Imaging Appendicitis

Plain film from www.learningradiology.com www.learningradiology.com

CT, US, MRI all PACS BIDMC

Diagnosing Appendicitis in the Emergency Department

with Imaging Heather Burns Gunn, HMS III Gillian Lieberman, MD Radiology Core BIDMC November 2007

Let’s meet our patient in the emergency room

Let’s meet our patient in the emergency room

Patient CH: History       

24 yo woman presents to ED with 2 days of abdominal pain init in itia iall lly y diffu diffuse se,, cramp crampy y pa pain in in epi epiga gast stri ricc ar area ea pain migrated to RLQ 12 hours ago and became sharper several episodes of N/V in last 12 hours denies diarrhea, constipation, melena, BRBPR endorses reduced appetite

Patient CH: Physical Exam & Labs 

Physical exam normal except abdominal exam   



Soft, non-distended, tender RLQ No rebound tenderness + Rovsing’s sign (pain in RLQ during palpation of LLQ)

Labs of note:  WBC: 

16.6 with 83% Neutrophils Creatinine: 0.9

DDx of RLQ pain • GI – – – – – – – – – – – – –

Appendicitis Crohn’s Right sided diverticulitis Mesenteric adenitis Epiploic appendagitis Bowel ischemia Right colonic neoplasia Infectious ileocolitis Mucocele of the appendix Typhilitis Sigmoid diverticulitis Intussusception Pseudomembraneous or cytomegalovirus colitis – Perforated peptic ulcer – Perforated cholecystitis – Pancreatitis

• Renal – Acute pyelonephritis – Renal and urinary tract obstruction

• Gynecological – – – – – – – –

Pelvic inflammatory disease Hemorrhagic ovarian cyst Ovarian vein thrombosis Ovarian dermoid Necrotic uterine leiomyoma Ovarian torsion Endometriosis Ruptured ectopic pregnancy

Yu J et al. Helical CT evaluation of acute right lower quadrant pain. AJR 2005.

DDx of RLQ pain • GI – – – – – – – – – – – – –

Appendicitis Crohn’s Right sided diverticulitis Mesenteric adenitis Epiploic appendagitis Bowel ischemia Right colonic neoplasia Infectious ileocolitis Mucocele of the appendix Typhilitis Sigmoid diverticulitis Intussusception Pseudomembraneous or cytomegalovirus colitis – Perforated peptic ulcer – Perforated cholecystitis – Pancreatitis

• Renal – Acute pyelonephritis – Renal and urinary tract obstruction

• Gynecological – – – – – – – –

Pelvic inflammatory disease Hemorrhagic ovarian cyst Ovarian vein thrombosis Ovarian dermoid Necrotic uterine leiomyoma Ovarian torsion Endometriosis Ruptured ectopic pregnancy

Yu J et al. Helical CT evaluation of acute right lower quadrant pain. AJR 2005.

• COMMON Appendicitis is the most common cause of acute abdomen.1 • EXPENSIVE: In 2004, 300,000 cases in US alone, total healthcare cost of 5.8 billion.2 • DANGEROUS: Before universal acceptance of appendectomy as standard of care, mortality for appendicitis was more than 50%.3 1

Davies G et al. The burden of appendicitis related hospitalizations in the United States in 1997. Surg Infect 2004. 2

Otero H et al. Imaging utilization in the management of appendicitis and its impacton hospital charges. Emerg Radiol 2007. http://history1900s.about.com/library/photos/blywwiip251.htm

3

Weyant MJ et al. Is imaging necessary for the diagnosis

Before 1997, because of appendicitis’ high mortality rate, surgeons agreed that a 20% negative appendectomy rate was acceptable. That is no longer the case . . .

. . . because of advances in imaging in emergency departments.

Colson M et al. High negative appendectomy rates are no longer acceptable. Am J Surg 1997. Rhea J et al. The status of appendiceal CT in an urban medical center 5 years after its introduction: experience with 753 patients. AJR 2005.

