Prescrotal urethrotomy for urethroscopic ablation of a hemorrhagic urethral mucosal mass

Abstract

A 7-year-old neutered male Staffordshire bull terrier dog was presented for investigation of chronic profuse urethral hemorrhage. A vascular mucosal mass lesion was identified in the proximal penile urethra on ultrasound examination; prescrotal urethrotomy was performed to allow rigid urethroscopy and mass removal. Histopathological changes were consistent with proliferative urethritis.

Key clinical message:

Prescrotal urethrotomy to facilitate rigid urethroscopy has not been previously described and is a useful technique to allow visualization of the male canine proximal penile urethra distal to the pelvic flexure. Proliferative urethritis is an important differential diagnosis for dogs presenting with profuse urethral hemorrhage.

Case description

A 7-year-old neutered male Staffordshire bull terrier dog was investigated for severe episodic urethral hemorrhage. The dog was presented on 3 occasions over 3 y for investigation of these clinical signs. The first episode of urethral hemorrhage resolved spontaneously without intervention or further investigation. When the dog was examined for a second episode 18 mo after the initial presentation, a positive contrast retrograde urethrogram was performed. This identified a filling defect in the proximal penile urethra immediately distal to the pelvic flexure. Further investigation of the cause of the hemorrhage via flexible urethroscopy was attempted but was unsuccessful due to the inability to pass the smallest available suitable endoscope (a 2.6-mm flexible endoscope; Intramed Laboratories, San Diego, California, USA) past the os penis. When the hemorrhage again resolved spontaneously, the owner declined further invasive investigations. The dog was presented for a third time 1 y later, following a 5-day history of continuous bleeding from the penis, with subsequent development of lethargy and inappetence.

At presentation, there was continuous dripping of frank blood from the penis with intermittent passage of large volumes of clotted blood. Physical examination revealed pale mucous membranes, a heart rate of 120 beats/min associated with synchronous but reduced peripheral pulse quality. The results of abdominal palpation and cardiopulmonary auscultation were within normal limits. Rectal examination was unremarkable. Examination of the penis and prepuce revealed continuing hemorrhage from the urethral orifice with no other abnormalities detected. The clinical examination was otherwise within normal limits. Hematology revealed a regenerative anemia; hematocrit 0.24 L/L [reference range (RR): 0.37 to 0.55 L/L], reticulocyte count 240.3 × 10⁹/L (RR: 11 to 110 × 10⁹/L). Platelets were clumped on the blood film but a manual count confirmed adequate platelet numbers. Coagulation times (partial thromboplastin time and activated partial thromboplastin time) were normal. A buccal mucosal bleeding time was performed and was within normal limits. Biochemistry analysis was unremarkable. Urinalysis performed on a sample obtained by catheterization demonstrated macroscopic hematuria but was otherwise unremarkable. Urine culture was negative.

Intravenous fluid therapy (IVFT) using compound sodium lactate (Hartmann’s Lactated Ringers; B. Braun Melsungen AG, Melsungen, Germany), 4 mL/kg body weight (BW) per hour, with a 10 mL/kg BW bolus at the onset of therapy, and antifibrinolytic therapy using tranexamic acid (Cyklokapron; Mylan, Hatfield, UK), 10 mg/kg BW, IV, q8h, was started before conducting further investigations. Over the first 12 h of hospitalization the dog exhibited cardiovascular decompensation in response to the continued severe blood loss; repeat hematology showed a hematocrit of 0.12 L/L. One unit of type compatible DEA 1.1 negative packed red blood cells was administered, resulting in stabilization of cardiovascular parameters. A repeat hematocrit was 0.20 L/L following administration of the blood product.

A focused ultrasound examination of the urinary tract was performed (Figure 1). The kidneys, urinary bladder, and prostate were all considered to be within normal limits. Initial ultrasound examination of the urethra was unremarkable. Ultrasound examination of the urethra utilizing concurrent retrograde saline flushing (Aqupharm 1, 9 mg/mL sodium chloride solution; Animalcare, Nether Poppleton, York, UK) using an 8 French rigid dog catheter and a syringe to cause maximal urethral distention, revealed an intraluminal mass within the proximal penile urethra immediately distal to the pelvic flexure. The mass appeared to be continuous with the urethral mucosa and caused partial obstruction of the urethral lumen. Doppler examination demonstrated vascular flow within the mass, particularly on the luminal aspect. A review of imaging studies performed 1 y previously confirmed that the small filling defect of the proximal penile urethra noted on retrograde positive contrast radiography (Figure 2) was consistent with the location of the mass identified ultrasonographically. Due to the severe ongoing penile hemorrhage further investigations were conducted.

Figure 1.

Doppler ultrasound image of urethral mass, demonstrating vascular flow.

Figure 2.

Lateral, retrograde, positive-contrast urethrogram. Filling defect visible within the proximal penile urethra (white arrow).

