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Embolization
Brandt C. Wible, MD; T. Gregory Walker, MD, FSIR
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KEY FACTS

  • Terminology

    • Preprocedure

      • Outcomes

        TERMINOLOGY

        • Definitions

          • Embolization: Therapeutic technique using direct/transcatheter introduction of intravascular agent for hemorrhage control/devascularization/occlusion
            • Various available agents
              • Subclassified as temporary and permanent agents
          • Temporary embolic agents
            • Gelatin sponge
              • Gelfoam (Upjohn; Kalamazoo, MI)
                • Sheet form; can cut into pledgets/create slurry
              • Surgifoam (Ethicon; Somerville, NJ)
                • Sheet form similar to Gelfoam
                • Powder form (40- to 60-μm particle diameter) causes distal occlusion; possible ischemia/infarction
              • Consider use to rapidly embolize arterial hemorrhage, combine/sandwich with coil embolization, temporarily occlude shunting prior to definitive treatment, occlude percutaneous transhepatic access, or when permanent embolization not ideal
                • Not ideal for small vessel embolization
              • Inexpensive, readily available, rapid preparation and effect
              • May be prepared as single torpedo or slurry
              • Recanalization of embolized vessel is unpredictable, usually occurring within weeks to months
            • Autologous clot
              • Delivery of patient's thrombosed blood products
              • Short effective duration (hours)
          • Permanent embolic agents
            • Coils: Mechanical metal occluding device; assumes coiled configuration upon exiting catheter, blocks vessel with fibers, swelling hydrogel; various sizes, configurations and shapes (e.g., straight, tornado-tapered shape, 2D or 3D shapes)
              • Consider coil use when catheter can be advanced to targeted vessel
              • "Pushable" 0.035" or 0.018" coils: Inexpensive, straight-forward delivery
                • Azur peripheral pushable HydroCoil (Terumo)
                • Nester, Hilal, Tornado embolization coils (Cook Medical; Bloomington, IN)
                • VortX embolization coils (Boston Scientific)
              • May be advanced and deployed through catheter with "coil-pusher" wire or careful (semiforceful) injection with 1- to 3-cc syringe of saline
              • May not be possible to remove/snare if malpositioned
              • Detachable 0.035" or 0.018" coils: May be retrieved if in suboptimal location/configuration
                • Axium detachable coil (ev3; Plymouth, MN)
                • Azur HydroCoil (Terumo; Somerset, NJ)
                • GDC, Interlock, Matrix coils (Boston Scientific; Natick, MA)
                • DeltaPaq, DeltaWind microcoils (Micrus Endovascular; San Jose, CA)
                • Orbit Galaxy (Codman Neurovascular)
              • Consider detachable coil use in critical vessels, high-flow shunts or areas where nontarget embolization could inadvertently occur (e.g., gastroduodenal artery)
              • Retrieval not always possible if coil fully deployed or too much time elapsed
              • Multiple detachment designs exist (e.g., mechanical, electrical)
            • Particles: Micron-sized solids; lodge at precapillary/capillary level; occlude vessels/devascularize tissue
              • Contour PVA (Boston Scientific)
                • Polyvinyl alcohol (PVA) particles; nonspherical irregular sizes
                • Occlude more proximal than vs. similar-sized spherical particle (bead)
                • Can clump, resulting in proximal vessel/catheter occlusion
              • PVA foam embolization particles (Cook Medical)
              • Contour SE microspheres (Boston Scientific)
                • Calibrated PVA microspheres (teardrop shape)
              • Bead Block (Terumo Medical)
                • Calibrated PVA hydrospheres
              • Embospheres (Biosphere Medical; Rockland, MA)
                • Calibrated acrylic polymer microspheres
                • Slightly compressible during delivery
                • EmboGold variant tinted red
              • Embozene microspheres (CeloNova BioSciences; Peachtree City, GA)
                • Hydrogel microsphere with Polyzene-F coating
              • Consider use within end-arteries when distal arteriole/organ embolization desired
              • May lead to significant embolization and subsequent ischemia of distal tissue/organ
              • Do not use in cases of vascular shunting or collateral vasculature
              • Concerns include nontarget embolization
            • Plug occluding device: Woven nitinol expandable mesh cylindrical plug
              • Amplatzer Vascular Plug (St. Jude Medical; Saint Paul, MN)
                • Mechanically occludes target vessel in similar manner to coil embolization
                • Allows precise positioning, short landing zone, rapid occlusion
                • Recommended to oversize 30% beyond target vessel diameter
                • AVP 4 design delivered via 0.038" catheter
                • Less trackable through tortuous vessels vs. coils
            • Liquids: A variety of nonsolid embolic
              • Consider use for specific clinical situations: Complex embolic target requiring embolic penetration beyond catheter into nidus [arteriovenous malformation (AVM)], desire to solidify target vessel (intracranial aneurysm), oncologic use (hepatocellular carcinoma), nonvascular target (biliary leak)
              • Sufficient training and well-developed understanding of each specific liquid embolic's properties and risks is necessary prior to use
              • Delivery of liquid embolics often require advanced training and experience and can be challenging to properly deploy
