Uterine atony

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Uterine atony: a short, easy-to-understand overview

What it is
- Uterine atony means the uterus does not contract well after delivery. This helps explain why heavy bleeding (postpartum hemorrhage) can happen. It is the most common cause of postpartum hemorrhage, responsible for about 80% of cases.

Why it happens (risk factors)
- Labor problems: very long or very short labor, complicated delivery, cesarean delivery
- Uterine distension: many babies, big baby, polyhydramnios (excess amniotic fluid), fibroids
- Placenta problems or retained placental tissue
- Inherited or acquired blood clotting issues
- Obesity (high BMI)
- Use of medications that affect contractions (e.g., magnesium sulfate)
- Prior postpartum hemorrhage
- Uterine fatigue or damage to the muscle

Signs and diagnosis
- Heavy bleeding after birth that won’t stop
- A soft, “boggy” uterus that doesn’t firm up when touched
- Blood loss may be difficult to measure accurately; doctors also check the uterus’s tone during a physical exam
- They may use ultrasound to rule out other problems and may test blood if a clotting issue is suspected

Prevention
- Active management of the third stage of labor: routine uterine massage and giving a small amount of oxytocin right after delivery
- Identifying risk factors early to plan care and resources

Treatment (what helps if atony occurs)
- Immediate steps: maintain uterine massage, keep IV access, give fluids or blood as needed
- Uterotonic medications to stimulate contractions (may be used alone or in combination):
- Oxytocin (Pitocin), carbetocin
- Methylergometrine (ergot), carboprost (Prostin), misoprostol, dinoprostone
- If bleeding continues: tamponade (packing the uterus or using a balloon like Bakri) to apply pressure and stop bleeding, often with a Foley catheter for bladder drainage
- If necessary, surgical options to stop the bleed (e.g., tying off blood vessels, uterus-sparing procedures, or in severe cases, hysterectomy)

Outcomes and long-term
- Uterine atony increases risk of postpartum hemorrhage and can be dangerous if not treated promptly
- Recurrence risk in future pregnancies is about 2–3 times higher
- After a bleeding episode, some women develop anemia and may need iron therapy or a transfusion

What to watch for after birth
- If heavy bleeding begins or worsens, seek urgent medical help
- Blood tests and ongoing observation help guide further treatment and recovery