What Is Atony of the Uterus?
Atony of the uterus, also called uterine atony, is a serious condition that can occur after childbirth. It occurs when the uterus fails to contract after the delivery of the baby, and it can lead to a potentially life-threatening condition known as postpartum hemorrhage.
After the delivery of the baby, the muscles of the uterus normally tighten, or contract, to deliver the placenta. The contractions also help compress the blood vessels that were attached to the placenta. The compression helps prevent bleeding. If the muscles of the uterus don’t contract strongly enough, the blood vessels can bleed freely. This leads to excessive bleeding, or hemorrhage.
If you have atony of the uterus, you’ll need immediate treatment to help stop the bleeding and to replace the lost blood. Postpartum hemorrhage can be very serious. However, early detection and treatment can lead to a full recovery.
The main symptom of atony of the uterus is a uterus that remains relaxed and without tension after giving birth. Atony of the uterus is one of the most common causes of postpartum hemorrhage. A postpartum hemorrhage is defined as loss of more than 500 milliliters of blood after delivery of the placenta.
The symptoms of hemorrhage include:
- excessive and uncontrolled bleeding following the birth of the baby
- decreased blood pressure
- an increased heart rate
- a backache
There are several factors that may prevent the muscles of the uterus from contracting after labor. These include:
- prolonged labor
- very rapid labor
- overdistention of the uterus, or excessive enlargement of the uterus
- the use of oxytocin (Pitocin) or other drugs or general anesthesia during labor
- induced labor
You may be at a higher risk of atony of the uterus if:
- you’re delivering multiples, such as twins or triplets
- your baby is much larger than average, which is called fetal macrosomia
- you’re older than 35 years of age
- you’re obese
- you have too much amniotic fluid, which is called polyhydramnios
- you’ve had many prior births
Uterine atony can also occur in women who don’t have any risk factors.
Atony of the uterus is usually diagnosed when the uterus is soft and relaxed and there’s excessive bleeding after giving birth. Your doctor may estimate the blood loss by counting the number of saturated pads or by weighing the sponges used to absorb blood.
Your doctor will also perform a physical exam and to rule out other causes of bleeding. This includes making sure there are no tears in the cervix or vagina and that no pieces of the placenta are still in the uterus.
Your doctor may also test or monitor the following:
- pulse rate
- blood pressure
- red blood cell count
- clotting factors in the blood
Atony of the uterus causes up to 90 percent of postpartum hemorrhage cases, according to Blood Transfusion in Clinical Practice. Hemorrhage usually happens after the placenta is delivered.
Other complications of uterine atony include:
- orthostatic hypotension, which is lightheadedness or dizziness due to low blood pressure
- an increased risk of postpartum hemorrhage in a later pregnancy
Anemia and fatigue after birth also increase the chances of a mother having postpartum depression.
A serious complication of atony of the uterus is hemorrhagic shock. This condition can even be life-threatening.
Treatment is aimed at stopping the bleeding and replacing the blood that was lost. The mother may be given IV fluids, blood, and blood products as soon as possible.
Treatment for atony of the uterus includes:
- uterine massage, which involves your doctor placing one hand in the vagina and pushing against the uterus while their other hand compresses the uterus through the abdominal wall
- uterotonic drugs including oxytocin, methylergonovine (Methergine), and prostaglandins, such as Hemabate
- blood transfusions
In severe cases, the treatment includes:
- surgery to tie off the blood vessels
- uterine artery embolization, which involves injecting small particles into the uterine artery to block blood flow to the uterus
- hysterectomy if all other treatments fail
Postpartum hemorrhage is a major cause of death after birth in countries that have limited healthcare facilities and a lack of trained healthcare personnel. Death from postpartum hemorrhage is much less common in the United States. It occurs in less than 1 percent of cases.
A woman’s risk of dying from the condition increases when there are delays in transport to a hospital, in making the diagnosis, and in receiving the recommended treatment. Complications are rare if proper treatment is given.
Atony of the uterus can’t always be prevented. It’s important that your doctor knows how to manage this condition in all stages of labor. If you’re at high risk of atony of the uterus, you should deliver your baby in a hospital or center that has all the adequate equipment to deal with blood loss. An intravenous (IV) line should be ready and medication should be on hand. Nursing and anesthesia staff should be available at all times. It may also be important to notify the blood bank of the potential need for blood.
Your doctor should continually monitor your vital signs and the amount of bleeding that occurs after birth to detect hemorrhage. Oxytocin given right after delivery can help the uterus contract. Uterine massage right after delivery of the placenta may also reduce the risk of atony of the uterus and is now a common practice.
Taking prenatal vitamins, including iron supplements, can also help prevent anemia and other complications of uterine atony and hemorrhage after delivery.