A Farrell bag is a small collection bag that connects to a feeding tube system and acts as a pressure relief valve, allowing excess gas and stomach contents to escape during tube feeding without opening the system to the outside air. It sits between the feeding pump and the patient’s tube, using a Y-shaped connector that lets formula flow in while simultaneously letting built-up pressure vent into the bag. This prevents the nausea, bloating, and vomiting that many tube-fed patients experience when gas and fluid have nowhere to go.
The Basic Mechanism
The Farrell bag works on a simple principle: gravity and pressure equalization. During a tube feeding, formula is pumped into the stomach or intestine at a set rate. But the stomach also produces its own fluids and gas, and some patients can’t move those contents through their digestive tract fast enough. Without somewhere for that pressure to go, the patient feels uncomfortably full or starts retching.
The Farrell system solves this by adding a second pathway. A Y-shaped port splits the line into two directions. One side connects to the feeding pump delivering formula. The other side connects to the Farrell bag, which hangs at roughly the same level as the patient’s stomach. When pressure inside the stomach rises above a certain point, excess gas and fluid travel up into the bag instead of staying trapped. Once the pressure equalizes, the formula from the pump can resume flowing normally into the patient. This back-and-forth happens passively, without any manual intervention.
The key advantage over older methods is that the system stays closed. Traditional venting required disconnecting the feeding tube and leaving the port open to air, which increased the risk of contamination and meant losing formula and stomach contents. The Farrell bag keeps everything sealed. Whatever vents into the bag can, in many cases, drain back down into the feeding tube once pressure normalizes, so the patient still receives the nutrition they need.
How the System Is Set Up
The Farrell bag connects through a Y-port that sits between the feeding pump’s tubing and the patient’s gastrostomy or nasogastric tube. The system has two clamps, typically one white and one blue, that control which direction fluid flows during setup.
To prime the system, both clamps are closed first. The feeding set attaches to the Y-port. Then the white clamp opens, allowing formula to travel a short distance up the tubing toward the Farrell bag. This step is important because it removes air from that portion of the line. Once the tubing toward the bag has a small amount of formula in it, the white clamp closes, the blue clamp opens, and the rest of the feeding line finishes priming as usual. This sequence ensures there are no air pockets that could interfere with the pressure-balancing function.
The Farrell bag itself hangs from an IV pole, positioned so gravity can assist with the flow of vented contents back toward the patient when pressure drops.
What to Watch For During Use
One important detail that catches many caregivers off guard: when a Farrell bag is in use, the feeding pump will not alarm if there is a blockage in the tubing. Normally, a pump detects resistance and triggers an alert when the line is clogged. But with the Farrell system attached, backed-up formula simply diverts into the bag instead of building pressure in the line. The pump keeps running as if nothing is wrong.
This means you need to visually monitor the level of formula in the Farrell bag throughout the feeding. If the bag is steadily filling up and the level isn’t going back down, that’s a sign the feeding tube itself is blocked. The formula is flowing from the pump but can’t get into the patient, so it all routes into the bag instead. If this happens, the blockage needs to be cleared using whatever flushing method your care team has recommended.
If formula continues to back up into the bag and won’t flow down into the feeding tube even after troubleshooting, that’s a reason to contact your healthcare team. Persistent backflow can mean the tube is kinked, displaced, or obstructed in a way that needs professional attention.
Replacement Schedule
The Farrell bag is a single-use disposable device with a maximum recommended use of 24 hours. Standard practice is to change the Farrell bag every time the feed bag is changed. This keeps the system clean and reduces the risk of bacterial growth in the formula residue that collects in the bag and tubing over time.
Who Benefits From a Farrell Bag
Farrell bags are most commonly used in pediatric care, particularly for children with gastrostomy tubes who experience frequent retching, gagging, or bloating during feeds. These symptoms often indicate that the stomach isn’t emptying quickly enough to keep up with the rate of formula delivery, a condition called delayed gastric emptying. The Farrell bag doesn’t fix the underlying motility issue, but it manages the symptoms by giving excess pressure a safe escape route.
Adults with feeding tubes can benefit as well, especially those with gastroparesis or neurological conditions that affect gut motility. For patients who previously needed frequent manual venting (disconnecting the tube and using a syringe to release gas), the Farrell bag can be a significant quality-of-life improvement. It eliminates the need to interrupt feedings, reduces mess, and lets the patient or caregiver sleep through overnight feeds without stopping to vent every hour or two.
The system is also useful for patients transitioning from continuous to bolus feeds, when the stomach is being asked to handle larger volumes and may need time to adjust. By cushioning those pressure spikes, the Farrell bag makes the transition more comfortable and reduces the likelihood of vomiting or feed intolerance.