Transcatheter Therapeutic Embolization of Genitourinary Pathology

Emerging Treatment

EMERGING TREATMENT Transcatheter Therapeutic Embolization of Genitourinary Pathology John F. Ward, MD, Thomas E. Velling, MD Naval Medical Center, San Diego With the advent of smaller vascular catheters and improved imaging techniques, percutaneous transcatheter embolization has become a valuable adjunct for the treatment of patients with various genitourinary pathologic conditions. Multiple embolic agents are now employed in an array of situations to devascularize organs, stop bleeding, and occlude passageways. [Rev Urol. 2000;2(4):236-245, 252] Key words: Embolization • Genitourinary tract • Nephrectomy • Occlusive therapy T ranscatheter embolization has a role in the management of renal cell carcinoma (RCC), renal trauma, ureteral occlusion, bladder hemorrhage, pelvic bleeding following trauma or surgery, correction of internal spermatic vein varicoceles, and high-flow arterial priapism. In this article, we briefly review the choices open to urologists and their patients and the materials available to interventional radiologists. Images detailing the treatment and anatomy in each case are provided. Principles of Transcatheter Embolic Techniques Multiple materials for the occlusion of vessels have been evaluated during the development of embolization techniques. The choice of an embolic material for a specific clinical situation depends on a variety of considerations: the size of the vessels or organ to be embolized, the size of the catheter that can be deployed to the target region, whether repeated embolization through a specific arterial or venous vasculature is anticipated, and whether temporary or permanent occlusion is desired. Agents that offer temporary occlusion (days to weeks) with spontaneous dissolution are absorbable gelatin sponge, microfibrillar collagen, and autologous clot (Figure 1). The most commonly used agent, absorbable gelatin sponge (1C), is usually rolled into small, torpedo-shaped pieces and placed in a tuberculin syringe (1A). Multiple sponge rolls are then injected, with normal saline, directly into the vascular catheter, which has been positioned at the site of desired embolization. Agents that provide permanent vascular occlusion are polyvinyl alcohol particles (1B), metal coils (1D), and detachable balloons. Liquid sclerosing agents are also extensively used to achieve permanent vascular occlusion. Their liquid state allows peripheral embolization well beyond the limits of the smallest available vas- 236 REVIEWS IN UROLOGY FALL 2000 Embolization cular catheter. The distribution of these agents can be more difficult for the interventionist to control, however. They are best deployed through the use of an open-ended balloon catheter that prevents reflux of the sclerosing agent. By far, the most common such agent now employed is absolute ethanol (1E).1 Therapeutic Embolic Infarction of Renal Cell Carcinoma Lalli and associates,2 using a dog model and various synthetic particles to induce embolus formation, first described the concept of therapeutic renal artery embolization (RAE) in 1969. Therapeutic embolic infarction of RCC in humans became an increasingly accepted procedure following its successful application, by Almgård and associates3 in 1973, in 19 patients with advanced metastatic disease. Half of these patients subsequently underwent radical nephrectomy, and the authors subjectively surmised that the surgical procedure was “technically easier than forecasted when the patient was first examined.” Since then, various techniques of renal embolization that employ various thrombotic agents have been reported.4-7 Proponents of therapeutic RAE have espoused its usefulness in the management of RCC, for varying reasons. Early investigators of RAE, with or without subsequent nephrectomy, emphasized potential survival benefits, especially in patients with metastatic renal cancer.8-12 This benefit was believed to be secondary to enhanced immunologic responses induced by RAE, tumor lysis, and the resulting immunologic stimulation. This stimulation was thought to result in the regression of distant metastatic disease. Preliminary reports on the use of RAE to treat patients with metastatic renal cancer appeared in 1975 from the University of Texas M.D. Anderson Cancer Center (UT-MDACC).10 Fifty pa- tients received combination therapy with preoperative RAE and the parenteral administration of progesterone (medroxyprogesterone acetate, 400 mg intramuscularly twice weekly). This was followed by