The retroperitoneal space (retroperitoneum) is the

anatomical space {{set index article In anatomy, a spatium or anatomic space is a space (cavity or gap). Anatomic spaces are often landmarks to find other important structures. When they fill with gases (such as air) or liquids (such as blood) in pathological ways, ...

(sometimes a potential space) behind (''retro'') the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mes ...

. It has no specific delineating anatomical structures. Organs are retroperitoneal if they have peritoneum on their anterior side only. Structures that are not suspended by

mesentery The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intesti ...

in the abdominal cavity and that lie between the parietal peritoneum and abdominal wall are classified as retroperitoneal. This is different from organs that are not retroperitoneal, which have peritoneum on their posterior side and are suspended by mesentery in the abdominal cavity. The retroperitoneum can be further subdivided into the following: *Perirenal (or perinephric) space *Anterior pararenal (or paranephric) space *Posterior pararenal (or paranephric) space

Retroperitoneal structures

Structures that lie behind the

are termed "retroperitoneal". Organs that were once suspended within the abdominal cavity by

but migrated posterior to the peritoneum during the course of

embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

to become retroperitoneal are considered to be secondarily retroperitoneal organs. * Primarily retroperitoneal, meaning the structures were retroperitoneal during the entirety of development: ** urinary ***

adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex ...

s ***

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

s *** ureter ** circulatory *** aorta *** inferior vena cava ** digestive ***

anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segme ...

* Secondarily retroperitoneal, meaning the structures initially were suspended in

and later migrated behind the peritoneum during development ** the

duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine m ...

, except for the proximal first segment, which is intraperitoneal ** ascending and descending portions of the colon (but not the transverse colon, sigmoid and the cecum) ** pancreas, except for the tail, which is intraperitoneal

Subdivisions

;Perirenal space It is also called the perinephric space. Bounded by the anterior and posterior leaves of the renal fascia. It contains the following structures: *

Adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex ...

Kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

* Renal vessels * Perirenal fat, which is also called the "adipose capsule of the kidney" and may be regarded as being part of the renal capsuleUniversity of Michigan
- Lab Manual - Kidneys & Retroperitoneum ;Anterior pararenal space Bounded by the posterior layer of

and the anterior leaf of the renal fascia. It contains the following structures: *

Pancreas The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an ...

* Ascending and descending colon *

Duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine m ...

;Posterior pararenal space Bounded by the posterior leaf of the renal fascia and the muscles of the posterior abdominal wall. It contains only fat ("pararenal fat"), and is also called the "paranephric body", or "pararenal fat body".

Clinical significance

Bleeding from a blood vessel or structure in the retroperitoneal such as the aorta or inferior vena cava into the retroperitoneal space can lead to a retroperitoneal hemorrhage. * Retroperitoneal fibrosis * Retroperitoneal lymph node dissection It is also possible to have a

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

in this area, more commonly a

metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, the ...

; or very rarely a primary neoplasm. The most common type is a

sarcoma A sarcoma is a malignant tumor, a type of cancer that arises from transformed cells of mesenchymal ( connective tissue) origin. Connective tissue is a broad term that includes bone, cartilage, fat, vascular, or hematopoietic tissues, and sar ...

followed by

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include en ...

, extragonadal germ cell tumor, and Gastrointestinal stromal tumor/GIST. Examples of tumors include ** Primary retroperitoneal carcinoma ** Pseudomyxoma peritonei **Examples of sarcomas include: ** Soft-tissue sarcoma *** liposarcoma ***

leiomyosarcoma Leiomyosarcoma is a malignant (cancerous) smooth muscle tumor. A benign tumor originating from the same tissue is termed leiomyoma. While leiomyosarcomas are not thought to arise from leiomyomas, some leiomyoma variants' classification is evolvi ...

*** Undifferentiated pleomorphic sarcoma, a clinically distinct sarcoma of the area

References

{{Authority control Abdomen

Retroperitoneal structures

Subdivisions

Clinical significance

See also

References