A straight catheter is a straight flexible tube which is inserted in through the urethra opening and into the bladder to drain urine from the bladder. It is prescribed for and used by people who are unable to completely empty or void their bladder on their own due to many factors including but, not limited to nerve damage, spina bifida, multiple sclerosis (MS), trauma, and other causes. Catheterization with a single use disposable straight catheter is done intermittently several times a day to empty the bladder and is not left inside the urethra for long periods of time, which is where you’d see the use of a foley catheter or balloon type catheter.
The history of the catheter dates back to ancient times in Syria and Greece where they used reeds and metal tubes (called a katheter). In 1752 a flexible catheter, made with metal segments, was invented by Benjamin Franklin to help his brother who suffered with bladder stones. And more recently in the 1940s the invention of the modern day disposable catheter by David S. Sheridan.
The tip of the catheter is the part which is inserted into the urethra opening and into the bladder with the front being tapered to make insertion easier. Instead of opening in the front, the openings, called eyelets are on the sides of the tip also making the catheter easier to insert. The tip can be straight or may contain a slight bend. The bent tips are often referred to as either a Coude or Olive tip and for some people, based on their technique or their own physiology, find these easier to insert through the sphincter muscles leading into the bladder. A medical professional will consult the patient on which type of tip they should use as what may work well for one person may not work for someone else.
The tube of the catheter is the length of the catheter which goes from the tip to the drainage outlet and varies in length, diameter, and material, and may also be coated or pre-lubricated. The length of the catheter will typically range from 6 inches to 16 inches to accommodate requirements based on the length of the urethra and the patient’s age and gender. The diameter is measured on a French Scale, also referred to as French Gauge, can be abbreviated as Fr, Fg, FR, or F, and typically for straight catheters will range from 10FR to 16FR. You can convert the French scale to millimeters and get a close approximation by dividing the value by 3. For example, a catheter with a 9FR size will have a diameter of about 3mm and a catheter with a 18FR diameter will be 6mm. This size is based on the external diameter of the catheter and not the internal diameter which the urine flows through. The tube of the catheter can be made of a number of different materials including but, not limited to plastic, rubber, silicone, pvc, latex, and vinyl. Each varying in the level of stiffness. Usually this is based on preference under the direction of a physician. Patients may also opt for one material over another based on allergies such as reactions to rubber or latex. It is not recommended to reuse a catheter however, for patients who do, they find that some materials are more durable and safer to wash and keep clean. Note, reuse of catheters has been attributed to urinary tract infections and you should always consult with your doctor first if you intend to reuse your catheters as each person is different and will have different requirements. Catheters may also be coated or pre-lubricated. Some of these will require that water is put on the coating to activate it prior to use and some will also include the water as part of the packaging. For those that are not coated it is necessary for the patient to provide their own lubrication, usually in the form of a disposable single use 3 or 5 gram packet or a flip top tube, prior to inserting the catheter.
Catheter Drainage Outlet
The drainage outlet is the end of the catheter which is opposite the tip. It is the part of the catheter which the urine will flow out of. Usually the end will be a funnel which can serve to keep urine from getting misdirected as it exits the tube and used by health care professionals to attach a syringe for certain medical procedures (not typically done by those who self catheterize).
Note, you should always consult with your doctor on the type of catheter that is right for you and the proper use of a catheter. Each person is different and may have different requirements.