Functions and classifications of pigtail drainage catheter

Pigtail drainage catheter is a commonly used ureteral stent in urology. It has two J-shaped coils at both ends, one end in the renal pelvis and the other end in the bladder. Its core functions are drainage, support, prevention of stricture, and protection of kidney function.

- Drainage of urine, relieving obstruction: Ensures unobstructed urine flow, alleviates hydronephrosis, and protects kidney function when postoperative edema, blood clots, or residual stones cause blockage.
- Support for the ureter, preventing stenosis/adhesion: Opens up edematous or narrowed segments, preventing postoperative ureteral stenosis and closure, and reducing the risk of re-obstruction.
- Facilitate the expulsion of residual stones: Dilates the ureter, creating a pathway for small stone fragments and reducing the risk of residual stones.
- Prevention of urinary leakage and infection: Reduces urine extravasation, and unobstructed drainage reduces the probability of reflux and infection.
- Intraoperative protection: Placed before gynecological/gastrointestinal surgeries to avoid accidental injury to the ureter during surgery.

- Internal Double-J Stent: The entire stent is placed inside the ureter, with one end in the renal pelvis and the other in the bladder. It is not exposed on the body surface and is most commonly used after urinary tract stone surgery or ureteral surgery.
- External Drainage Pigtail Stent (Fistula Tube): One end is coiled and left in the organ/body cavity, while the other end protrudes through the body surface to connect to a drainage bag. Examples include nephrostomy tubes and abdominal/thoracic/abscess drainage tubes.

- Silicone Tubes: Soft, biocompatible, and minimally irritating, suitable for long-term placement.
- Polyurethane (PU) Tubes: Moderately rigid, provide strong support, and ensure smooth drainage; primarily used for short-term post-operative care.
- Alloy-Coated/Antibacterial-Coated Tubes: With an antibacterial coating, reducing the risk of infection and stones; suitable for patients requiring repeated catheterization or those at high risk of infection.

Using French (Fr) as the unit, commonly used clinically are: 4Fr, 5Fr, 6Fr, 7Fr, and 8Fr.

- Small diameter (4–5Fr): For children and those with thin ureters;
- Standard diameter (6–7Fr): The mainstream size for adults;
- Large diameter (8Fr and above): For drainage of blood clots, pus, and large amounts of effusion.

- Standard Single-Loop Pigtail Tube: Single loop at both ends, universal design.
- Multi-Loop/Spiral Type: More loops, stronger fixation, preferred for patients prone to displacement.
- Anti-Slip/Anti-Reflux Type: Built-in anti-reflux valve to reduce kidney infection caused by urine reflux.
- Length Differentiation: Available in adult and pediatric sizes, selected according to ureteral length.

- Standard Single-Loop Pigtail Tube: Single loop at both ends, universal design.
- Multi-Loop/Spiral Type: More loops, stronger fixation, preferred for patients prone to displacement.
- Anti-Slip/Anti-Reflux Type: Built-in anti-reflux valve to reduce kidney infection caused by urine reflux.
- Length Differentiation: Available in adult and pediatric sizes, selected according to ureteral length.