A gastrostomy tube -- commonly abbreviated as "G-tube" -- is a tube that is placed into your child's stomach. The word "gastrostomy" comes from two Latin root words for "stomach" (gastr) and "new opening" (stoma). This tube is used to give your child an alternate way to get their fluid, nutrition, and / or medications. It may also be used to vent your child's stomach for air.
The tube stays in your child's stomach because there is a bumper at the end of the tube inside the stomach, and there is a plastic piece around the tube outside the child's body. These keep the tube from sliding in and out of the opening. The plastic piece should not slide around on the tube. The tube should be able to move in and out of the child's stomach just slightly. The plastic bar should be snug against the skin (about the depth of a dime), but it should not cause pressure. You may need to loosen or tighten the plastic piece if your child gains or loses weight.
At the end of the tube there is a feeding adaptor and medicine port. These connect to a syringe or feeding set to deliver nutrition and / or medications. The adaptors close at the end when you aren't using the tube.