Pelvic venous disorders (PeVD) in women represents a wide variety of overlapping symptoms that can be the result of different pathophysiology including chronic pelvic pain, lower extremity and/or vulvar varicosities, lower extremity swelling/pain, and left flank pain with hematuria. PeVD resulting in venous origin chronic pelvic pain (VO-CPP) most commonly affects multiparous and premenopausal women, occasionally persisting in post-menopausal women that are untreated. The presenting symptoms vary depending on the venous anatomy, physiology and/or presence of escape points, which can be complex. A common cause and the earliest reported cause of PeVD is pelvic venous insufficiency (PVI) (also known as ovarian vein reflux), although non-thrombotic iliac vein lesions (NIVL) can lead to collateral flow through the pelvic reservoir and serve as a source of chronic pelvic pain (CPP) as well. NIVL lesions can occur independently or coexist with PVI and clear recommendations on the pattern of treatment are still under development. The definition of PVI includes non-cyclical chronic pelvic pain greater than 6 months and the presence of pelvic varicosities. Symptoms suggestive of VO-CPP include pain that is worse in gravity dependent positions such as sitting or standing, pain exacerbation following intercourse and at the end of the day following long periods of gravity dependence. The pain typically improves while lying flat and with reversal of gravity dependence. For the purposes of this article, we will be discussing the pathophysiology of PVI and focusing on treatments such as Ovarian Vein Embolization (OVE) and embolization of the pelvic venous reservoir.

Pelvic venous disease most commonly affects multiparous and premenopausal women, likely secondary to hormonal effects on valvular incompetence. Symptoms that suggest a venous origin to chronic pelvic pain include pain that is worse with sitting upright or standing, post-coital pain, and peri-menstrual pain. Pain improvement with lying flat can also support the reversal of gravity dependent venous hypertension. Non-specific symptoms such as urinary frequency, urgency, low back pain and rectal pain can also occur. Additional symptoms related to escape points to the vulva or lower extremities may also be present. On physical exam, some patients may have point tenderness over the ovaries or cervical motion tenderness. Clinicians should evaluate for vulvar, perineal, or lower extremity varicose veins which may be pelvic origin veins and further suggest pelvic venous insufficiency. Visualization of venous escape veins from the pelvis or recurrent lower extremity varicose veins following prior complete treatment can be a clinically significant indicator of pelvic origin lower extremity varicose veins.

The etiology of VO-CPP can be complex and is best characterized according to the SVP classification.1 The pelvic pain is classified according to symptoms (S), location of varices (V) and physiology (P), taking into account the anatomy and hemodynamics. Ovarian vein reflux is the most common etiology of VO-CPP where valvular incompetence leads to reflux and increased pressure in the pelvic venous reservoir which can lead to chronic pelvic pain. Left common iliac vein (LCIV) compression, also known as non-thrombotic iliac vein lesions (NIVL) can impede venous outflow, with resultant left internal iliac vein reflux causing increased pressure and pain in the pelvic venous reservoir. Less commonly, a significant left renal vein (LRV) compression can result in left ovarian vein reflux and lead to pelvic pain as well. Using the SVP classification in the workup, diagnosis, and management of patients with suspected VO-CPP is recommended. The SVP classification tool represents one of the priorities from the research consensus panel on PeVD with development of a disease specific quality of life tool as another important research question to answer.2 Development of this tool and subsequent clinical research on this patient population will assist in more clearly defining the clinical presentation of patients who are suspected to have VO-CPP.

Non-invasive pre-procedural imaging should be performed to assess the etiology of PeVD. Transabdominal ultrasound (TAUS) can be performed by skilled operators to evaluate for pelvic varices as well as the associated etiology. Ovarian vein size can be measured to help identify increased suspicion for retrograde flow and the presence of reflux can be delineated using pelvic/abdominal augmentation as well as Color Doppler and spectral Doppler. TAUS can also be used to evaluate for NIVL depending on body habitus and the presence of bowel gas. Performance of this study 6 hours after fasting will reduce bowel gas and ease visualization. (Author please add Reference) Although TAUS is an active tool to identify venous reflux and differentiate the several sources of pelvic varices, Computed Tomography (CT) and Magnetic Resonance Imaging (MR) venography are often utilized. CT and MRV are cross sectional imaging options that can demonstrate ovarian vein pathology, iliac vein compression, and presence of pelvic varices. Time-resolved MR angiography can also be useful when available to identify venous insufficiency (Figure 1). Non-invasive imaging criteria that have been accepted for the diagnosis of PeVD includes dilated ovarian veins larger than 6mm due to the increased incidence of reflux, at least one pelvic varix larger than 5mm diameter, and reversal of flow in the ovarian vein. (Author please add Reference)