              • Ethanol: 96-98%, immediately denatures cellular proteins/causes small vessel thrombosis
                • Can be used to ablate whole organ (e.g., kidney)
                • Also useful as sclerosant
                • Extremely painful during delivery; consider general anesthesia
                • Caution: Ensure ethanol not injected where shunting is present
                • Not visible during delivery (unless mixed 4:1 with Lipiodol); calculate desired volume of ethanol using dilute contrast
              • Lipiodol (Guerbet; Paris, France): Ethiodized oil; iodine-containing poppy seed oil
                • Used in conventional transarterial chemoembolization where it acts as fluoroscopically visible chemotherapeutic delivery agent and transient arterial embolic
                • Can occlude lymphatic leaks (50-75%) during lymphangiogram
                • Added to other embolics during delivery (e.g., ethanol, "glue")
                • Dissolves soft plastics (e.g., catheter hub, syringe, 3-way stopcock)
              • N-butyl cyanoacrylate (n-BCA) Trufill (Cordis; Bridgewater, NJ)
                • Solidifies on contact with ionic medium (e.g., blood)
                • Liquid "glue" polymer is mixed with Lipiodol immediately prior to delivery
                • Ratio with more Lipiodol (5:1) slows rate of glue polymerization/solidification; ratio with less Lipiodol (2:1) increases rate of polymerization/solidification
                • Nonionic preparation of table, gloves, catheters, syringes vital
                • All equipment must be meticulously flushed with nonionic solutions (e.g., D5W)
                • "Glue" is flushed through catheter with nonionic solution
                • Typically, small volumes of n-BCA/Lipiodol necessary
                • Caution: Catheter can become "glued" to vessel during delivery
                • Has nonvascular applications, since occlusion does not require platelets/coagulants
              • Onyx (ev3 Neurovascular; Irvine, CA)
                • Ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (DMSO)
                • Radiopaque-suspended micronized tantalum powder added for increased visibility; tantalum may become visible through skin if treating superficial vascular malformations
                • Precipitates from outside-in on contact with aqueous solution as DMSO dissipates
                • Forms "foam" embolic with lava-like flow characteristics
                • Nonadhesive; catheter very unlikely to stick to vessel during delivery; allows slower, more deliberate injection vs. n-BCA "glue"
              • Thrombin solution
                • Off-label use, percutaneously thrombose access-related pseudoaneurysms
                • Reconstituted in 1,000 U/mL concentration
                • Rapidly converts fibrin to fibrinogen, activates coagulation cascade; causes thrombotic occlusion of target
                • Be aware that label warns not for intravascular injection
                • Extremely small volumes (0.2-0.5 cc) typically necessary
                • Severe potential effects of nontarget embolization; Doppler distal pulse during delivery
                • Caution: Do not use if patient had prior allergic reaction to thrombin
            • Sclerosing agents
              • Detergents: Causing vessel occlusion via inflammation/thrombosis
                • Consider use in varicose veins, venous malformations, pelvic congestion syndrome, balloon-occluded retrograde transvenous obliteration
                • Can use as liquid, or mix with air (or CO2) to form foam
                • Advantage of foam: Increased contact with wall, with less-administered sclerosing agent
                • Sodium tetradecyl sulfate-STS (Sotradecol): Mild sclerosant; typically 3% STS (available in 2-mL vials) is mixed with air/CO2 (3 mL air: 2 mL STS: Add 1 mL Lipiodol for visualization as needed)
                • Polidocanol: Widely used in Europe
                • Ethanolamine oleate iopamidol (Ethamolin): Widely used in Japan
                • Sodium morrhuate (Scleromate): Fallen out of favor
              • Ethanol: Immediate protein denaturation and cell death
              • Boiling contrast: Not often used due to patient pain, operator risk
              • Lymphocele sclerotherapy
                • Doxycycline: Intracavitary injection effective for treatment of lymphatic malformations, inexpensive, widely available
                • Intracavitary injection of tetracycline, bleomycin, talc, fibrin glue have also been described
            • Oncologic agents
              • Consider use in specific oncologic situations
              • Drug-eluting beads
                • LC Beads (DC Beads in Europe) (AngioDynamics, Latham, NY): Blue tint, sizes include 100-300 µm, 300-500 µm, and 500-700 µm
                • QuadraSphere (Merit Medical, South Jordan, UT) spheres enlarge over time: 30-60 µm, 50-100 µm, 100-150 µm, and 150-200 µm
                • Chemotherapeutics are bound to spheres ionically (irinotecan) or osmotically (doxorubicin) and delivered to tumor where chemotherapeutics release from beads, resulting in significantly higher concentrations at tumor bed than can be achieved via IV delivery
              • Radioactive particles: Beta-emitting particle, yttrium-90; embedded on microspheres
                • SIR-Spheres (Sirtex Medical; North Sydney, AU); resin microspheres, greater number of particles per dose
                • TheraSpheres (Nordion; Ottawa, Canada); glass microspheres with greater activity per particle
                • Utilized for selective internal radiation therapy
            • Stents: Used in association with embolization coils
              • Stent-assisted coil embolization: Noncovered stent placed across wide neck aneurysm
                • Coils introduced through stent interstices into aneurysm/pseudoaneurysm using microcatheter

