Catheters – An Introduction

What are catheters? 

A catheter is a medical device resembling a thin, hollow tube that is either flexible or rigid. Catheters are made from medical grade materials and offer a broad range of applications. These medical instruments are are manufactured in order to be used for various applications, including but not limited to cardiovascular, gastrointestinal, urological, ophthalmic, and neurovascular medical situations.

Catheters are commonly inserted in the body duct, cavity, or vessels, and this process is known as catheterization. Contrary to popular belief, catheters or similar devices have been used for thousands of years. In fact, the ancient Sumerians are often cited as the first civilization that invented the device, which was then referred as ‘Katheter’. Let’s take a look at some of the features and uses of catheters in today’s medical field.

Features 

Catheters are constructed by employing a range of polymers such as nylon, silicone rubber, nitinol, latex, polyurethane, polyethylene terephthalate (PET), and thermoplastic elastomers. Of all these materials, silicone rubber is the common choice as it is not only inert but also nonreactive to the body fluids, as well as various medical fluids that may get in contact with it. Polymer, on the other hand, is the weakest material,  causing many fractures in the catheters.

The type of material used in the catheters also depends on its application. For instance, modern intermittent catheters are commonly used for bladder applications and are made of polyurethane with varying sizes for men, women, and children. Thin hydrophilic surface coating produces the most advanced catheters, causing a slippery film when immersed in water for safer and comfortable insertions. Other than the construction material, catheters also come with different tips like filter, caps, and cap for a case that are used in guiding the catheter to the target vessels. 

Uses

The application of a catheter will depend on the body part that it is inserted into. Some of the common uses of catheters include:

• Draining urine from the urinary bladder, also known as urinary catheterization
• Draining urine from kidney(s) by nephrostomy, usually inserted through the skin
• Draining of fluids, like an abdominal abscess
• Administering intravenous fluids, parenteral nutrition, or medications with a peripheral venous catheter
• Used in angiography, angioplasty, balloon sinuplasty, balloon septostomy, catheter ablation, and cardiac electrophysiology testing, all of which employ the Seldinger technique
• Measuring blood pressure directly in a vein or artery
• Measuring intracranial pressure directly
• Administering anesthesia into epidural space, subarachnoid space, or near brachial plexus
• Administering oxygen, breathing gasses, and volatile anesthetic agents directly to the lungs with the help of a tracheal tube
• Subcutaneous administration of insulin using an insulin pump and infusion set
• Administering fluids or drugs into the vein near the heart or inside the atrium via central venous catheter
• Administering artificial insemination via an intrauterine catheter that washes away sperm directly into the uterus

Catheters for Men

Catheters are available in a variety of shapes, sizes, and designs. These design specifications are based on individual users – men and women. If you are in need of catheters, here’s a look at three of the best male catheters available in the market:

1. Male Intermittent Catheters

A typical male intermittent urinary catheter is 16 inches long and is available in French sizes 10Fr to 24Fr. Other variations, such as 12-inch, is also available. Plastic, vinyl, red rubber and silicone are some of the most popular catheter materials used.

Intermittent catheters are widely recommended for men suffering from any spinal cord injuries (such as quadriplegics and paraplegics) that make urination difficult. They are also used in conditions that lead to urinary retention issues or incomplete bladder emptying.

These catheters also come in hydrophilic and antibacterial varieties. Antibacterial catheters contain Nitrofurazone – which is effective against some Gram-positive bacteria. The protective coating sustains and nurtures the integrity of urethral mucosa and keeps you safe from Urinary Tract Infections (UTIs).

2. Male External Catheters

Unlike intermittent catheters, an external catheter is not connected to your bladder. It consists of a sheath or outer covering, attached to a urinary catheter bag, which is placed on your urinary organ. For this reason, an external catheter is also known as a condom catheter or a Texas catheter.

