This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Prostate and seminal vesicles, Subject name: Surgery
A 72 years old patient with BPH underwent transurethral resection of prostate under spinal anaesthesia. After one hour, he developed vomiting and altered sensorium. The most probable cause is: 
Select and explain. 
A. Hyperkalemia, B. Water intoxication, C. Rupture of bladder, D. Over dosage of spinal anesthetic agent
B: Water intoxication
Answer: B: Water intoxication 
Explanation: - If surgery prolonged or when the size of prostate >75gm it leads to dilutional hyponatremia or water intoxication known as TUR syndrome. TUR syndrome (Dilutional Hyponatremia or water intoxication)* Results from a hypervolemic, hyponatremic state due to absorption of the hypotonic irrigating solution.* Clinical features: Nausea, vomiting, confusion, hypeension, bradycardia, & visual disturbances * The risk increases with resection time > 90 minutes or gland size > 75 gm* Rx- Diuresis (furosemide) and in severe cases, hypeonic saline (3%) administration.