1

Acute non-trauma abdomen

Benjamin M Yeh, MD

UC Department of RadiologySFUC Department of RadiologySF

Disclosure

• General Electric: Research Agreement, consultant, speaker

• NIH R01; R21

2

3

Appendix found…is it appendicitis?

• Appendiceal enlargement – Accuracy depends on

threshold» 6 mm: Poor specificity,

many false positivesmany false positives» 12 mm: Poor sensitivity

• Wall Thickening• Periappendiceal fat

stranding• Fascial thickening• Arrowhead sign• Hyperenhancement

Ives, et al. Acta Radiol 2008:15;996-1004

Complications of AppendicitisComplications of Appendicitis

4

Troublesome common scenariosscenarios

Appendix not seen

• If secondary signs present – Probable appendicitis (37-53%)

• If secondary signs absentAppendicitis unlikely (< 2%)– Appendicitis unlikely (< 2%)

• Consider – Coronal / Sagittal reformations– Left lateral decubitus positioning

Ganguli et al, Radiology 2006; 241:175-80Daly, et al. AJR. 2005:184:1813-20

Nikolaidis, et al. AJR. 2004: 183:889-92

5

Normal appendix but secondary signs of inflammation

• 26% appendicitis

• Consider alternate diagnosis– Crohns

– Right-sided diverticulits

– Colitis

– Omental torsion

Daly, et al. AJR 2005:184:1813-20

Radiological appendicitis but no surgical concern

• Patients with CT findings of appendicitis (n=498)– 13 (3%) did not receive treatment

5 (38%) f th 13 b tl– 5 (38%) of these 13 subsequently underwent appendectomy for acute appendicitis within 1.5 yrs

» 4 were perforated

Stengel, et al, Submitted

Alternative diagnosesAlternative diagnoses

6

Right-sided diverticulitis

• Younger mean age than left-sided diverticulutis

R l f t• Rarely perforates

Jhaveri et al. JCAT 2002

CT techniqueCT technique

7

Unenhanced CT

• Sensitivity: 95-96%

• Specificity 92-99%

• Alternate Diagnosis in 35% of true negatives

• Does not assess for hyperenhancement nor gangrene

Lane, et al. Radiology 1999; 213:341-6

Cakirer, et al. Emergency Radiology 2002:9:155-61

Review of CT findings

of bowel ischemia

8

Do CT findings reflect the causeof bowel ischemia?of bowel ischemia?

9

10

11

Bowel Obstruction

Find the transition point

12

SBO: Getting to the point!• Diminishing bowel

contrast– Contrast dilutes out near

the transition point

• Small bowel feces sign Dilated bowel with 30 seconds– Dilated bowel with particulate matter

– Suggests high grade obstruction

• Prior surgical incisions

• Bowel tracking 1 – 2 minutes

Take home points

• Use landmarks to find critical structures– Ileocecal valve appendix– Gonadal vein ovary

• Assess severity of bowel disease– Perforation / gangrene

• Consider alternative diagnoses

• SBO: Use shortcuts to find transition point

Ben.yeh@ucsf.edu