Condom catheters are made from latex rubber, silicone or polyvinyl and are attached to the tip of the penis with the help of a jockey’s type strap, latex inflatable cuff, double-sided adhesive or a foam strap.

Texas catheters are attached to urine bags with a drainage tube. The urinary bag should be cleaned at least twice a day and disposed after a month of use. Some condom catheters are reusable and are ideal for men who suffer from persistent urinary incontinences.

Reusable condom catheters are also recommended for men who have undergone a major prostate surgery and experience urinary incontinence but do not want to wear adult diapers. If you have just undergone any prostate-related surgery, it is best to use a Texas catheter.

3. Male Indwelling Catheters

A male indwelling catheter is also known as a Foley catheter for men. It consists of a closed, sterile system catheter which is inserted into the urethra. This allows the bladder to drain. For men, the recommended size for an indwelling catheter should be up to 16 inches in length.

Indwelling catheters tend to be unisex. They can be used by both men and women suffering from urinary incontinences due to an obstruction or blockage in the urethra or incomplete bladder emptying after urination.

Indwelling catheters are also recommended for sick and terminally ill men. In some cases, the incontinence hinders monitoring of urinary output quantity- requiring an indwelling catheter to fix the problem. Such catheters need to be replaced every four weeks.

Catheters for Women

When it comes to dealing with urinary incontinences, patients have a variety of catheters to choose from. With the advancement in technology, new and improve urinary catheters are being produced that keep the individual safe from infections and provide lasting relief.

Consulting your physicians is the first step towards choosing the right catheter for yourself. Catheters are typically divided into two broad heads: the male and female catheters. The differentiation is due to catheters being designed according to a shape of urinary organs of both genders.

If you are a woman suffering from urinary incontinences, here is what you need to know about catheters:

Size of the Catheter

The female catheter is six inches long and comes in French sizes 8Fr-24Fr. These are the standard dimensions for female catheters. This French catheter scale (French units or Fr) measures the outer diameter of catheters, needles and a range of other surgical instruments.

1Fr is equal to 0.33mm. This corresponds to 0.13 inches or about 1/77 inch in total diameter. Therefore, the Fr denotes the circumference of a catheter in millimeters. If you are shopping for catheters online, make sure that your catheter falls within the prescribed Fr range for women.

Types of Catheters

For all practical purposes, there are no “specified” catheters for men and women. Most of them are designed to be unisex. However, their dimensions vary – depending on whether they are designed for men or women.

Here is a look at some of the most popular female catheters:

1. Intermittent

Intermittent catheters are used by women suffering from urinary retention, incomplete bladder emptying or any spinal cord injury. They contain antibacterial properties that keep you safe from urinary tract infections.

Furthermore, they have a hydrophilic coating which absorbs and binds water to the catheter to create a thick and slippery surface that can easily be placed around your urethra and keep the body part lubricated.

Hydrophilic Intermittent catheters are highly demanded and extremely popular among women. These catheters are easy to apply, do not itch or irritate and lead to patient satisfaction. They also keep the urethra moist and reduce the risk of urethral damage, due to friction.

2. External

Women can also opt for an external catheter, which is connected to an external urine bag through a drainage tube. The catheter drains pass urine to a urine bag, which is then emptied and reused. However, female external catheters are impractical for bed-ridden elderly women.

3. Indwelling Catheters

Indwelling catheters are also known as Foley catheters. The female Foley catheter ranges from 12Fr to 18Fr. Foley catheters are unisex. They can be used by women suffering from bladder obstructions and urinary retention. Moreover, a Foley catheter is recommended by doctors and physicians whenever alternate methods to drain urine (such as medication, surgery or sterile intermittent catheterization) fail.

Whenever a suprapubic procedure is in order, doctors insert an intermittent catheter into a woman’s lower abdomen, through a small incision. Hydrophilic Foley catheters work best for this process. The catheter is also used after a hysterectomy procedure when most women find it difficult and painful to urinate.