Plain film from www.learningradiology.com

. . . because of advances in imaging in emergency departments.

Colson M et al. High negative appendectomy rates are no longer acceptable. Am J Surg 1997. Rhea J et al. The status of appendiceal CT in an urban medical center 5 years after its introduction: experience with 753 patients. AJR 2005.

Before we consider our menu of imaging tests to narrow our diagnosis . . . . What additional lab test should we order for our patient CH? A pregnancy test! + A positive pregnancy test will change our imaging options. - A negative pregnancy test will remove ectopic pregnancy from our differential.

ACR appropriateness criteria for RLQ Pain fever, leukocytosis, and classic presentation for appendicitis in adults Rating Radiologic Procedure

(1 = least appropriate, 9 = most appropriate)

Relative Radiation Level

CT abdomen and pelvis with contrast

8

High

US abdomen RLQ graded compression

6

None

CT abdomen and pelvis without contrast

6

High

X-ray chest

5

Min

US pelvis transabdominal and transvaginal

5

None

X-ray abdomen supine and upright

5

Low

X-ray colon barium enema double-contrast

4

Med

X-ray colon barium enema single-contrast

4

Med

MRI abdomen and pelvis

4

None

X-ray small bowel series with barium

3

Low

NUC gallium scan abdomen

3

High

NUC WBC scan abdomen pelvis

3

Med

X-ray small bowel enteroclysis

2

Med www.acr.org

ACR appropriateness criteria for RLQ Pain fever, leukocytosis, pregnant woman Rating Radiologic Procedure

(1 = least appropriate, 9 = most appropriate)

Relative Radiation Level

US abdomen RLQ graded compression

8

None

MRI abdomen and pelvis

7

None

US pelvis transabdominal and transvaginal

6

None

CT abdomen and pelvis with contrast X-ray chest

6

High

CT abdomen and pelvis without contrast

5

High

X-ray chest

4

Min

X-ray abdomen supine and upright

2

Low

X-ray colon barium enema double-contrast

2

Med

X-ray small bowel enteroclysis

2

Med

X-ray colon barium enema single-contrast

2

Med

NUC WBC scan abdomen pelvis

2

Med

X-ray small bowel series with barium

2

Low

NUC gallium scan abdomen

2

High www.acr.org

Comparison of Appropriate Tests Not pregnant 1. CT C+ abd/pelv 2. US abd RLQ graded compression 3. CT C- abd/pelv 4. X-ray chest 5. US pelvis transabd & transvag

Pregnant 1. US abd RLQ graded compression 2. MRI abd and pelvis 3. US pelvis transabd & transvag 4. CT C+ abd/pelv 5. CT C- abd/pelv

Pregnant Woman and Appendicitis •

COMMON: Acute appendicitis is most common surgical emergency during pregnancy.1 • TRICKY: Clinical diagnosis can be difficult2 – Appendix may have moved due to gravid uterus – pain may not localize to RLQ – Leukocytosis can be physiological during pregnancy – Nausea and vomiting common in both pregnancy and appendicitis

•

DANGEROUS: In appendicitis, fetal loss is more than 30% with ruptured appendix and 2% with unruptured appendix.3

Cobben

al.

for clinically suspected appendicitis during pregnanc

MR Abdomen – Sagittal: PACS BIDMC

Consideration in imaging the appendix (besides whether or not patient is pregnant or a child): Where is the appendix?

Variability in the location of the appendix

Anterior view

Posterior view

Variability in the location of the appendix

Most common locations

26% 18% Anterior view

Posterior view

Exploring the Menu of Tests • • • •

Plain films Ultrasound MRI CT


Plain films Ultrasound MRI CT

Abdominal Plain Films

Companion Patient 1: Abdominal Plain Film of Appendicitis

• Abdominal plain films are neither sensitive nor specific for acute appendicitis.1 • X-ray of chest often ordered in acute abdomen – to check for free air under diaphragm – because chest disease can simulate abdominal conditions.2

• Some radiographic signs of acute appendicitis:3 – – – – –

Appendicolith Scoliosis RLQ fluid levels Ileus Bowel wall edema

1Rao

Abdominal plain film of appendicoliths from www.learningradiology.com

P et al. Plain abdominal radiography in clinically suspected appendicitis: diagnostic yield, resource use, and comparison with CT. American Journal of Emergency Medicine 1999.

