Bladder cancer is among the ten most common types of cancer in the world, with about 550,000 new cases per year. According to GLOBOCAN (Global Cancer Incidence, Mortality and Prevalence) data, bladder cancer accounts for 3% of cancer diagnoses worldwide. It is more common, especially in developed countries. A total of 90% of bladder cancer diagnoses are made in people 55 years of age or older, and the disease is four times more common in men than in women. NMIBC are divided into four groups as low-medium-high and very high risk according to EORTC (European Organization for Research and Treatment of Cancer). Early recurrence was reported as 15%, late recurrence as 25% and progression as 9% with BCG treatment in medium and high risk NMIBC. TURBT is the basic approach in diagnosis and treatment.

The obturator nerve passes through the obturator foramen of the pubis and innervates the adductor muscles of the thigh. It lies within the pelvic cavity close to the prostatic urethra, bladder neck and inferolateral bladder wall. In TURBT, when the bladder is filled with irrigation fluid, the obturator nerve is very close to the bladder sidewall. While performing TURBT of lateral wall bladder tumors, neighboring obturator nerve stimulation may occur during surgical resection, resulting in adductor contraction and leg jerking. This condition, called the obturator reflex, occurs between 55.3% and 100% of lateral bladder tumors.

Serious complications can occur in TURBT, one of which is bladder perforation that may require laparotomy and open repair. Perforation is also associated with poor patient outcomes due to the spread of the tumor into the abdominal cavity and the inability to apply single immediate instillation of intravesical chemotherapy. One of the most important factors affecting the success of TURBT is the presence of residual tumor as a result of incomplete resection. Incomplete resection is associated with both general recurrence and particularly local recurrence, as well as shortening disease-free survival. One of the most important indicators of complete resection is the presence of the detrusor muscle in the TURBT specimen. However, in 10% of all cases, it has been reported that there is no detrusor muscle tissue in the TURBT specimen. Various methods such as administration of muscle relaxants under general anesthesia, less filling of the bladder, reduction of electric current, using a 90-degree classical loop, using bipolar plasmakinetic energy and performing tumor resection with small pieces have been proposed in order to prevent the failure and complications due to obturator reflex that may occur in TURBT.

In combination with spinal anesthesia, ONB is one of the most effective methods used to inhibit the obturator reflex. The importance of spinal anesthesia has increased especially due to the COVID-19 outbreak. Surgery under local / regional anesthesia is recommended as much as possible, especially during the pandemic process, compared to general anesthesia. In this way, it is aimed to reduce the risk of aerosol generating procedures and subsequent viral transmission. ONB has gained more importance in recent years as a result of being performed together with spinal anesthesia.