The gold standard diagnostic test for PVI remains catheter-based venography, which can be performed in the same setting as embolization. The Society of Interventional Radiology clinical practice guidelines from 2010 proposed diagnostic venography criteria of ovarian veins >5mm, ovarian vein reflux/valvular incompetence, reflux across the midline via pelvic collaterals, reflux into vulvar or thigh varices, and stagnation of contrast in pelvic veins.3 However, more recently the SIR Research Consensus Panel identified an overall lack of standardization of diagnostic imaging criteria and recommended developing a consensus on clinical imaging criteria as a research priority.2

After a thorough work up and physical examination, Ovarian Vein Embolization (OVE) is a minimally invasive treatment for ovarian vein reflux.4 The procedure can be performed as an outpatient procedure typically with moderate sedation. Venous access can be obtained via the right internal jugular (IJ) or femoral vein approach using a 5-9 French sheath. Sheath size choice depends on size of preferred occlusion balloon catheters and if simultaneous intravascular ultrasound will be performed to assess for iliac vein stenosis. If there is a plan to perform Intravascular Ultrasound (IVUS), then a 9 French sheath should be used. Sometimes using a longer or curved sheath can be helpful to maintain stable access in the left renal vein. The suggested order of venography is left renal vein, left ovarian vein followed by embolization, right ovarian vein followed by embolization, bilateral internal iliac veins followed by further pelvic reservoir embolization if indicated. First, the left renal vein is catheterized, and venography is performed to assess for ovarian vein reflux and rule out hemodynamically significant renal vein compression. The best catheters to select the renal vein are multipurpose and Cobra catheters from the IJ and Cobra catheters from the femoral vein. Selecting and catheterizing the renal vein works best over a hydrophilic wire. Next, the left ovarian vein should be catheterized, and venography should be performed. Please be aware that there are a variety of techniques that can be used during ovarian venography including significant table tilt, balloon occlusion venography and Valsalva during venography. Left ovarian embolization should be performed after confirmation of valvular incompetence and filling of pelvic venous reservoir and stagnation of contrast within the reservoir. Sclerosant and embolic choices vary and there is no data to strongly suggest using specific tools. There is published literature on sclerosant use and cyanoacrylate glue usage for treatment of the ovarian veins and pelvic varices with migration of cyanoacrylate glue in up to 4% of cases.5 The locally preferred sclerosant for the pelvic reservoir is Sodium Tetradecyl Sulphate 3% (STS) prepared as foam or slurry and endovascular coils are preferred for embolization of the ovarian vein. There is no clear data differentiating the occlusive result among coil embolization techniques and a variety of strategies exist including deployment of coils throughout the ovarian vein and selective occlusive coil packs intermittently in the ovarian vein. Live fluoroscopy allows for clear visualization of coils and sclerosant to prevent inadvertent non-target embolization and coil migration. (Figure 2) If detachable coils are utilized, microcatheter use is suggested and coils are often oversized by approximately 20% to prevent coil migration. While sclerosis of the pelvic reservoir and coil embolization of the ovarian vein are overall preferred, there are no studies showing statistically significant differences in outcomes among sclerosis alone, coil embolization alone or a combination of sclerosis and embolization.

