ABSTRACT

Uterine Arteriovenous Fistulas (AVFs) are rare but clinically significant vascular abnormalities that can lead to severe, sometimes life-threatening, vaginal bleeding, particularly in women of reproductive age. Prompt diagnosis and treatment are essential to prevent serious morbidity. Radiologic imaging is the mainstay of diagnosis, revealing increased and abnormal uterine vascularity. Three principal treatment approaches are available: (i) Medical management, including hormonal therapy, methotrexate, or uterotonics; (ii) Interventional radiology, particularly Uterine Artery Embolization (UAE); and (iii) Surgical management, most notably hysterectomy. Clinical presentation often includes irregular or profuse per-vaginal bleeding, which may result in hemodynamic instability, necessitating transfusion or emergency intervention. Given the condition's prevalence among women wishing to preserve fertility, minimally invasive options like UAE are preferred. Angiography serves as both a diagnostic and therapeutic tool, aiding in the localization and embolization of AVFs. This paper presents ten cases of uterine AVFs diagnosed through imaging and managed with UAE, followed by an analysis of clinical outcomes and implications for fertility preservation.

Keywords: Uterine AVF, uterine AVM, embolization, interventional radiology, abnormal uterine bleeding, fertility preservation.

INTRODUCTION

Uterine arteriovenous malformations (AVMs) represent rare vascular disorders involving abnormal, high- flow communications between the arterial and venous systems within the uterus. First documented in the early 20th century by Dubreil and Loubat, they were initially described as "cirsoid aneurysms"—a term reflecting the convoluted nature of these vessels [1-4]. These lesions are classified as either congenital or acquired, with the acquired forms accounting for most cases in contemporary practice. Histologically, AVMs bypass the capillary bed, forming fistulous links between arterial and venous structures in the myometrium, giving rise to rapid, unregulated blood flow [2].

The classic presentation is heavy or irregular uterine bleeding, often unresponsive to standard gynecologic management and sometimes necessitating emergency care. Suspicion should be heightened in the context of obstetric hemorrhage that fails to respond to conventional interventions [5]. Additional manifestations may include chronic pelvic pain, anemia, fatigue, menorrhagia, or incidental detection during imaging performed for other indications [6, 7]. Due to its low incidence and variable presentation, uterine AVM is often misdiagnosed, leading to inappropriate interventions such as dilatation and curettage (D&C), which can cause catastrophic hemorrhage.

AVMs are categorized into congenital and acquired types [1, 3, 4, 8]. Congenital AVMs stem from abnormal

vascular development during embryogenesis, often presenting in adolescence or early adulthood. They usually have multiple feeding arteries and draining veins and may be associated with genetic abnormalities, such as RASA-1 mutations located on chromosome 5q13-22 [1, 4, 9].

Acquired AVMs, on the other hand, are more common and frequently result from uterine trauma—typically following procedures such as curettage, cesarean sections, or myomectomy. They can also occur in association with conditions like gestational trophoblastic disease, endometrial cancer, and pelvic infections [7, 10- 13]. Their actual incidence remains difficult to ascertain but may reach up to 0.63% after pregnancy-related interventions [2-4]. Their presentation often overlaps with other uterine pathologies like retained products of conception or placental site subinvolution [5, 14], underscoring the importance of precise diagnosis.

This case series presents a comprehensive overview and emphasizes the diagnostic modalities and therapeutic outcomes of UAE in patients with acquired uterine AVMs/AVFs, with special attention to fertility preservation.

Imaging plays a pivotal role in the diagnosis and management of uterine AVMs. Initial evaluation typically includes transvaginal or transabdominal ultrasound with color Doppler, which is widely accessible and cost-effective. On B-mode imaging, AVMs may appear as ill-defined, hypoechoic, or heterogeneous lesions with serpiginous vascular channels in the myometrium.

Color Doppler imaging is crucial, revealing a characteristic mosaic flow pattern, indicative of turbulent blood flow. Spectral Doppler further confirms the presence of low-resistance, high-velocity flow (RI 0.27-0.75, PSV 25-110 cm/s) [15]. In the setting of suspected AVM, these findings are essential for raising clinical suspicion.

MRI provides additional anatomical detail, especially useful in complex or equivocal cases. T1- and T2- weighted images typically reveal multiple flow voids representing abnormal vasculature within the uterus or parametrium [16]. MRI is also valuable in excluding alternative diagnoses and defining lesion extent.

Digital subtraction angiography (DSA) is both diagnostic and therapeutic. It confirms the presence of arteriovenous shunting, identifies the feeding arteries and draining veins, and allows real-time embolization. DSA remains the gold standard in both diagnosis and intervention.

The choice of therapy for uterine AVMs depends on bleeding severity, patient stability, fertility goals, and

lesion characteristics. While hormonal or cytotoxic medications may provide symptom control in select cases, embolization has become the standard for rapid and definitive management [3].

The UAE is favored due to its minimally invasive nature, rapid recovery time, and fertility preservation potential. Embolic agents commonly include PVA particles (250-710 microns), gel foam, Histoacryl glue, or metallic coils. UAE offers a high rate of success in symptom control and AVM obliteration while avoiding the need for hysterectomy.

CASE SERIES

We report ten cases of uterine AVMs (Table 1) managed with UAE between the ages of 25 to 43. Presenting symptoms were most often post-abortion or postpartum bleeding. Imaging confirmed the diagnosis in all cases, and DSA-guided UAE was performed with excellent technical success.

