Acute Abdominal Pain and CT

CT in AcuteAbdominal Pain

Mindy M. Horrow, MD, FACR

Director of Body Imaging

Albert Einstein Medical Center

All photos retain the copyrights of their original owners

•Technique

•Gastrointestinal Tract

•Pancreas

•Biliary System

•Spleen

•Genitourinary Tract

•Vascular System

CT Protocol

•Intravenous contrast

•Oral contrast

•Timing, acquisitions

•Collimation

*Clear communication betweenradiologist, patient and referringclinician is essential to narrowdifferential diagnosis and tailor CT exam

Introduction

•Acute abdomen: Severe abdominalpain developing rapidly

•Fast, accurate diagnosis essential todecrease morbidity and mortality

•CT has accuracy of 95% in thesepatients

Taorel et al: Gastrointest Radiol 1992; 17:287

Siewert et al: AJR 1997; 168:173

Mindelzun et al: Radiol 1997; 205:43

Urban et al: RadioGraphics 2000; 20:725

Small BowelObstruction dueto femoral hernia

Small Bowel Obstruction

•For high grade obstruction, sensitivity 90-96%, specificity 96%

•Low grade obstruction - sensitivity 50% andmay require barium study

•Causes:

Adhesions (64-79%)

Hernia (15-25%)

Tumor (10-15%)

Megibow et al: Radiology 1991; 180:313

Maglinte et al: Radiology 1993; 188:61

CT Findings ofSmall Bowel Obstruction

•Decompressed colon

•Transition from dilated tonondilated small bowel

•When no obstructing mass orhernia, most likely cause isan adhesion

Closed loop small bowel obstruction

with early signs of ischemia

Simple vs. Strangulated SBO

•Caused by obstruction of proximalbowel 2° closed loop obstruction withvenous congestion of involved loop

•Venous congestion  vesselengorgement  bowel hemorrhage fluid transudates into peritoneum

Simple vs. Strangulated SBO

•Findings:

Poor bowel wall enhancement

Twisting of mesenteric vasculature (beaksign)

Peculiar C or U shaped bowel configuration

Mesenteric edema

Appendicitis

Appendicitis

•CT Findings:

Dilated appendix (> 6 mm)without filling by oral contrast

Periappendiceal inflammation

Increased enhancement of wall

Appendicolith

•Accuracy 94-98%

Ruptured

Appendicitis

Rupturing appendicitis

Perforated Appendicitis

•Extra-luminal air

•Extra-luminal appendicolith

•Abscess

•Defect in enhancing wall

•Phlegmon

* More common in the elderly

Horrow, White et al: Radiology (in press)

Sigmoid diverticulitis

With rectal contrast

Cecal diverticulitis with

perforation

Diverticulitis

•93% sensitive, near 100% specific

•Much more sensitive than barium enemabecause CT can visualize the pericolonicprocess

•CT findings: inflammation adjacent tocolon with diverticula, often wallthickening. May also see phlegmon,extra-luminal air or abscess

Cho et al: Radiology 1990; 176:111

AcutePancreatitis

Hemorrhagic

Pancreatitis

Acute Pancreatitis

with splenic arterypseudoaneurysm

Splenic artery

PSA

Acute Pancreatitis

•CT findings correlate well with severity ofdisease, predicts clinical outcome

•Findings include: focal/diffuse enlargement,peripancreatic inflammation, areas ofdecreased attenuation  necrosis, phlegmon,peripancreatic collections, hemorrhage,abscess

Acute Pancreatitis

•Vascular complications: splenic veinthrombosis or splenic arterypseudoaneurysm

•Technique crucial: IV contrast, timing

Balthazar: Radiology 2002; 223:603

Choledocholithiasis

w biliary dilatation

S/p cholecystectomy

Acute Cholecystitis

with

Ruptured Gallbladder

Gallstone Ileus

Biliary System

•Acute cholecystitis: inflammation, wallthickening/enhancement, calculi,distention.

