Editing Retroperitoneum (section)

== Gastrointestinal viscera ==

* The non-urologic viscera within the retroperitoneum includes the pancreas, 2nd and 3rd parts of the duodenum, and the colon

=== Pancreas ===
* '''Head''' '''lies anterior to the IVC and is''' '''surrounded by the 2nd portion of the duodenum'''.
** '''This portion is at risk of injury during right kidney procedures'''
* The neck connects the head to the body, which crosses the abdomen anterior to the aorta to the origin of the superior mesenteric artery.
* '''The tail of the pancreas is closely associated with the spleen'''
** '''This portion is at risk of injury during left kidney procedures because of its proximity to the upper pole of the left kidney and left adrenal.'''
** '''In addition, the stomach is anterior to the upper pole of the left kidney and must be accounted for during transperitoneal left renal surgery'''

=== Duodenum ===
* 20-25 cm in length
* May be mobilized medially using a Kocher maneuver to expose these right-sided retroperitoneal structures
* '''Can be divided into 4 distinct parts:'''
*# '''First (superior) portion'''
*#* '''Intraperitoneal'''
*#* Extends from the pylorus to the neck of the gallbladder
*# '''Second (descending) portion'''
*#* '''Retroperitoneal'''
*#* '''Critically important to the urologist because of its proximity to the right renal hilum'''
*#* '''The common bile duct and the main pancreatic duct combine to enter the 2nd portion at the ampulla of Vater (hepatopancreatic ampulla).'''
*# '''Third (horizontal or inferior) portion'''
*#* '''Retroperitoneal'''
*#* '''Crosses the body from right to left and lies posterior to the SMA and anterior to the aorta'''
*# '''Fourth (ascending) portion'''
*#* '''Intraperitoneal'''
*#* Ascends and becomes intraperitoneal as it transitions into the jejunum

=== Colon ===
* '''The ascending colon and hepatic flexure overlie the right-sided retroperitoneal structures, and the splenic flexure and descending colon cover the left-sided retroperitoneal structures.'''
* '''To gain access to the kidneys transperitoneally, the ipsilateral colon must be reflected medially in most instances. This can be performed by mobilizing the colon at the white line of Toldt (see above). Care must be taken to divide the hepatocolic and splenocolic ligaments sharply when necessary to avoid iatrogenic injury to the liver and spleen, which is often due to excessive retraction during attempts to obtain adequate exposure.'''