Surgical Approaches to the Urogenital System

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Key Takeaways

• Urine's cytotoxic nature and impairment of wound healing necessitate meticulous surgical technique to minimize urinary contamination of tissues and the peritoneal cavity, employing copious lavage and closed suction drainage when significant contamination occurs.
• The choice of surgical approach is dictated by the specific urogenital organ involved, its location, and the nature of the lesion, with ventral midline celiotomy serving as a versatile default for abdominal organs like the bladder and reproductive tract, while paracostal incisions are preferred for renal access.
• Urethral surgery, particularly in male dogs, presents significant challenges due to anatomical fixation within the pelvic canal, often requiring specialized perineal or caudal celiotomy approaches, and necessitates careful tension-free closure with fine absorbable monofilament suture and indwelling catheterization to maintain luminal patency.
• Complications such as urine leakage (uroabdomen) are identified by elevated peritoneal fluid creatinine levels (>2x serum), while hemorrhage is assessed via serial packed cell volume and ultrasonography, and obstruction is diagnosed by progressive azotaemia and ultrasonographic hydronephrosis.
• While minimally invasive options like laparoscopy are feasible for procedures such as cystotomy and ovariectomy, their widespread application in companion animals is limited by equipment cost, training requirements, and the small size of urogenital structures, making open surgery the current mainstay.

This article provides a structured reference for surgical exposure of the canine and feline urogenital tract, from kidney to external genitalia. It is written for practicing veterinarians who perform or plan these procedures and need a reliable framework for patient positioning, incision selection, and closure strategy. The content addresses the procedural question of how to reach each anatomic structure with adequate visualization while minimizing morbidity, and it deliberately excludes disease-specific management.

The urogenital system presents unique surgical challenges. Urine has well-documented negative effects on wound healing, and the small size of companion animal urogenital structures has historically limited endoscopic alternatives, making open surgery the mainstay of treatment Complications of upper urinary tract surgery in companion animals. Careful decision making, microsurgical technique, and interventional radiology have improved success rates, but the foundation of good outcomes remains a well-planned approach Complications of upper urinary tract surgery in companion animals. This article emphasizes the decisions that precede the first incision: patient positioning, incision location, tissue handling, and closure principles that apply across species.

At a Glance

Physiologic and Anatomic Foundations

Tissue Response to Urine and Surgical Trauma

Urine is cytotoxic to peritoneal mesothelium and impairs leukocyte function, collagen synthesis, and epithelialization. The surgeon must therefore limit urinary contamination of the abdomen, protect wound edges with moistened laparotomy sponges, and lavage thoroughly after any urinary spillage. These principles apply with equal force to the ureter, where the thin wall and tenuous blood supply make suture placement and tissue handling especially consequential Complications of upper urinary tract surgery in companion animals. The ureter receives its blood supply segmentally, and extensive dissection of the adventitia devascularizes the wall, predisposing to stricture or dehiscence.

Anatomic Constraints by Region

The kidney lies retroperitoneally, partially protected by the rib cage. The right kidney is more cranial than the left in both dogs and cats, which affects incision placement. The bladder is a mobile, intra-abdominal organ when distended but retracts into the pelvic canal when empty, so a full bladder is easier to exteriorize but more fragile. The urethra is fixed within the pelvic canal in its midportion, which limits exposure and makes this region the most challenging to approach surgically. The vagina is entirely pelvic in the dog, whereas the feline vagina is shorter and more accessible.

Species Differences That Affect Approach

Cats have a proportionally shorter abdomen and a more cranial kidney position than dogs. Feline renal surgery is therefore best performed through a paracostal incision with the patient in lateral recumbency. The feline urethra is narrow and easily traumatized, and the male cat has a penile urethra that is surgically inaccessible except at the perineum. These differences are not academic, they determine whether a planned approach is feasible in a given patient.

Patient Positioning and Preparation

Lateral Recumbency for Renal Surgery

The patient is positioned in lateral recumbency with the affected kidney uppermost. A towel roll or sandbag placed beneath the dependent flank opens the space between the last rib and the wing of the ilium. The forelimbs are pulled cranially and the hindlimbs caudally to elongate the flank. The incision is made just caudal and parallel to the last rib, extending from the epaxial muscles dorsally to the ventral abdominal wall. This approach provides direct access to the retroperitoneal space and allows the kidney to be delivered into the incision with gentle traction.