a transabdominal radical nephrectomy at an unprescribed interval from the time of RAE. This initial report favored the regression of renal cancer metastases and a lengthening of patient survival. An update of this study population, which consisted of 100 patients, was presented almost a decade later, using historical controls from the UT-MDACC.11 This long-term follow-up study found only slightly increased survival in patients undergoing preoperative RAE (P = .11). The overall response rate decreased from the previously published 36% to 28%, with similar distributions of patients. A subanalysis of this patient population did reveal a statistically significant survival rate in patients receiving prenephrectomy RAE if minimal pulmonary metastases (parenchymal metastases only) were present (P = .018). Patients with mediastinal or hilar adenopathy, pleural effusions, or nonpulmonary metastases showed no increased survival whether or not prenephrectomy RAE was performed (P = .96). Kaisary and associates12 prospec- tively studied 55 patients, of whom 23 had metastases at presentation. Embolization and adjuvant nephrectomy were performed, along with delayed skin hypersensitivity testing, in an attempt to demonstrate a heightened immune response to embolization. As in the UT-MDACC study, they found no improvement in overall survival with preoperative RAE, an overall response rate of 29%, and no significant changes in the immunologic status of the patient. This study also employed adjuvant medroxyprogesterone acetate in 10 patients and vinblastine in 6 patients, with no significant difference found between treatment groups. The smaller number of patients in this study did not allow for adequate subanalysis of patients with regard to metastatic site. To date, no study (prospective or retrospective) has convincingly and reproducibly demonstrated a survival benefit to adjuvant RAE before radical nephrectomy—with or without the postoperative use of steroids or chemotherapeutics—in patients who have metastatic RCC at the time of presentation. Other authors13,14 have advocated RAE for palliation of symptoms; for persistent hemorrhage from large, inoperable tumors; or as an alternative Figure 1. Commonly employed embolic agents: (A) a tuberculin syringe loaded with rolled absorbable gelatin sponge; (B) 300-µm polyvinyl alcohol particles; (C) an absorbable gelatin sponge and rolled “torpedoes”; (D) a nondeployed (left) and a deployed (right) vascular coil (note the filamentous nature of the coil); and (E) absolute ethanol. FALL 2000 REVIEWS IN UROLOGY 237 Embolization continued A B C Figure 2. Right renal mass treated with renal artery embolization immediately before right radical nephrectomy. (A) A contrast-enhanced CT scan of an 11-cm right renal mass in a 54-year-old woman presenting with flank pain, hematuria, and a palpable mass. (B) A digital subtraction aortogram following absolute ethanol/oil emulsion embolization of both the right renal artery and multiple parasitizing vessels; the left colon outline is not contrast material in the bowel wall but is an artifact of peristalsis and digital subtraction. (C) A bivalved kidney showing large lower-pole renal mass; note the ruler and the apparent decreased size of the mass from that anticipated preoperatively based on CT scan measurements. to nephrectomy in patients too poor in health to withstand the rigors of an extensive surgical procedure. Its use has even been extended to patients with end-stage kidney disease and severe hypertension or proteinuria,15 native kidneys in transplant recipients,16 irreversibly rejected allografts,17 and nonfunctioning hydronephrotic kidneys.18 The safety of this procedure in patients with an indwelling nephrostomy tube, where there has previously been a reluctance to perform RAE because of fear of infection, was recently demonstrated by Hom and associates.14 Six of 8 patients had indwelling nephrostomy tubes. All were treated periprocedurally with intravenous antibiotics and postembolization instillation of gentamicin through the nephrostomy tube. No patient developed a severe infection when treated in this manner, and all nephrostomy tubes were safely removed following the procedure. More recently, proponents of prenephrectomy RAE have hoped to make resection easier by creating a plane of edema surrounding the infarcted kidney or by decreasing operative blood loss, especially in larger tumors.19,20 Therapeutic embolization 238 REVIEWS IN UROLOGY FALL 2000 of the posteriorly located renal artery (Figure 2) permits the surgeon to