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ULTRASOUND EVALUATION OF THE

APPENDIX

Jean Yves Sewah, RDMS, RVT

KAISER PERMANENTE WLA

➢Discuss the importance of ultrasound in the evaluation of the appendix

➢Review the anatomy of the appendix and surrounding landmarks

➢Recognize clinical signs/symptoms and laboratory indicators of appendicitis

➢Set up a systematic protocol for evaluation of the appendix

OBJECTIVES

250.000 cases of appendicitis are reported in the USA yearly

Appendicitis is the most common surgical abdominal emergency in North America

Left untreated, the appendix may burst, infectious materials spill into the abdominal cavity: peritonitis

EPIDEMIOLOGY OF APPENDICITIS

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In children under 3 years of age, the rate of perforation of the appendicitis is 80-100%

In children 10-17 years old, this rate drops to 10-20%

Perforated appendix increases the mortality and morbidity rate

Delay in diagnosis leads to increase perforation rate

FACTS ABOUT EARLY DETECTION

At time of surgery…

If the appendix is ruptured, the complication rate is about 60%.

If the appendix is not ruptured, the complication rate drops to about 3%.

EARLY DETECTION IS KEY

With health care reform, there is more pressure on restraining costs .

Readily availability of US, relative low cost, lack of adverse effects, real time interaction, safe.

US is becoming the first modality of choice, especially in the pediatric population where it is critical to reduce exposure to undue radiation.

Why Ultrasound Instead of CT ?

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Worm-shaped

Blind-ended tubular structure at the end of the cecum, posterior to the terminal ileum

Length: ~ 10 cm

Antero-posterior diameter: 3-6 mm

ANATOMY OF THE APPENDIX

1/3 of the way between the ASIS and umbilicus.

This is the location of the base of the appendix where it attaches to the cecum.

MCBURNEY POINT

Lumen of the appendix becomes blocked

often by fecal material (fecalith or fecal stasis), foreign body or tumor.

Blockage may occur from infection

causes the appendix to swell in response and its opening gradually closes

What are the Causes of Appendicitis?

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RLQ pain (+++)

Periumbilical pain

Anorexia / Loss of appetite

Nausea, vomiting, diarrhea

Low grade fever

Child becomes indifferent to his/her favorite shows on mommy/daddy smart phone.

Symptoms of Appendicitis

Not specific

CBC: Complete blood cell count

WBC (white blood cell count): elevated, > 10.500 (80-85% in adults). Neutrophilia > 75%

In infants, WBC is unreliable, may not mount a normal response to infection.

C-REACTIVE PROTEIN. Increased, > 1MG/DL. lacks specificity.

URINALYSIS: helps differentiate from UTI ( urinary tract conditions).

Laboratory tests for appendicitis

AP diameter no more than 6 mm (transverse plane)

No peristalsis

Partially compressible

Shown in two planes (transverse and sagittal)

Gut-like, tubular structure, blind-ended, tracked down to the cecum

Posterior to the terminal ileum

Normal Appendix

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Non compressible

7 mm or greater (AP diameter).

Appendicolith.

Edema of mesoappendix and fat.

Hyperemia.

ACUTE APPENDICITIS

Using high-frequency linear array transducer

Start with graded compression over the area of maximum tenderness as indicated by the patient

Place the transducer in a transverse plane and apply deep graded compression

helps displace the gas and bring the bowel closer to the probe

CURRENT PROTOCOL FOR EVALUATION OF THE APPENDIX

If the appendix is not seen in that location, then trigger the next approach.

Start at the hepatic flexure and then slowly move down toward the cecum.

Keep moving down slowly to explore the entire RLQ area.

The appendix may not be seen due to bowel gas and / or body habitus.

CURRENT PROTOCOL

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TECHNIQUE

15 MHz linear array transducer.

9 MHZ linear array, we do not suggest curved array transducer.

Graded compression.

Systematic approach.

SUGGESTED PROTOCOL

Identify the iliac artery in transverse plane. Typical location of the mid portion of the appendix.

Look for the “draped” appendix over the iliac artery

Track the appendix to the tip of the cecum. Also show the blind end of the appendix at the distal tip.

Evaluate for hyperemia (using Color and Power Doppler)

Show split screen comparison of the appendix with and without compression

SUGGESTED PROTOCOL

Show a cineclip of the appendix during compression.

Evaluate for rebound tenderness at the RLQ.

IF THE APPENDIX APPEARS NORMAL…

Quickly explore the right kidney ( hydronephrosis, stones).

Also explore right ovary (echogenicity, cyst, mass, Doppler flow).

SUGGESTED PROTOCOL

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Posterior to the cecum.

Lateral to the cecum.

Pelvic location

Those are difficult to demonstrate.

Common sites for missed appendicitis.

Other Locations

STEP BY STEP PROTOCOL WITH US IMAGE ILLUSTRATION

REMEMBER, NON VISUALIZATION OF THE APPENDIX DOES NOT EXCLUDE APPENDICITIS!!!

IDENTIFY THE ILIAC VESSELS

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TRACK THE APPENDIX TO THE CECUM

SHOW BLIND-ENDING

Orient the probe parallel to the vessel

See the mid portion of the appendix anterior to the vessels

Distal tip of the appendix is deep in the pelvis

This is commonly seen in children and thin women

“DRAPED” APPENDIX OVER THE ILIAC VESSELS

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“DRAPED” APPENDIX OVER THE ILIAC VESSELS

“DRAPED” APPENDIX OVER THE ILIAC VESSELS

“DRAPED” APPENDIX OVER THE ILIAC VESSELS

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Normal appendixwith and without compression

Normal Appendix Sagittal

Normal Appendix Transverse

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Normal Appendix Transverse

Look at the Right kidney.

Look at the right ovary.

HOWEVER, IF I CAN NOT SEE THE APPENDIX AT ITS TYPICAL LOCATION, WHAT TO DO?

look at the other locations of the appendix.

Appendix normal, what’s next?

Terminal ileum is medial to the cecum.

Smaller than the cecum.

Has smooth gas pattern.

Has peristalsis.

The appendix may be posterior but also deep to the ileum.

Posterior to the Terminal Ileum

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Posterior to the terminal ileum

Common in children and male.

Anterior to the Iliacus Muscle

Adjacent to the right adnexa.

Endovaginal approach.

Pelvis Location

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Pelvis Location endov Sag

Pelvis Location Endov Trans

Retrocecal appendix Sag

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Retrocecal appendix Trans

Why showing the distal tip?

Segmental distal appendicitis

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Non compressible appendix : split screen with and w/o compression

Acute appendicitis

Acute appendicitis: hyperemia

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Pelvic appendicitis

Retrocecal appendicitis

SAMPLE CASES OF APPENDICITIS

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Do not be on the rush, taking few images of the RLQ to show you are looking for the appendix

Do not be discouraged, keep trying Seek help from a

colleague; ultimately, you will be proficient at this exam

Conclusion: be organized!!!

US of the appendix is not only about finding a positive case of appendicitis, but primarily attempt to identify a normal appendix.

For most experienced sonographers, it may sometimes take up to 15 minutes to find a portion of the appendix.

Finding the entire appendix and showing that it is normal rules out appendicitis: the management of that patient will be different.

Know what to look for

Help reduce radiation exposure

(CT remains gold standard)

You will become more proficient in the sonographic evaluation of the appendix

Help reduce radiation exposure