Varicocele Embolization: Interventional Radiologist's Perspective

Abstract

The goal of this article is to review the patient selection criteria, technical pearls, and outcomes of percutaneous varicocele embolization. This article will provide a brief overview of the history of the procedure, angiographic approach, and materials used in contemporary embolization. The success rates and complications of the varicocele embolization will also be discussed.

Varicocele is a collection of varicose veins within the pampiniform plexus that result from venous backflow of blood within the internal spermatic vein (ISV). ^{1 2} Varicoceles have been found to be associated with pain and decreased testicular function, as marked by impaired sperm function and fertilization outcomes. ^{3 4} Prevalence rates range from 10 to 15% in men of reproductive age, approach rates as high as 35% in men with primary infertility and further increases with age. ^{2 5} There are numerous indications for treatment, including chronic testicular pain (orchialgia), infertility, testicular atrophy, and recurrent varicocele refractory to previous treatments. ⁶ Surgical ligation has traditionally been the standard treatment for varicocele, but advances in technology have increased the amount of nonsurgical treatment options with comparable results. A common and effective nonsurgical option is percutaneous embolization of the ISV, which has the advantages such as minimal invasiveness, lower cost, shorter recovery time, and decreased rates of adverse events. ^{7 8 9} In fact, a meta-analysis by Liu et al recently showed that patients undergoing endovascular treatment had fewer complications than patients undergoing surgery while maintaining comparable procedure outcomes. ¹⁰ Complications such as testicular pain and atrophy are markedly decreased due to the decreased risk of testicular artery damage, making it a safe and effective treatment option. ¹¹

In this article, we aim to review the clinical and technical details of percutaneous varicocele embolization while providing a summary of currently available evidence. We will provide a brief overview of the patients who are good candidates for percutaneous embolization and review angiographic approach, various embolic agents, success rates, and complications of the procedure.

Vascular Anatomy

Understanding the anatomy and potential variant anatomy is crucial in providing successful treatment and preventing failure and/or recurrence. The male gonadal veins are formed by the confluence of the pampiniform plexus (spermatic venous plexus) as they ascend out of the inguinal canal. In most cases, the left gonadal vein drains into the left renal vein, while the right gonadal vein drains directly into the anterolateral wall of the inferior vena cava (IVC) just inferior the right renal vein. This common normal anatomy leads to a much higher incidence of left-sided varicocele due to increased hydrostatic pressure as a result of the acute anatomical angle formed at the confluence of the left gonadal vein and left renal vein. Anatomical variations in the pattern of the left gonadal vein do exist, including duplicated gonadal vein or left renal vein; a single gonadal vein with collaterals to retroperitoneal, paravertebral, and left renal veins; multiple veins draining into the left renal vein; or multiple veins draining into the IVC. Additionally, right gonadal vein pattern variations occur, including variations in the right gonadal vein drainage into the right renal vein. Variant anatomies should be recognized in order to provide proper treatment while minimizing the risk of complications and varicocele recurrence. ^{12 13 14 15 16}

Diagnosis

Clinical examination has historically been used to diagnose varicocele. Ultrasound with color Doppler is the most widely used radiological modality for diagnosing and evaluating varicoceles. Confirmation of a varicocele diagnosis requires vein diameter to be larger than 2 mm with an abnormally brisk and prolonged accentuation of blood flow while the patient is performing the Valsalva maneuver ( Fig. 1 ). For most cases, the simultaneous presence of vein dilatation and reflux are required for diagnosis of varicocele. Ipsilateral right-sided varicocele requires further renal ultrasound or abdominal CT imaging to evaluate for the possibility of venous compression, given the possibility of venous compression to exclude associated abdominal/pelvic masses. ^{17 18} Potential venous compression on the left due to Nutcracker syndrome should be considered, especially if there is history of hematuria.

Fig. 1.

Images of a 23-year-old man with a left varicocele presenting originally with daily symptoms while standing associated with left scrotal swelling and intermittent left testicular pain. Pampiniform plexus on the left measures up to 3.2 mm (double arrow).

Patient Selection

There is continued debate over treatment indications for varicocele. Testicular pain (orchialgia), infertility, and varicocele recurrence following surgical ligation (postsurgical recurrence of varicocele) have been shown to be good treatment indicators and will benefit from percutaneous embolization. ^{19 20 21} Interventional treatment of varicocele is indicated in cases of aesthetic concerns, infertility, testicular pain, and testicular volume loss in the pediatric population. Treatment of varicocele for infertility should be considered when the female partner has normal or correctable fertility status and sperm analysis reveals an abnormality. ^{19 20 22} A practice committee from European Association of Urology Guidelines on Male Sexual and Reproductive Health recommends treatments in infertile men with a clinical varicocele, abnormal semen parameters, or otherwise unexplained infertility in a couple in which the female partner has a good ovarian reserve or correctable fertility. ¹⁸ Varicocele repair carries the potential benefit of correcting the underlying pathology of infertility in a cost-effective way for well-selected patients. Other factors that should be considered in deciding whether to offer varicocele treatment versus assisted reproductive techniques include age and time available for conception, as it may take 3 to 6 months after varicocele correction for sperm parameters to improve. Predictors of improvement after varicocele treatment such as varicocele size, follicle-stimulating hormone level, and preoperative total motile sperm count should be taken into account.

