G-Tube Bumpers: Internal and External Fixation Devices
The two round plastic pieces below a new gastrostomy tube are the internal bumper (inside the stomach) and the external bumper (against the abdominal skin), which work together to secure the tube by sandwiching the stomach and abdominal wall between them.
Function and Positioning
These bumpers serve as the primary retention mechanism for gastrostomy tubes:
- The internal bumper sits against the gastric mucosa on the inside of the stomach wall 1
- The external bumper rests against the skin on the outside of the abdominal wall 1
- Together, they create compression that holds the anterior stomach wall against the anterior abdominal wall, maintaining the gastrostomy tract 1
Critical Positioning Guidelines
The external bumper must be positioned approximately 1 cm or more from the abdominal wall to allow free movement of at least 5 mm 1. This spacing is essential because:
- Excessive tension between the internal and external bumpers can cause serious complications 1
- Too-tight positioning leads to pressure-related skin lesions and local ischemia 1
- Proper spacing prevents the most common complication: wound infection (occurring in approximately 15% of cases) 1
- Adequate space reduces risk of buried bumper syndrome, where the internal bumper migrates through the gastric wall (occurs in 0.3%-2.4% of patients) 1
Proper Care and Maintenance
To maintain appropriate bumper positioning:
- Use a Y-compress or cut drain sponge placed OVER (not under) the external bumper to cushion movements and avoid applying excessive tension 1
- The tube should be pushed approximately 2-3 cm ventrally and carefully pulled back to the resistance of the internal fixation flange during dressing changes to prevent adhesions 1
- Daily inspection during the first 7-10 days is critical to ensure the external bumper maintains at least 5 mm of free movement 1
Common Pitfall to Avoid
The most critical error is placing the external bumper too tightly against the skin. This mistake causes:
- Local ischemia and tissue necrosis 1
- Increased infection risk 1
- Buried bumper syndrome, where the internal bumper erodes through the gastric wall into the abdominal wall 1, 2
- Gastric ulceration and potential hemorrhage 1, 3
Always ensure the external bumper can move freely at least 5 mm along the tube shaft 1.