Everything there is to know about catheters 

Catheters are one of the most used hospital consumables. A catheter is a soft/slightly flexible, hollow tubular device with an inflatable balloon component used to drain urine from the bladder. Catheters are made from a rubber material, polyvinyl chloride plastics, or silicone material. The removal of urine from the kidneys is crucial. When not drained as at when due, retained urine is dangerous to the kidneys. There can be backflow, growth of microorganisms, or harm to the organs from the toxic components of the urine. There are some specialized male and female catheters. They are mostly used for a short period until a patient regains the ability to drain urine by him/herself. 

History of catheters

The idea of a catheter has been around since as early as 3000BC. Several materials such as leaves, straw, copper, gold, silver, brass, onions, etc. were used in the early days. Ductile catheters were introduced in around the 11th century, but the silver was the most widely used material then. It is flexible enough and has some antiseptic properties too. Benjamin Franklin, a colonial statesman, first developed it. 

Rubber catheters became very popular in the 19th century. At first, there were many complications, but the advent of rubber vulcanization resolved this. Rubber vulcanization made the rubbers firmer and more durable. Dr. Frederic Foley developed the modern latex balloon rubber in 1935. This classic design is still widespread today, and they are regarded as Foley catheters. The French (Fr) scale used for the measurement of the external diameter of catheters was developed by Joseph Charriere, a manufacturer of surgical instruments in the 19th century. 1 French (Fr) is equivalent to 0.33 mm. This scale is still in use till today. 

Despite antiseptic principles, some patients still contract infections from catheterization. This led to the development of sterile intermittent catheterization, made possible through the efforts of Sir Ludwig Guttman and Dr. Jack Lapides of the University of Michigan. Now, intermittent sterile catheterization is the gold standard for intensive care. 

Indications to use a urinary catheter

A urinary catheter is used to gain access to the contents of a bladder. The bladder gets decompressed, and the contents are drained through the tube into a urine bag. The conditions where this becomes applicable include urinary retention or urinary incontinence. It is also applicable when a person (with good urinary health) cannot control how and when they urinate. This can be due to altered mental status, unconsciousness, immobilization, and so on. Catheters aid the diagnosis of urogenital bleeding, especially in emergencies. 

The various indications to use a catheter for purposes discussed above include:

  • Urinary flow obstruction. This may be due to kidney stones, bladder stones, severe prostatic hyperplasia, blood clots in the urine, hydronephrosis, pelvic organ prolapse in women, etc.
  • Injury to the nerves of a bladder. An example is a neurogenic bladder or nerve damage from diseases such as Multiple sclerosis, Parkinson's disease, etc. 
  • Spinal cord injury
  • Spina bifida. This is a congenital disability resulting from the poor development or closure of the spinal cord in the uterus. 
  • Surgery on the prostate gland, genital area such as hysterectomy
  • Altered mental status from diseases such as dementia or other Central nervous system disorders
  • Medications that cause urinary flow or bladder obstruction. They include antipsychotic agents, antidepressants, opioids, and anesthetic agents. This is as a result of their anticholinergic activity.
  • Hygienic care for bedridden patients
  • Indicated conditions. These conditions include stroke, multiple sclerosis, diabetes complications, and so on. 

The different kinds of catheterization and their indications are highlighted below:

  • Intermittent catheterization. This is indicated for collecting a sterile urine sample or measuring residual urine to diagnose some conditions. This procedure also provides relief to patients experiencing bladder distention. It is also used for intermittent bladder decompression for neurogenic bladder. Intermittent catheterization can also come up during the management of other certain diseases. 
  • Acute indwelling catheterization. This is applicable for post-surgical patients or during surgeries involving the bladder, pelvic, urethra, etc. It is also applicable during any short-term urinary retention or obstruction and generally for very ill patients. This kind of catheterization is used for instilling medication into the bladder.
  • Chronic indwelling catheterization. This is indicated for any situation of long-term urinary retention or obstruction, such as refractory bladder outlet obstruction. It is also used to quicken the healing of perineal ulcers. 