Treatment

Different techniques of varicocele repair have been developed, such as surgical and microsurgical varicocelectomy, laparoscopic varicocelectomy, and percutaneous embolization. These approaches are aimed at eliminating venous reflux, preserving vascular and lymphatic testicular structure, and, at the same time, improving pregnancy rates and improvement of sperm concentration relative to those observed for patients who do not undergo such treatment. The recent meta-analysis comparing surgical versus endovascular varicocele treatments showed that endovascular intervention is associated with lower rates of adverse events and reduced postoperative morbidity than surgical treatment (RR, 0.63; 95% confidence interval [CI], 0.45–0.88; p  = 0.006), allows the patients to quickly recover and reduces the pain secondary to procedure. Recurrence rates (RR, 1.04; 95% CI, 0.80–1.34; p  = 0.79) and pregnancy rates (RR, 1.03; 95% CI; 0.86–1.24; p  = 0.72) were comparable for both approaches ¹⁰ ; however, data in literature are not homogenous.

Embolization

Technique

Percutaneous retrograde varicocele embolotherapy typically does not require hospital stay or admission, as the procedure is often performed in an outpatient setting with patients under moderate sedation. ²¹ It is important that patients be kept under light sedation after initial access in order for patients to properly cooperate with performing Valsalva during venography if needed. Access can be obtained either via the right internal jugular vein or right common femoral vein, with preference dependent on the side of varicocele treatment. Access through the right internal jugular is the best approach for the right-sided varicocele due to a more favorable catheterization angle of the right ISV from the IVC (using a hockey stick catheter). Either the right common femoral vein or right internal jugular vein can be used for accessing the left ISV (using a cobra or hockey stick catheter).

Patients with left-sided varicoceles are often better suited and have higher success rates when undergoing percutaneous embolization compared to patients with right-sided or bilateral varicoceles. The failure rate is 2.3% when treating left varicocele with endovascular embolotherapy compared to 19.3% in the right side. This was attributed to a significantly more difficult catheterization of the ISV in right-sided varicocele. ²²

After obtaining access, a 5- or 6-Fr sheath can be placed into the selected vein. Left renal venogram with Valsalva can be performed prior to catheterization of the ISV to confirm reflux. The left renal vein is then cannulated, typically with hydrophilic wires and catheters with subsequent selective catheterization of the left ISV (using the same catheter or a microcatheter). The origin of the left ISV usually projects at the left side of the adjacent vertebral body. Once reflux and expected anatomy is confirmed, ISV will be catheterized and the tip of the catheter will be placed just above the inguinal canal. Subsequent diagnostic venography with Valsalva can properly evaluate the venous anatomy, and evaluate potential collateral vessels requiring embolization. Operators can utilize anatomical landmarks such as the superior femoral head and acetabulum to confirm location before embolization.

Embolic Agents

Numerous factors are involved in the selection of embolic material, including operator preference, product availability and cost, patient anatomy, and embolic agent safety. Because of the potential for treatment failure and varicocele recurrence due to hidden anatomical collaterals or spermatic vein spasm, it is crucial to select a durable and effective embolic agent to successfully occlude all collaterals and prevent potential embolic agent migration. Different embolization techniques with numerous embolizing agents have been used and shown good technical and clinical results. Embolic agents include both mechanical agents (coils or plugs) and liquid agents (glue or sclerosing agents) either alone or in combination.

Coils are the most commonly used embolic agents for endovascular varicocele treatment due to their wide availability and ease of handling. Because the treatment goal includes complete occlusion of the gonadal vein, it is imperative that the coils are packed tightly. If coils are used as the only embolic agent, it is equally important to identify, catheterize, and embolize all the collaterals draining the varicoceles. Coils successfully obliterate the lumen of the vessel either mechanically or by inducing thrombosis, as in the case of bare Platinum, hydrogel-coated coils or fibered coils, respectively. Disadvantages of coils may include their decreased effectiveness compared to surgical clipping in the presence of collateral vessels. They are unable to fill the collateral pathways that exist. This may lead to varicocele recanalization and a failure rate due to technical fault ranging from 3 to 28%. ^{6 23 24}

Vascular plugs are another mechanical embolic agent with benefits including decreased risk of embolic agent migration when compared to coils and reduced procedure time due to their ease in delivery and release. This also allows the operator to retrieve and reposition the plug during the procedure for proper placement. Plugs are, however, relatively expensive compared to pushable coils which is a potential disadvantage. ²⁵

