Omental Infarction and Epiploic Appendagitis Scott Nguyen MD Oct 10, 2006

Epiploic Appendagitis Small adipose protrusions from serosal surface of colon 50-100 located along taenia throughout colon Most located at sigmoid or rectum, cecum Supplied by small artery and vein through the narrow pedicle Mobility of the fat-laden heavy appendix makes it prone to torsion, kinking, or stretching resulting in venous thrombosis

Omental Infarction Segment of Omentum succeptible to infarction as a result of torsion or venous thrombosis Primary and Secondary Predilection for Right Abdomen Primary and Secondary Secondary – associated w/ another intraabdominal process (omental cyst, hernia, tumor, adhesion, post surgery) Predilection for Right Abdomen d/t abnormality in embryonic formation of the Right side of the omentum and Right epliploic vessels Right omentum longer and more mobile

Risk Factors for Torsion or Infarction OBESITY Fat accumulation in appendices – pedunculated nature and mobility increase chances of torsion Fat deposition may outgrow the bloody supply predisposing to ischemia Heavy exercise and excessive stretching – excess movement of omentum

EA – prevalence in LLQ often misdiag as diverticulits OT – R abdomen…cholecystitis or appy European Radiology 1999 1886-92

Epiploic Appendigits J Clinical Ultrasound 2002 30:481-95 Only few series in literature…..few cases over many years Concentrated in LLQ Since diverticulitis was often working diagnosis, CT was method of choice in diagnosing these Often initially thought to be diverticulitis CT confirmed that was EA J Clinical Ultrasound 2002 30:481-95

Epiploic Appendagitis often misdiagnosed as Diverticulitis Retrospective Korean study comparing 8 EA to 18 Diverticulitis Often confused for Diverticulitis EA – no assoc GI sx, few w/ fever and leukocytosis IF do BE then will see no diverticulitis and see mass effect from appendix inflammation

Omental Infarction More often found at exploration for possible appendicitis Higher likelihood of resection Several reports in children, especially obese

Normal Epiploic Appendices

US normal epiploic appendices

CT Epiploic Appendagitis Typical CT findings -- central hypodensity is fat of appendix, w/ surrounding inflamm rim Adjacent colon is normal Inflamm can adhere to anterior abd wall

Tendency to Abut abdominal wall

Sometimes can see central hyperdensity w/in append -- area of necrosis or hemorrhage, or thrombosis 2nd image w/ normal contrast filled diverticula

Sonogram Sonographic findings – hyperechoic ovoid lesion, Hypoechoic rim. Hypoechoic center – necrosis. US easy cause these usu right underneath abd wall

Treatment Epiploic Appendagits Conservative No surgery necessary Symptoms treated with analgesics No antibiotics necessary Most literature support Imaging saves patient from exploratory laparotomy Repeat imaging often shows complete resolution of inflammation Occasionally fibrous band or calcified appendage may remain

CT at 6 weeks to see almost resolution of inflammation

Epiploic Appendagitis Rarely complications of nonoperative management 4 cases of abscess formation 1 case intestinal obstruction from adhesions

Omental Infarct Usually ill defined heterogenous fat density if in early stage ( < 15 days) Cake like density

Sometimes can see whorling of omentum……consistent w/ omental torsion

Evolves to a smaller, well defined lesion w/ a continous hyperdense rim > 30 days

Evolutionary changes in omental infarcts Evolutionary changes in omental infarcts. Unlike epiploic appendagitis, which resolves completely upon repeat imaging. F/u imaging usually results in smaller fat lesion w/ hyperdense rim

Evolutionary changes

Micrographs reveal a intense inflammatory infiltrate into the fat

Treatment of Omental Infarction Observation NSAIDS No need for antibiotics Rarely abscess

Largest Series in Literature 40 patients, 1988-1997 20 epiploic appendagitis 11 Omental infarction 9 Unspecified abdominal focal fat infarction All had CT or US No patients had to undergo exploration No antibiotics Most had symptoms resolve w/in 7 days

Appendices Epiploicae “They rarely excite much notice, except to be cursed as an impediment to precise anastomosis of the colon or gratefully acknowledged as an added measure of protection when used to reinforce a precarious suture line.”