Dorsal Recumbency for Bladder and Urethral Surgery

Ventral midline celiotomy is the standard approach for the bladder and proximal urethra. The incision extends from the umbilicus to the pubis, and it can be extended cranially if needed for concurrent abdominal exploration. The bladder is located by following the median ligament, which is divided to allow exteriorization. For urethral surgery, the incision is extended caudally to the pubic brim, and the prepubic tendon may be partially divided to improve exposure of the pelvic urethra.

Positioning for Perineal Urethral Surgery

The patient is placed in sternal recumbency with the hindquarters elevated and the tail reflected dorsally and secured. This position provides access to the perineal urethra in males and the vestibule in females. The approach is used for urethrostomy, urethral diverticulectomy, and repair of perineal urethral trauma.

Incision Selection and Exposure

Paracostal Approach to the Kidney

The paracostal incision is made through skin, subcutaneous fat, and the external and internal abdominal oblique muscles. The transversus abdominis muscle is divided in the direction of its fibers, and the retroperitoneal space is entered. The kidney is located by palpation and delivered into the incision. The renal vessels are identified and isolated before any parenchymal incision is made. Closure is performed in layers, with the transversus abdominis and internal oblique closed together and the external oblique closed separately.

Ventral Midline Celiotomy for Bladder and Uterus

The ventral midline approach is the most versatile urogenital approach in companion animals. It provides access to the bladder, urethra, uterus, ovaries, and vagina. The linea alba is incised sharply, and the incision is extended cranially or caudally as needed. The bladder is exteriorized by gentle traction on its apex, and stay sutures are placed to maintain position during cystotomy. The uterus is located dorsal to the bladder and traced to the ovaries.

Flank Approach as an Alternative

The flank approach is used for ovariectomy in selected patients, particularly those with large mammary masses that preclude a ventral midline incision. It provides limited exposure and is not recommended for procedures requiring extensive abdominal exploration. The approach is made through the same muscle layers as the paracostal incision but is positioned more caudally.

Closure Principles

Renal Closure

Renal incisions are closed with absorbable monofilament suture in a mattress pattern that apposes the capsule and underlying parenchyma. The capsule is the only layer that holds suture reliably, parenchymal sutures cut through renal tissue. Hemostatic agents may be used to augment closure, but they do not replace accurate suture placement.

Cystotomy Closure

The bladder is closed in one or two layers with absorbable monofilament suture. A single layer appositional pattern is sufficient for most cystotomies, provided the mucosa is inverted and the suture is placed through the seromuscular layer without penetrating the lumen. The bladder should be distended with saline after closure to test for leakage. Closure site dehiscence is a recognized complication, particularly when the bladder wall is inflamed or when closure is performed under tension Urogenital surgery in foals.

Urethral Closure

Urethral incisions are closed with fine absorbable monofilament suture in an appositional pattern. The urethral mucosa is delicate, and suture bites should be small and placed with magnification if available. A urinary catheter is placed before closure to maintain luminal diameter and is left in place postoperatively to divert urine from the suture line.

Approach Selection by Organ

The choice of surgical approach follows a hierarchy of decisions: which organ is diseased, what portion of that organ requires exposure, whether the procedure is elective or emergent, and what equipment is available. Patient body condition, concurrent disease, and prior abdominal surgery modify the final choice.

Kidney and Proximal Ureter

The paracostal approach provides direct access to the ipsilateral kidney and proximal ureter with minimal abdominal contamination. It is preferred for nephrectomy, renal biopsy, and proximal ureterolithotomy. Bilateral renal disease requiring simultaneous access, such as bilateral ureteral obstruction, demands a ventral midline celiotomy instead.

A ventral midline approach is also indicated when the surgeon must examine both kidneys, palpate the entire urinary tract, or address concurrent abdominal disease. The exposure is less direct than the paracostal approach, and deep retraction is required to reach the kidneys dorsally. In deep-chested dogs, the kidneys lie more cranially and dorsally, making the midline approach more challenging. In cats, the kidneys are more mobile and caudal, and the midline approach is generally easier.