An IV catheter was placed in the cephalic vein and the dog was premedicated with dexmedetomidine (Dexdomitor; Zoetis UK, Leatherhead, UK), 1 μg/kg BW, and methadone (Comfortan; Dechra Veterinary Products, Shrewsbury, UK), 0.2 mg/kg BW, given intravenously. Anesthesia was induced using Propofol (PropoFlo Plus; Zoetis UK) given intravenously to effect and maintained using sevoflurane (SevoFlo; Zoetis UK). A lumbosacral epidural injection of levobupivicaine (Chirocaine; Abbvie, Maidenhead, UK), 1 mg/kg BW, and preservative-free morphine (morphine sulfate; Martindale Pharmaceuticals, Romford, UK), 0.2 mg/kg BW, was administered following induction of anesthesia and cefuroxime (Zinacef; GlaxoSmithKline UK, Brentford, UK), 20 mg/kg BW, IV, was given 20 min before the start of surgery. Pulse oximetry, electrocardiogram (ECG), arterial blood pressure, end-tidal CO₂ and inhaled anesthetic agent concentrations were monitored throughout the procedure. While the dog was under anesthesia, IVFT (Hartmann’s Lactated Ringers; B. Braun Melsungen AG) was administered at a rate of 5 mL/kg BW per hour.

The dog was placed in dorsal recumbency and an anal purse string suture was placed. A rigid 8 French urinary catheter was advanced from the penis into the bladder; an approximately 2-cm incision was made through the prescrotal skin and urethral mucosa onto the catheter. Stay sutures were placed in the urethral wall to expose the opening and the catheter was removed. A guide wire was advanced into the urethra via the urethrotomy incision and a 5-mm, rigid endoscope cannula for a 2.7-mm cystoscope was passed over this into the urethra. The guide wire was removed and a 2.7-mm 30° cystoscope (Karl Storz, Tuttlingen, Germany) was then advanced into the cannula.

Using positive pressure saline (Aqupharm 1, 9 mg/mL sodium chloride solution; Animalcare) lavage for insufflation from a pressure bag attached to the ingress channel of the cystoscope cannula, the endoscope was advanced into the urethra. An approximately 3 × 6 mm pedunculated mucosal mass was visualized on the caudal aspect of the proximal penile urethra, immediately distal to the pelvic flexure (Figure 3). The mass was red, firm and obstructing approximately 2/3 of the area of the urethral lumen. There was also an area of mucosal proliferation/irritation on the urethral wall immediately opposite the mass.

Figure 3.

Urethroscopic image of the proximal penile urethra, demonstrating the mass and an area of mucosal proliferation/irritation.

A retractable monopolar electrosurgical loop was advanced within its sheath down the instrument channel of the cystoscope. The loop was advanced from the sheath to encircle the mass before the sheath was then advanced to the base of the mass in order to close the loop. Prior to removal, attempts were made to snare the mass using a transcutaneous suture to prevent dislodgment with the irrigation fluid flow. This was technically difficult due to the small size of the mass and its fluctuation in the fluid flow; efforts were ultimately unsuccessful and were abandoned after a few attempts. The electrosurgical loop was activated and tightened simultaneously, underlying the base of the mass and cauterizing the mucosa (Figure 4). Grasping forceps were then advanced to grasp and remove the mass, which was now oscillating in the flow of lavage solution. The electrosurgical loop was used to similarly remove and cauterize the area of mucosal proliferation opposite the site of the mass. The urethrotomy incision was left open to heal by second intention. An 8 French indwelling Foley catheter was placed along the length of the urethra via the urethral orifice at the end of surgery and maintained with drainage every 4 h for 12 h before removal. Robenacoxib (Onsior; Elanco UK AH, Basingstoke, UK), 2 mg/kg BW, SC, q24h was given on recovery from surgery then continued orally at the same dose for 7 d following surgery. The ongoing antifibrinolytic therapy with tranexamic acid (Cyklokapron) was discontinued 24 h after surgery. Hematology analysis 24 h after surgery demonstrated stable mild anemia and reticulocytosis as previously noted (HCT: 0.20 L/L, reticulocytes: 224.5 × 10⁹/L) and platelet counts remained normal (206 × 10³/μL, RR: 200 to 500 × 10³/μL). Following removal of the urinary catheter there was mild intermittent hemorrhage from the urethrotomy site associated with urination. The dog was discharged 2 d after surgery; the intermittent hemorrhage was reported by the owner to resolve 1 d following discharge.

Figure 4.

Urethroscopic image of the proximal penile urethra following electrosurgical removal of the mass and area of mucosal proliferation/irritation.

