Uterine Atony: Symptoms, Types, Causes and Treatment

Uterine atony is a critical obstetric emergency and the leading cause of postpartum hemorrhage (PPH) worldwide. Despite advances in maternal healthcare, uterine atony remains a key contributor to maternal morbidity and mortality, especially in resource-limited settings. Understanding its symptoms, types, causes, and treatment options is essential for both healthcare professionals and expectant mothers. This comprehensive article draws on research evidence to provide a detailed overview, with practical tables and clear explanations under each heading.

Symptoms of Uterine Atony

Recognizing the symptoms of uterine atony quickly can be life-saving. Uterine atony typically develops in the immediate postpartum period and manifests with signs that should prompt urgent medical attention. Many women and their caregivers may not be familiar with the specific features of this condition, which can delay treatment and increase risks.

Symptom	Description	Onset	Source(s)
Heavy Bleeding	Sudden, excessive vaginal bleeding after birth	Immediate postpartum	4 5
Soft Uterus	Uterus feels boggy or soft on abdominal exam	Immediate postpartum	5 4
Hypovolemia	Signs of shock: rapid pulse, low BP, pallor	Rapid after bleeding	4 5
No Clots	Blood loss often not accompanied by clots	Immediate postpartum	4

Table 1: Key Symptoms

Heavy Vaginal Bleeding

The hallmark symptom of uterine atony is heavy, uncontrolled vaginal bleeding after delivery. This blood loss is typically much more than the expected 500 mL after a vaginal birth or 1,000 mL after a cesarean section. The bleeding is often continuous and may soak multiple pads or sheets within a short period 4 5.

Soft or "Boggy" Uterus

Upon examination, the uterus is not firm and contracted as it should be after delivery. Instead, it feels soft, enlarged, and poorly defined—often described as "boggy." This is a key clinical sign that helps distinguish uterine atony from other causes of postpartum hemorrhage 5 4.

Signs of Shock

As blood loss increases, symptoms of hypovolemic shock may develop rapidly. These include a rapid, weak pulse, low blood pressure, dizziness, pallor, and cold, clammy skin. In severe cases, confusion or loss of consciousness may occur 4 5.

Absence of Blood Clots

Unlike some other causes of postpartum hemorrhage, bleeding from uterine atony is often not accompanied by large blood clots, as the uterus is not contracting effectively to expel them 4.

Types of Uterine Atony

While the term "uterine atony" broadly refers to the failure of the uterus to contract after childbirth, clinicians recognize several patterns and classifications that can affect both prognosis and management. Understanding these distinctions can help guide more targeted interventions.

Type	Key Feature	Clinical Relevance	Source(s)
Primary Atony	Occurs immediately post-birth	Most common, acute	4 5
Secondary Atony	Develops hours after birth	Can be delayed, insidious	5
Refractory Atony	Unresponsive to first-line meds	Needs advanced management	9
Partial Atony	Uterus partially contracts	May mask full diagnosis	9

Table 2: Types of Uterine Atony

Primary vs. Secondary Uterine Atony

• Primary uterine atony is the most common type, occurring within the first 24 hours after delivery. This is when the majority of dangerous postpartum hemorrhages happen and when rapid intervention is most critical 4 5.

• Secondary uterine atony develops later, sometimes hours after an initially stable postpartum period. Its insidious onset can make it more difficult to detect promptly, underscoring the importance of ongoing monitoring 5.

Refractory Uterine Atony

Some cases of uterine atony do not respond to initial treatments such as oxytocin or other uterotonic agents. These are termed refractory uterine atony and require escalating interventions, including surgical procedures or interventional radiology 9.

Partial Uterine Atony

In partial atony, only some segments of the uterus fail to contract, while others do so adequately. This can result in less dramatic, but still significant, bleeding, and may mask the true severity of the problem if not carefully assessed 9.

Causes of Uterine Atony

Uterine atony is multifactorial, with both modifiable and non-modifiable risk factors. Some causes are related to the pregnancy itself, while others are influenced by labor management and maternal health.

Cause/Risk	Description	Impact Level	Source(s)
Prolonged Labor	Labor lasting >6 hours	Major	1 2 3 9
Overdistension	Multiple gestation, polyhydramnios, macrosomia	Major	2 3 9
Oxytocin Use	High infusion rates, induction, augmentation	Major	3 9
Short Interpregnancy	<24 months between pregnancies	Modifiable	1
Grand Multiparity	≥5 pregnancies	Major	4
Artificial ROM	Artificial rupture of membranes	Moderate	3
Previous PPH	History of prior postpartum hemorrhage	Major	4
Prematurity	Delivery before term	Moderate	3

Table 3: Key Causes and Risk Factors

Prolonged and Difficult Labor

Labor that is unusually long or difficult—especially when exceeding six hours—is strongly associated with uterine atony. Prolonged contractions can tire out the uterine muscle, reducing its ability to contract effectively after delivery 1 2 3 9.