Abdominal Plain Films of Appendicitis

Upright abdominal plain film

Altering position of this pediatric patient revealed two different radiographic signs of appendicitis.

Companion patient 2

Supine abdominal plain film



Scoliosis due to RLQ splinting

Appendicolith


Companion patient 2




Scoliosis due to RLQ splinting

Appendicolith


Companion patient 2



Plain films √ Ultrasound MRI CT

Ultrasound • • • • •

No radiation exposure – good for pregnant women and children Patient need not be cooperative – good for children Sensitivity for diagnosing appendicitis = 0.861 Specificity for diagnosing appendicitis = 0.812 Findings on ultrasound:3 – Appendiceal Findings • • • •

Diameter of appendix ≥ 6 mm  MOST SENSITIVE AND SPECIFIC FINDING Lack of compressibility of appendix  2ND MOST SENSITIVE AND SPECIFIC Intraluminal fluid Doppler flow in wall

– Periappendiceal Findings • • • •

Inflammatory fat changes Cecal wall thickening Periileal lymph nodes Peritoneal fluid

1,2 Terasawa T

et al. Systematic review: computed tomography and ultrasonography to detect acute appendicitis in adults and adolescents. Ann Inten Med 2004.

Ultrasound of Appendicitis Note how round appendix is despite compression with ultrasound transducer  non-compressible appendix

Appendix diameter is larger than 6 mm

Companion Patient 3

Ultrasounds of Appendicitis

Companion Patient 4

Intraluminal fluid

Companion Patient 5

Doppler flow in wall

Why would you ever use anything else to diagnose appendicitis in pregnant women? • The Drawbacks to US: – Graded compression US is sometimes not feasible because of enlarged uterus1 – Negative predictive value of nonvisualized appendix is .902

1Pedrosa

I et al. MR imaging evaluation of acute appendicitis in pregnancy. Radiology 2006.


Plain films √ Ultrasound √ MRI CT

MRI • • • •

No radiation exposure – good for pregnant women Sensitivity for diagnosing appendicitis = 1.001 Specificity for diagnosing appendicitis = 0.942 Findings on MRI:3 – Diameter of appendix ≥ 6 mm – Thickening of appendiceal wall with high intensity on T2 weighted images – Dilated lumen filled with high intensity material on T2 weighted images – Increased intensity of periappendiceal tissue on T2 weighted images

1,2 Pedrosa 3

I et al. MR Imaging Evaluation of Acute Appendicitis in Pregnancy. Radiology 2006. Nitta N et al. MR imaging of the normal appendix and acute appendicitis. Journal of Magnetic Resonance Imaging 2005.

MRI of appendicitis in a pregnant woman

• Appendix diameter ≥ 6 mm • Dilated lumen filled with high intensity material

Companion Patient 6: MR T2 SSFSE ( S ingle S hot F ast S pin E cho) Coronal PACS BIDMC

MRI of appendicitis in a pregnant woman Appendix is dilated Appendiceal walls are thickened and high intensity Increased intensity of periappendiceal tissue indicating inflammatory changes

Companion Patient 7: MR T2 SSFSE ( S ingle S hot F ast S pin E cho) Coronal PACS BIDMC


Plain films √ Ultrasound √ } for children and pregnant women } for pregnant women MRI √ CT – test of choice for non-pregnant adults

CT • • • • • •

Test of choice for non-pregnant adults and adolescents CT is credited with drop in negative appendectomy rate from 20% to 3% 1 Since CT provides view of entire abdomen and pelvis (unlike US), other diagnoses may be made. Sensitivity for diagnosing appendicitis = 0.992 Specificity for diagnosing appendicitis = 0.953 Findings on CT:4 – Diameter of appendix ≥ 6 mm – Periappendiceal inflammatory changes • Fat stranding • Fluid collections • Phlegmon • Abscess formation