initially dissect and secure the anteriorly located renal vein or perform venacavotomy with decreased concern for controlling the renal artery before venous occlusion. Early investigators of RAE in renal cancer subjectively reported their impression that preoperative RAE decreased blood loss and lessened operative time.6,9-12 Subsequent reports quantifying the effect preoperative RAE has on the surgical extirpation of the kidney and tumor have shown conflicting results. Bakal and associates21 reported on 93 consecutive patients undergoing RAE before radical nephrectomy, compared with 69 control patients undergoing surgery without preoperative RAE. Patients with large hypervascular tumors (volume greater than 250 mL) who underwent complete embolization received significantly smaller mean blood transfusion volumes than did control patients (250 vs 800 mL; P = .01) when groups were stratified by tumor size. If the embolization was incomplete or collateral vascularity could not be controlled, transfusion rates were actually higher than in those patients who had not undergone preoperative RAE. The investigators theorized that this may be because the surgeon was unaware of additional supplying vessels or overestimated the ability to control residual arterial inflow from nonembolized vessels after the main renal artery ligation. Other authors have used estimated blood loss rather than transfusion volume as their outcomes measurement, a recognized subjective measurement confounded by observer bias,9,10,22,23 or have failed to stratify for the size and vascularity of large tumors.24,25 The literature is also confounded by a lack of uniformity in embolizing agents. The more proximal occlusion achieved with absorbable gelatin sponge cubes, coils, and autologous tissue may make this occlusion less effective than the more distal occlusion achieved with ethanol. All studies are also confounded by a nonuniform interval (ranging from hours to months), both within and between studies, between RAE and nephrectomy.11,20,26,27 A review of the change in attitudes of urologists toward the use of RAE was conducted recently in Britain and Ireland and was compared with a similar survey conducted a decade earlier.28 A 71% response rate was received Embolization Main Points • A survival benefit to adjuvant renal artery embolization before nephrectomy in patients with metastatic renal cell carcinoma has yet to be convincingly shown. • Percutaneous ureteral embolization has excellent success rates and results in symptom resolution. • Pelvic embolization can be effective in controlling pelvic or bladder bleeding following injury. • Percutaneous management of internal spermatic vein varicocele may be preferable to surgical ligation for recurrent varicoceles. • The treatment of choice for high-flow arterial priapism is embolization of the penile artery with an absorbable substance. from the 210 urologists surveyed. Of these, 35% believe the technique still has a place in the management of renal tumors—most commonly, for palliation of hematuria or pain in unfit or inoperable cases, or as the sole treatment modality in patients with widespread metastatic disease. Only 7% believe it is also useful as a preoperative adjunct to radical nephrectomy for very large tumors or tumors with renal vein involvement. A similar survey, conducted a decade earlier in A these islands, found 60% of urologists routinely employing this technique before the extirpation of large renal tumors from patients both with and without metastatic disease.29 RAE is not without its side effects and potential complications. The postinfarction syndrome is characterized by flank pain, fever, elevated white blood cell (WBC) count, nausea, vomiting, and paralytic ileus.30 The pain, which may be severe and may require either parenteral narcotics or B an epidural analgesic to control, generally begins 30 to 60 minutes following the completion of embolization and will persist for 24 to 48 hours. The WBC count will rise to 15,000/µL to 20,000/µL, frequently with a left shift. Temperature of 40°C (104°F), along with nausea, vomiting, and ileus, will persist for 72 hours or longer. Ninety percent of patients will experience this syndrome to varying degrees, and its severity may, in part, be related to the thrombotic agent used. Recognition of the postinfarction syndrome is important. An incorrect diagnosis of renal abscess may be made from the signs and symptoms associated with the presence of gas in the mass (apparent on a CT scan). The gas is secondary to the extensive necrosis