Uterine Atony: Why It Occurs and How to Treat It
Uterine atony is the most common and also the most serious cause of postpartum hemorrhage. This is one of the most delicate obstetric complications that exist. When such a hemorrhage is severe, it puts the mother’s life at risk.
It’s estimated that the disease develops in up to 5% of natural deliveries. It has to do with a defect in the muscle fibers that are present in the wall of the uterus. This leads to the fact that the vessels of the organ don’t stop bleeding after delivery.
Hemorrhage caused by atony of the uterus has different levels of severity. In all cases, it’s considered a medical emergency that should be treated immediately.
What is uterine atony?
Atony of the uterus is the inability of the uterus to contract after delivery, which is the third stage of labor, in which placental abruption occurs. Under normal conditions, the uterus should contract to close the blood vessels.
If the uterus lacks tone, the blood vessels remain open, and hemorrhage occurs. It’s estimated that up to 70% of cases of postpartum hemorrhage are due to this condition.
It can lead to hypovolemia or decreased blood volume, hemodynamic instability, and shock. The worst feared outcome is maternal death.
There are two types of uterine atony:
- Early atony: This is the most frequent and occurs in the delivery room itself.
- Late atony: This is less common and occurs in the moments after leaving the delivery room.
Why does it occur?
Early uterine atony is usually due to the mother not producing enough oxytocin naturally. Oxytocin is a hormone that promotes contraction of the uterus in labor and postpartum. Other possible causes of both early and late uterine atony include the following:
- Overdistension of the uterus: This occurs when the uterus has become excessively elastic and then fails to regain its shape. It’s due to multiple pregnancies or because the baby is very large.
- Placental accretism: This occurs when there is abnormal adhesion of the placenta to the wall of the uterus. In this case, it’s very attached, and there are difficulties in removing it.
- Delayed delivery of the placenta: This happens when the placenta takes more than 20 minutes to come out.
- Muscle fatigue: In this case, the uterus doesn’t contract properly due to fatigue if labor has lasted a long time.
- Tocolytic drugs: These produce an inhibition of contractions and sometimes lead to uterine atony.
- Injury or trauma to the uterus.
- Anatomical alterations in the organ: the presence of fibroids.
- Incomplete expulsion of the placenta.
- Clots.
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Risk factors
A woman who has had atony of the uterus after childbirth is more likely to develop it in subsequent deliveries. Likewise, there are other factors that increase the risk:
- Having a large baby
- Placenta previa
- Multiple gestations
- Advanced age of the mother
- Fetal death in utero
- Prolonged or precipitous labor
- Having had several pregnancies
- Premature detachment of the placenta
- Previous postpartum hemorrhage
- Abnormal increase of amniotic fluid or polyhydramnios
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Symptoms and diagnosis of atony of the uterus
The main manifestation of atony of the uterus is bleeding of varying intensity. Sometimes it comes on suddenly and is copious, while at other times, it occurs gradually and is less severe.
In addition to the outflow of blood from the vagina, there is also blood and clots retained within the uterus. The diagnosis is made by an examination in which the physician palpates the abdomen. The uterus feels soft and enlarged, and there is profuse expulsion of blood with gentle massage.
The medical professional also examines the vagina, the birth canal, and the cervix to determine if there’s any tearing. This is usually complemented by blood tests to determine the effects of the hemorrhage and to establish if there’s a coagulation problem.
Treatment
The initial treatment of uterine atony is carried out through two measures: a uterine massage, or Credé maneuver, and the administration of oxytocin. When the mother begins to bleed, massage is applied in which the abdomen is rubbed to promote contraction of the uterus.
Sometimes a bimanual maneuver is applied. In this, one hand is massaged inside the uterus and the other outside.
If this doesn’t work, oxytocin is administered to stop the bleeding. When this measure is also ineffective, a surgical approach is necessary with one of the following procedures:
- Instrumental curettage: A spoon-like instrument is introduced from the vagina into the uterus. This drags and removes the remains of clots and the endometrium.
- Ligation of pelvic vessels: The blood vessels that carry blood to the uterus are sutured. By reducing blood flow to the uterus, bleeding is also reduced.
- Embolization of the uterine vessels: A catheter is introduced through the femoral artery until it reaches the arteries of the uterus. Small particles of plastic or gelatin are then inserted to interrupt the flow of blood.
- A plication or capitonage is performed: These are compressive sutures done in the uterus. They’re considered the last options before a hysterectomy.
- Hysterectomy: This is the definitive removal of the uterus. It’s only considered if the mother’s life is in danger.
Can uterine atony be prevented?
It’s not possible to prevent uterine atony before delivery. However, more and more measures are being taken to prevent it from happening. It’s now very common for a uterotonic drug to be given to the mother during the first minute of the baby’s life. This helps the organ to contract. Uterine atony can cause major hemorrhage leading to significant blood loss. If not attended to quickly, and even if it is, it could lead to multi-organ failure.
All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.
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