From the Guidelines
Posterior low lying placenta and uterine atony require immediate attention, with uterine atony being the most common cause of early postpartum hemorrhage, typically managed with uterine massage and uterotonic drugs such as oxytocin, as stated in the 2020 study by the Journal of the American College of Radiology 1.
Management of Posterior Low Lying Placenta and Uterine Atony
For a posterior low lying placenta, close monitoring throughout pregnancy is essential, with follow-up ultrasounds at 32-34 weeks to assess if it has moved away from the cervix. If it remains low-lying near term, cesarean delivery may be necessary to prevent hemorrhage.
Uterine Atony Management
For uterine atony, immediate management includes:
- Uterine massage
- Administration of uterotonics such as oxytocin (10-40 units IV) 1
- Methylergonovine (0.2 mg IM)
- Carboprost (0.25 mg IM)
- Misoprostol (800-1000 mcg rectally) If bleeding persists despite medical management, mechanical interventions like intrauterine balloon tamponade, uterine compression sutures, or arterial embolization may be required. In severe cases unresponsive to other measures, hysterectomy may be necessary, as supported by the 2020 study by the Journal of the American College of Radiology 1.
Key Considerations
These conditions require vigilant monitoring as they both increase the risk of postpartum hemorrhage. Uterine atony occurs because the myometrial fibers fail to contract properly after delivery, while a low-lying placenta can cause bleeding due to its proximity to the dilating cervix or during delivery, highlighting the importance of prompt and effective management to prevent morbidity and mortality, as emphasized in the study by the Journal of the American College of Radiology 1.
From the Research
Posterior Low Lying Placenta and Uterine Atony
- Posterior low lying placenta is associated with increased obstetric risks, including postpartum hemorrhage (PPH) 2
- Uterine atony is a common cause of primary postpartum hemorrhage, which remains a major cause of pregnancy-related mortality for women worldwide 3
- Oxytocin is the first-line agent for preventing and treating uterine atony, with methylergonovine and carboprost as effective second-line agents 3
- A systematic review found that oxytocin bolus 0.5-3 UI is considered an effective prophylactic dose for preventing uterine atony during Caesarean delivery 4
Risk of Postpartum Hemorrhage
- Women with resolved low placentation, including those with posterior low lying placenta, are at increased risk of postpartum hemorrhage compared to those with normal placentation throughout pregnancy 2
- The risk of postpartum hemorrhage is higher in women with posterior placental location, even if the low lying placenta resolves by term 2
- A systematic review and meta-analysis found that the majority of second trimester low-positioned placentas will be located towards the fundus at the time of follow-up, but a cut-off value for anterior and posterior placentas that included all women at high risk could not be determined 5
Management of Uterine Atony
- Oxytocin, methylergonovine, carboprost, and misoprostol are commonly used to restore uterine tone and prevent postpartum hemorrhage 3
- The use of additional uterotonic medication, such as methylergonovine and carboprost, may be necessary in women with uterine atony who do not respond to oxytocin 3
- A systematic review found that oxytocin infusion dose size and requirement, as well as bolus injection rate, remain unanswered questions in the management of uterine atony 4