruction, mainly in acute colonic pseudo-obstruction, Ogilvie's syndrome.

Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breath rate. As more blood is lost the women may feel cold, their blood pressure may drop, and they may become unconscious.

Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood within the first 24 hours following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breath rate. As more blood is lost the women may feel cold, their blood pressure may drop, and they may become restless or unconscious. The condition can occur up to six weeks following delivery.

The most common cause is poor contraction of the uterus following childbirth. Not all of the placenta being delivered, a tear of the uterus, or poor blood clotting are other possible causes. It occurs more commonly in those who: already have a low amount of red blood, are Asian, with bigger or more than one baby, are obese or are older than 40 years of age. It also occurs more commonly following caesarean sections, those in whom medications are used to start labor, and those who have an episiotomy.

Prevention involves decreasing known risk factors including if possible procedures associated with the condition and giving the medication oxytocin to stimulate the uterus to contract shortly after the baby is born. Misoprostol may be used instead of oxytocin in resource poor settings. Treatments may include: intravenous fluids, blood transfusions, and the medication ergotamine to cause further uterine contraction. Efforts to compress the uterus using the hands may be effective if other treatments do not work. The aorta may also be compressed by pressing on the abdomen. The World Health Organization has recommended non-pneumatic anti-shock garment to help until other measures such as surgery can be carried out. In 2017 study found that tranexamic acid decreased a woman's risk of death.

In the developing world about 1.2% of deliveries are associated with PPH and when PPH occurred about 3% of women died. Globally it occurs about 8.7 million times and results in 44,000 to 86,000 deaths per year making it the leading cause of death during pregnancy. About 0.4 women per 100,000 deliveries die from PPH in the United Kingdom while about 150 women per 100,000 deliveries die in sub-Saharan Africa. Rates of death have decreased substantially since at least the late 1800s in the United Kingdom.

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

- overdistention of the uterus

- multiple gestations

- polyhydramnios

- fetal macrosomia

- prolonged labor

- oxytocin augmentation of labor

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

- precipitous labor (labor lasting less than 3 hours)

- magnesium sulfate treatment of preeclampsia

- chorioamnionitis

- halogenated anesthetics

- uterine leiomyomata

- full bladder

- retained colyledon, placental fragments

- placenta previa

- placental abruption

- constriction ring

- incomplete separation of the placenta