Atony of the uterus: why it occurs and how to treat it


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Uterine atony is not a very common problem, but the risk of its occurrence is real. Currently, there are some measures that help prevent it.

Atony of the uterus 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 bleeding is severe, it puts the life of the mother at risk.

It is estimated that the disease develops in up to 5% of natural births. It has to do with a defect in the muscle fibers that are present in the wall of the uterus. This leads to the vessels of the organ not stopping bleeding after delivery.

Hemorrhage caused by atony of the uterus has different levels of severity. In all cases, it is considered a medical emergency that must be attended to immediately.

What is atony of the uterus?

Uterine atony is the inability of this organ to contract after delivery, which is the third stage of labor, in which placental abruption takes place. Under normal conditions, the uterus should contract to close the blood vessels.

If tone in the uterus is lacking, the blood vessels remain open and bleeding occurs. It is estimated that up to 70% of cases of postpartum hemorrhage are due to this cause.

It can lead to hypovolemia or decreased blood volume, hemodynamic instability, and shock. The feared result is the death of the mother.

There are two types of atony of the uterus:

  • Precocious: it is the most frequent and occurs in the same delivery room.
  • Late: it is less common and occurs in the moments after leaving the delivery room.
Delivery with atony of the uterus.
At the end of labor, delivery occurs. The placenta comes out and the uterus must contract to prevent profuse bleeding.

Why happens?

Early uterine atony is usually due to the mother not producing enough oxytocin naturally. Oxytocin is a hormone that promotes the contraction of the uterus during childbirth and postpartum.

Other possible causes of uterine atony, both early and late, are the following:

  • Overdistention of the uterus: occurs when the uterus has become excessively elastic and then fails to recover its shape. It is due to multiple pregnancies or because the baby is very large.
  • Placental accreta: occurs when there is an abnormal adherence of the placenta to the wall of the uterus. It is very stuck and there are difficulties to remove it.
  • Late placental delivery: when the placenta takes more than 20 minutes to deliver.
  • Muscle fatigue: the uterus does not contract due to fatigue if the labor has lasted a long time.
  • Tocolytic drugs: produce an inhibition of contractions and sometimes lead to atony of the uterus.
  • Injuries or trauma to the uterus.
  • Anatomical alterations in the organ: presence of fibroids.
  • Incomplete expulsion of the placenta.
  • clots

Risk factor’s

A woman who has had atony of the uterus after giving birth is more likely to develop it in subsequent deliveries. Likewise, there are other factors that increase the risk:

  • Big baby.
  • Previous placenta.
  • Multiple gestation.
  • Advanced age of the mother.
  • Fetal death in utero.
  • Prolonged or precipitated labor.
  • Having had multiple pregnancies.
  • Premature abruption of the placenta.
  • Having previously presented postpartum hemorrhage.
  • Abnormal increase in amniotic fluid or polyhydramnios.

Symptoms and diagnosis of uterine atony

The main manifestation of atony of the uterus is hemorrhage of varying intensity. On some occasions, it appears suddenly and is copious, while 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 doctor feels the abdomen. The uterus feels soft, enlarged, and there is profuse discharge of blood on gentle massage.

Likewise, the professional makes an exploration of the vagina, the birth canal and the cervix to determine if there are any tears. The usual thing is that it is complemented with blood tests to determine the effects of the hemorrhage and establish if there is any coagulation problem.

Treatment

The initial treatment of uterine atony is carried out through two measures: 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 given to stop the bleeding. When this measure is also not effective, it is necessary to perform a surgical approach with one of the following procedures:

  • Instrumental curettage: an instrument similar to a spoon is inserted from the vagina to the uterus. Thus, the remains of clots and the endometrium are dragged and extracted.
  • Pelvic vessel ligation: the blood vessels that carry blood to the uterus are sutured. By decreasing blood flow to that organ, bleeding is also reduced.
  • Embolization of the uterine vessels: a catheter is inserted through the femoral artery until it reaches the arteries of the uterus. Small plastic or jelly particles are then inserted to stop the flow of blood.
  • Plication or capitonage: they are compressive sutures that are made in the uterus. It is considered the last option before a hysterectomy.
  • Hysterectomy: is the definitive removal of the uterus. It is only considered if the mother’s life is in danger.
Hysterectomy for atony of the uterus.
Hysterectomy is the last option. It is reserved for cases with serious vital risk.

Can uterine atony be prevented?

It is not possible to prevent atony of the uterus before delivery. However, more and more measures are being taken to prevent it from happening.

Today, it is common for a uterotonic drug to be applied to the mother within the first minute of the baby’s life. This helps the organ to contract.

Atony of the uterus can cause major bleeding leading to significant blood loss. If it is not attended to quickly, and even if it is, it could lead to multi-organ failure.

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