A urinary catheter is a hollow, flexible tube temporarily or permanently inserted into the bladder to drain urine. This procedure is necessary when a patient cannot empty their bladder naturally due to obstruction, nerve damage, or major surgery. For millennia, practitioners struggled to achieve continuous and comfortable bladder drainage. Early designs caused significant discomfort, trauma to the urethral lining, and a high risk of infection, driving the need for a softer, more reliable solution.
Early Rigid Devices
The earliest forms of urinary catheters date back to ancient civilizations, with records from 3000 B.C. describing the use of hollow reeds and curled palm leaves to relieve bladder congestion. As metallurgy advanced, practitioners transitioned to using rigid tubes made from various metals, including bronze, lead, and silver. These metal devices were often stiff and unforgiving, requiring careful and sometimes painful maneuvering to navigate the curved male urethra.
During the Roman Empire, and later through the 18th century, devices were still primarily composed of metal, which created a constant risk of injuring the internal tissues. While some metal catheters were made malleable to allow for shaping, they remained firm during insertion and could not adapt to a patient’s anatomy. This lack of flexibility meant that catheters could not be left in place for long periods, necessitating repeated, traumatic insertions to manage chronic retention.
The Dawn of Flexibility: Early Attempts
A significant shift toward pliability occurred in the 18th century when American polymath Benjamin Franklin designed a flexible silver catheter for his brother, who suffered from kidney stones. This design was a notable improvement, featuring a coiled, segmented tube that was less rigid than traditional metal rods. The true evolution, however, began with the introduction of natural rubber in the 1700s, offering an unprecedented level of softness compared to metal.
Early rubber catheters were far more comfortable but had a severe drawback: the material often weakened at body temperature, leaving debris inside the bladder. A major breakthrough came in the mid-19th century with the vulcanization of rubber, a process pioneered by Charles Goodyear that greatly increased the material’s strength and durability. This innovation enabled the mass production of stable, soft rubber catheters that did not disintegrate within the body.
French instrument maker Joseph-Frédéric-Benoît Charrière standardized the measurement system for catheter diameters, now known as the French gauge. Other flexible designs emerged, such as the Nelaton catheter, a soft, non-retaining rubber tube with a smooth, rounded tip. While these rubber and gum elastic tubes solved the problem of rigidity, they still relied on external taping or elaborate internal shapes to hold them securely in the bladder.
The Definitive Flexible Design: The Foley Catheter
The inventor of the modern, self-retaining flexible catheter was Dr. Frederick B. Foley, a urologist. Dr. Foley recognized that the challenge for long-term catheterization was the lack of an effective, non-irritating mechanism to keep the tube securely in the bladder. He first described his novel concept in 1929, initially designing it as a device to control bleeding after prostate surgery.
Foley integrated a retention mechanism directly into the catheter tube, creating a dual-channel structure. The main channel acts as the drainage lumen, allowing urine to flow out of the bladder. A separate, smaller channel runs down the length of the tube to a small balloon near the tip.
Once the catheter is inserted into the bladder, sterile water or saline is injected through the second channel to inflate the balloon. The balloon rests against the bladder neck, preventing the tube from slipping out. This simple solution eliminated the need for external straps, tape, or complicated internal retention shapes that had proven unsatisfactory.
Dr. Foley demonstrated his design in 1935, and it was quickly adopted for continuous urinary drainage, not just post-surgical care. The self-retaining feature revolutionized patient care by allowing the catheter to remain safely in place for extended periods. The “Foley catheter” became the standard indwelling device, significantly improving the management of urinary retention and reducing the burden of constant re-catheterization.