        PREPROCEDURE

        • Indications

          • Contraindications

            • Getting Started

              PROCEDURE

              • Patient Position/Location

                • Procedure Steps

                  • Alternative Procedures/Therapies

                    POST PROCEDURE

                    • Things to Do

                      • Things to Avoid

                        OUTCOMES

                        • Problems

                          • Complications

                            • Expected Outcome

                              Selected References

                              1. Horbach SE et al: Sclerotherapy for low-flow vascular malformations of the head and neck: A systematic review of sclerosing agents. J Plast Reconstr Aesthet Surg. 69(3):295-304, 2016
                              2. Spiotta AM et al: Comparison of techniques for stent assisted coil embolization of aneurysms. J Neurointerv Surg. 4(5):339-44, 2012
                              3. Etezadi V et al: Endovascular treatment of visceral and renal artery aneurysms. J Vasc Interv Radiol. 22(9):1246-53, 2011
                              4. Zhu X et al: Utility of the Amplatzer Vascular Plug in splenic artery embolization: a comparison study with conventional coil technique. Cardiovasc Intervent Radiol. 34(3):522-31, 2011
                              5. Duffy DM: Sclerosants: a comparative review. Dermatol Surg. 36 Suppl 2:1010-25, 2010
                              6. Lee BB et al: Management of arteriovenous malformations: a multidisciplinary approach. J Vasc Surg. 39(3):590-600, 2004
                              7. de Giovanni JV: The use of Amplatzer devices to occlude vascular fistulae. J Interv Cardiol. 14(1):45-8, 2001
                              8. Jackson JE et al: Treatment of high-flow vascular malformations by venous embolization aided by flow occlusion techniques. Cardiovasc Intervent Radiol. 19(5):323-8, 1996
                              9. Jander HP et al: Transcatheter gelfoam embolization in abdominal, retroperitoneal, and pelvic hemorrhage. Radiology. 136(2):337-44, 1980
                              Related Anatomy
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                              Related Differential Diagnoses
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                              References
                              Tables