Although mechanical embolic agents are commonly used, liquid agents are effective for treating varicocele. One of the main advantages of using liquid embolics is the decreased varicocele recurrence rates due to their ability to penetrate and occlude collateral vessels around the ISV. Liquid embolic agents include glues such as N-butyl cyanoacrylate (NBCA) or N-butyl cyanoacrylate methacryloxy sulfolane (NBCA-MS) and foam or liquid sclerosing agents such as polidocanol, sodium tetradecyl sulfate (Sotradecol), sodium morrhuate, or ethanolamine oleate. These are often used in combination with solid agents such as coils or balloons to increase procedure effectiveness in a technique called sclero-embolization. ^{24 25}

Sclerotherapy is an effective and commonly used embolic technique that introduces a foreign sclerosant substance (either liquid or foam) into the vessel lumen. The goal is to occlude the vessel by coating the vessel walls and lumen to induce inflammation and venous endothelial damage. Foam sclerotherapy has been shown to improve testicular function and seminal parameters after 3- and 9-month follow-up visits. Gandini et al further showed increased pregnancy rates by 39%. ²⁶ The cost of sclerotherapy has been shown to be a fraction of the cost of open surgery, with Abdulmaaboud et al reporting an average three-fourths to four-fifths lower price. ^{10 27} Although it is difficult to translate this finding into other institutions since costs can be institution specific, there could quite possibly be a general reduced financial burden for patients and health care institutions. Combined with the reported decreased complications following the procedure, it may be an optimal first-line treatment for varicocele. A commonly reported potential disadvantage to sclerotherapy is pain associated with injection.

Foam sclerotherapy is performed by mixing the sclerosing agent with air or CO ₂ via a three-way stop cock (Tessari method). Sotradecol is a commonly used sclerosant and is available in 1% (10 mg/mL) and 3% (30 mg/mL) concentrations (1–2 mL of sclerosant to 5–10 mL of CO ₂ and 5–10 mL of the foamed mixture). In our institution, a combination of coil embolization and 3% sodium tetradecyl sulfate (STS) foam sclerotherapy is performed. This includes three levels of coil embolization. The first 0.035-in pushable coil stack is placed at the lowest point of the vertical segment of the ISV before swinging medially as a good anatomical landmark. A second 0.035-in pushable coil stack is placed at the level of the mid-ISV. The catheter is subsequently advanced between the two coil nests and contrast is injected between the middle and lower coil stacks. Then approximately 5 to 10 mL of sclerosing foam (mixture of 2 mL of 3% STS, 10 mL of CO ₂ ) is administered slowly under fluoroscopic guidance which can displace the contrast. Interventionist can have the patients perform a gentle Valsalva during the foam injection to force it into the collaterals. Lastly, a nest of detachable coils is formed just below the renal vein confluence. In case of presence of large predominant collaterals, selective catheterization and embolization with one or more embolic agents is performed. Completion venography is done to confirm adequacy of treatment ( Figs. 2 and 3 ). It is crucial, though, to be attentive when performing sclerotherapy to ensure the embolic agent is not washed into the IVC from the left renal vein. ^{25 28 29} Additionally, in a systematic review including 898 patients treated with coils and 1,628 patients treated with a combination of coils and sclerosing agents, results showed a mean technical success rate of 92% for both groups and an average recurrence rate of 9.1% for patients in the coils group and 8.44% for the combined treatment (without significant difference between the two groups). ²⁴

Fig. 2.

Illustration of selective catheterization and embolization of the left internal spermatic.

Fig. 3.

Images of a 22-year-old man with a left varicocele accompanied by testicular pain. Patient had failed surgical repair and was referred for varicocele embolization. ( a ) Digital subtraction angiography images show selective catheterization of the left internal spermatic vein before embolization. ( b, c ) Angiography and fluoroscopy images show technically successful embolization of the left internal spermatic vein (arrows—coils). There was clinical success, as the patient was pain free on 6-month follow-up.

Postprocedure Follow-up

Varicocele embolization is safe and well tolerated without a high complication rate. Complications include embolic material migration, left renal vein thrombosis, or pampiniform plexus thrombophlebitis. Post embolization systemic symptoms include testicular and back pain, nausea, and low-grade fevers. Following the procedure, patients are allowed to return to regular daily activities after 24 hours but are encouraged to avoid strenuous activities such as heavy lifting for 2 weeks postprocedure. A 1- and 6-month follow-up visit is recommended, where scrotal ultrasound will take place.

Future Directions

Varicocele treatment has been shown to alleviate pain and discomfort and fertility, regardless of treatment approach. High-quality randomized controlled trials are needed to compare the efficacy and outcomes of surgical versus endovascular approach as well as different embolic agents and techniques.

Funding Statement

Funding This study was not supported by any funding.