Principles of Drainage
Executive Summary
Surgical drains are specialized devices designed to evacuate intraperitoneal fluid collections for diagnostic, prophylactic, or therapeutic purposes. While diagnostic drains assess fluid to establish a diagnosis, prophylactic drains are frequently utilized in upper gastrointestinal surgery to prevent harmful accumulations (such as bile or pancreatic juice) or to detect early postoperative complications like anastomotic leakage or hemorrhage. Therapeutic drainage is reserved for managing established infected collections, such as abscesses or bilomas.
The selection of a drainage system is primarily determined by the mechanism of action—passive versus active—and the clinical objective. Current evidence suggests a shift toward closed-suction active systems to minimize retrograde infection risks. Furthermore, the routine use of prophylactic drainage is increasingly scrutinized, with specific evidence-based recommendations suggesting "no drain" for several common procedures, including laparoscopic cholecystectomy and hepatic resections without biliodigestive anastomosis.
Functional Classification of Drains
Drains are categorized based on their mechanical operation and the type of system (open vs. closed).
Passive Drains
Passive systems, such as Penrose and Easy Flow devices, rely on natural pressure gradients, gravity, muscle contraction, and overflow to evacuate fluid.
Mechanism: They provide a secondary route of access but cannot be sealed.
Design: Easy Flow drains often feature intraluminal corrugations (inlays) to prevent total collapse of the tube.
Requirement: The abdominal wall opening must be large enough to accommodate the drain, as these devices are potentially collapsible.
Active (Closed-Suction) Drains
Active drains, such as Jackson-Pratt and Blake drains, maintain a negative pressure gradient to facilitate fluid removal.
Jackson-Pratt: Oval-shaped with numerous orifices and intraluminal corrugations.
Blake: Features four channels along the sides with a solid core center.
Material: Typically radiopaque silicone products.
Comparative Analysis of Drain Systems
The following table outlines the clinical trade-offs between open (passive) and closed-suction (active) systems:
Sump Drains
Sump drains are double- or triple-lumen tubes designed for high-volume or thick collections.
Mechanism: A large outflow lumen is connected to suction, while a smaller lumen serves as a vent to allow air to enter. This breaks the vacuum at the tube tip, preventing surrounding tissues from occluding the drainage holes.
Lavage: Some models include a third lumen specifically for the instillation of lavage solutions.
Prophylactic Drainage Principles
Prophylactic drainage aims to manage expected fluid collections that could lead to intra-abdominal abscesses or to provide early warning of postoperative complications.
Placement and Technique
Drain Orifice: Created via a penetrating cut with a scalpel. A Kelly clamp is typically used to penetrate the abdominal wall diagonally, creating a tunnel that helps seal the cavity upon drain removal.
Anatomical Targets: Drains are placed in spaces prone to fluid accumulation, including:
Subhepatic space
Right subphrenic space
Left subphrenic space
Parapancreatic space
Perianastomotic Drainage
When used to detect anastomotic leaks, drains should not be placed in direct contact with the anastomosis. Instead, a safety margin is required to prevent drain-related erosions or pressure-induced leaks.
Evidence-Based Recommendations for Prophylactic Use
The routine use of drains is controversial. The following table summarizes recommendations based on surgical procedure:
Therapeutic Drainage and Catheter Management
Therapeutic drainage is indicated for infected collections like abscesses or bilomas. These typically occur in specific anatomic spaces, including Morison’s pouch, the left subhepatic space, and the omental sac.
Percutaneous vs. Surgical Drainage
The choice between percutaneous (radiologically guided) and surgical intervention depends on the complexity of the collection:
Catheter Technology
Most postoperative collections are managed percutaneously using standard aseptic techniques under ultrasound or CT guidance.
Techniques: Seldinger or trocar techniques.
Self-Locking (Pigtail) Catheters: These feature "memory" to maintain a loop shape at the end, preventing displacement. A radiopaque band identifies the proximal area of the loop.
Insertion: A stylet is introduced intraluminally to straighten the catheter for insertion; once the stylet is removed, the loop reforms.
Best Practices in Drainage Management
Successful drainage requires adherence to specific technical "tricks" to ensure efficacy and patient safety:
Infection Control: Use closed drain systems whenever possible and minimize the duration of drainage to reduce retrograde infection risks.
Safety Margins: Place drains near, but never in direct contact with, anastomotic sutures to avoid drain-induced erosions.
Vascular Safety: Position intraperitoneal drains so they do not rub against or lie in direct contact with blood vessels or hollow organs.
Functional Assessment: Do not rely on a drain if it is non-productive but clinical suspicion of a collection remains; drains can be occluded by tissue or debris.
Fluid Limitations: Drains are often ineffective at evacuating thick blood clots or very viscous bleeding.
Guidance: Difficult-to-reach collections should be manipulated and positioned under fluoroscopic guidance by interventional radiologists.