induced by the devascularization of the kidney. Unintended embolization of nearly all surrounding organs as well as migration of coils to the lungs has been reported. Several cases of colonic infarction, presumably caused by aortic and inferior mesenteric artery reflux, have been described.31,32 Skin necrosis, Figure 3. Ureteral occlusion in a 69-year-old man with recurrence of transitional cell carcinoma of the ureter. The patient has received external beam radiation therapy postcystectomy for locally extensive disease. Ureteroscopy shows a mass widely invasive into the right ureter. This patient, with significant, persistent hematuria, required multiple homologous blood transfusions. (A) Nephrostogram showing external compression of a mass on the distal right ureter (arrow). (B) Nephrostogram following ureteral occlusion using a distally placed coil (open arrow) before instillation with liquid polyacrylonitrile (closed arrow). FALL 2000 REVIEWS IN UROLOGY 239 Embolization continued B A C Figure 4. Embolization of a bleeding pelvic artery 24 hours following transvaginal needle bladder suspension. The patient required 10 units of packed red blood cells. (A) Selective injection of anterior trunk of the right internal iliac artery revealing a proximally located, abnormal, truncated branch (arrow). (B) A selective arteriogram of the abnormal vessel seen in A using a microcatheter, now showing extravasation consistent with active pelvic bleeding. (C) An arteriogram of the right internal iliac artery following selective embolization of a bleeding vessel using vascular coils (the faint outline seen at the arrow). most likely from reflux into lumbar arteries, has also been reported.33 Using a balloon occlusion catheter with ethanol injection through the end hole can prevent reflux and its complications. This method also enhances the toxic and vaso-occlusive effect of the ethanol. Therapeutic angioinfarction of a kidney with RCC has enjoyed a roller coaster of enthusiasm during the past 2 decades. Despite extensive efforts by numerous authors to quantitate a beneficial effect on systemic disease or to make the removal of large hypervascular renal tumors easier, neither indication has been consistently substantiated in the literature. Anecdotal reports have extended its use to the amelioration of pain, hematuria, proteinuria, or even the systemic symptoms associated with the primary tumor.34 Despite this, in selected cases, many senior surgeons continue to report the benefits of performing prenephrectomy RAE. Therapeutic Ureteral Occlusion Percutaneous ureteral embolization (Figure 3) has been used for several years to control urine leaks caused by 240 REVIEWS IN UROLOGY FALL 2000 vesicovaginal fistula, persistent urine leaks related to prior pelvic surgery, or persistent hematuria secondary to an unresectable malignancy. Excellent technical success rates with symptom resolution have been reported. Farrell and associates35 performed 34 ureteral occlusions in 22 patients. Embolization was performed through preexisting nephrostomy tube tracts and was achieved using coils and/or gelatin sponge pledgets. Nephrostomy tubes were then placed for permanent external urinary diversion. The authors reported 100% technical success, with symptom improvement in all patients within 72 hours. Dong and colleagues36 have recently used a gelatin-like substance, liquid polyacrylonitrile, to achieve permanent ureteral occlusion. They report excellent technical and clinical results in all treated patients. Therapeutic Embolization of the Bladder Pelvic embolization may be an effective method of controlling persistent hematuria caused by radiation cystitis, chemical cystitis, or direct tumor invasion of the bladder in patients who are unresponsive to direct intravesical instillation of therapeutic agents or surgery.37,38 Selective embolization of the anterior division of the hypogastric artery is desired. Transpelvic collaterals are extremely abundant in the normal patient and are often exaggerated in patients with long-standing pelvic tumor or inflammatory disease of the bladder or adjacent organs. It is therefore necessary to perform bilateral embolization of the anterior division of both hypogastric arteries, even if the bleeding can be predominantly localized to 1 wall of the bladder. For this reason, it is important to try to avoid embolization of the posterior division of the hypogastric artery; this can result in ischemia and pain in the gluteal muscles. Pelvic embolization (Figure 4) is also an effective way to control