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For the material method of my thesis, with perineal urethrostomy of tom

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https://todaysveterinarypractice.com/urology-renal-medicine/…

Here is a full draft of the Materials and Methods section for your prospective clinical thesis on perineal urethrostomy (PU) in domestic male cats. Adapt names, dosages, institutional details, and sample size to your actual study.

Materials and Methods

2.1 Study Design and Ethical Approval

This prospective clinical study was conducted between [start date] and [end date] at [name of institution/veterinary teaching hospital]. The study was approved by the Institutional Animal Care and Use Committee (or equivalent ethics board; approval number: XXXX) and was carried out in accordance with institutional guidelines for the use and welfare of laboratory and clinical animals. Owner written informed consent was obtained before enrollment of each patient.

2.2 Animals

Male domestic cats (Felis catus) presented to the veterinary clinic with urethral obstruction refractory to conservative management, or with recurrent urethral obstruction, were considered for inclusion. Inclusion criteria were: confirmed urethral obstruction unresponsive to catheterization (two or more failed attempts or recurrence within [X] months), owner consent for surgical intervention, and body weight > 2.0 kg. Exclusion criteria included: concurrent severe systemic disease precluding general anesthesia (ASA status V), coagulation disorders, neoplasia of the urinary tract, or incomplete medical records.
A total of [n] cats were enrolled. For each animal, signalment (age, breed, body weight, reproductive status), clinical history (duration and number of previous obstructive episodes, prior catheterizations), and preoperative laboratory data were recorded.

2.3 Preoperative Assessment and Stabilization

All cats underwent a thorough physical examination upon admission. Preoperative diagnostics included:
  • Hematology and serum biochemistry: Complete blood count (CBC) and serum chemistry panel including blood urea nitrogen (BUN), creatinine, total protein, albumin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, glucose, sodium, potassium, and chloride.
  • Urinalysis: Urine specific gravity, dipstick analysis, sediment examination, and urine culture with antimicrobial sensitivity testing.
  • Abdominal ultrasound: To assess bladder wall integrity, presence of uroliths, and to rule out concurrent upper urinary tract pathology.
  • Radiography: Lateral and ventrodorsal projections of the caudal abdomen and pelvis to detect radiopaque calculi and evaluate perineal anatomy.
Cats with azotemia, hyperkalemia (> 6.5 mEq/L), acidosis, or dehydration were stabilized before anesthesia. Stabilization consisted of intravenous (IV) fluid therapy with lactated Ringer's solution or 0.9% NaCl at a rate calculated to correct estimated fluid deficits over 4-8 hours, supplemented as needed with 10% calcium gluconate (0.5-1.0 mL/kg IV slowly over 10-15 minutes) for severe hyperkalemia-associated cardiac arrhythmias. Urinary decompression was achieved by cystocentesis and/or careful urethral catheterization (open-ended tomcat catheter, 3.5 Fr) using sterile technique. Surgery was deferred until serum potassium was < 6.0 mEq/L, creatinine showed a downward trend, and the patient was hemodynamically stable.

2.4 Anesthetic Protocol

Anesthetic risk was classified according to the American Society of Anesthesiologists (ASA) physical status scale. All cats were fasted for a minimum of 4 hours prior to anesthetic induction.
Premedication: Butorphanol tartrate (0.2-0.4 mg/kg IM) combined with medetomidine hydrochloride (10-20 µg/kg IM) or dexmedetomidine (5-10 µg/kg IM) was administered 15-20 minutes before induction. In cats with significant cardiovascular compromise (ASA III-IV), medetomidine was omitted and butorphanol (0.2 mg/kg IM) was combined with midazolam (0.2 mg/kg IM).
Induction: General anesthesia was induced with propofol (2-4 mg/kg IV to effect) or alfaxalone (2-3 mg/kg IV to effect) administered via a pre-placed 22-24 gauge cephalic catheter. The trachea was intubated with a cuffed endotracheal tube (2.5-3.5 mm internal diameter) and the cuff inflated to form a seal.
Maintenance: Anesthesia was maintained with isoflurane (1.5-2.0% end-tidal in 100% oxygen) delivered via a rebreathing or non-rebreathing (Bain) circuit depending on body weight.
Analgesia: A multimodal analgesic protocol was used:
  • Meloxicam (0.2-0.3 mg/kg SC once, preoperatively) for perioperative anti-inflammatory analgesia, provided renal function was adequate (creatinine < 2.0 mg/dL).
  • Buprenorphine (0.01-0.02 mg/kg IM or transmucosally q8-12h) continued for 3-5 days postoperatively.
  • Loco-regional analgesia: pudendal nerve block or epidural analgesia with bupivacaine (0.25%, 0.2 mL/kg) ± morphine (0.1 mg/kg preservative-free) was performed at the discretion of the attending anesthesiologist.
Monitoring: Continuous intraoperative monitoring included pulse oximetry (SpO2), capnography (EtCO2), Doppler blood pressure, ECG, and rectal temperature. IV fluid support was maintained throughout the procedure.

