Non-Vascular :
Palliative Stenting for Malignant Obstructions
Animals are routinely euthanized due to the local effects of a tumor rather than the systemic effects associated with a large cancer burden. For example, malignant obstructions of the urinary tract associated with transitional cell carcinomas or prostatic tumors can result in life-threatening signs associated with complete urinary tract obstruction. Malignant obstructions in the gastrointestinal tract typically occur due to carcinomas or leiomyosarcomas and patients can present with chronic vomiting, weight loss, and/or tenesmus, dyschezia, and constipation depending upon the location of the obstruction. IR techniques involving the placement of intra-luminal stents to palliate similar malignant obstructions in humans have been described. Palliative stenting procedures in the upper (Figure 14) and lower (Figure 15) urinary tract, respiratory tract, cardiovascular system, and upper and lower gastrointestinal tracts to relieve luminal obstructions due to neoplasia in animals as small as a ferret have been performed under fluoroscopic guidance.18,38,39 These IR techniques are rapid, safe, minimally-invasive, and effective in most circumstances, and complications have been minor and uncommon.
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Figure 14. Percutaneous antegrade placement of ureteral stent to relieve malignant ureteral obstruction secondary to transitional cell carcinoma in a dog. (A) Percutaneous pyelocentesis with an 18 gauge catheter and contrast ureteropyelogram demonstrating hydronephrosis (*) and hydroureter (white arrows). A marker catheter (black arrows) has been placed in the colon for stent sizing. (B) Fluoroscopic-guided antegrade passage of an angled hydrophilic guidewire and catheter (white arrows) across the obstruction and out the penis. (C) Retrograde ureteral dilation with a 6Fr ureteral dilator placed over-the-wire (white arrows). (D) Indwelling multifenestrated 4.7Fr x 12 cm ureteral stent (white arrows) passed retrograde over the guidewire spanning the urinary bladder (UB) to the renal pelvis (white asterisk) for urinary decompression. |
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Figure 15. Urethral stent placement for malignant urethral obstruction. (A) Retrograde contrast urethrocystogram of male dog demonstrating narrowed urethral lumen at the level of the prostatic urethra (black arrows). Notice the marker catheter in the rectum (3) used to determine radiographic magnification and extrapolate normal urethral diameter (4) and obstruction length. (B) Urethroscopy of malignant urethral obstruction and loss of lumen patency. (C) Retrograde contrast urethrocystogram following self-expanding metallic stent in prostatic urethra demonstrating restored urethral patency (black arrows). (D) Urethroscopy following stent placement with restored urethral lumen. |