pelvic or bladder bleeding following iatrogenic injuries to the pelvic vessels surrounding the bladder during needle suspensions for urinary incontinence or vaginal hysterectomy. Superselective arteriography can often identify the point of injury and bleeding for selective embolization. Embolization A Varicocele Embolization Transcatheter embolization of the internal spermatic vein (Figure 5) has been used as an alternative treatment for varicocele since the 1970s. Coils are the most commonly used embolic agent, though the use of detachable balloons, ethanol, and hot contrast material has also been described. With regard to pregnancy, seminal parameters, and recurrence, clinical results for percutaneous venous embolization are similar to those seen with open surgical ligation. Sayfan and colleagues39 compared surgical ligation with percutaneous embolization and found no statistical difference in pregnancy rates. In a study of 346 patients, Shlansky-Goldberg and associates40 compared surgery with embolization and looked at seminal parameters as well as pregnancy rates. These researchers were not able to demonstrate a statistically significant difference between the techniques. Percutaneous management of internal spermatic vein varicocele has several advantages over surgical ligation for recurrent varicoceles, in which the B previously operated field can be challenging and the risk of testicular devascularization is increased. First, recovery time is shorter. Second, bilateral varicoceles can be treated in 1 procedure through the same access site. Finally, percutaneous varicocele embolization can be performed under local anesthesia with conscious sedation.39-41 Overall technical success rates range between 85% and 100%, with a 2% to 12% recurrence rate. Complications are minor and rare but do include infection and hematoma at the site of percutaneous access. Therapeutic Embolization of Idiopathic Priapism High-flow arterial priapism (HFAP) has long been recognized as an entity distinct from veno-occlusive priapism,42 which is the consequence of full and unremitting corporeal venoocclusion. Veno-occlusive priapism leads to acidosis and ischemia within the lacunar spaces of the penis and can result in ulceration, gangrene, impotence, or even the need for penile amputation. HFAP is an arterial-lacunar fistula, not a traditional arteriove- Figure 5. Left varicocele embolization with coils in a 23-year-old man with oligoasthenospermia who had a persistent grade 3 left varicocele 6 months following open subinguinal varix ligation. (A) A left internal spermatic venogram. (B) Multiple coils in an embolized left internal spermatic vein. nous fistula in which blood passes directly from the arterial to the venous system, bypassing the capillary network. In HFAP, the blood bypasses the helicine artery and passes directly into the lacunar spaces, maintaining penile tumescence. Arterial priapism follows unregulated arterial inflow to the lacunar spaces from a lacerated cavernous artery.43 This is believed to be secondary to perineal or penetrating penile trauma, though there are reports of veno-occlusive priapism “converting” to HFAP, either through the necrosis of the corpora (secondary to prolonged ischemia) or iatrogenically (via multiple intracorporeal needle insertions during corporeal injections and aspirations).44 It is important to distinguish arterial from veno-occlusive priapism, since the clinical management differs according to the underlying pathophysiology. History, physical examination, corporeal aspirate quality, and color flow Doppler sonography establish the diagnosis of arterial priapism. The most important aspect is often the history of recent perineal or penile trauma. Bright red corporeal aspirate with high oxy- FALL 2000 REVIEWS IN UROLOGY 241 Embolization continued Figure 6. A 28-year-old man with idiopathic high-flow arterial priapism (HFAP) for more than 8 months for whom medical therapy had failed. (A) A left internal pudendal arteriogram. The open arrow reveals normal intense contrast stain in the proximal portion of the corpus spongiosum, seen in the presence of vasodilatation of the penile arteries. This is not the source of the HFAP. The large closed arrow indicates the dorsal penile artery. (B) A microcatheter within the dorsal penile artery (arrow). (C) A left pudendal arteriogram following embolization with gelfoam of a dorsal penile artery. Note the sharp cutoff of the artery (at arrow). A C B gen tensions (PaO2 higher than 40 mm Hg) and minimal penile pain and tenderness provide