Final answer:
A flexible sigmoidoscopy is the medical procedure used to visualize the lower part of the large intestine, using an endoscope with a flexible fiber optic tube to transmit light and images.
Step-by-step explanation:
The procedure that requires visualization of the lower part of the large intestine is known as a flexible sigmoidoscopy. During this medical procedure, a doctor uses a device called an endoscope, which is equipped with a flexible fiber optic tube. This tube sends light down to illuminate the internal parts of the large intestine, and the reflected light is transmitted back through another fiber bundle, allowing the doctor to observe the internal environment. The transmitted images may be viewed on an eyepiece or video screen. Additionally, if needed, small surgical instruments can be utilized through another channel within the endoscope to perform tasks such as taking biopsies or removing polyps during the same procedure.