Following successful embolization of the left ovarian vein, right ovarian venography should be performed. From the IJ approach multipurpose catheters are often easiest to access the right ovarian vein, while from the femoral approach reverse curve catheters are most successful. If the right ovarian vein is non-dilated, catheterization can be technically challenging, therefore it is important to educate the patient of the possibility of technical failure of catheterization of both ovarian veins. Once the right ovarian vein is catheterized and venography is performed, embolization is recommended if dilated pelvic veins and reflux are noted, which can be performed in a similar fashion to that described above for the left ovarian vein. In studies that have compared outcomes of unilateral versus bilateral ovarian vein embolization, there was no statistically significant difference.6 Research evaluating long term outcomes of unilateral ovarian vein embolization have not clearly been performed to predict the recurrence rate of pelvic pain and/or pelvic varices, but there is the possibility of re-filling of the pelvic reservoir if coil embolization of left ovarian vein is performed in isolation without addressing the pelvic reservoir or the right ovarian vein. Additional upcoming research evaluating outcomes of OVE will help guide the optimal procedure to be performed in this patient population.

Following completion treatment of the pelvic reservoir from the ovarian vein approach, catheterization of the internal iliac veins and digital subtraction venography using a balloon occlusion catheter can provide assessment of residual filling of the pelvic reservoir and need for additional embolization. If additional dilated pelvic veins are identified, embolization can be considered. Liquid sclerotherapy utilizing sclerosant (STS or Polidocanol) through the balloon occlusion catheter is preferred for treatment of the pelvic reservoir via the internal iliac veins given risk of coil migration in this location. There is no consensus in the literature on whether to perform additional internal iliac vein embolization at the time of ovarian vein embolization or in a second session, although many providers describe outcomes following four vessel embolization (bilateral ovarian veins and bilateral internal iliac veins).7 Future research studies evaluating for outcomes of treatment strategies will assist in identifying the optimal embolization strategy for unilateral or bilateral ovarian veins as well as additional embolization of the internal iliac veins.

If left common iliac vein compression is also suspected based on non-invasive imaging, intravascular ultrasound and venography assessment is an important component of evaluation with upcoming research pending to clearly delineate if patients should undergo combined embolization and stenting or staged treatment.

Significant pain reductions on a visual analog scale were noted following ovarian vein embolization in a systematic review of twenty-one prospective case series, with low rates of repeat intervention.8 Technical success rates have been reported between 84-100% and early substantial pain relief was reported in 75% of patients.6 One systematic review with a mean follow up of 15 months reported greater than 80% of patients reporting benefit from the procedure.9 DeGregorio et al. evaluated outcomes of VAS pain scores following four vessel embolization and reported significant reduction in visual analog scale pain scores of 85.8%-93.8% at 1 year and 92.2%-92.4% at 5 years post intervention.7 While symptomatic recurrence rates have been reported between 7-20% at one year, these patients can potentially benefit from reintervention.10 Additionally, these high rates of recurrence were noted among a variety of embolization techniques, some of which may not have included treatment of the pelvic reservoir which can be a source of recurrence. There is no significant data reported on potential effects of embolization on fertility, however studies have shown there is no significant impact on hormone levels or menstrual cycles.11

Transient post procedural pelvic pain and low back pain (post embolization syndrome) is common and managed best with non-steroidal anti-inflammatory drugs if needed.8 Serious complications from venography and ovarian vein embolization are rare. Access site hematoma, venous perforation and coil migration have been reported but are uncommon.6,8,9 Coil migration has been reported ranging from 1 - 4% in multiple studies and systematic reviews with embolization of the internal iliac veins/branches related to that higher incidence.6,7,8,9,12,3

The absence of randomized controlled data collection verifying the presence of VO-CPP as the source of symptoms as well as the outcomes of intervention have limited implementation of this treatment for the great majority of patients. Additional studies are in the process of development and funding including a randomized, placebo-controlled trial of ovarian vein and pelvic vein embolization in women with chronic pelvic pain and pelvic varices that will assess the impact of embolization versus control. In addition to clear outcomes data and randomization, this will add important disease specific information for the identification and management of these patients. There is also a lack of standardized tools to assess patient's quality of life related to venous origin CPP.2 Following the research consensus panel, the important component of this disease process related to development of a PeVD specific quality of life tool is underway. This will allow for further advancement in the optimal management and/or treatment modality for this complicated disease process.