corroborating information. Color flow Doppler sonography, with a focal area of turbulent flow visualized, correctly predicted the arteriographic presence of an arterial-lacunar fistula in 4 of 7 cases reported by Bastuba and associates.45 Presently, there are 4 treatment al- B A ternatives for arterial priapism. Mechanical intervention consists of prolonged external compression of the perineum for several hours, including the local application of ice, in an at- C Figure 7. A 48-year-old woman with bilateral hydronephrosis secondary to distal ureteral obstruction from cervical cancer. Following bilateral percutaneous nephrostomy tube placement, the patient had persistent hematuria and flank pain. She required aggressive blood product transfusion. (A) A digital subtraction left renal arteriogram with extravasation of contrast from the interlobar artery (arrow). (B) An arteriogram following superselective deployment of a vascular coil (arrow). (C) A coned view of the coil in the interlobar artery (open arrow); the closed arrow indicates a microcatheter. 242 REVIEWS IN UROLOGY FALL 2000 Embolization continued A B C Figure 8. A 24-year-old man with pelvic fracture and persistent hemodynamic instability despite pelvic fixation. (A) A retrograde urethrogram showing complete urethral disruption at the urogenital diaphragm. (B) A digital subtraction selective arteriogram of the anterior division of the right internal iliac artery; the closed arrow indicates a truncated and likely transected vessel off the anterior division, while each open arrow denotes multiple bleeding vessels. (C) An arteriogram demonstrating the resolution of pelvic bleeding following occlusion with absorbable gelatin sponge of the anterior branch of the internal iliac artery (arrow). 244 REVIEWS IN UROLOGY FALL 2000 tempt to occlude proximal arterial inflow and allow healing of the arterial laceration. Pharmacologic intervention with -agonists and methylene-blue to counteract smooth muscle relaxation is often not effective because of an inability to trap these agents in the penis, leading to systemic complications as well as the inability of these substances to address the underlying pathophysiology (namely, the arteriallacunar fistula). Surgical resection of the arterial-lacunar fistula46 and ligation of the internal pudendal artery47 or cavernous artery have also been reported.48,49 In 1977, Wear and associates50 described embolization of the proximal artery supplying the arterial-lacunar fistula with autologous clot or absorbable gelatin sponge. This produced a transient interruption of arterial flow through the lacerated vessel with subsequent dissolution of the embolic substance by endothelial mediated lytic mechanisms to reestablish the arterial flow. Ideally, the internal pudendal arteries should be selectively catheterized via embolization of the penile artery using an absorbable substance, such as gelatin sponge or autologous clot (Figure 6). If this is not possible or is ineffective, the anterior division of the hypogastric artery can be occluded. The short-term efficacy and minimal morbidity of this approach have been well documented in the literature and have defined this technique as the treatment of choice for HFAP.43,51 Few long-term results of therapeutic arterial embolization for HFAP are available. In the largest single institution report, Bastuba and associates45 reported on 7 patients who, over a 7-year period, presented to their institution in Boston with HFAP. Following the failure of mechanical and pharmacologic treatments, superselective transcatheter embolization of the ipsilateral common penile artery was performed following diagnostic arteriography. Priapism resolved in all cases, although 4 patients required repeated embolization. The repeated arteriographic studies for recurrent priapism in these 4 patients revealed restoration of the previously occluded cavernous artery. Full erectile function returned and was maintained throughout the study period in 6 of 7 patients at a median of 26 months. Restoration of erectile function occurred between 2 weeks and 5 months following embolization. The delayed restoration was theorized to be caused by resolution of the clot, the quantity of which was related to the duration of the priapism. Reestablished cavernous artery flow in previously embolized arteries was demonstrated on follow-up ultrasonography in all 7 patients. Embolization in Renal Trauma Most severe renal arterial injuries, such as transection, intimal tears, or thrombotic occlusion, will require surgical