A uterine artery pseudoaneurysm (UAP) is a rare but potentially serious complication women can face after gynecologic surgery, and it is among the top causes of postpartum hemorrhage. A ruptured pseudoaneurysm can be life-threatening and should be considered as a differential diagnosis in patients with unexplained vaginal bleeding.
Transvaginal color Doppler ultrasound can accurately diagnose this complication by revealing the tell-tale back-and-forth swirl, also known as the "yin-yang" sign.
What Are Pseudoaneurysms?
In a uterine aneurysm, the blood vessel wall is weakened and bulges; a pseudoaneurysm occurs when the blood vessel wall is damaged and blood leaks out, collecting in surrounding tissue. Although uncommon, a UAP is more likely to occur after surgery or trauma, such as dilation and curettage, a cesarean section, vaginal delivery or cervical conization. After these events, the wall of a uterine artery may be lacerated and fail to seal properly, forming a UAP.
Like an aneurysm, a pseudoaneurysm rupture can cause life-threatening hemorrhaging. The sac of this fragile vascular lesion is typically only walled by a single layer of soft tissue and is sustained by arterial blood pressure, according to the journal Gynecology and Minimally Invasive Therapy, which is why complications can be so risky for patients.
Early, accurate diagnosis of a UAP is needed to prevent possible hemorrhage. The Journal of Emergency Medicine recommends that a UAP be considered as a first diagnosis when patients present with vaginal bleeding in the ER, particularly those who have recently delivered or had surgery. The journal notes that while a UAP may not always be the cause of bleeding, delaying its diagnosis in favor of other more common considerations may lead to worsened hemorrhaging and less favorable patient outcomes.
Using Ultrasound to Diagnose Uterine Artery Pseudoaneurysms
Color Doppler ultrasound is a convenient, cost-effective option for evaluating and diagnosing UAP. On 2D ultrasound, the typical yin-yang sign seen with color Doppler appears as a swirling, anechoic structure.
On color Doppler ultrasound, bidirectional blood flow, represented in varying colors around the arterial cavity, can be seen. The blood flows forward into the aneurysm cavity, then flows back out into the supplying artery, according to BMC Women's Health. Color Doppler provides visualization of blood flow patterns and the characteristic signs of a pseudoaneurysm without the added cost or radiation exposure of a CT scan, making this a convenient, cost-effective option for evaluating and diagnosing UAP. This BMC case study showcases uterine artery pseudoaneurysm clinical images.
When it is detected, UAP can be successfully treated with arterial embolization. Although embolization is the preferred treatment, transvaginal ultrasound-guided thrombin injection is also a viable treatment option for some patients with severe vaginal bleeding.
Diagnosing a UAP early in patients presenting with unexplained vaginal bleeding is essential to ensuring timely treatment and protecting against an unexpected hemorrhage. Color Doppler ultrasound is a reliable, effective diagnostic tool to detect the characteristic signs of a pseudoaneurysm.