                              Tables

                              KEY FACTS

                              • Terminology

                                • Preprocedure

                                  • Outcomes

                                    TERMINOLOGY

                                    • Definitions

                                      • Embolization: Therapeutic technique using direct/transcatheter introduction of intravascular agent for hemorrhage control/devascularization/occlusion
                                        • Various available agents
                                          • Subclassified as temporary and permanent agents
                                      • Temporary embolic agents
                                        • Gelatin sponge
                                          • Gelfoam (Upjohn; Kalamazoo, MI)
                                            • Sheet form; can cut into pledgets/create slurry
                                          • Surgifoam (Ethicon; Somerville, NJ)
                                            • Sheet form similar to Gelfoam
                                            • Powder form (40- to 60-μm particle diameter) causes distal occlusion; possible ischemia/infarction
                                          • Consider use to rapidly embolize arterial hemorrhage, combine/sandwich with coil embolization, temporarily occlude shunting prior to definitive treatment, occlude percutaneous transhepatic access, or when permanent embolization not ideal
                                            • Not ideal for small vessel embolization
                                          • Inexpensive, readily available, rapid preparation and effect
                                          • May be prepared as single torpedo or slurry
                                          • Recanalization of embolized vessel is unpredictable, usually occurring within weeks to months
                                        • Autologous clot
                                          • Delivery of patient's thrombosed blood products
                                          • Short effective duration (hours)
                                      • Permanent embolic agents
                                        • Coils: Mechanical metal occluding device; assumes coiled configuration upon exiting catheter, blocks vessel with fibers, swelling hydrogel; various sizes, configurations and shapes (e.g., straight, tornado-tapered shape, 2D or 3D shapes)
                                          • Consider coil use when catheter can be advanced to targeted vessel
                                          • "Pushable" 0.035" or 0.018" coils: Inexpensive, straight-forward delivery
                                            • Azur peripheral pushable HydroCoil (Terumo)
                                            • Nester, Hilal, Tornado embolization coils (Cook Medical; Bloomington, IN)
                                            • VortX embolization coils (Boston Scientific)
                                          • May be advanced and deployed through catheter with "coil-pusher" wire or careful (semiforceful) injection with 1- to 3-cc syringe of saline
                                          • May not be possible to remove/snare if malpositioned
                                          • Detachable 0.035" or 0.018" coils: May be retrieved if in suboptimal location/configuration
                                            • Axium detachable coil (ev3; Plymouth, MN)
                                            • Azur HydroCoil (Terumo; Somerset, NJ)
                                            • GDC, Interlock, Matrix coils (Boston Scientific; Natick, MA)
                                            • DeltaPaq, DeltaWind microcoils (Micrus Endovascular; San Jose, CA)
                                            • Orbit Galaxy (Codman Neurovascular)
                                          • Consider detachable coil use in critical vessels, high-flow shunts or areas where nontarget embolization could inadvertently occur (e.g., gastroduodenal artery)
                                          • Retrieval not always possible if coil fully deployed or too much time elapsed
                                          • Multiple detachment designs exist (e.g., mechanical, electrical)
                                        • Particles: Micron-sized solids; lodge at precapillary/capillary level; occlude vessels/devascularize tissue
                                          • Contour PVA (Boston Scientific)
                                            • Polyvinyl alcohol (PVA) particles; nonspherical irregular sizes
                                            • Occlude more proximal than vs. similar-sized spherical particle (bead)
                                            • Can clump, resulting in proximal vessel/catheter occlusion
                                          • PVA foam embolization particles (Cook Medical)
                                          • Contour SE microspheres (Boston Scientific)
                                            • Calibrated PVA microspheres (teardrop shape)
                                          • Bead Block (Terumo Medical)
                                            • Calibrated PVA hydrospheres
                                          • Embospheres (Biosphere Medical; Rockland, MA)
                                            • Calibrated acrylic polymer microspheres
                                            • Slightly compressible during delivery
                                            • EmboGold variant tinted red
                                          • Embozene microspheres (CeloNova BioSciences; Peachtree City, GA)
                                            • Hydrogel microsphere with Polyzene-F coating
                                          • Consider use within end-arteries when distal arteriole/organ embolization desired
                                          • May lead to significant embolization and subsequent ischemia of distal tissue/organ
                                          • Do not use in cases of vascular shunting or collateral vasculature
                                          • Concerns include nontarget embolization
                                        • Plug occluding device: Woven nitinol expandable mesh cylindrical plug
                                          • Amplatzer Vascular Plug (St. Jude Medical; Saint Paul, MN)
                                            • Mechanically occludes target vessel in similar manner to coil embolization
                                            • Allows precise positioning, short landing zone, rapid occlusion
                                            • Recommended to oversize 30% beyond target vessel diameter
                                            • AVP 4 design delivered via 0.038" catheter
                                            • Less trackable through tortuous vessels vs. coils
                                        • Liquids: A variety of nonsolid embolic
                                          • Consider use for specific clinical situations: Complex embolic target requiring embolic penetration beyond catheter into nidus [arteriovenous malformation (AVM)], desire to solidify target vessel (intracranial aneurysm), oncologic use (hepatocellular carcinoma), nonvascular target (biliary leak)
                                          • Sufficient training and well-developed understanding of each specific liquid embolic's properties and risks is necessary prior to use