Uterine Overdistension

Conditions that stretch the uterus beyond normal capacity increase the risk of atony. This includes:

• Multiple gestation (twins, triplets)
• Polyhydramnios (excess amniotic fluid)
• Large babies (macrosomia)

Overdistension physically impairs the muscle’s ability to contract down after delivery 2 3 9.

Use of Oxytocin and Labor Interventions

Excessive or prolonged use of oxytocin (for induction or augmentation) can desensitize uterine muscle receptors, reducing their responsiveness and increasing atony risk. Artificial rupture of membranes and frequent labor interventions also contribute 3 9.

Short Interpregnancy Interval

Insufficient time between pregnancies (less than 24 months) does not allow the uterus to recover fully, predisposing women to atony in subsequent deliveries 1.

Grand Multiparity and Previous PPH

Women who have had five or more pregnancies (grand multipara) or a history of previous postpartum hemorrhage are at elevated risk, likely due to uterine muscle fatigue or scarring 4.

Other Contributing Factors

• Prematurity: The preterm uterus may be less contractile 3.
• Maternal infections (chorioamnionitis) and obesity have also been implicated 9.
• Augmented labor and assisted delivery may further increase risk 2 3.

Treatment of Uterine Atony

Timely and aggressive management of uterine atony is vital to prevent severe morbidity or death. Treatment is typically stepwise, escalating from medications to surgical interventions if needed.

Treatment	Description	Indication	Source(s)
Uterotonics	Oxytocin, methylergonovine, carboprost, misoprostol	First-line	5 7 9
Uterine Massage	Manual stimulation of uterine contraction	First-line	5 4
Tamponade	Balloon or gauze to compress uterus	Refractory cases	5 9
Compression Suture	B-Lynch or uterine flexion suture	Surgical, severe	6 8
Hysterectomy	Surgical removal of uterus	Life-saving, last resort	6 4
Tranexamic Acid	Antifibrinolytic agent	Adjunct in bleeding	5

Table 4: Treatment Approaches

Uterotonic Medications

Oxytocin is the gold standard, administered intravenously or intramuscularly to stimulate uterine contractions. If oxytocin fails, second-line agents include methylergonovine (ergometrine), carboprost (a prostaglandin), and misoprostol. Each has distinct side-effect profiles and is chosen based on patient comorbidities and resource availability 5 7 9.

• Oxytocin: First-line, effective in most cases.
• Methylergonovine: Potent, but contraindicated in hypertension.
• Carboprost: Useful but avoided in asthma.
• Misoprostol: Widely used, especially where other options are unavailable 7 9.

Mechanical and Surgical Interventions

Uterine massage is performed manually to stimulate contraction and is an immediate, non-invasive measure 5 4. If bleeding persists:

• Uterine tamponade involves inserting a balloon or packing to apply pressure from within 5 9.
• Compression sutures (such as the B-Lynch technique or modified uterine flexion suture) physically compress the uterus to stop bleeding 6 8. These are quick, effective, and fertility-sparing in many cases.
• Hysterectomy is reserved for when all other measures fail or the patient’s life is at risk, as it ends fertility 6 4.

Adjunctive Therapies

• Tranexamic acid and recombinant factor VII may help control bleeding by promoting clot stability, especially when other methods are insufficient 5.
• Arterial embolization can be considered if facilities and expertise are available 9.

Prevention Strategies

Active management of the third stage of labor, including routine administration of uterotonics, significantly reduces the risk of uterine atony and PPH 5 9. Early identification of risk factors and skilled birth attendance are vital 1 2.

Conclusion

Uterine atony remains a leading cause of postpartum hemorrhage and maternal mortality. Understanding its early symptoms, risk factors, clinical types, and up-to-date treatment strategies is crucial for effective prevention and management.

Key Points:

• Uterine atony manifests as heavy bleeding and a soft, boggy uterus immediately after birth.
• It can be classified as primary, secondary, refractory, or partial, each with implications for management.
• Major causes include prolonged labor, uterine overdistension, oxytocin overuse, short birth intervals, and grand multiparity.
• First-line treatment is rapid administration of uterotonic drugs, with escalation to mechanical, surgical, or adjunctive therapies if needed.
• Prevention through active management and early risk identification can dramatically reduce maternal mortality.

Prompt recognition and response can save lives—making awareness and preparedness essential for all involved in childbirth care.