Laparoscopic approaches to the kidney are described in companion animals but require specialized instrumentation and insufflation equipment. The principal advantage is reduced morbidity, but the small size of the structures and the need for intracorporeal suturing limit current applications complications of upper urinary tract surgery in companion animals.

Urinary Bladder

The ventral midline celiotomy is the standard approach for cystotomy. It allows complete exteriorization of the bladder, inspection of both ureteral papillae, and palpation of the urethra as it exits the pelvis. This approach is required for cystic calculi, bladder neoplasia, and traumatic rupture.

A caudal midline incision extended to the pubis improves exposure of the bladder neck and proximal urethra. In male dogs, the prepuce is retracted laterally, and the incision is made paramedian to the prepuce to avoid entering it. In female dogs, the incision remains on the midline.

The flank approach to the bladder is reserved for cystostomy tube placement or for patients with severe ventral abdominal disease that precludes a midline incision. It provides limited access to the contralateral side and the bladder neck, and it is not appropriate for procedures requiring complete bladder exploration.

Urethra

Urethral exposure varies markedly by sex and by the location of the lesion.

In the male dog, the penile urethra is approached through a ventral midline incision over the penis, with the patient in dorsal recumbency. The perineal urethra requires a perineal approach with the patient in sternal recumbency, the hindquarters elevated, and the tail reflected dorsally. The intrapelvic urethra is accessed through a caudal celiotomy with pubic symphysiotomy or osteotomy in rare cases.

In the female dog, the urethra is short and intrapelvic. Exposure requires a caudal ventral midline celiotomy, and the urethra is identified dorsal to the pubic symphysis. Pubic symphysiotomy or osteotomy may be necessary for lesions of the mid-urethra or for urethral neoplasia.

In the cat, the perineal urethrostomy approach is performed with the patient in sternal recumbency, the tail reflected, and the perineum clipped and prepared. The approach is familiar to most practitioners and provides access to the distal urethra and bulbourethral glands.

Reproductive Tract

Ovariectomy and ovariohysterectomy are performed through a ventral midline celiotomy in both dogs and cats. The incision length varies with patient size and the surgeon's ability to exteriorize the ovarian pedicles.

Vaginal approaches are used for vaginal masses, strictures, and foreign bodies. The dorsal recumbent position with the hindlimbs flexed and abducted allows access to the vaginal vestibule and cranial vagina. Episiotomy may be required for larger masses or for exposure of the cranial vagina.

Cesarean section uses a ventral midline celiotomy with the patient in dorsal recumbency. The gravid uterus is exteriorized, and hysterotomy incisions are made along the antimesometrial border of each uterine horn.

Decision Checklist for Approach Selection

The following sequence applies to any urogenital procedure:

1. Confirm the diagnosis and identify the exact location of the lesion with imaging. Ultrasonography, radiography, or contrast studies are usually required before surgery.
2. Determine whether the lesion is unilateral or bilateral. Bilateral disease changes the approach.
3. Assess the patient's body condition. Obese patients require longer incisions and deeper retraction.
4. Review prior surgical history. Adhesions may alter the approach or require adhesiolysis before the target organ can be reached.
5. Select the approach that provides the most direct access to the lesion with the least tissue trauma.
6. Plan the closure before making the incision. Consider tension, tissue quality, and the need for drainage.
7. Prepare the patient for the possibility of a second approach. For example, a paracostal approach may need to be converted to a midline celiotomy if the ureter cannot be mobilized sufficiently.

Instrumentation and Equipment

Standard laparotomy instruments are sufficient for most urogenital procedures. Fine-tipped forceps, magnifying loupes, and microsurgical needle holders improve precision for ureteral and urethral surgery. The small size of urogenital structures in companion animals has limited the widespread application of endoscopic methods, and open surgery remains the mainstay of treatment complications of upper urinary tract surgery in companion animals.

Suture selection follows the tissue being repaired. The renal capsule holds sutures well when the kidney is healthy, but it tears easily in inflamed or edematous tissue. The bladder wall holds sutures reliably when the lumen is decompressed and the tissue is handled gently. The urethra is the most delicate of the three, and tension-free closure with fine monofilament suture is critical.

