INTRODUCTION AND BRIEF HISTORY
Maximilian Carl Nitze is credited with the invention of modern cystoscope, which was primarily used for inspection of the bladder. This was publicly demonstrated in 1879. It used an electrically heated platinum wire for illumination, a cooling system which used flowing ice water and telescopic lens for visualization. In 1887, following the invention of the light bulb by Thomas Edison, Nitze constructed a cystoscope that did not require the cooling system.
Cystoscopes are manufactured by various companies namely, Karl Storz, GmbH, Richard Wolf GmbH and Olympus Inc. We shall be describing the instruments by Karl Storz GmbH with some technical detailing from other manufacturers where ever necessary.
For many years, Karl Storz™ cystoscopes were utilizing the older nomenclature for sizes of the cystoscopes. In the nineties, the numbering of cystoscope sheath changed. Although the nomenclature changed, the actual size did not (Table 1). For the purpose of uniformity we will describe the new Storz numbering schema.
The parts of a rigid cystoscope assembly (Figure 1) are as follows:
- Cystoscope sheath
- Cystoscope obturator
- Light cable
All cystoscopes are made of stainless steel alloy. The cystoscope sheath is calibrated in French (Fr), this is considered to be the outer circumference of the instrument in millimeters (mm). Fr is same as Charriere (Ch). This method of calibration was described by Joseph Frederic Benoit Charriere. Fr takes into consideration the diameter of the instrument.
One mm is equal to three French. It is also written as F, Fr or Ch.
THE CYSTOSCOPE SHEATH
The cystoscope sheath (Figure 2) will be discussed under the following headings:
- Cystoscope sheath.
- Inlet and outlet vent.
- Color code disk.
- Numbering on the sheath and Albarrans sheath lever.
- Cystoscope sheath: The details of cystoscope sheath (Karl Storz, GmbH) are as follows:
- Length of an adult cystoscope sheath regardless of size is 22 cm. The cross section of the sheath is not round but oval. However, the size of the sheath is referred to in French(Fr), this can be considered as a ‘misnomer’ as mentioned, because if it is to be referred in French it should be circular contrary to its oval shape (Figure 2).
- Markings on the shaft (Figure 2): The proximal 10 centimeters from the vesical end devoid of any markings. Markings are engraved on the sheath at every 1 cm thereafter for the next 13 cm. The markings help in estimation of prostatic urethral length (In comparison, VIU sheath has similar markings all along the length of the sheath).
- Method to measure prostatic urethral length: The cystoscope is introduced along the entire length. The cystoscope is withdrawn under endoscopic vision till the bladder neck. The marking on the external meatus is noted (Point A). Thereafter, the cystoscope sheath is withdrawn till the verumontanum and a note of the marking is done (Point B). The number of markings on the sheath between point A and point B is noted, this is the length of the prostatic urethra.
- The distal end of the sheath is bulbous dorsally and smooth without sharp edge. This helps in atraumatic introduction of the scope (Figure 3). Such a design of the tip is essential if a instrument is to be passed under vision (without a obturator), e.g. cystoscope sheath, ureterorenoscope.If the beak is not of such design then that instrument should be passed through the meatus with obturator, e.g. VIU sheath, resectoscope sheath.
Salient features to remember regarding cystoscope sheath:
- Old and new nomenclature is changed without change in size
- All adult sheaths have same length
- Only 17 Fr sheath has different beak configuration, rest have same configuration.
- Bridges and telescopes remain same irrespective/regardless of size of sheath.
- Cystoscope beak: Sheaths with size 19 Fr onwards are long oblique beaks, 17 Fr sheath is short beak sheath, this is used for female cystourethroscopy. The short beak is 2 cm in length (diamond shaped opening for irrigation at the beak with) while the long beak has a length of 2.5 cm. The gradual withdrawal of the cystoscope sheath helps in visualization of the urethra in females.Longer beaks would result in leakage of irrigation fluid after introduction into a short female urethra leading to nondistension of the urethra and poor vision, this problem can be circumvented with shorter 17 Fr sheath (known as female cystoscope sheaths), this problem can also be circumvented by use of (Figure 4) the Nickel adapter used for female urethroscopy.The adapter should be pressed against the urethral orifice after insertion of the cystoscope to avoid leakage of irrigation fluid and the resultant collapse of the urethra.
- Inlet and outlet vent: One for the inlet and one for the outlet allows ingress and egress of the irrigation flow which the surgeon can control (Figure 1).
- Color code disk: This is a metal disk on which there is plastic color code cover. With prolonged use or repeated autoclaving it tends to get damaged.
