I had blood work done 5 days after my colonostrohy during which I received anesthesia. Could this have affected my WBC count?

Unlikely. The anesthetic would have a minimal effect of your white count, unless a you received a steroid which can temporarily increase wbc. Suspect cause would be from colonoscopy.
Possibly. Any invasive procedure can cause a temporary elevation of your wbc. As long as no other problems coexist then it should be fine. Severe abdominal pain after a colonoscopy with an elevated WBC should prompt immediate attention by a physician.
Yes possible in some. During the procedure most likely you received propofal , which causes temporary suppression of immuno system, and body's inflammatory response, which may result in fall of WBC count and every thing reverses to normal in a day or two.