Using CO₂ laser cystotomy to remove urinary bladder polyps in a dog

By Jakub Kaczmarek, DVM For The Education Center
Originally Published In Veterinary Practice News, September 2019 – Download as a PDF

Polypoid cystitis is a rare disease of the urinary bladder in dogs, characterized by inflammation of the bladder mucosa and development of a polypoid mass. Clinical awareness of polypoid cystitis is important. Not every urinary bladder mass has to be neoplastic. Further, it is also important to note the approach and prognosis are different for dogs with polypoid cystitis when compared to those with transitional cell carcinoma. Unfortunately, polypoid cystitis cannot reliably be diagnosed macroscopically, and a histopathology is required for accurate diagnosis.

Hematuria is the most common clinical sign and is likely a consequence of hemorrhage from the polyp mucosa from chronic irritation. Recurrent urinary tract infection (UTI) (Proteus spp, Escherichia coli, and Staphylococcus spp were the most common bacteria isolated in one study^[1]) and cystic calculi also are common in affected dogs.^[1]

The patient

Max, an 11-year-old, 4-kg, castrated male Yorkshire terrier, presented with chronic hematuria. Urinalysis revealed hematuria, no presence of crystals, and the urine culture was negative. Bloodwork was within normal reference ranges. An abdominal ultrasound revealed the presence of two intraluminal bladder masses: 0.7 cm x 0.36 cm and 0.69 cm x 0.38 cm (Figure 1A). In the bladder neck region, at least three uroliths were diagnosed (0.77 cm x 0.48 cm) (Figure 1B). Cystotomy with mass excision was recommended.

Anesthesia

The patient was premedicated with midazolam (0.2 mg/kg IV), as well as levomethadone hydrochloride with fenpipramidi hydrochloridum (0.5 mg/kg and 0.025mg/kg IV). The patient was then induced with propofol (3 mg/kg IV) and anesthesia was maintained with isoflurane.

The procedure

The patient was placed in dorsal recumbency, while the caudal part of the abdomen was clipped and prepared for sterile surgery. Access to the caudal part of the abdominal cavity (via parapreputial skin incision) was performed using a CO₂ laser (Aesculight®, Bothell, Wash., USA) at 15 watts in the continuous SuperPulse mode and with a 0.25-mm focal spot size (Figure 2A). Minor hemorrhage was controlled during approach also with the CO₂ laser using a defocusing technique. Caudal midline abdominal incision was performed using the same setting as previously described. To ensure intra-abdominal organs do not get damaged during the celiotomy, a Williger raspatory was held against the linea alba while performing the incision (Figure 2B).

The bladder was exteriorized and one stay suture was placed at the apex (4-0 PDS II). The ventral cystotomy was performed, with the CO₂ laser set at 15 watts in the continuous SuperPulse mode and with a 0.8-mm focal spot size. No bleeding occurred. Once again, a Williger raspatory was held against the bladder wall, first to secure the dorsal part of the bladder wall and second to increase the tension of the bladder wall (Figure 2C). Uroliths were removed with the help of a soft-edged surgical spoon (Figure 2D). Next, the bladder was flushed (normograde and retrograde) with 500 ml of sterile saline. The polyps were excised at their base using the CO₂ laser (15 watts in the continuous SuperPulse mode and with a 0.4-mm focal spot size) (Figure 2E). Here, too, no bleeding occurred. After removing the polyps, the bladder apex was ablated with the CO₂ laser, this time using the 3-mm wide ablation tip (laser settings were as follows: 12 watts, repeat mode, 10 Hz pulse frequency, 10 msec pulse duration, 40 percent duty cycle, SuperPulse) (Figure 2F). This step was performed twice (Figure 2G). The bladder was closed without complication using PDS 4-0 in two layers: the first layer (muscularis) was closed via continuous pattern, followed by Cushing suture pattern. The celiotomy was closed with PDS 3-0 using continuous suture pattern. Subcutis and cutis were closed using single interrupted pattern (Figure 2H). Uroliths, polyps, urine, and a small part of a bladder wall were sent to the lab for further investigation.

The patient was discharged the next day with no signs of hematuria or stranguria. He was given meloxicam (0.2 mg/kg per oz. SID) and amoxicillin with clavulanic acid (16 mg/kg per oz. BID) until the bacterial culture results came back. Laboratory findings showed a presence of calcium oxalates, the urine culture was negative, and polyps had no sign of malignancy; however, there were signs of chronic hemorrhagic inflammation. Max recovered very well and the owner did not report any hematuria. The skin incision healed without complications (Figure 2I). Ultrasound control (after five and 15 days) showed no leakage, no signs of local peritonitis, and a reduction of the bladder wall thickness (which may suggest reduction of inflammation in its apex region) (Figure 3 shows an ultrasound image 15 days after the surgery).

The urinary bladder is a rapidly healing organ—mucosal defects heal in as little as five days and full-thickness defects obtain 100 percent of their strength in comparison to normal urinary bladder tissue in 14 to 21 days.^[2] Due to high vascularity, good visualization during a surgical procedure can be difficult. The CO₂ laser provides very good and safe hemostasis during this type of procedure. Combined with other benefits (such as reduced inflammation and postoperative pain among others), the laser is a great tool, allowing both surgeon and patient to benefit.

After graduating with a degree in veterinary studies in Wroclaw, Poland, in 2013, Jakub Lukasz Kaczmarek, DVM, began a two-year surgical internship at the referral clinic in Birkenfeld, Germany. He is currently a resident of the European College of Veterinary Surgeons (ECVS) at a reference clinic in Augsburg, Germany.

References

1. Martinez I, Mattoon JS, Eaton KA, Chew DJ, DiBartola SP. Polypoid cystitis in 17 dogs (1978-2001). J Vet Intern Med. 2003 Jul-Aug;17(4):499-509.
2. Hastings JC, Van Winkle W, Barker E, et al. The effect of suture materials on healing wounds of the bladder. Surg Gynecol Obstet. 1975; 140(6):933–7.