- Numbering on the sheath and Albarrans sheath lever:
- Size of the sheath is indicated by a number written on the sheath at the level of inlet/outlet channel.
- The numbers written in two circles behind the above indicate the largest size of the catheter, two of which can be passed simultaneously through the sheath.
- Behind the above is a single circle with a numerical value, denoting the single largest catheter, which can be passed through the sheath.
- The above catheter size are the maximum size with scope and Albarrans lever in situ, so if simple bridge is used maximal permissible catheter size will increase by 1 Fr. So the maximum size of catheter that can be passed through 19 Fr sheath with simple bridge is 7 Fr, (for 20 Fr is 8 Fr, for 22 Fr is 11 Fr and for 25 Fr is 13 Fr).
- Albarrans lever (Figure 5): It is Bridge with a deflecting lever, which can be used to deflect the ureteric catheter to align the catheter with the ureteric orifice. It has two channels through which two catheters can be passed simultaneously. A circular knob near the eyepiece end of the device is used to deflect the lever and thus, the ureteric catheter to up to 90º. Pointer on the knob tells the degree of deflection. Albarrans lever can be attached to sheath size 19 Fr or more.
- Locking knob on the sheath: It has a zero (0) mark engraved which corresponds with same (0) mark on the obturator or the bridge (Figure 2).
Bridges (Figure 6)
Adult cystoscope bridges are universal and can fit into all sizes of sheaths. Length of bridge is 6 cm. Specially designed cystoscopes are available wherein the bridge and the telescope cannot be detached, they are called as ‘integrated cystoscopes’. These cystoscopes have advantages of having a smaller shaft size with a comparatively larger working channel.
The advantages of detachable bridge are:
- It helps in empting the bladder efficaciously.
- It helps in passing larger size catheter after detaching the bridge.
- It helps in attaching the Elick's evacuator for evacuation of stone fragments/ clots/chips, etc.
Types of Bridges (Classification)
- Without side channel
- With one side channel
- With two side channel.
Parts of Bridge
- Telescope channel: It accommodates the telescope.
OBTURATORS (Figure 7)
They are specific for a given sheath. Once attached to the sheath it makes the tip of the sheath smooth thereby snuggly fitting to it. The length of the obturator is 26 cm.
Parts of obturator are as follows:
- Vesical end knob: This helps in smooth atraumatic insertion of the cystoscope.
- Shaft: Connects the vesical end knob and the locking mechanism.
- Locking mechanism: Zero (0) should correspond to zero (0) of the sheath when locked.
Specifications of Obturators (Figure 7)
The obturator of 17 Fr sheath (new) has a smaller distal end without any groove. In addition, the sheath of 17 Fr sheath has a diamond shaped opening at the distal end which helps in irrigation egress. The obturator of 19 Fr sheath (new) onwards has a groove which helps in egress of irrigation. The sheath size is engraved on the obturator. The 17 Fr obturator has a smaller knob but is same in length. Rest of the obturators have same shape and length but vary in the size according to the size of the sheath. Points which differentiate a cystoscope, Sachse's and resectoscope obturator are detailed in Figure 7. The differentiation is based on size of the knob and the presence and absence of groove (Table 2).
SPECIAL TYPES OF CYSTOURETHROSCOPES AND ITS USES
Extended length cystoscope-urethroscope: The working length is 29 cm. It is 22 Fr, the color code is blue. The compatible telescope bridge has one instrument channel; it is for use of 10 Fr instruments. A catheter deflecting mechanism is also compatible with the extended length cystoscope-urethroscope, it is for use of 9 Fr instruments.
The telescopes are classified depending on the viewing angle. They are available as 0º, 30º, 70º, 120º and 12º (Figure 8). Adult telescopes can be used with any adult sheaths. They need to be used with a bridge. The color coding for the telescopes are as follows, green code for 0º, red code for 30º, yellow code for 70º and white code for 120º for Storz (Figure 8). Even though the color codes seem confusing it is paramount for universal recognition. Straight forward telescopes (0º) is focused to view straight ahead, is usually used for urethroscopy. Forward oblique telescopes (30º) best affords visualization of the base and anterolateral aspect of the bladder, this is the most commonly used telescope. Lateral telescope (70º) to view the bladder dome.
