Obturator Nerve Stimulation During Transurethral Resection of Bladder Tumors
J.K. Denney, MD, N.T. Bennett, MD, T.G. Monk, MD,
Dept of Anesthesiology, University of Florida
Introduction: Bladder cancer is the second most common
urological malignancy in the United States. Approximately 80% of
patients initially present with superficial transitional cell
carcinoma and the majority of patients undergo transurethral
resection (TURBT) for diagnosis and treatment of this disease.
Although TURBT is generally considered a minimally invasive
procedure, serious intraoperative complications can occur.
Case Report: A 58-year-old man with hematuria presented for
cystoscopy, retrograde pyelograms, and possible ureteroscopy.
His medical history was significant for a cadaveric renal
transplant, transitional cell carcinoma of the bladder,
hypertension, type II diabetes, atrial fibrillation, and
transient ischemic attacks. In addition, he had undergone
multiple cystoscopies and transurethral resection of bladder
tumors (TURBT) without complications. The patient had good
exercise tolerance without any chest pain or shortness of
breath. A recent electrocardiogram showed sinus rhythm with a
rate of 60 beats/min. His medications included quinidine
gluconate, azathioprine, prednisone, furosemide, diltiazem
hydrochloride, clonidine, glipizide, potassium chloride,
omeprazole, and simvastatin. The patient was 178 cm tall and
weighed 99.5 kg; blood pressure was 122/80 mmHg and heart rate
was 67 beats/min. Preoperative hematocrit was 41.2%. BUN/CR was
22 and 1.2, respectively. General anesthesia was induced with
200 mg propofol, 150 mg thiopental, and 500 µg fentanyl. A #4
laryngeal mask airway was placed without difficulty. Spontaneous
respirations were maintained. Anesthesia was maintained with a
propofol infusion, fentanyl, and nitrous oxide. Cystoscopy
revealed multiple tumors throughout the bladder. Upon resection
of the tumors in the right lateral bladder wall, the obturator
nerve was stimulated causing forceful adduction of the patient’s
right leg. Bleeding was then noted from the urethra and
cystoscopy demonstrated profuse bleeding in the bladder. The
patient rapidly became hemodynamically unstable. Additional IV
access was obtained, vasopressors were administered, and the
patient was paralyzed and intubated. Despite vasopressors (phenylephrine
hydrochloride, 400 µg, and ephedrine, 120 mg) and aggressive
hydration, the patient’s systolic blood pressure was 50-60 mmHg
for 15 min. Oxygen saturation in the 90s was maintained despite
hypotension. Aggressive resuscitation was initiated and an
emergency exploratory laparotomy was performed. Laparotomy
showed a 1 cm laceration in the bladder wall and injuries to a
large vesical vein, the obturator artery, and the obturator
vein. The patient remained stable throughout the laparotomy and
was transported to the surgical intensive care unit (SICU)
intubated and in stable condition. The patient received a total
of 15 L of crystalloid, 1 L of colloid, 10 units of packed red
blood cells, and 3 units of fresh frozen plasma. The total blood
loss was 5 L and the postoperative hematocrit was 37%. The
patient had multiple postoperative complications, including
renal and respiratory failure. Postoperatively the patient
remained intubated in the SICU, developed sepsis, and expired on
postoperative day 19.
Discussion: During transurethral resection of the lateral
bladder, the bladder neck, and less commonly the prostate, the
obturator nerve is frequently stimulated. The obturator nerve is
a branch of the lumbar plexus (L2-4), which runs along the
lateral pelvic wall on the obturator internus muscle and passes
through the superior middle aspect of the obturator canal to
enter the thigh. Stimulation of the obturator nerve causes
contraction of the adductor muscles in the thigh, which can
cause perforation of the bladder, bleeding, and incomplete tumor
resection. Multiple studies have been performed to develop
techniques to decrease or eliminate this reflex. These
techniques include reversing the polarity of the power supply to
the electrical unit and changing the site of the inactive
electrode, lower bladder volumes during TURBT, the use of a
neuromuscular blocker, and successful infiltration of the
obturator nerve with a local anesthetic. The only technique that
can reliably eliminate adductor contraction is complete
neuromuscular blockade.
