Uterine Atony: Symptoms, Causes & Treatment

Uterine atony is the inability of the uterus to contract following a vaginal or cesarean birth, which can result in postpartum hemorrhage requiring immediate treatment to avoid potentially life-threatening complications.

Risk factors for uterine atony include prolonged labor, twin pregnancy, chorioamnionitis (infection of the bag of waters), maternal obesity, or use of magnesium sulfate to treat preeclampsia or eclampsia.

It may be possible to prevent uterine atony by identifying risk factors during pregnancy. Uterine atony requires immediate treatment to prevent complications like hypovolemic shock due to postpartum hemorrhage. 

Common symptoms

The main symptoms of uterine atony are:

• Heavy or prolonged vaginal bleeding following delivery;
• Continuous bleeding or passing large clots;
• Back pain;
• Low blood pressure;
• Rapid heart beat;
• Skin that is cold, pale, and clammy;
• Dizziness or feeling like you are about to faint.

The symptoms of uterine atony are caused by excessive blood loss that should be identified by an OB provider immediately postpartum so that treatment can be given to prevent complications like hypovolemic shock.

Confirming a diagnosis

The diagnosis of uterine atony is made on exam by an OB provider immediately following a vaginal or cesarean delivery. 

This exam is done by palpating the uterus, which should feel firm. In the case of uterine atony, the uterus will feel soft and enlarged, with bleeding coming from the cervix (the opening to the uterus).

Possible causes

Uterine atony is caused by the inability of the uterine muscle to contract following delivery of the placenta, resulting in heavy vaginal bleeding (postpartum hemorrhage). 

Under normal conditions, the uterus contracts following delivery of the placenta in order to clamp down on the blood vessels that connected the uterus and the placenta to prevent excessive bleeding.

Uterine atony can also occur during the birth or following a miscarriage.

Risk factors

Factors that can increase the risk of uterine atony include:

• Maternal age greater than 35;
• Prolonged labor or very fast labor;
• Polyhydramnios (too much amniotic fluid) or chorioamnionitis (infection of the bag of waters);
• Twin or triplet pregnancy;
• Very large baby (fetal macrosomia);
• Maternal obesity with a BMI >40;
• Large uterine fibroids;
• Use of magnesium sulfate to treat preeclampsia or eclampsia.

Uterine atony can also be caused by a retained placenta, placenta previa or accreta, placental abruption, or blood clotting problems. 

Pregnant people who experienced uterine atony in a previous pregnancy are at increased risk of it happening again.

Treatment options

Treatment of uterine atony is managed by a team of specialists including your OBGYN or midwife and needs to be initiated immediately following delivery to prevent postpartum hemorrhage and additional complications.

The treatment of uterine atony includes:

1. Medications

The use of medications for the treatment of uterine atony are indicated to help the uterus contract.

The most common medications for uterine atony are:

• Oxytocin (Pitocin), given as an intramuscular (IM) injection or through an IV;
• Methylergometrine (Methergine), given as an IM injection every 2 to 4 hours;
• Carboprost (Hemabate), given as an IM injection every 15 to 90 minutes for a maximum of 8 doses;
• Misoprostol (Cytotec), given rectally.

An IV should be placed to help replace fluids lost through excessive bleeding. A blood transfusion may also be necessary.

2. Uterine tamponade

Uterine tamponade is done by an OBGYN in order to slow down or stop a hemorrhage.

This type of treatment involves plugging the uterus to stop the flow of blood, which usually involves placing a Bakri balloon in the uterus and then inflating it.

The medical team will also place a urinary catheter to help drain the bladder.

3. Surgery

Surgery may be needed if other treatments are not enough to stop the bleeding caused by uterine atony.

This surgery is performed by an OBGYN and may consist of different techniques, such as uterine curettage to remove retained pieces of placenta, uterine artery ligation (tying off the uterine arteries to control bleeding), or ligation of the internal iliac artery. 

In more serious cases, your doctor may recommend performing a total hysterectomy in order to resolve the hemorrhage, which involves the removal of the uterus and the cervix.

Identification and prevention 

It may be possible to prevent uterine atony starting with identifying risk factors for uterine atony during prenatal care.

Your OB provider can also help prevent uterine atony by performing uterine massage as part of the third stage of labor, which corresponds to the period when the placenta is being expelled.

Administering oxytocin (Pitocin) following delivery of the placenta can also help the uterus to contract more effectively in order to avoid a postpartum hemorrhage.

Possible complications

The main complications of uterine atony are:

• Postpartum hemorrhage;
• Hypovolemic shock;
• Anemia;
• Disseminated intravascular coagulation (DIC);
• Infection of the uterine lining (endometritis);
• Acute kidney injury, liver damage, or heart failure.

Uterine atony is a potentially life-threatening condition that needs to be managed emergently, immediately following delivery, and requires continued monitoring even after the situation has been resolved.