repair but, occasionally, angiography and embolization can be helpful or can even be the primary mode of therapy, depending on both the mechanism and the severity of the injury. More focal arterial injuries—from stab wounds, biopsies, and even nephrostomy tube placement—are commonly managed with angiography and embolization (Figure 7). These types of injuries include branch arterial transection, pseudoaneurysm formation, arteriovenous fistula, and arteriocaliceal fistulas.52-57 Clinically, patients may present with flank pain, persistent gross hematuria, or falling hematocrit temporally related to the incident. A noncontrast CT scan may demonstrate a perinephric or retroperitoneal hematoma. Left untreated, the patient may progress to renovascular hypertension, massive blood loss, or even loss of renal function. Pledgets of absorbable gelatin sponge and coils are the favored embolic agents in larger arterial branch- Embolization es. Microcoils deployed through coaxially placed microcatheters are generally used for smaller-branch arterial injuries. It is important to place the embolic material as close to the lesion as possible to minimize the extent of renal parenchymal infarction that will result following embolization of a renal end artery. One must also be careful to appropriately size coils used to treat arteriovenous fistulae, to prevent migration to the lungs.52,54 Pelvic Trauma Post-traumatic pelvic hemorrhage is associated with high mortality rates, in spite of aggressive transfusion.58,59 Most of these patients have sustained multiple injuries, frequently with severe pelvic fractures. External fixation devices are used initially to stabilize the pelvis and control bleeding; however, many of these patients will still require angiographic evaluation and embolization to control the hemorrhage.60 Concomitant injuries to the urethra and bladder are frequently present. Single femoral arterial access is the preferred route. Bilateral internal iliac arteries need to be evaluated because of frequency of bleeding from both sides of the pelvis following pelvic fracture. Evaluation can often be performed quickly through a single femoral artery access site, but patients with tortuous iliac vessels or steep aortic bifurcation may require bilateral femoral access. Angiography can demonstrate contrast extravasation, intimal disruption, vessel occlusion, pseudoaneurysm, spasm, or arteriovenous fistula formation. Once the bleeding vessels are identified, selective embolization (Figure 8) can then be carried out. Absorbable gelatin sponge is the agent of choice.60,61 In exsanguinating and unstable patients, rapid coil embolization of the proximal internal iliac artery can be performed safely in a rapid manner. Neither the frequency nor the etiol- ogy of impotence following embolization is well documented. Its occurrence is not uncommon, but it may be caused by vascular or neurologic insult that occurs at the time of the original pelvic trauma, rather than as a result of arterial embolization.62,63 ■ References 1. Buchta K, Sands J, Rosenkrantz H, Roche WD. Early mechanism of action of arterially infused alcohol U.S.P. in renal devitalization. Radiology. 1982;145:45-48. 2. Lalli AF, Peterson N, Bookstein JJ. Roentgenguided infarction of kidneys and lungs. A potential therapeutic technique. Radiology. 1969;93: 434-435. 3. Almgård LE, Fernström I, Haverling M, Ljungqvist A. Treatment of renal adenocarcinoma by embolic occlusion of the renal circulation. Br J Urol. 1973;45:474-479. 4. Gianturco C, Anderson JH, Wallace S. Mechanical devices for arterial occlusion. AJR. 1975;124:428435. 5. Freeny PC, Bush WH Jr, Kidd R. Transcatheter occlusive therapy of genitourinary abnormalities using isobutyl 2-cyanoacrylate (Bucrylate). AJR. 1979;133:647-656. 6. Swanson DA, Wallace S, Johnson DE. The role of embolization and nephrectomy in the treatment of metastatic renal carcinoma. Urol Clin North Am. 1980;7:719-730. 7. Barry JW, Bookstein JJ, Alksne JF. Ferromagnetic embolization: experimental evaluation. Radiology. 1981;138:341-349. 8. Rabe FE, Yune HY, Richmond BD, Klatte EC. Renal tumor infarction with absolute ethanol. AJR. 1982;139:1139-1142. 9. Christensen K, Dyrelborg U, Andersen JF, Nissen HM. The value of transvascular embolization in the treatment of renal carcinoma. J Urol. 1985; 133:191-193. 10. Bracken RB, Johnson DE, Goldstein HM, et al. Percutaneous transfemoral renal artery occlusion in patients with renal carcinoma: preliminary report. Urology. 1975;6:6-10. 