Although the word “space”, automatically refers our thought to a geometrically defined place or to some space-term of physical science, here we will deal with spaces that are located in the digestive system of the human body, in which until now we considered that there are two such “spaces”, but in recent years a “third space” has also been revealed.
“As “first space” we characterize the lumen, the internal, that is, the cavity of the gastrointestinal or digestive tract -as it is also called-, which consists of the esophagus, stomach, small and large intestine. In this area, the usual endoscopies are carried out.
The “second space” is represented by the peritoneum
cavity, containing everything outside the alimentary canal and inside the abdominal cavity.
The “third space” is an imaginary space, which is essentially “revealed” artificially in practice, and is located inside the wall of the gastrointestinal tract, which consists of several individual layers,” explains Mr. Georgios Katsoras Specialist Gastroenterologist & Interventional Endoscopist, Supervising Gastroenterologist at Metropolitan Hospital and continues: “The basic principle of the ‘third space’ approach is to create a portal of entry initially in the inner lining of the alimentary canal wall, called the mucosa. This is done with the help of special microscopic tools which pass through the endoscopes. Then, a tunnel is created between the layers of the wall, usually the mucosa, and another layer, the one responsible for movement, called the muscularis. This tunnel essentially represents the “third space”.

But why is the “third space” so important?

The “revelation” of this space has been, in recent years, the spearhead of modern gastroenterology, as, based on it, many therapeutic problems of the past were solved. At the same time, the opportunity was given, through this space, for surgical science to attempt in the “second space” and to intervene in various ailments, adjunctively or autonomously.
“It is not difficult to imagine what we could achieve by passing the endoscope through the stomach, for example, in the “second space” (in the peritoneal
cavity) and remove the diseased gallbladder or inflamed appendix. And, today, from imagination we have passed into practice. The first studies have already been carried out with a currently small number of patients who have successfully undergone endoscopic appendectomy and cholecystectomy, while more are expected. However, the very important fact that these patients recovered very quickly, without pain and without external incisions or scars on their abdominal wall, is already recorded in favor of the method. It is now considered a given that in the future, in the achievement of complex operations, both specialties will coexist: gastroenterologists and general surgeons.
But let us return to the “third space” which, curiously, is the intermediate space in terms of the approach of the second from the first space – an approach inconsistent with the transition from number to number as we learned in mathematics (1, 2, 3), as in our case we go from the first to the third and from the third to the second space (1, 3, 2).
In recent years, through the “third space” we have succeeded in the treatment of rare and non-diseases, with a series of new type operations, which are classified as minimally invasive operations, in contrast to the past which required painful surgeries,” the gastroenterologist points out.
Such conditions are achalasia and other esophageal motility disorders, Zenker’s diverticulum, submucosal tumors, and certain polyps.
Achalasia of the esophagus is a rare condition in which, without knowing the cause, there is a gradually worsening contraction of the circular muscle fibers of the wall of the organ, an inability of the lower esophageal sphincter to relax, resulting in difficulty in swallowing and remaining solid foods as well as liquids in the esophagus for a long time.
“In this case, we enter the third space endoscopically, in the way we mentioned above, we cut the problematic muscle fibers with special microknives and restore the smooth functioning of the esophagus and, consequently, swallowing. This method is called POEM and was performed for the first time by the Japanese doctor Haruhiro Inoue. In the same way, we also manage other types of motor disorders of the esophagus (such as diffuse esophageal spasm) or the stomach (such as gastroparesis).
We can also selectively remove tumors that grow within the wall of the esophagus or stomach avoiding a surgical procedure or remove polyps that have infiltrated the deeper layers of the wall (with the ESD technique).
Thus, in recent years, the exploration and management of all three spaces of the gastrointestinal tract with the help of sophisticated endoscopes and methods has made the endoscopic treatment of multiple digestive diseases the only way, because it ensures excellent results painlessly, with minimal complications, without aesthetic residues of surgical operations such as postoperative scars, and with the shortest possible stay in the Hospital”, concludes Mr. Katsoras.