Case 1

A 43-year-old female presented with torrential bleeding post-D&C. Ultrasound showed increased vascularity, and MRI confirmed AVM with venous varices (Fig. 1a & b). DSA revealed bilateral uterine artery feeders (Fig. 1c & f). Embolization was completed with PVA particles (Fig. 1d & e). Follow-up imaging showed complete resolution. The patient later delivered two full-term, healthy children.

Case 2

A 34-year-old female experienced severe postpartum bleeding three days after a miscarriage. Serial ultrasounds showed unchanged increased myometrial vascularity (Fig. 2a & b). Angiography demonstrated a high-flow lesion supplied predominantly by the right uterine artery (Fig. 2c & e). Bilateral UAE using 355-500 micron PVA particles was successful (Fig. 2d & f). Follow-up ultrasound showed resolved vascularity, though fertility outcome is undocumented.

Case 3

A 27-year-old female had persistent bleeding following a miscarriage diagnosed as a subchorionic hematoma. MRI later revealed a focal AVM. UAE with both PVA and gel foam led to resolution. She conceived twice afterward and delivered without complications.

Case 4

A 27-year-old with heavy bleeding post-D&C showed echogenic material with high vascularity on Doppler. MRI confirmed AVM. The UAE with PVA was successful with complete vascular obliteration.

Case 5

A 28-year-old with profuse bleeding post-miscarriage had serpiginous vessels noted on ultrasound. Angiography confirmed a large AVM with bilateral supply. Embolization led to full symptom resolution. She later delivered two children successfully.

Case 6

A 33-year-old referred with a presumptive diagnosis of scar pregnancy had MRI and angiography confirming bilateral AVM. UAE with 250-355 micron PVA particles resolved the lesion. Later follow-up showed no vascularity.

Case 7

A 32-year-old with a history of caesareans and D&Cs presented with unexplained menorrhagia. Imaging showed AVM with feeders from both uterine and left ovarian arteries (Fig. 3a-d). Embolization involved PVA particles, Histoacryl glue, and coil occlusion. Post- procedure DSA showed complete cessation of flow (Fig. 3e & f).

Case 8

A 31-year-old, post-D&C for a non-viable pregnancy, experienced persistent menorrhagia. AVM was diagnosed on colour Doppler and MRI pelvis (Fig. 4a-d). UAE was conducted using 355-500 micron PVA particles (Fig. 4a-h). Two years later, she had a successful pregnancy.

Case 9

A 27-year-old presented with bleeding at six weeks postpartum. MRI revealed an AVM and a myometrial defect. Bilateral UAE was performed using 355-500 micron PVA particles. Follow-up imaging confirmed complete resolution.

Case 10

A 25-year-old with angiographically confirmed AVM showed a large lesion fed by the left uterine artery and draining into pelvic veins. UAE was performed using a combination of 355-1000 micron PVA particles, achieving embolization.

DISCUSSION

Uterine AVMs, though rare, are a critical differential for abnormal uterine bleeding that is unresponsive to conventional measures. Timely imaging and accurate diagnosis are vital to avoid life-threatening haemorrhage. DSA-guided UAE has become the cornerstone of treatment, offering prompt bleeding control, high success rates, and fertility preservation.

Our case series demonstrates that all patients were successfully treated without the need for hysterectomy. Success rates for embolization are consistent with literature reports, where initial success is observed in 61% of cases and increases to 91% with repeat interventions [1, 17].

Hysterectomy remains a last resort, typically reserved for refractory cases or patients without fertility concerns [2]. Techniques such as balloon occlusion and preoperative embolization have been documented in the literature for complex cases requiring surgery [2, 5, 18]. However, in our cohort, arterial embolization was sufficient.

Though the UAE is generally safe, risks such as uterine synechiae, premature ovarian failure, and early menopause exist, particularly in women under 45 or those undergoing bilateral embolization [1, 21-24]. One retrospective study found 88% of pregnancies post-UAE resulted in cesarean section, with preterm delivery in 25%, and postpartum hemorrhage in 20% [1, 19]. Another reported 33 successful pregnancies out of 56 among 1200 treated women [1, 20]. In a group of 75 women trying to conceive post-bilateral UAE, 15 achieved pregnancy.

These outcomes highlight the importance of individualized treatment planning. Hyper-selective embolization and protective coiling of ovarian collaterals may mitigate adverse reproductive effects [1].

CONCLUSION

UAE is a highly effective, minimally invasive therapy for uterine AVMs, particularly suited for women of reproductive age who desire fertility preservation. When performed in a timely and targeted manner, UAE can rapidly control life-threatening hemorrhage while minimizing complications. Accurate diagnosis through imaging and long-term follow-up are essential to ensuring successful outcomes. Routine imaging is recommended for at least one year following embolization to assess vascular resolution and monitor reproductive health. As awareness and access to interventional radiology grow, the UAE should be regarded as the first-line treatment for symptomatic uterine AVMs.

CONSENT FOR PUBLICATION

Individual patients' consents for publication were not taken as no patients' identifiers are included in the study, as per policy of our institutional review board.

CONFLICT OF INTEREST

The authors declare no conflict of interest.

ACKNOWLEDGEMENTS

Declared none.

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