ABD CAVITIES
ANATOMY
Peritoneum: thin membrane consisting of a single layer of mesothelial cells that are supported by subserosal fat cells, lymphatic cells, and WBCs.
Visceral: lines surface of organs
Parietal: lines outer walls of peritoneal cavity
Mesentery: fatty folds containing a network of blood vessels and lymphatics sandwiched b/n layers of peritoneum. There are 3 true mesenteries that each supply a portion of the bowel and connect to the posterior abdominal wall.
SB mesentery: supplies both the jejunum and ileum. Oriented obliquely from the ligament of Trietz in the LUQ to the ileocecal junction in the RLQ.
Transverse mesocolon: mesentery to the transverse colon connecting the posterior transverse colon to the posterior abd wall.
Divides peritoneal cavity into supramesocolic and inframesocolic compartments
SB mesentery divides inframesocolic compartment into L and R infracolic recesses.
Sigmoid mesentery: mesentery to the sigmoid colon.
Greater and lesser omentum are specialized mesenteries that attach to the stomach. They DO NOT connect to the posterior abd wall.
Greater omentum: large, drape-like mesentery in the anterior abdomen, which connects the stomach to the anterior aspect of the transverse colon.
Lesser omentum: connects stomach to liver.
ACUTE ABDOMEN
PERITONEUM
ABDOMINAL CYSTIC LESIONS
RSNA APPROACH TO CYSTIC LESIONS IN ABD.pdfMESENTERY
RETROPERITONEUM
RETROPERITONEAL HEMORRHAGE
Hemorrhage in the RP or posterior abd wall mm; high attenuation poorly marginated collection that initially accumulates near site of bleeding and can spread throughout RP and even into thigh, genitals, abd walls, and peritoneum.
Look for associated findings to locate cause:
Coagulopathy/AC: high density collection w/ cellular-fluid level (hemotocrit sign) +/-bleeding into several spaces
Relatively common finding in hospitalized and chronically ill patients, especially those on systemic AC.
Trauma: pelvic fx, spine trauma, renal/adrenal, and vascular injury
Ruptured AAA: large eccentric aneurysm; draped aorta, disrupted calcs with periarotic hematoma +/- active extravasation contiguous w aorta.
Active bleeding: linear, flame-shaped density, isodense to vessels
Sentinal clot sign: high attenuation (60-80 HU) layering along organ of origin.
Chronic hematoma: lower density (20-40 HU) w rim enhancement.
Spontaneous perirenal hemorrhage: consider underlying tumor, vasculitis, or coagulopathy.
Source of bleeding is most often venous, but arterial (particularly aortic) bleeding has a much more ominous prognosis and must be ruled out.
Though NECT is sufficient to diagnose RP hemorrhage, if there is concern for active bleeding requiring intervention, need to get multiphase CTA.
TX
Coagulopathic bleeds: most are self-limited, require no intervention beyond stopping medicine and supportive care such as infusion of blood products.
Active bleeds: angiographic embolization.
Surgery: ruptured aneurysm, tumor, trauma, presence of severe motor dysfunction or abd compartment syndrome.
SOFT TISSUE SARCOMAS
RSNA SARCOMA OF ABD PELVIS PART 1.pdfRSNA SARCOMA OF ABD PELVIS PART 2.pdfABDOMINAL WALL
RSNA IMAGING OF ABD WALL MASSES.pdf