2.5 Surgical Technique

All surgeries were performed by the same surgeon [or describe surgeon experience level] under standard aseptic conditions.
Positioning: Cats were placed in ventral (sternal) recumbency with the pelvis elevated using a folded towel, and the hindlimbs extended caudally over the edge of the surgery table. Alternatively, dorsal recumbency with the hindlimbs tied cranially was used when concurrent cystotomy was anticipated, as this provides ergonomic access to both the perineum and the ventral abdomen. A purse-string suture (2-0 nylon or polypropylene) was placed in the anus to minimize intraoperative fecal contamination. The perineal and perianal regions were clipped and aseptically prepared with povidone-iodine or chlorhexidine gluconate scrub.
Surgical procedure (Wilson-Harrison technique, modified):
  1. An elliptical skin incision was made around the prepuce and scrotum. If the cat was intact, castration was performed concurrently.
  2. The penis was mobilized by blunt and sharp dissection using Metzenbaum scissors, freeing it from the surrounding subcutaneous tissue and perineal musculature.
  3. The ischiocavernosus muscles were transected bilaterally at their attachment to the ischium using Stevens tenotomy scissors or Metzenbaum scissors.
  4. The retractor penis muscle was identified on the ventral surface of the penis and dissected away to expose the urethral body.
  5. The penile urethra was dissected cranially to the level of the bulbourethral glands. The pelvic urethra was identified and the dissection continued until the urethra was of adequate diameter (minimum 4-6 mm) to prevent postoperative stricture. Two Gelpi retractors were used to improve visualization.
  6. The distal penile urethra was amputated. A longitudinal incision was made on the dorsal aspect of the remaining urethra to extend the stoma opening cranially.
  7. The urethral mucosa was sutured to the perineal skin using 4-0 or 5-0 monofilament absorbable suture (poliglecaprone 25 or polyglycolic acid) on a taper-cut needle, in a simple interrupted or simple continuous pattern, beginning at the most cranial aspect of the urethrotomy incision and proceeding caudally. Each suture passed through: (1) urethral mucosa, (2) fibrous tunica albuginea, and (3) split-thickness perineal skin. Excessive tension was avoided to prevent mucosal ischemia.
  8. The remaining perineal skin defect was closed in a routine interrupted pattern using 3-0 or 4-0 monofilament absorbable suture.
  9. The anal purse-string suture was removed at the end of the procedure.
  10. A sterile urethral catheter (3.5-5 Fr open-ended tomcat catheter) was placed in all cats at the end of surgery and maintained for [24-72 hours] postoperatively, connected to a closed urinary collection system.

2.6 Postoperative Management

All cats were hospitalized for a minimum of 48-72 hours postoperatively. The following postoperative protocols were applied:
  • Analgesia: Buprenorphine (0.01-0.02 mg/kg transmucosally or IM q8-12h) and meloxicam (0.05 mg/kg PO q24h if renal function was stable).
  • Antimicrobial therapy: [Specify antibiotic used, dose, route, and duration based on your protocol or local sensitivity data].
  • Fluid therapy: IV fluid therapy was continued until the cat urinated spontaneously following catheter removal.
  • Urethral catheter care: The catheter and collection system were monitored and flushed with 1-2 mL of sterile saline q8h to maintain patency.
  • Wound care: The surgical site was cleaned twice daily with dilute chlorhexidine. An Elizabethan collar was placed on all cats for 3 weeks to prevent self-trauma.
  • Monitoring: Urine output, hematuria severity, stoma appearance, and voiding behavior were documented daily during hospitalization.

2.7 Follow-up and Outcome Assessment

Cats were re-evaluated at [postoperative day 10], [3 weeks], [3 months], and [6 months or longer] after surgery. At each visit, the following were assessed:
  • Stoma patency: Ability to pass a 3.5 Fr catheter through the stoma without resistance.
  • Voiding function: Observation of urine stream width and force; owner-reported voiding behavior.
  • Urinalysis and urine culture: Performed at each follow-up to screen for urinary tract infection (UTI).
  • Complications: Classified as early (within 30 days) or late (> 30 days). Early complications included hemorrhage, urethral dehiscence, wound infection, UTI, urine scalding, and recatheterization requirement. Late complications included urethral stricture/stenosis, recurrent obstruction, UTI, and urinary incontinence.
  • Owner satisfaction: Assessed via structured questionnaire using a 5-point Likert scale.

2.8 Statistical Analysis

Continuous data were reported as mean ± standard deviation (SD) or median (interquartile range, IQR), depending on normality assessed by the Shapiro-Wilk test. Categorical data were expressed as frequencies and percentages. Comparisons between groups (if applicable, e.g., sternal vs. dorsal recumbency, or by operator experience) were performed using Student's t-test or Mann-Whitney U test for continuous variables, and chi-square or Fisher's exact test for categorical variables. Kaplan-Meier survival analysis was used to estimate time to stricture or re-obstruction. A p-value < 0.05 was considered statistically significant. All analyses were performed using [statistical software, e.g., SPSS v26, GraphPad Prism 9, or R v4.x].
Key references to cite in your thesis:
Notes for customization:
  • Replace brackets [ ] with your actual values (sample size, dates, doses, institution name).
  • If you used a specific suture material throughout, name it consistently (e.g., poliglecaprone 25, Monocryl).
  • If all surgeries were performed under epidural analgesia, specify that and cite the MedCrave case series as a reference for that technique variant.
  • The statistical section can be simplified if this is a descriptive case series rather than a comparative study.
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