The rigidity of intermittent catheters vary. The softer versions often come with an outer insertion sleeve or a gripper. The function of the sleeve and the gripper is to enable the user to grab the catheter at any point upon the insertion. Both sleeve and gripper are useful to control a catheter that is made of a soft material, as it might bend outside the urethra when inserted. Firmer catheters can be inserted in a smoother movement, as they can overcome normal resistance in the urethra.

• Clean: The clean technique is defined by self-catheterisation with a no-touch technique. This means that the person doing the catheterisation has direct contact with the catheter connector, but the catheter itself must not be touched. When using clean technique there is a potential risk of contamination, and it is important to wash both hands as well as the opening to the urethra thoroughly with soap and water. Always follow the instructions provided by the manufacturer. The clean technique is used outside of hospitals (1).
• Sterile: The sterile technique is defined by a catheterisation where the person inserting the catheter is wearing sterile gloves and has no direct contact with the catheter. The technique is often performed by health care professionals in hospital settings (1).

• Standard catheters: Standard catheters are the most common catheter type. These catheters are primarily straight and typically come in standard lengths of approx. 40 cm for men and approx. 20 cm for women. The firmness of standard catheters varies.
• Compact catheters: Most compact catheters are similar to the standard catheters, but shorter and packed more discrete. Often, they are easier to use due to the shorter length (kilde).
• Sleeve catheters: The sleeve catheters are soft catheters covered with an insertion sleeve. The sleeve protects the catheter from contamination during insertion.
• Catheter sets: Catheter sets are standard, compact or sleeve catheters pre-connected with a drainage bag to collect the urine.

• Nelaton tip: Is defined by a straight tip and is for both men, women, and children with no special catheter needs
• Tieman/coudé tip: Is defined by a curved tip and is primarily for men. The tips design to make it easier for men with enlarged prostate to insert a catheter.
• Flexible tip: Is defined by a flexible often ball shaped tip which gently guides the catheter through any curves or bends in the urethra.

Most intermittent catheters come with two eyelets or holes close to the catheter tip. The urine is drained when the eyelets reach the bladder.

The shape, size, positioning, manufacturing process and surface treatment of the eyelets are important for how the catheter performs and how gentle it is to the urethra.

To insert an intermittent catheter in the most safe and comfortable way, it needs to be lubricated. A slippery surface eases the insertion and reduces the risk of damaging the urethra. There are several kinds of surface treatments for intermittent catheters.

• Uncoated: Catheters which must have a gel added manually before use.
• Gel coated: Catheters that are coated in gel and can be inserted without any further preparation. The challenge with gel coated catheters is that the coating can be rubbed off during insertion leaving the catheter uncoated. The coating can be left in the urethra and bladder when removing the catheter.
• Hydrophilic coated: Catheters that are pre-coated with a dry hydrophilic coating. The coating needs to be activated by adding drinking or sterile water for 30 seconds. This will allow the coating to swell into a slippery smooth layer. The coating layer stays on the surface of the catheter during use.
• Hydrophilic coated ready to use: Catheters that are coated with a hydrophilic coating and come immersed in water, ready to use so you don’t need to bring nor think about access to water no wait for optimum hydration of the coating (13,14).

It is key to the success of the catherisation to find the right catheter size. The size of an intermittent catheter refers to the outside diameter of the catheter. The measuring unit is used in 1/3 mm and is referred to Charriére or French. The size should not be too big as this might complicate insertion. The size should not be too small as the urine might then flow on the outside of the catheter. In general, the bigger size, the better flow. However, several specific parameters such as the inner diameter (ID), the tip inlet area to inner lumen area ratio (AR), and resistance from the inlet tip also influence catheter flow rates. Hence, it is not possible to predict the actual flow rate of urinary catheters based on the packaging information or specifications (Ref: Journal of Pediatric Urology (2017) 13, 377.e1e377.e6).

Often the size of the catheter can be identified by the color of the connector.