11. Swanson DA, Johnson DE, von Eschenbach AC, et al. Angioinfarction plus nephrectomy for metastatic renal cell carcinoma: an update. J Urol. 1983; 130:449-452. 12. Kaisary AV, Williams G, Riddle PR. The role of preoperative embolization in renal cell carcinoma. J Urol. 1984;131:641-656. 13. Nurmi M, Satokari K, Puntala P. Renal artery embolization in the palliative treatment of renal adenocarcinoma. Scand J Urol Nephrol. 1987;21:9396. 14. Hom D, Eiley D, Lumerman JH, et al. Complete renal embolization as an alternative to nephrectomy. J Urol. 1999;161:24-27. 15. McCarron DA, Rubin RJ, Barnes BA, et al. Therapeutic bilateral renal infarction in end-stage renal disease. N Engl J Med. 1976;294:652. 16. Goldin AR, Naude JH, Thatcher GN. Therapeutic percutaneous renal infarction. Br J Urol. 1974;46: 133-135. 17. Lorenzo V, Diaz FD, Perez L, et al. Ablation of irreversibly rejected renal allograft by embolization with absolute ethanol: a new clinical application. Am J Kidney Dis. 1993;22:592-595. 18. Hirao Y, Okajima E, Yoshida K, et al. Renal ablation with absolute ethanol for nonfunctioning hydronephrosis. Eur Urol. 1993;24:203-207. 19. Wallace S, Chuang VP, Swanson D, et al. Embolization of renal carcinoma. Radiology. 1981; 138:563-570. 20. Ben-Menachem Y, Crigler CM, Corriere N Jr. Elective transcatheter renal artery occlusion prior to nephrectomy. J Urol. 1975;114:355-359. 21. Bakal CW, Cynamon J, Lakritz PS, Sprayregen S. Value of preoperative renal artery embolization in reducing blood transfusion requirements during nephrectomy for renal cell carcinoma. J Vasc Interv Radiol. 1993;4:727-731. 22. Leinonen A. Embolization of renal carcinoma. Ann Clin Res. 1985;17:299-305. 23. Jitsukawa S, Tachibana M, Deguchi N. Renal devitalization with ethanol injection in management of patients with advanced hypernephroma. Urology. 1984;23:87-92. 24. Singsaas MW, Chopp RT, Mendez R. Preoperative renal embolization as adjunct to radical nephrectomy. Urology. 1979;14:1-4. 25. Giuliani L, Carmignani G, Gelgrano E, et al. Usefulness of preoperative transcatheter embolization in kidney tumors. Urology. 1981;17:431-434. 26. Teasdale C, Kirk D, Jeans WD, et al. Arterial embolization in renal carcinoma: a useful procedure. Br J Urol. 1982;54:616-619. 27. Ellman BA, Parkhill BJ, Curry TS, et al. Ablation of renal tumors with absolute ethanol: a new technique. Radiology. 1981;141:619-626. 28. Lanigan D, Jurriaans E, Hammonds JC, et al. The current status of embolization in renal cell carcinoma—a survey of local and national practice. Clin Radiol. 1992;46:176-178. 29. Ritchie AW, Chisholm GD. Management of renal cell carcinoma: a questionnaire survey. Br J Urol. 1983;55:591-594. 30. Chuang VP, Wallace S, Swanson DA. Technique and complications of renal carcinoma infarction. Urol Radiol. 1981;2:223-228. 31. Cox CG, Lee KR, Price HI, et al. Colonic infarction following ethanol embolization of renal-cell carcinoma. Radiology. 1982;145:343-345. 32. Sutherland PD, Howard PR, Marshall VR. Colonic infarction following ethanol embolization of the kidney. Br J Urol. 1986;58:337. 33. Twomey BP, Wilkins RA, Mee AD. Skin necrosis: a complication of alcohol infarction of a hypernephroma. Cardiovasc Intervent Radiol. 1985;8: 202-203. 34. Craven WM, Redmond PL, Kumpe DA, et al. Planned delayed nephrectomy after ethanol embolization of renal carcinoma. J Urol. 1991;146: 704-708. 35. Farrell TA, Wallace M, Hicks ME. Long term results of transrenal ureteral occlusion with use of Gianturco coils and gelatin sponge pledgets. J Vasc Intervent Radiol. 1997;8:449-452. 36. Dong PR, McKay JE, Link DP, McGahan JP. Permanent ureteral occlusion with use of liquid polyacrylonitrile. J Vasc Intervent Radiol. 1997;8:655657. 37. Lang EK. Transcatheter embolization of pelvic vessels for control of intractable hemorrhage. Radiology. 1981;140:331-339. 38. McIvor J, Williams G, Greswick Southcott RD. Control of severe vesical haemorrhage by therapeutic embolisation. Clin Radiol. 1982;33:561567. 39. Sayfan J, Saffer Y, Orda R. Varicocele treatment: prospective randomized trial of 3 methods. J Urol. 1992;148:1447-1449. 40. Shlansky-Goldberg RD, VanArsdalen KN, Rutter CM, et al. Percutaneous varicocele embolization versus surgical ligation for the treatment of infertility: changes in seminal parameters and pregnancy outcomes. J Vasc Intervent Radiol. 1997;8: 759-767. 41. Nieschlag E, Behrett M, Schlingheider A, et al. Surgical ligation vs angiographic vena spermatica: a prospective randomized study for the treatment of varicocele related infertility. Andrologia. continued on page 252 FALL 2000 REVIEWS IN UROLOGY 245