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What is uterine atony?
Uterine atony (atony of the uterus) occurs when your uterus doesn’t contract (or tighten) properly during or after childbirth. It’s a serious complication that can cause life-threatening blood loss. Uterine atony (or the muscular tone of your uterus) describes a uterus that is soft, or lacking tone.
During pregnancy, your baby grows in your uterus and gets blood, oxygen and nutrients from the placenta. Blood vessels and arteries supply blood to your baby through the placenta. After delivery, your uterus contracts to deliver the placenta. These contractions help prevent bleeding because they compress the blood vessels that connect your uterus to the placenta. Without pressure on these blood vessels, they can bleed freely and cause postpartum hemorrhage (excessive bleeding after birth).
Uterine atony can also occur during a miscarriage or other uterine surgeries, and it can be a complication of vaginal births or C-sections. Uterine atony happens in about 2% of all childbirths in the United States; however, not all cases lead to postpartum hemorrhage.
Atony of the uterus requires immediate medical intervention. Most people have a full recovery when it's treated promptly.
What happens if your uterus doesn't contract after birth?
When muscles in your uterus don't contract after giving birth, you’re at risk for excessive blood loss. After you give birth, blood vessels in your uterus break open to allow the placenta to detach from your uterine wall. Contractions help squeeze your blood vessels shut. When the muscles aren't squeezing enough, the blood flows freely, and you're at risk for severe bleeding. This is a medical emergency because it can be life-threatening.
What are the risk factors for uterine atony?
Uterine atony has several risk factors. These factors can prevent your uterus from contracting after delivery:
- This is your first baby or you’ve had more than five babies.
- You’re having twins, triplets and more.
- Your baby is larger than average (fetal macrosomia).
- You’re older than 35.
- You have too much amniotic fluid (polyhydramnios).
- You have obesity.
- You have uterine fibroids.
Healthcare providers also believe if the following factors are present during labor, your uterus may not contract after delivery:
- You’ve had a very long labor or very fast labor.
- You’ve had a difficult labor.
- Your labor is induced.
- You have chorioamnionitis (an infection of the membranes covering your baby).
- You've had general anesthesia.
- You have an enlarged uterus.
You’re at high risk for uterine atony if you have more than two risk factors. For people who have known risks, healthcare providers can make preparations before delivery so they are ready for quick action.
Symptoms and Causes
What causes atony of the uterus?
Uterine atony occurs when your uterine muscles don’t contract sufficiently in response to oxytocin, a hormone your body releases before and during childbirth to stimulate contractions.
What are the symptoms of uterine atony?
The biggest sign of uterine atony is prolonged or excessive bleeding from your uterus. Your healthcare provider detects most cases of uterine atony soon after your baby is born. Additionally, your uterus is relaxed, weak and loose after delivery.
Other symptoms of uterine atony are:
- Low blood pressure.
- Fast heart rate.
- Feeling dizzy or faint.
- Pale appearance.
- Losing consciousness.
- Being unable to pee.
- Pain, especially in your back.
Diagnosis and Tests
How is uterine atony diagnosed?
Healthcare providers learned how to spot uterine atony early and treat it fast. They can usually diagnose it by feeling the size and softness of your uterus after delivery. This typically involves your provider placing one hand on your abdomen while also performing a vaginal examination (fingers from the other hand are inside your vagina). In addition, some providers may weigh or count the sponges or pads used to absorb the blood to calculate how much blood you lost.
If you have uterine atony, your uterus is large, soft and weak. In a typical delivery, your uterus should begin contracting (tightening or hardening) and shrinking after delivery.
Uterine atony is the leading cause of postpartum hemorrhage, so your provider will also examine you for:
- Tears in your cervix, vagina or uterus.
- Retained placental tissue.
Your provider will continue to watch for changes in your blood pressure and heart rate. They may order blood tests to look at your red blood cell count and blood clotting factor (how fast your blood clots or coagulates).
Management and Treatment
How is uterine atony treated?
Uterine atony is an emergency and requires quick action from your healthcare team. The goal of treatment is to stop the bleeding as soon as possible and replace any lost blood or fluids. Even after the bleeding is under control, you may need a blood transfusion or IV fluids to replace what was lost.
Your pregnancy care provider typically begins treatment by massaging your uterus to promote stronger contractions. Depending on the severity, this may be enough to treat uterine atony.
In addition to uterine massage after delivery, your provider may use several medications to help your uterus contract. These medications include:
- Oxytocin (Pitocin®).
- Methylergonovine (Methergine®).
- Prostaglandins like 15-methyl-PGF2 (Hemabate®), misoprostol (Cytotec®) or dinoprostone.
- Ergot alkaloids like ergometrine.
Applying pressure to the uterine walls (tamponade techniques)
Your pregnancy care provider may need to apply more pressure to your uterus to limit the amount of blood loss. These techniques involve packing your uterus with gauze or inflating a balloon inside your uterus. With these methods, your provider places direct pressure on your uterine wall to stop the bleeding.
Surgery may be necessary if all other methods don't stop the bleeding. The surgeries to treat uterine atony are:
- Uterine curettage: Your provider scrapes retained blood or placental tissue from your uterus.
- Uterine artery ligation: A procedure to tie off blood vessels in your uterus.
- Uterine artery embolization: A procedure that uses small sand-like particles to block blood flow to your uterus.
- Hysterectomy: Removing your uterus is the final measure if all else fails.
What are the complications of uterine atony?
Complications of uterine atony include:
- Fatigue or being overly tired.
- Feeling dizzy or lightheaded due to low blood pressure.
- Increased risk for hemorrhage in future pregnancies.
How can I prevent uterine atony?
Uterine atony can't usually be prevented. If you're at risk, your healthcare provider may take steps ahead of time to prepare for excessive bleeding. This could include having extra help or equipment in the delivery room or delivering your baby at a different hospital. You can take steps to have a healthy pregnancy by taking prenatal vitamins, attending all of your prenatal appointments and maintaining a healthy weight during pregnancy.
If you’ve experienced heavy bleeding during a previous delivery, please make sure to let your obstetrician know.
Outlook / Prognosis
Can uterine atony happen twice?
Yes, you can experience uterine atony more than once. You're at higher risk if you've already had uterine atony.
A note from Cleveland Clinic
Uterine atony is a complication that occurs after childbirth. If you experience this serious condition, your pregnancy care team needs to treat you quickly to save you from losing too much blood. Talk to your healthcare provider about uterine atony and if you’re at risk. Knowing if you’re at risk ahead of time can help you prepare for emergency care if you need it.
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