                                          • Delivery of liquid embolics often require advanced training and experience and can be challenging to properly deploy
                                          • Ethanol: 96-98%, immediately denatures cellular proteins/causes small vessel thrombosis
                                            • Can be used to ablate whole organ (e.g., kidney)
                                            • Also useful as sclerosant
                                            • Extremely painful during delivery; consider general anesthesia
                                            • Caution: Ensure ethanol not injected where shunting is present
                                            • Not visible during delivery (unless mixed 4:1 with Lipiodol); calculate desired volume of ethanol using dilute contrast
                                          • Lipiodol (Guerbet; Paris, France): Ethiodized oil; iodine-containing poppy seed oil
                                            • Used in conventional transarterial chemoembolization where it acts as fluoroscopically visible chemotherapeutic delivery agent and transient arterial embolic
                                            • Can occlude lymphatic leaks (50-75%) during lymphangiogram
                                            • Added to other embolics during delivery (e.g., ethanol, "glue")
                                            • Dissolves soft plastics (e.g., catheter hub, syringe, 3-way stopcock)
                                          • N-butyl cyanoacrylate (n-BCA) Trufill (Cordis; Bridgewater, NJ)
                                            • Solidifies on contact with ionic medium (e.g., blood)
                                            • Liquid "glue" polymer is mixed with Lipiodol immediately prior to delivery
                                            • Ratio with more Lipiodol (5:1) slows rate of glue polymerization/solidification; ratio with less Lipiodol (2:1) increases rate of polymerization/solidification
                                            • Nonionic preparation of table, gloves, catheters, syringes vital
                                            • All equipment must be meticulously flushed with nonionic solutions (e.g., D5W)
                                            • "Glue" is flushed through catheter with nonionic solution
                                            • Typically, small volumes of n-BCA/Lipiodol necessary
                                            • Caution: Catheter can become "glued" to vessel during delivery
                                            • Has nonvascular applications, since occlusion does not require platelets/coagulants
                                          • Onyx (ev3 Neurovascular; Irvine, CA)
                                            • Ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (DMSO)
                                            • Radiopaque-suspended micronized tantalum powder added for increased visibility; tantalum may become visible through skin if treating superficial vascular malformations
                                            • Precipitates from outside-in on contact with aqueous solution as DMSO dissipates
                                            • Forms "foam" embolic with lava-like flow characteristics
                                            • Nonadhesive; catheter very unlikely to stick to vessel during delivery; allows slower, more deliberate injection vs. n-BCA "glue"
                                          • Thrombin solution
                                            • Off-label use, percutaneously thrombose access-related pseudoaneurysms
                                            • Reconstituted in 1,000 U/mL concentration
                                            • Rapidly converts fibrin to fibrinogen, activates coagulation cascade; causes thrombotic occlusion of target
                                            • Be aware that label warns not for intravascular injection
                                            • Extremely small volumes (0.2-0.5 cc) typically necessary
                                            • Severe potential effects of nontarget embolization; Doppler distal pulse during delivery
                                            • Caution: Do not use if patient had prior allergic reaction to thrombin
                                        • Sclerosing agents
                                          • Detergents: Causing vessel occlusion via inflammation/thrombosis
                                            • Consider use in varicose veins, venous malformations, pelvic congestion syndrome, balloon-occluded retrograde transvenous obliteration
                                            • Can use as liquid, or mix with air (or CO2) to form foam
                                            • Advantage of foam: Increased contact with wall, with less-administered sclerosing agent
                                            • Sodium tetradecyl sulfate-STS (Sotradecol): Mild sclerosant; typically 3% STS (available in 2-mL vials) is mixed with air/CO2 (3 mL air: 2 mL STS: Add 1 mL Lipiodol for visualization as needed)
                                            • Polidocanol: Widely used in Europe
                                            • Ethanolamine oleate iopamidol (Ethamolin): Widely used in Japan
                                            • Sodium morrhuate (Scleromate): Fallen out of favor
                                          • Ethanol: Immediate protein denaturation and cell death
                                          • Boiling contrast: Not often used due to patient pain, operator risk
                                          • Lymphocele sclerotherapy
                                            • Doxycycline: Intracavitary injection effective for treatment of lymphatic malformations, inexpensive, widely available
                                            • Intracavitary injection of tetracycline, bleomycin, talc, fibrin glue have also been described
                                        • Oncologic agents
                                          • Consider use in specific oncologic situations
                                          • Drug-eluting beads
                                            • LC Beads (DC Beads in Europe) (AngioDynamics, Latham, NY): Blue tint, sizes include 100-300 µm, 300-500 µm, and 500-700 µm
                                            • QuadraSphere (Merit Medical, South Jordan, UT) spheres enlarge over time: 30-60 µm, 50-100 µm, 100-150 µm, and 150-200 µm
                                            • Chemotherapeutics are bound to spheres ionically (irinotecan) or osmotically (doxorubicin) and delivered to tumor where chemotherapeutics release from beads, resulting in significantly higher concentrations at tumor bed than can be achieved via IV delivery
                                          • Radioactive particles: Beta-emitting particle, yttrium-90; embedded on microspheres
                                            • SIR-Spheres (Sirtex Medical; North Sydney, AU); resin microspheres, greater number of particles per dose
                                            • TheraSpheres (Nordion; Ottawa, Canada); glass microspheres with greater activity per particle
                                            • Utilized for selective internal radiation therapy
                                        • Stents: Used in association with embolization coils
                                          • Stent-assisted coil embolization: Noncovered stent placed across wide neck aneurysm
                                            • Coils introduced through stent interstices into aneurysm/pseudoaneurysm using microcatheter