– – – – –

Wall thickness ≥ 3 mm Extraluminal air Adjacent adenopathy Adjacent bowel wall thickening Focal cecal wall thickening

1,2,3Rhea

J et al. The status of appendiceal CT in an urban medical center 5 years after its introduction: experience with 753 patients. AJR 2005. 4Moteki T et al. New CT criterion for acute appendicitis: maximum depth of intraluminal appendiceal fluid. AJR 2007.

CT Coronal Reconstruction of Appendicitis: Companion Patient 8

Focal cecal wall thickening. Extensive fat stranding. Dilated appendix.

PACS BIDMC

Axial CT of appendicitis: Companion Patient 9

PACS BIDMC

Where’s the appendix?

Axial CT of appendicitis: Companion Patient 9

PACS BIDMC

Dilated appendix, not filling with contrast

Axial CT of Appendicitis: Companion Patient 10

Dilated appendix, not filling with contrast.

PACS BIDMC


Appendix not filling with contrast

PACS BIDMC


Fat stranding

PACS BIDMC

Dilated appendix

Axial CT of Appendicitis: Companion Patient 13 Where is this man’s inflamed appendix? Look for the fat stranding.

Axial CT of Appendicitis: Companion Patient 13 An aside: do you notice any other abnormality in this man’s pelvis?

CT Coronal Reconstruction of Appendicitis: Companion Patient 13

A kidney transplanted into the pelvis.

Coronal Reconstruction CT: Companion Patient 14

That’s the appendix, but is this appendicitis? Where’s the appendix in this coronal reconstruction?

PACS BIDMC

Appendix is filled with contrast. Appendix diameter = 5.0 mm (less than 6.0 mm) No periappendiceal inflammatory changes to be seen!

Normal appendix

PACS BIDMC

Coronal Reconstruction CT: Companion Patient 14

Back to our patient CH . . . • she wasn’t pregnant • her renal function was fine (creatinine was 0.9)

. . . so she was given a CT scan with contrast.

Patient CH: Axial CT

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Let’s find the appendix.

PACS BIDMC

Patient CH: Axial CTs

An elongated and dilated appendix.

Considerable fat stranding (as well as air in appendiceal lumen)

Patient CH: Axial CTs

Diagnosis: acute appendicitis!

An elongated and dilated appendix.

Considerable fat stranding (as well as air in appendiceal lumen)

We have our diagnosis but let’s look at the coronal reconstructions as well.

Patient CH’s CT: Coronal Reconstruction

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Some individual coronal slices. PACS BIDMC


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The appendix pops in and out of plane in this slice.

Dilated appendix Air bubble Plenty of fat stranding


Air in appendix lumen does not rule out appendicitis. Air is present in lumen of appendix in over 15% of cases of appendicitis imaged on CT.1

PACS BIDMC

• The patient CH was taken to OR • Laparoscopic appendectomy • Pathological findings: erythematous appendix, measuring 9.5 cm in length, average of 1.2 cm in diameter. Dilated lumen of up to 0.8 cm containing some fecal material. • After removing the appendix and irrigating the abdomen, the surgeons turned the case over to a different team – can you guess which kind?

Take another look at the CT coronal reconstruction . . . .

CH’s CT: Coronal Reconstruction

Retrocecal appendix

Right ovarian dermoid cyst

PACS BIDMC

• Ob/Gyn service felt it was not prudent to remove dermoid at this time. • Patient was discharged from hospital two days later with plans for Ob/Gyn follow up.

Many thanks to . . . • Gillian Lieberman, MD • Melissa Gerlach, MD • Bettina Siewert, MD • Anne Catherine Kim, MD • Rich Rana, MD • Andrew Hines-Peralta, MD • Maria Levantakis

Imaging Appendicitis

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