The use of catheters is one of the leading causes of hospital-acquired urinary tract infections (UTI). The symptoms of this may include fever, chills, body aches, cloudy or foul-smelling urine, blood in urine, burning sensations in the urethra or genital region, etc. This is why sterile catheterization is still strictly recommended for intensive care.

Other complications include:

  • kidney injury from long-term indwelling catheterization,
  • kidney stones
  • blood in the urine 
  • allergic reactions to the catheter material (some people are allergic to latex rubber)

Contraindications to the use of a urinary catheter include trauma of any sort to the urethra or lower urinary tract. When not sure or slightly suspected, a urethrogram or retrograde urethrography can be carried out to confirm the suitability of a catheter usage. Signs may include blood at the meatus, perineal or scrotal hematoma, high riding prostate, pelvic fractures, etc. 

Alternative devices

There are some alternatives to using a catheter. However, these alternatives are not applicable all the time. They include an external 'condom' catheter when the male patient is willing and no urinary retention or obstruction is present. Also, urinary incontinence may be managed with bedside commode, urinal, and continence garments. 

The need for catheterization and the kind that is indicated must be confirmed before embarking on the process. 

General specifications of a catheter

The most important specification that identifies a urinary catheter is the external diameter. This is measured using a French (Fr) scale. The scale correlates with the usual measurement scales in that 1 Fr = 0.33mm. Thus, examples of French sizes and their actual external diameter (mm) include Fr 8 (2.66mm), Fr 12 (4mm), Fr 16 (5.33mm), Fr 18 (6mm), and so on.

Other specification parameters include:

  • Overall length- Catheter length from the tip to the end of the funnel
  • Effective length- a length that is available (and that can) for insertion into the body
  • Effective shaft length- free length region of the catheter, that is, excluding the tip, balloon, funnel, access ports, etc.
  • Balloon capacity- This is the volume of liquid that will fill up the balloon up to the point of inflation, usually 10 mL. A compliant balloon expands in size as internal pressure keeps rising while a non-compliant balloon only expands to a specific size or size range regardless of further internal pressure. 
  • Funnel- this is the proximal portion of the device that can be connected to a urine bag.
  • The surface may be coated to enhance lubricity.
  • They are generally made from latex, rubber, silicone, and other polymers.

How to use a catheter

A catheter is inserted into a patient by a nurse or physician. The patient is kept in a supine position with legs considerably spread. With sterile gloves on, the device and the balloon should be checked for any factory errors. The distal portion of the device is coated with a lubricant, and a sterile drape should is used for the process. 

The non-dominant hand should be used to separate the labia or hold the penis as appropriate. The dominant hand should clean the peri-urethral mucosa. Them, the dominant hand, is used to pick up the catheter and insert it (after identifying the urinary meatus) up to 1 or 2 inches beyond where urine is observed. The balloon is then inflated using sterile liquid. Next, the catheter is pulled to move the balloon up, and the attachment to the drainage system should be made.

After these steps, the doctor confirms the device's functionality, discards used materials, and washes his or her hands appropriately. 

Market Leaders

The leading brands of different kinds of catheters include: 

  • Brad- This is a pioneer manufacturer of catheters. The company, Brad Urologic Division, has existed for over 100 years. Their latest product, Magic3 Go Hydrophilic female catheter, is doing excellently in the market. 
  • Coloplast- This is a top brand, founded in 1957. They produce excellent catheters and other devices for ostomy, wound, skincare, and surgical urology. 
  • Compact Cath- This is a leading brand that has revolutionized devices for intermittent catheterization. 
  • Cure- Cure catheters are of different kinds; closed system, Coude, and intermittent straight catheters. They all contain custom-made smooth and polished eyelets for easy insertion. 
  • B Braun- B Braun's Actreen line of catheters is an excellent brand too. Although still available in the market, this product line was discontinued recently in December 2019. 


Catheters have effectively prevented various cases of kidney damage and scarring. Voiding of urine is very important to urinary and renal health. Urinary retention itself might be an indication of renal impairment. More often, there are newer designs of catheters, which shows technological improvements and continual research towards improving the devices.