Basic Structure of a Cystoscopy

A cystoscope is a relatively complex optical endoscope. There are many types, each with different constructions, but the main components include the sheath, endoscope, cannula, obturator, and accessories.

 

The sheath's function is to allow the endoscope to be inserted smoothly, to irrigate the bladder, and to provide illumination. The basic structure of a concave cystoscope consists of three parts: the anterior end, the shaft, and the posterior end. The anterior end is very short, about 1.5 cm long, and forms an angle with the shaft. It comes in concave and convex shapes. The anterior end houses the light source (except for McCarthy cystoscopes, which do not have a built-in light source). The bulb voltage is fixed, typically 2.5 volts, 3 volts, or 4.5 volts. Modern cold-light fiber optic cystoscopes use a tungsten bromine lamp as the light source. A fiber optic bundle is connected to the cystoscope, and the light is guided by a beam guide fixed inside the shaft to a small window at the anterior end of the sheath. Therefore, there is no bulb at the anterior end of the sheath, but the light is soft and extremely bright. This new type of fiber optic cystoscope, because it has no bulb light source at the front end and does not generate heat, is also called a cold light source cystoscope.

 

A small tungsten filament bulb is installed inside a hollow window at the front end of a conventional cystoscope. At the front end of either a concave or convex sheath, there is an oval window fitted with a sealed glass. Light from the bulb or cold light source shines through this window, illuminating the field of view. A small metal screw cap at the top allows for removal or tightening for bulb replacement or inspection. One end of the tungsten filament inside the bulb is attached to the side metal tube at the rear of the bulb; this metal tube is insulated from its surroundings but connected to an insulated metal wire; this insulated metal wire is connected along the endpiece to one pole at the rear end; the other end of the tungsten filament is in contact with the top metal cap and connected to the other pole at the rear end via the sheath itself.