However, CT can be relatively unremarkable

•Choledocholithiasis: high attenuationnidus in duct, dilated ducts

Spleen

•Infarction: wedge shapedareas of decreasedattenuation extending tosurface, if diffusely hypo-attenuating may be globalinfarction

Genitourinary Tract

•Acute Pyelonephritis

•Renal Infarction

•Ureteral Calculi

•Pelvic Inflammatory Disease

Acute Pyelonephritis

Acute Pyelonephritis

•Protocol: IV contrast, 1-2 acquisitions

•CT findings: striated/wedge shapedareas of hypoperfusion, renalenlargement, perinephric inflammation.Delayed views may demonstrate areasof increased attenuation

Patient with atrial fibrillation

Left atrial thrombus

Renal infarct

Renal Infarction

•Due to: embolism, aortic dissection,trauma, thrombosis, trauma

•Protocol: IV contrast, early acquisition

•CT findings: focal parenchymaldefect(s) involving cortex and medullabut not capsule, may be global

Patient with right flank pain

Mild right renal enlargement

& hydronephrosis

Mild hydroureter

Right ureterovesical junction calculus

supine

prone

Ureteral Calculi

•Technique: no oral or IV contrast, narrowcontinuous slices

•Sensitivity 97%, specificity 96%

•CT findings:

1° - hydronephrosis, hydroureter, obstructingcalculus

2° - perinephric stranding, renal enlargement

•Other diagnoses

Smith et al: AJR 1996; 166:97

Pelvic inflammatory disease

with left pyosalpinx and

cul-de-sac collections

Bilateral pyosalpinges

Bilateral TOAs

with peritonitis

and hydronephrosis

Pelvic Inflammatory Disease

•Ultrasound is primary modality

•Technique - oral / IV contrast

•CT findings: pelvic inflammation,unilateral/bilateral adnexalmasses, hydrosalpinx, ascites.Findings overlap with otherdiagnoses.

PID vs. Appendicitis

•Missed appendicitis

•Missed perforated appendicitis

•Appendiceal abscess vs. TOA

•Ruptured appendicitis causing TOA

Missed appendicitis- enlarged appendix

appears similar to small bowel loops

Initially interpreted as

bilateral pyosalpinges

with free fluid

One week later after appropriate outpatient

antibiotics, symptoms persisted

Pelvic US showed normal ovaries and pus in cul-de-sac= ruptured appendicitis

TOA or

Appendicealabscess?

RLQ pain with fever for several days

right TOA and pyometra

68 year old with abnormal appendix

Small bowelobstructionwith earlyischemia

Patient with atrial

fibrillation and acute

abdominal pain

SMA embolism with

complete thrombosis

and subsequent

bowel infarction

Bowel Ischemia

•Causes: vascular occlusion/thrombosis - arterial/venous,hypoperfusion. May also resultfrom vascular compromise 2° bowelobstruction, hernia,intussusception

•Sensitivity ~80%, findings ofischemia may be nonspecific

Bowel Ischemia

•CT findings: non-patent vessels,bowel wall thickening with lowattenuation edema; air in bowel wall,mesentery or portal veins; thoughpneumatosis not specific forischemia.

Frager et al: AJR 1996; 166:67

Balthazar et al: Radiology 1997; 205:519

Ruptured aortic aneurysm

Vascular System

•Aortic Aneurysm Rupture

•Aortic Dissection

•Hemorrhage

Aortic Aneurysm Rupture

•Technique: CT angiography withmultiplanar 20/30 reconstructions;rapid IV bolus with narrow collimation,no oral contrast

Aortic Aneurysm Rupture

CT findings: retroperitoneal hematoma,contrast extravasation, if impendingrupture may see > 1 cm increase inaneurysm in 6 mos, draped aorta sign,high attenuation crescent, break-incalcified rim