28-y-o female with RLQ pain, nausea, low-grade fever, WBC

Zissin R, Head of CT

Meir Medical center

Ac abd. pain - a diagnostic challenge

RLQ - DD• Acute appendicitis (AA)• Epiploic appendagiitis / Omental

infarction - non-surgical mimicker of AA

• GI related: Crohn’s disease (CD), Rt-sided diverticulitis, Inf. enteritis (Yersinia), Perforated cecal ca

• Mesenteric lymphadenitis • Acute GUT pathology:

Ac Pyelonephritis Renal colic

Gynecologic etiology

• The most common cause of RLQ pain and 28% of ac. abdominal pain

• Treated surgically !!! Perforation rate ~ 20%, (more common <9y and >60y)

• The most common emergency in children and pregnant women.

• 6% chance during lifetime for each person• Classic history: periumbilical pain

migrating to RLQ only in 50%, atypical presentation mainly children, women 20-40y, elderly

Acute appendicitis

Imaging modalities in acute abdomen

• Plain abdominal films: supine & erect – LIMITED INDICATIONS

• US – non invasive, no radiation• CT – semi invasive, radiation ! • Contrast media studies: imaging of

bowel only (barium, gastrografin) – radiation

Plain abdominal films - Indications:

1. Detection of free air: Common causes: perforation of hollow viscus, post-operation, peritoneal dialysis

2. Gas (air) distribution: intestinal obstruction – dilated loops, air/fluid levelsdisplaced loops – a secondary sign of mass effect

3. Detection of pathological calcificationsMost common: calculi (20% of gallstones; 80% urolithiasis), vascular, intra-abdominal radiopaque foreign bodies

• Usually insensitive in AA but can suggest an alternative diagnosis

Ultrasound

• Advantages: - Lack of radiation, non-expensive and availability

- Aids in diagnosing alternative causes• Disadvantages :

- Operator dependent !! - Sen 85-90%, Spec 92-96%,

As NPP is too low CT• Mainly in children & childbearing age

women

• Aperistaltic, noncompressible, blind-ended, fluid-filled, tubular structure with distinct wall layers arising from the cecal base

• Outer diameter > 6 mm • Appendicolith • Periappendiceal fluid

collection

Computed Tomography - CT

• Radiation! (excludes pregnancy, consider benefit versus radiation risk)

• Semi invasive exam. – IV injection of CM

19721972

-זהו מכשיר ה-זהו מכשיר הCTCT 19721972 הראשון בעולם משנת הראשון בעולם משנת : : ,ניתן היה לסרוק איתו רק את המח, ניתן היה לסרוק איתו רק את המח – רזולוציה נמוכהרזולוציה נמוכה,, דקות דקות 55זמן סריקת תמונה – זמן סריקת תמונה

20052005

התפתחות בחומרה ותוכנההתפתחות בחומרה ותוכנה -כיום מכשירי ה- כיום מכשירי הCTCT מסוגלים לסרוק את כל הגוף מסוגלים לסרוק את כל הגוף

תוך מספר שניות, במהירות גבוהה וברזולוציה תוך מספר שניות, במהירות גבוהה וברזולוציה מצוינת מצוינת

Type of CT examinations

• Diagnostic study• Interventional

procedure:- F. N. A (fine needle aspiration)

- Diagnostic puncture (bacteriological evaluation)

- Drainage of abscess, fluid collections

• Screening - Virtual colonoscopy- Cardiac CT- Low dose chest CT

Radiation on CT

• Abd CT (~ 500 CXR)(BE-350 CXR, Upper GIT-150 CXR)

• Typical effective dose 10mSv (time provide for equivalent effective dose from background radiation – 3.3y)

• Malignancy risk: 5%/1Sv 1 to 2000

Technical notes – Abdominal CT

• Optimal technique: Oral+IV Contrast Media - Oral (for maximum GIT opacification)

-IV (semi-invasive) ~120cc 2,5-4cc/sec

Optional: - Rectal - Cysto CT • Delayed scan as necessary

5 tissues

densities

Everything should be made as simple as possible, but not simpler.

Albert Einshtein

air ca++

fluidfat soft tissue

Acute Appendicitis• CT diagnosis depends on combined

appendicular and periappendicular signsCT sens. 94-97%; spec. 97-99%; accuracy 93-98%; NPV & PPV 94-98%

• Appendicular signs: distended (>6mm), unopacified thickened wall (>2mm) app. appendicolith

• Periappendicular signs: pericecal fat strandingscecal mural thickening-“arrowhead”

Periap. Abscess

Conservative therapy + P.C. abscess drainage > 3cm

Epiploic appendagitis

• Torsion of EA-infarction and sec. inflammatory changes

• Clinical presentation – L/RLQ signs of peritonitis, mimicking ac. diverticulitis/ appendicitis

• Benign, self-limited course

An oval-shaped fat density with a rim of soft-tissue density juxtaposed to the serosal colonic surface

Crohn’s Disease (CD) - terminal ileitis

• Diarrhea- most common presentation• Gradual, progressive RLQ pain - 45-95%• Role of CT:

In known cases - for detection of:- complications (abscess, enterovesical fistula, perianal disease)- alternative diagnosis (look for the appendix)

* CD may be first diagnosed on CT in pts. presented with acute abdomen – RLQ pain

CT in CD

• Direct imaging of the bowel wall (normal <3mm)

• Secondary signs in surrounding mesentery:-mesenteric vascular engorgement-fluid within the mesenteric root-peri-bowel fat stranding, ”creeping fat”-mesenteric adenopathy

• To guide P.C. interventional procedures

Stones and Obstruction

• Non contrast scan• Determine the level

of obstruction: calculi, and associated parenchymal changes

GOOD LUCKGOOD LUCK