Self-retaining retractors, including Balfour and Gelpi retractors, improve exposure in deep-chested patients. A malleable retractor protects the viscera during renal and ureteral dissection. Suction and laparotomy sponges are essential for keeping the field dry, particularly when urine leakage is present.

Monitoring and Postoperative Assessment

Intraoperative monitoring includes pulse oximetry, capnography, and blood pressure measurement. Urine output is monitored with an indwelling urinary catheter when the bladder has been opened. The catheter keeps the bladder decompressed during healing and allows detection of postoperative hemorrhage.

Postoperative monitoring focuses on the integrity of the urinary tract. Abdominal ultrasound is used to detect urine accumulation. Serum creatinine and potassium concentrations are measured daily in patients with suspected urine leakage. Fever, lethargy, and peritoneal effusion suggest peritonitis and warrant immediate investigation.

The high rate of complications associated with surgical incisions in the ureter has driven a strong trend toward endoscopic methods in human medicine, but the small size of urogenital structures in companion animals has prevented the widespread application of these techniques complications of upper urinary tract surgery in companion animals. Careful surgical technique and meticulous closure remain the most important factors in preventing complications.

Approach Selection Table

The correct approach is determined by the location of the lesion, the patient's conformation, and the surgeon's experience. When the approach is uncertain, the ventral midline celiotomy is the safest default because it provides the greatest flexibility for conversion to other exposures.

Recognized Complications and Early Detection

Urogenital procedures carry a distinct complication profile because urine impairs wound healing and suture holding in tissue. The most consequential failure is urine leakage from a renal, ureteral, or cystotomy closure. Leakage typically declares itself within 24 to 72 hours as progressive abdominal distension, reduced urine output through the urinary catheter, and rising creatinine in peritoneal fluid relative to serum. Serial abdominal palpation, ultrasound assessment for free fluid, and abdominocentesis with fluid creatinine measurement remain the most reliable early detection tools. A fluid creatinine value more than twice the serum value confirms uroabdomen and mandates re-exploration without delay.

Postoperative hemorrhage occurs most often after renal surgery, particularly when the renal capsule is stripped extensively or when hilar dissection is carried too deeply. Tachycardia, pale mucous membranes, and a falling packed cell volume in the first 12 hours should prompt immediate ultrasonographic evaluation of the retroperitoneal space. Delayed hemorrhage, appearing at 5 to 10 days, suggests vascular ligature slippage or infection at the ligature site.

Obstruction of urine outflow is a recognized complication after ureteral surgery, where edema at the anastomosis or reimplantation site can transiently reduce patency. A sudden drop in urine production with progressive azotaemia and ultrasonographic hydronephrosis distinguishes obstruction from dehiscence. Contrast imaging or antegrade pyelography may be required to confirm the level of obstruction.

Infection and abscess formation complicate a small but consistent proportion of urogenital closures. Persistent fever, lethargy, and incisional drainage beyond day 3 should raise suspicion. Ultrasonography can identify fluid pockets adjacent to the kidney or bladder, and culture of aspirated material guides antimicrobial selection. The negative effects of urine on wound healing and the high rate of complications associated with upper urinary tract incisions are well documented in the comparative surgical literature, which has driven a strong trend toward endoscopic methods in human medicine, though the small size of urogenital structures in companion animals has limited the widespread application of endoscopy and surgery remains the mainstay of treatment Complications of upper urinary tract surgery in companion animals.

Common Errors and Corrective Actions

The most frequent error in cystotomy closure is failure to include the submucosa in each suture bite. The mucosa alone holds poorly and tears under tension, producing a closure that leaks or dehisces. The corrective action is deliberate full-thickness bites that incorporate mucosa, submucosa, and muscularis, with suture placement 3 to 4 mm from the incision edge.

Inadequate mobilization of the kidney before renorrhaphy is another recurring mistake. Attempting to close a renal incision under tension tears the capsule and parenchyma. The surgeon should mobilize the kidney fully from its retroperitoneal attachments before closure, and if tension persists, consider partial nephrectomy or nephrectomy instead of a compromised repair.

Urethral surgery errors center on excessive dissection. Stripping the periurethral vascular plexus devascularises the urethra and predisposes to stricture. Dissection should be limited to the minimum required for exposure, and the surgeon should preserve the dorsal and lateral attachments where possible.

