From the Guidelines
Postpartum hemorrhage is primarily caused by uterine atony, which accounts for more than 75% of cases, as it is typically a clinical diagnosis and initially treated by uterine massage and uterotonic drugs such as oxytocin 1. The most common causes of postpartum hemorrhage can be broken down into several key categories, including:
- Uterine atony: This is the most common cause, accounting for more than 75% of cases, and occurs when the uterus fails to contract effectively after delivery 1.
- Trauma to the genital tract: This includes lacerations, hematomas, and other injuries that can occur during delivery 1.
- Retained placental tissue: This can cause bleeding and is typically seen in the delayed postpartum hemorrhage population 1.
- Coagulation disorders: These can be inherited or acute, related to conditions such as amniotic fluid embolism, placental abruption, or HELLP syndrome 1. Other less common but serious causes of postpartum hemorrhage include:
- Uterine inversion
- Uterine rupture
- Abnormal placentation (placenta accreta, increta, or percreta) It is essential to promptly recognize and treat postpartum hemorrhage, as it can rapidly lead to hypovolemic shock, organ failure, and maternal death if not addressed quickly and effectively 1. Management begins with uterine massage and uterotonics, and if bleeding persists, additional interventions such as bimanual compression, balloon tamponade, or surgical interventions may be necessary 1.
From the FDA Drug Label
Overdosage with oxytocin injection (synthetic) depends essentially on uterine hyperactivity whether or not due to hypersensitivity to this agent Hyperstimulation with strong (hypertonic) or prolonged (tetanic) contractions, or a resting tone of 15 to 20 mm H2O or more between contractions can lead to tumultuous labor, uterine rupture, cervical and vaginal lacerations, postpartum hemorrhage, uteroplacental hypoperfusion and variable deceleration of fetal heart, fetal hypoxia, hypercapnia or death Maternal deaths due to hypertensive episodes, subarachnoid hemorrhage, rupture of the uterus and fetal deaths due to various causes have been reported associated with the use of parenteral oxytocic drugs for induction of labor and for augmentation in the first and second stages of labor Postpartum Hemorrhage Increased blood pressure In any event the cases reported did not require specific therapy for the elevated blood pressure. Use in patients with chorioamnionitis. During the clinical trials with carboprost tromethamine, chorioamnionitis was identified as a complication contributing to postpartum uterine atony and hemorrhage in 8/115 (7%) of cases, 3 of which failed to respond to carboprost tromethamine
Causes of postpartum hemorrhage include:
- Uterine hyperactivity due to hypersensitivity to oxytocin
- Hyperstimulation with strong or prolonged contractions
- Uterine rupture
- Cervical and vaginal lacerations
- Uteroplacental hypoperfusion
- Chorioamnionitis contributing to postpartum uterine atony and hemorrhage 2, 2, 3
From the Research
Causes of Postpartum Hemorrhage
- Uterine atony is a leading cause of postpartum hemorrhage, as stated in studies 4, 5, 6, 7, 8
- Trauma, including iatrogenic trauma, increases the risk for postpartum hemorrhage 6
- Birth canal/perineal lacerations and intrapelvic arterial injuries are also etiologies of postpartum hemorrhage 4
- Retained placental tissue is another cause of postpartum hemorrhage 5, 7, 8
- Coagulation disorders can also contribute to postpartum hemorrhage 5, 7
Risk Factors for Postpartum Hemorrhage
- Women with a history of postpartum hemorrhage in a previous pregnancy are at increased risk of postpartum hemorrhage in a subsequent pregnancy 6
- General anaesthetic or oxytocin, an over-distended uterus, a prolonged or precipitous labour, or high parity can increase the likelihood of uterine atony 7
- Unnecessary cesareans, episiotomies, and other genital tract trauma can also increase the risk of postpartum hemorrhage 6