Which endoscopic procedure involves the introduction of a tube directly into the stomach through the abdominal wall?

The procedure that involves the introduction of a tube directly into the stomach through the abdominal wall is known as percutaneous endoscopic gastrostomy (PEG). This technique is used to provide nutrition to patients who cannot ingest food orally due to various medical conditions. During a PEG procedure, an endoscope is used to visualize the stomach and guide the placement of a feeding tube through a small incision in the abdominal wall directly into the gastric cavity. This allows for long-term nutritional support and is particularly useful for patients with swallowing difficulties or other contraindications to oral feeding.

In contrast, endoscopy refers broadly to the examination of internal structures using an endoscope and does not specify a particular procedure or access point. Proctoscopy is a specific type of endoscopy that focuses on the rectum and lower part of the colon, making it unrelated to the stomach. Capsule endoscopy involves swallowing a small capsule with a camera that takes images of the gastrointestinal tract as it passes through, again, not involving direct access through the abdominal wall. Thus, only the percutaneous endoscopic gastrostomy option is directly related to placing a tube into the stomach through the abdominal wall.