It views structures around bladder neck like postprostatic pouch. Retrospective telescopes (120º) help to visualize the anterior bladder neck from inside. With conventional system, the viewing angle was relevant but with Hopkins 2, the use of 70º and 120º has gone down. In addition, with the use of flexible cystoscopes on the rise the 70º and 120º telescopes have become obsolete. These color codes differ with the make (Figure 8). The eyepiece can be fitted with a camera. The eye-piece is black in color and has the catalog number engraved on it. The light cable can be attached to the telescope directly. Size of telescopes available − 4 mm, 30 cm (fits in all cystoscope sheaths and VIU sheaths, resectoscope sheaths).
The Rod-lens System (Figure 9)
In 1966, the collaboration between Karl Storz and Professor HH Hopkins led to the new design of rod-lens system. This was a major development for the progress of endourology since the description of cystoscope by Maximilian Nitze.
The key difference in the conventional optical system and the rod-lens system is that the Hopkins rod-lens system employs special glass rods with customized finished ends. The rod-lens system reduced the air spaces between lens with long rods of glass which were ground, contoured, and polished at both ends, there are short gaps of air in between. Once this endoscopic image is transported back through the telescope, it is magnified at the ocular lens. The degree of magnification is to some extent dependent on the diameter of the viewing lens.
The image and optical image transmission differs in rigid and flexible endoscopes. In the flexible endoscopes, typically there are two sets of fiberoptic glass bundles which are either coherent or noncoherent. The coherent bundles help in transmission of images, as a result the image of a fiberoptic scope has a ‘honeycomb’ appearance. This is called as the ‘Moire effect’. The noncoherent bundles help in transmission of light.
The Hopkins rod-lens system offers the following advantages over the conventional system:
- Better light transmission offers images of improved quality and contrast.
- The image resolution is better.
- Improvement in refractive index.
- Increase in viewing angle.
- Decrease in profile of telescope shaft.
Advantages of Hopkins II Lens
- Wider viewing angles.
- Lens diameter has been increased and air spaces have been decreased.
- 30º Hopkins II covers areas which could be only seen by a 70º lens earlier.
- Greater brightness.
- Greater brilliance.
- Higher resolution.
Basic structure of telescope (Figure 10).
Rod-lens are glued with special adhesive cement which is a special alloy, effectively making it water proof. The special adhesive helps in preventing permeation of water into the rod-lens system.
- Light pillar: Figure 11 shows the adapters and light pillars for various manufacturers. The light cable configuration differs with the make. Hence, the structure of light pillar varies. The use of adapters helps the use interchangeable for example a specific custom made Wolf adapter can be used with the adapter on a Storz instrument.
Parts of Telescope
- Shaft: Angulation at the tip varies depending on the viewing angle (diagram).
- Eyepiece: It is typically black in color, the size is universal and adapts to any camera head.
Flexible Cystourethroscope (Figure 12)
The advantage of flexible instrumentation is ease in patient positioning resulting in better patient comfort. It is useful in manipulation across difficult curves and high bladder necks and median lobes. The ability to flex the endoscope helps in complete visualization of the bladder easily. Within the shaft of a flexible cystourethroscope are generally three fiberoptic bundles—two noncoherent bundles of fibers that transmit light and a single coherent bundle of glass fibers that constitutes the imaging bundle. Unlike its rigid counterpart, the image obtained by the fiberoptic bundle is not a single image, but rather a composite matrix of each fiber within the bundle. The image obtained is analogous to a newspaper photograph—that is, it is composed of multiple dots merging into a single reconstructed image known as ‘honeycomb’ effect.2 It is same as flexible nephroscope hence also called as flexible cystonephroscope.
All are digital, they do not need a separate camera or light cable attachment. Specifications (Storz, Gmbh).
- Outer diameter—15.5 Fr
- Instrument channel—7 FrDirection of view 0º
- Field of visioin—110
- Working length—35–40 cmThe distal tip moves up for 180º and down for 140º.The accessories which are compatible with flexible cystoscope are. All have to be flexible in nature:
- Grasping forceps—5 Fr, 73 cm
- Biopsy forceps—5 Fr, 73 cm
- Stone basket—5 Fr, 60 cm
- Ball electrode—4 Fr, 73 cm.
Logic (up is up). This means when the lever is turned down the deflection occurs downward and Antilogic (down is up). This means when the lever is tuned down the deflection goes up.
The cystoscope accessories are discussed in the chapter on accessories.
- Karl Storz catalogue, endourology, 5th edition, 1/97.
- Babyan RK, Wang DS chapter one basic principles optics of flexible and rigid endoscopes Smith endourology, 2nd edition, Page 3.
- Karl Storz catalogue, 5th edition, 1/97 Cyst 1B.