                                    PREPROCEDURE

                                    • Indications

                                      • Contraindications

                                        • Getting Started

                                          PROCEDURE

                                          • Patient Position/Location

                                            • Procedure Steps

                                              • Alternative Procedures/Therapies

                                                POST PROCEDURE

                                                • Things to Do

                                                  • Things to Avoid

                                                    OUTCOMES

                                                    • Problems

                                                      • Complications

                                                        • Expected Outcome

                                                          Selected References

                                                          1. Horbach SE et al: Sclerotherapy for low-flow vascular malformations of the head and neck: A systematic review of sclerosing agents. J Plast Reconstr Aesthet Surg. 69(3):295-304, 2016
                                                          2. Spiotta AM et al: Comparison of techniques for stent assisted coil embolization of aneurysms. J Neurointerv Surg. 4(5):339-44, 2012
                                                          3. Etezadi V et al: Endovascular treatment of visceral and renal artery aneurysms. J Vasc Interv Radiol. 22(9):1246-53, 2011
                                                          4. Zhu X et al: Utility of the Amplatzer Vascular Plug in splenic artery embolization: a comparison study with conventional coil technique. Cardiovasc Intervent Radiol. 34(3):522-31, 2011
                                                          5. Duffy DM: Sclerosants: a comparative review. Dermatol Surg. 36 Suppl 2:1010-25, 2010
                                                          6. Lee BB et al: Management of arteriovenous malformations: a multidisciplinary approach. J Vasc Surg. 39(3):590-600, 2004
                                                          7. de Giovanni JV: The use of Amplatzer devices to occlude vascular fistulae. J Interv Cardiol. 14(1):45-8, 2001
                                                          8. Jackson JE et al: Treatment of high-flow vascular malformations by venous embolization aided by flow occlusion techniques. Cardiovasc Intervent Radiol. 19(5):323-8, 1996
                                                          9. Jander HP et al: Transcatheter gelfoam embolization in abdominal, retroperitoneal, and pelvic hemorrhage. Radiology. 136(2):337-44, 1980