Students and less experienced clinicians commonly misidentify the ureters during ovariohysterectomy or cystotomy, particularly in obese patients or those with retroperitoneal fat. The discriminating check is to trace the structure cranially to the kidney and caudally to the trigone before transecting anything. Similarly, the bladder is often mistaken for a mass when it is distended and displaced, decompression by catheterization before celiotomy prevents this error.

Troubleshooting Table

Evidence Limitations and Divergent Expert Opinion

The evidence base for urogenital surgical approaches in companion animals is largely derived from experimental models and retrospective clinical series instead of prospective randomised trials. Complication rates reported in the literature vary widely, and direct comparisons between approaches are rarely available. Expert opinion differs most notably on three points: whether routine ureteral stenting is beneficial after ureterotomy, whether omental wrapping of ureteral closures reduces leakage, and whether laparoscopic-assisted cystotomy offers meaningful advantages over open cystotomy for routine cases. These questions remain unresolved, and the surgeon should base decisions on individual patient anatomy and the specific pathology encountered.

In equine practice, the evidence is similarly limited. Reviews of urogenital surgery in foals emphasize that bladder surgeries are typically conducted through laparotomy while laparoscopic interventions are less common, and that postoperative complications often involve issues associated with abdominal procedures and potential bladder closure site dehiscence, along with systemic challenges like significant electrolyte imbalances or the risk of sepsis Urogenital surgery in foals. The comparative benefits of standing versus dorsally recumbent endoscopic approaches in horses are described in the literature, but patient temperament, size, and facility capabilities often determine the choice more than outcome data Standing female equine urogenital endoscopic surgery.

Referral and Escalation Criteria

Referral to a specialist surgeon is warranted when the procedure requires microsurgical technique, when the patient has had previous urogenital surgery with suspected adhesions, or when intraoperative findings exceed the planned scope of the approach. Ureteral reimplantation, ureteroneocystostomy, and repair of congenital anomalies such as ectopic ureters should be referred unless the surgeon has specific training and experience in these procedures. The comparative literature notes that veterinary surgeons now use microsurgical technique and interventional radiology to provide a high success rate in upper urinary tract surgery, which reflects the specialised skill set these procedures demand Complications of upper urinary tract surgery in companion animals.

Laboratory involvement is indicated for preoperative coagulation assessment in patients with suspected bleeding disorders, for urine culture before any planned urogenital procedure, and for histopathology of any mass encountered during the approach. Intraoperative consultation with a clinical pathologist may be needed for frozen section evaluation of margins.

Regulatory reporting obligations vary by jurisdiction. In most regions, surgical complications do not require reporting, but suspected adverse reactions to drugs or devices used during the procedure may be reportable to the relevant national authority. Practitioners should consult their professional body and national regulatory guidance. The American Veterinary Medical Association provides practice resources that include guidance on professional conduct and reporting obligations AVMA practice resources. Where notifiable disease is suspected, such as brucellosis in breeding animals, reporting obligations are governed by national veterinary authorities and international standards WOAH terrestrial animal health standards.

Frequently Asked Questions

How Should I Modify My Approach When Advanced Laparoscopic Equipment Is Unavailable?

Open surgical approaches remain the standard when laparoscopic instrumentation is not available. Ventral midline celiotomy provides excellent exposure to the bladder, uterus, and ovaries in dogs and cats. For renal surgery, a paracostal incision with the patient in lateral recumbency gives direct access without requiring specialized retractors. Flank approaches are useful for unilateral kidney procedures but limit access to the contralateral side. When microsurgical instruments are unavailable for ureteral work, loupe magnification and fine absorbable suture material on small needles improve outcomes. The trend toward endoscopic methods in human medicine has not fully translated to companion animals because of the small size of urogenital structures, so open surgery remains the mainstay of treatment Adin and Scansen on complications of upper urinary tract surgery.

What Are the Key Differences in Approach Selection Between Foals and Adult Horses?

