Comprehensive Study Guide on Urinary Catheters and Surgical Techniques

Anatomy and Applications of the Foley Catheter

The Foley catheter (Sonda Foley) is defined as a flexible urinary probe, typically manufactured from materials such as latex or silicone. This medical device is designed to facilitate the drainage of urine from the human body by being introduced through the urethra until it reaches the interior of the bladder. Due to its design and retention mechanism, it is classified as a permanent or indwelling (permanente) catheter. A primary characteristic of the Foley catheter is the presence of an inflatable balloon located at its tip. This balloon is inflated with a sterile solution once the catheter is in position, serving to keep the probe securely fixed inside the bladder.

Foley catheters are differentiated by the number of lumens or vias they contain. A 2-way (2 vías) catheter consists of one channel for the drainage of urine and a second channel specifically for the inflation or deflation of the retention balloon. A 3-way (3 vías) catheter expands on this by including a third channel intended for continuous irrigation. This specific configuration is utilized for performing bladder irrigations (lavaje de la vejiga) and for the elimination of small blood clots (pequeños coágulos). Such catheters are frequently indicated following prostate surgery (después de cirugía de próstata), in which case a larger caliber, such as $22-24\,Fr$, is employed. During the irrigation process, solutions such as physiological saline (suero fisiológico) or distilled water (agua destilada) are used to fill the bladder.

Temporary and Specialized Probes: Nelaton and Beguille

The Nelaton catheter is described as a flexible probe intended for temporary or intermittent use rather than long-term placement. Its primary function is to empty the bladder. Unlike the Foley model, the Nelaton catheter does not possess an internal balloon for fixation. In terms of physical dimensions, it typically has a length of approximately $35-40\,cm$ and comes in calibers ranging from $4-18\,Fr$.

The Beguille catheter (often associated with Tiemann-type probes) is a semi-rigid device characterized by a specialized curved and conical tip. This design is specifically tailored for patients with Benign Prostatic Hyperplasia (HPB, or Hiperplasia Prostática Benigna). The probe features a specific angulation of $40^{\circ}$, which is intended to facilitate its passage through the prostatic urethra, a site that often becomes significantly angulated due to prostatic enlargement. The tip is rounded and traumatic to ensure it does not generate "false urethral passages" (falsas vías uretrales) during insertion. Since it lacks an internal balloon, the Beguille catheter must be secured externally; a stitch (punto) is placed in the skin to fix the probe and prevent it from slipping out.

Suprapubic and Ureteral Catheterization: Pezzer and Double J

The Pezzer catheter is a semi-rigid medical probe consisting of a single lumen and a straight body. The distinguishing feature of this catheter is its tip, which is shaped like a mushroom (punta con forma de hongo). It is primarily placed via a suprapubic or renal route. This device is indicated to facilitate the direct drainage of urine from the kidney in the event of an obstruction. It enters the bladder through a surgical incision made above the pubis (vía suprapubica), which is necessary when the urethra is either injured or completely obstructed. For fixation, it is secured to the skin using a suture (punto de sutura). The Pezzer catheter typically features a caliber of $16-18\,Fr$ and a total length of $24-28\,cm$.

The Double J Catheter (Catéter Doble J) is a specialized ureteral device that takes its name from the "J" shape present at both of its tubular ends. This catheter, which has a diameter of roughly $3-4\,mm$, is placed along the length of the ureter. Its essential functions are to maintain the permeability of the ureter and to permit the passage of urine from the kidney down to the bladder when there is an obstruction. Furthermore, it is used following surgical procedures on the ureter to favor the healing (cicatrización) process. After a period of months, the surgeon typically removes the Double J catheter via a cystoscopy (cistoscopía) procedure.

Materials and Surgical Techniques for Catheterization

A standard urinary catheterization (sondaje) requires a specific array of materials to ensure sterility and patient safety. These include sterile gloves (guantes), iodopovidone (iodopovidona) for antisepsis, gauze (gasas), and syringes in volumes of $10\,ml$ and $20\,ml$. Lubrication is provided by lidocaine jelly (lidocaina en jalea). The catheter itself is often a Foley probe of $16-18\,Fr$, which is connected to a collection bag (bolsa colectora). Physiological solution ($0.9\%$) is used to inflate the retention balloon. A fundamental component of the surgical setup is the "pinza de campo" (forceps), which is used to pick up and manipulate the catheter.

The surgical technique for male patients involves the following sequential steps: 1. Conduct antisepsis of the glans penis. 2. Apply lidocaine jelly for local anesthesia and lubrication. 3. Elevate the penis to straighten the urethral path. 4. Introduce the catheter. 5. Verify the successful exit of urine. 6. Inflate the retention balloon. 7. Connect the catheter to the collection bag.

For female patients, the surgical technique is as follows: 1. Separate the labia minora (labios menores) to visualize the urethral meatus. 2. Perform antisepsis and apply lidocaine jelly. 3. Introduce the catheter through the urethra. 4. Verify the output of urine to confirm correct placement. 5. Inflate the balloon inside the bladder. 6. Connect the catheter to the collection bag.