Histopathology of the polypoid mass revealed it to be predominantly composed of acute hemorrhage and fibrin with associated reactive fibrovascular proliferation, consistent with hematoma formation. Embedded within the hemorrhage were aggregates of Gram-positive and Gram-negative coccoid bacteria without associated inflammation, possibly associated with secondary infection, or contamination. Although most of the mass was attributable to hematoma, there were changes in the included mucosal sections that were consistent with lymphoplasmacytic urethritis. Unfortunately, not enough tissue had been harvested from the mucosal lesion for histopathology submission.

At 3-week re-examination the dog was doing clinically well, with no further episodes of penile hemorrhage or dysuria; the urethrotomy incision had completely healed and there were no ongoing concerns. The owner was contacted by telephone 6 mo after surgery and there had been no recurrence of clinical signs. The owner was very satisfied with the clinical outcome.

Discussion

To the authors’ knowledge this is the first report of a prescrotal urethrotomy performed to facilitate rigid endoscopy of the proximal penile urethra in a male dog. Urethrotomy and urethroscopy were considered in this case to be preferable to an open approach, allowing enhanced magnification and visualization of the mass without the greater trauma of an open approach. Access to the urethra in a male dog is frequently restricted by the size of the os penis, preventing passage of a rigid endoscope. A flexible endoscope is frequently used in male dogs to visualize the length of the urethra; however, this significantly limits both image quality and size of the working channel compared to that when using a rigid cystoscope (1). A perineal urethrotomy has been described to facilitate rigid endoscopy of the bladder in male dogs (2); however, in this case such an approach was considered inappropriate due to the location of the lesion. Furthermore, at this site the urethra is deeper, and the approach is through more highly vascularized tissue compared to the prescrotal approach, increasing the technical difficulty for the surgeon. A prescrotal approach is considered to be optimal for a urethrotomy in the dog due to the superficial position of the urethra and paucity of surrounding cavernous tissue at this site, with the advantage that primary closure is not usually necessary. Potential complications described for this procedure include self-limiting hemorrhage from the urethrotomy site (seen in this case) and urethral stricture (uncommon and often considered to be associated with underlying disease at the site) (3).

A previous report (4) described management of a similar lesion in the same breed of dog. In that report, management was significantly more invasive; the dog received a transpelvic urethrostomy via ischial symphyseal ostectomy and phallectomy. While the outcome in that case was good, with the dog free of clinical signs 7 mo after surgery, the associated morbidity of the procedure performed was significant. In that case an invasive surgical option was undertaken due to clinical suspicion of neoplasia, based on ultrasound-guided aspirates for cytology suggesting squamous cell carcinoma associated with mild neutrophilic urethritis. However, the final diagnosis in that case was not suggestive of neoplasia, rather of “a ruptured vascular structure with thrombosis, hemorrhage, and repair tissue.” In our case, a more aggressive resection was not considered, as there was very low clinical suspicion of a neoplastic process due to the chronicity of the clinical signs. The technique herein describes a minimally invasive approach to biopsy and removal of masses within the penile urethra proximal to the os penis and distal to the pelvic flexure, with minimal morbidity and no long-term functional changes to the urinary system. While the possibility of recurrence of aggressive masses remains without surgical margins, this technique allowed histological examination of the lesion before more invasive options were considered, leaving these options available if excision with margins was subsequently deemed necessary.

The histopathological findings in this case did not support a neoplastic process, with histopathology findings instead demonstrating hematoma and concurrent chronic inflammatory changes. The frond-like appearance of the mucosa was consistent with proliferative urethritis, which has been described as an uncommon cause of urethral obstruction and hematuria in dogs (5–8), although to the authors’ knowledge there are no descriptions of proliferative urethritis causing hemorrhage to the extent observed in this case. Histopathology of mucosal sections associated with the hematoma showed lymphoplasmacytic inflammation, which is consistent with the most common histological finding of Borys et al (5) in proliferative urethritis in their case series (although the presentations can be variable, including purely neutrophilic inflammation). These changes are similar to the description by Liehmann et al (4) of a lesion at the same site (proximal penile urethra) causing significant hemorrhage, with a histopathological description of “a ruptured vascular structure with thrombosis, hemorrhage and repair tissue,” with a cytological finding of neutrophilic inflammation. Although that report did not draw conclusions on the nature of the mass beyond description of the histopathological findings, it would appear likely, from the histopathological and clinical description, that proliferative urethritis may have been the underlying etiology. This finding would suggest that proliferative urethritis presenting as profuse hemorrhage is not an exceptional finding and as such should be considered a differential diagnosis for significant urethral hemorrhage.

This case demonstrates the previously unreported occurrence of significant hemorrhage associated with proliferative urethritis, which clinicians should consider as a possible cause of significant urethral hemorrhage. The described technique of rigid urethroscopy via a prescrotal urethrotomy has also not been previously reported. This provides veterinarians with a useful option for video-endoscopic evaluation of the canine proximal penile urethra, for visual inspection, biopsy, and potential definite treatment, as was performed successfully in this case. CVJ