What is Retroperitoneal?

"Retro" is a prefix referring to the state of being prior to, located behind or in back of something. "Peritoneal" is a term referring or relating to a structure in the abdomen known as the peritoneum. "Retroperitoneal," therefore, is a term meaning behind, in back of or posterior to the peritoneum, which is a membrane that serves as a lining for the anatomical space in the abdominal cavity.

The retroperitoneal space technically is outside of the peritoneum, between the abdomen and the back. It sometimes is referred to as the retroperitoneum or extraperitoneum because of its location. This space is not specifically delineated by any abdominal structure, rather organs are said to be in the retroperitoneum if they are lined by peritoneum only on their anterior side.

The peritoneum that lines the abdominal cavity is known more specifically as the parietal peritoneum, and the lining of the actual organs located in the abdominal cavity is referred to as the visceral peritoneum. Retroperitoneal organs and structures include the right and left kidney, the pancreas and the aorta, which is the largest artery in the body. There are other organs and structures within this space as well. They include the bladder and adrenal glands; the inferior vena cava, which is the largest vein in the body; and part of the esophagus, the structure leading to the stomach.

When there is injury to any of the organs within the retroperitoneal space, pain and various sensations almost always will be felt in the patient's back. For example, in the case of an abdominal aortic aneurysm, a person often will complain of a tearing sensation in his or her back. An aneurysm is the dilation or ballooning of a section of the wall of an artery that has been weakened by disease or injury. Kidney stones, infection or kidney disease also could cause pain and strange sensations in the back, because the kidneys are located within the retroperitoneal space. Another serious medical condition that can occur in this space is known as a retroperitoneal pregnancy, which means that the baby is developing outside of the uterus.

Study of the retroperitoneal space usually is limited to books and courses used and taken by students of medicine or paramedicine. These people must take intensive courses in anatomy and physiology because of their legal permission to administer drugs. This knowledge also is needed to fulfill their responsibility to do patient assessments. Unique health problems affecting the retroperitoneum include hemorrhage or bleeding, lymph node dissection and fibrosis.