Foals tolerate ventral midline celiotomy well and this approach is preferred for bladder surgery, including repair of uroperitoneum. Laparoscopic interventions are less common in neonates because of body wall thickness and the need for specialized equipment. Standing laparoscopic approaches in adult mares are facilitated by the dorsal location of the reproductive organs and avoid the risks of general anesthesia, but patient temperament and facility restraint capabilities limit their use Dechant and Hendrickson on standing female equine urogenital endoscopic surgery. Dorsal recumbency with general anesthesia is required for laparoscopic surgery in adult males. Postoperative concerns in foals include bladder closure site dehiscence, electrolyte imbalances, and sepsis, particularly when passive transfer of immunity was inadequate Saitua et al on urogenital surgery in foals.

How Do I Decide Between Primary Closure and Delayed Closure of a Contaminated Cystotomy?

Primary closure is appropriate when the urine is grossly normal, the bladder wall is viable, and contamination is limited to urine spillage that was promptly lavaged. Delayed closure should be considered when there is frank pus, necrotic tissue, or gross fecal contamination from a concurrent intestinal injury. Urine impairs wound healing, and the complication rate for upper urinary tract incisions is high, which supports a cautious approach to primary repair in compromised tissue Adin and Scansen on complications of upper urinary tract surgery. When delayed closure is chosen, place a temporary drain, manage the patient with broad-spectrum antimicrobials based on culture results, and return for definitive closure once healthy granulation tissue is present.

What Should I Document in the Medical Record for a Urogenital Surgical Procedure?

Record the patient position, exact incision location, method of organ exteriorization, and the specific closure technique including suture material, size, and pattern. Document the volume and character of any urine or fluid spillage, lavage volumes used, and whether drains were placed. Note the estimated blood loss and any intraoperative complications such as inadvertent ureteral ligation or bladder wall tearing. Include a description of how ureteral patency was assessed, whether by catheterization, observation of urine flow, or other means. Postoperative monitoring parameters, including urine output, incision appearance, and pain scores, should be recorded at each assessment. This documentation supports continuity of care and provides a defensible record if complications arise.

How Should I Explain the Risks of Ureteral Surgery to an Owner?

Explain that the ureter is small and delicate, and that urine leakage from the repair site is the most common serious complication. Describe the options of medical management, open surgical repair, and referral for interventional radiology when available. Mention that microsurgical technique and interventional radiology have improved success rates in recent years Adin and Scansen on complications of upper urinary tract surgery. Be direct about the possibility of reoperation, the need for strict confinement during healing, and the financial implications of extended hospitalization. Provide written postoperative instructions and a clear point of contact for concerns. The American College of Veterinary Surgeons offers specialist summaries of surgical conditions and expected outcomes that can supplement your discussion ACVS animal health resources.

When Should I Refer a Urogenital Case instead of Proceed With Surgery?

Refer when the required expertise or equipment exceeds your practice capabilities. Specific indications include ureteral surgery requiring microsurgical instruments, laparoscopic procedures when you lack the necessary training, and revision surgery after a failed primary repair. Refer early when imaging suggests ectopic ureters, since these cases require advanced diagnostic imaging and minimally invasive techniques Saitua et al on urogenital surgery in foals. If the patient is unstable from electrolyte disturbances or sepsis, stabilize before transport. Discuss referral with the owner as a positive option that maximizes the chance of success, not as a failure of your care.

Related Clinical & Scientific Guides

• Perioperative Antibiotic Prophylaxis: Timing and Selection
• Surgical Approaches to the Femur and Stifle
• Fracture Healing Assessment: Radiographic and Clinical Evaluation

References and Further Reading

• Complications of upper urinary tract surgery in companion animals.. 2011.
• Historical perspectives guide advances in equine minimally invasive soft tissue surgery.. 2026.
• Urogenital surgery in foals.. 2025.
• Ursolic Acid against Prostate and Urogenital Cancers: A Review of In Vitro and In Vivo Studies.. 2023.
• Standing female equine urogenital endoscopic surgery.. 2000.
• Dorsally recumbent male equine urogenital endoscopic surgery.. 2000.
• American College of Veterinary Surgeons Animal Health Resources. American College of Veterinary Surgeons.
• MSD Veterinary Manual, Professional Edition. MSD Veterinary Manual.
• American Veterinary Medical Association Practice Resources. American Veterinary Medical Association.

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This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.