Serpiginous myometrial vessels and prominent parametrial vessels can be a sign of VUA [19], whereas the presence of a pseudoaneurysmal sac is a more specific finding [14,20,21]. CTA can also identify and localize the feeding arteries of arteriovenous malformation (AVM) for treatment planning [14]. However, CTA cannot reliably distinguish acquired VUA from failure of obliteration/subinvolution of the placental bed vessels, assess its severity, or need for intervention [19]. MRI Pelvis MRI is not commonly used in significant life-threatening early PPH as CT, in part related to access and time required to perform the study in an acute setting. MRI has an important role to play in distinguishing and/or confirming uterine dehiscence versus rupture, in particular when it is confusing on ultrasound (US) or CT. Although RPOC can be seen as an intracavitary mass with variable signal characteristics, distinction from blood products is limited in the absence of contrast administration. MRI is better than CT and US in detecting the myometrial defect with intact serosal layer in uterine dehiscence because of superior soft-tissue contrast [14,15]. However, in the immediate postpartum period, the cesarean section incision can be T1 and T2 hyperintense and may mimic a dehiscence [22]. Noncontrast MRI can be used to identify bladder flap, subfascial, and deep-seated pelvic hematomas, which depending on the time since delivery may demonstrate variable T1 and T2 signal characteristics [14,23]. The superior spatial resolution of MRI compared to US enables localization of the hematoma (eg, supralevator versus infralevator location in the perivaginal space) for potential targeted intervention [23]. On MRI fast-spin echo sequences, AVM demonstrates serpiginous signal voids with prominent parametrial vessels and focal disruption of the junctional zone [14].
Postpartum Hemorrhage. Serpiginous myometrial vessels and prominent parametrial vessels can be a sign of VUA [19], whereas the presence of a pseudoaneurysmal sac is a more specific finding [14,20,21]. CTA can also identify and localize the feeding arteries of arteriovenous malformation (AVM) for treatment planning [14]. However, CTA cannot reliably distinguish acquired VUA from failure of obliteration/subinvolution of the placental bed vessels, assess its severity, or need for intervention [19]. MRI Pelvis MRI is not commonly used in significant life-threatening early PPH as CT, in part related to access and time required to perform the study in an acute setting. MRI has an important role to play in distinguishing and/or confirming uterine dehiscence versus rupture, in particular when it is confusing on ultrasound (US) or CT. Although RPOC can be seen as an intracavitary mass with variable signal characteristics, distinction from blood products is limited in the absence of contrast administration. MRI is better than CT and US in detecting the myometrial defect with intact serosal layer in uterine dehiscence because of superior soft-tissue contrast [14,15]. However, in the immediate postpartum period, the cesarean section incision can be T1 and T2 hyperintense and may mimic a dehiscence [22]. Noncontrast MRI can be used to identify bladder flap, subfascial, and deep-seated pelvic hematomas, which depending on the time since delivery may demonstrate variable T1 and T2 signal characteristics [14,23]. The superior spatial resolution of MRI compared to US enables localization of the hematoma (eg, supralevator versus infralevator location in the perivaginal space) for potential targeted intervention [23]. On MRI fast-spin echo sequences, AVM demonstrates serpiginous signal voids with prominent parametrial vessels and focal disruption of the junctional zone [14].