Figure 20.5 Placement of a Foley catheter in the flank tube cystotomy procedure.

      For a paramedian tube cystostomy, general anesthesia is preferred, but a lumbosacral epidural and/or local anesthesia can also be utilized. The individual should be placed in dorsal recumbency and surgically prepped from sternum to pubis. If a uroabdomen exists, fluid stabilization and abdominal drainage should be performed prior to placement in dorsal recumbency. A 10‐ to 15‐cm paramedian skin incision is performed approximately 2 cm lateral to the sheath approximately midway between the preputial orifice and pubis. A left‐sided paramedian approach is preferred, so the rumen can assist with keeping abdominal viscera in the abdomen. If bladder rupture is suspected, the incision should be more caudal to assist with access to the smaller bladder often residing in the pelvis. Sharp and blunt dissection is used to access the linea alba and a routine celiotomy is performed. A paramedian celiotomy can be performed instead if preferred by the surgeon.

Once the urinary bladder is localized, stay sutures with 2–0 or 0 monofilament can be placed in the bladder to assist with the cystotomy (Figure 20.6). A routine cystotomy is performed with aspiration of urine. Removal of uroliths from the bladder trigone and proximal urethra can be assisted with the use of a surgical spoon (Figure 20.6), as well as copious lavage and aspiration of sterile saline. An 8‐ to 10‐French polypropylene catheter is then passed in a normograde fashion with hydropulsion to attempt resolution of the urethral obstruction. If the obstruction is not relieved or there is significant resistance, hydropulsion attempts should cease and the catheter should be removed. A stab incision is made 2 cm lateral to the paramedian skin through the skin and abdominal wall. A curved hemostat can be used intra‐abdominally and directed toward the skin and incised over while placing pressure on the hemostat. The hemostat is used to grab the balloon end of a 20‐ to 30‐French Foley catheter to assist with placement through the skin and abdominal wall. The balloon integrity of the Foley catheter should always be ensured prior to placement. Once the Foley catheter is in the abdomen, a separate stab incision is performed lateral to the primary cystotomy incision. A hemostat is placed through the stab incision of the bladder and the balloon end of the Foley is placed into the lumen of the bladder. The balloon is filled with the appropriate volume of saline.

Figure 20.6 Utilization of stay sutures to assist with bladder manipulation and cystotomy. Utilization of a surgical spoon to assist with urolith removal.

      Once filled, the balloon is directed toward the trigone of the bladder while the cystotomy incision is made and is sutured. A single‐ or double‐layer continuous inverting pattern using absorbable monofilament 0 or 2–0 suture is used for the cystotomy and, if needed, cystorrhaphy. The balloon of the Foley catheter is pulled flush against the bladder and abdominal wall. Some surgeons choose to place a purse string suture around the Foley catheter [27]. The celiotomy, subcutaneous tissues, and skin are closed in a routine fashion. During closure, copious lavage with saline into the Foley catheter is important to prevent occlusion from any blood clots. A Chinese finger cuff ligature is used to secure the Foley to the ventral abdomen. After placement of the Chinese finger cuff ligature, saline should be flushed through the Foley catheter to ensure patency and confirm the ligature is not too tight.

      A left flank tube cystotomy provides an economic alternative to tube cystotomy placement and avoids the risks associated with general anesthesia and dorsal recumbency. However, optimal access to the bladder is obtained through a ventral celiotomy. The left paralumbar fossa is aseptically prepped and flank anesthesia is performed. A 10‐ to 15‐cm vertical skin incision is made with a routine celiotomy. Care should be taken to make the paralumbar fossa incision somewhat caudal to allow adequate access to the bladder. A needle and extension set can be used to drain excess urine from the bladder in particularly painful individuals attempting recumbency during surgery. The Foley catheter is placed through a stab incision through the skin and abdominal wall as described above on the caudoventral aspect of the incision. The balloon end of the Foley catheter is then placed through the apex of the bladder wall using a hemostat and bluntly forcing through the bladder wall. The balloon is inflated. If access is possible, a cystotomy should be performed on the dorsal aspect of the bladder to remove as many cystoliths as possible. Often a cystotomy is difficult with a standing procedure, so tube cystotomy alone can be performed, but recovery time will often be prolonged without removal of cystoliths. Closure of cystotomy or cystorrhaphy should be performed with 0 or 2–0 monofilament absorbable suture in an inverting pattern. The balloon of the Foley catheter is then pulled flush against the bladder and abdominal wall. A Chinese finger cuff ligature is used to secure the Foley catheter to the ventral flank. The abdomen and skin are closed in a routine fashion.

      A one‐way valve should be affixed to the Foley catheter to prevent air aspiration and minimize bacterial contamination. The fingertip of an examination glove with the tip slit affixed to the Foley catheter is a cheap, convenient one‐way valve. After placement, a tube cystotomy must remain in place for a minimum of 7–10 days before removal to prevent any urine leakage from the defect created by the catheter. Urinary acidification should be implemented postoperatively for uroliths amenable to dissolution. Cystic acidification can also be administered with an acidifying solution seven days postoperatively with commercially available buffered acetic acid solution (Walpole's) or hemiacidrin (Renacidin^®) [28]. A less expensive alternative for cystic irrigation is diluted acetic acid or 5% ammonium chloride solution [29]. Once urine dribbling from the preputial orifice or urination is observed, the Foley catheter can be occluded to more safely assess urethral patency prior to removal. One study reported dribbling of urine six to seven days postoperatively and free urine flow from the urethra nine days postoperatively [26]. The Foley catheter should be occluded for 48–72 hours with observed normal voiding before the Foley balloon is deflated and catheter removed. An average of 10–12 days postoperatively is required for small ruminants before successful voiding and Foley catheter removal [12, 23]. However, normal voiding can take as long as four to six weeks, especially if removal of cystoliths is not performed.

      Complications of tube cystostomy include occlusion of the tube with blood clots, debris, uroliths, tube kinking, dislodgement or loss of catheter [26], balloon deflation, cystitis, uroperitoneum after catheter removal, adhesions to the urinary bladder, bladder atony, and failure to resolve urethral obstruction. Minimally invasive tube cystotomy [30] and laparoscopic‐assisted placement [31] of cystic catheters have been described in small ruminants. Prognosis for survival in cattle treated with tube cystotomy is reported to be as high as 90% [18]. In cases without urethral rupture, utilization of a tube cystotomy provides a good