Ultrasound for Appendicitis

Ultrasound for Appendicitis

by Stephen Alerhand MD (@SAlerhand)
EM Resident Physician, Icahn School of Medicine at Mount Sinai
Edited by Alex Koyfman MD (@EMHighAK)


A 27 year-old G1P1 female with no past medical history presents to the emergency department on a busy late-night shift complaining of lower abdominal pain since the morning. The pain is dull and intermittent, and though she cannot identify any aggravators or alleviators, the pain has steadily progressed over the course of the day to its current severe state. She has not eaten anything since the morning. She denies fever/chills, nausea/vomiting/diarrhea/constipation, dysuria/hematuria/discharge. Her last menstrual period was 3 weeks ago. She denies recent sexual intercourse.

Vital signs are within normal limits.

On exam, the patient moves within the stretcher with discomfort and is hunched over. Her abdomen is thin, soft, with tenderness to palpation in the right lower quadrant. Psoas sign is positive.

Note about Lower Abdominal Pain in Female Patients

You are concerned for appendicitis, though in most females with lower abdominal pain, the work-up is not complete without consideration for pelvic complaints such as pelvic inflammatory disease or ovarian torsion. For example, you may progress as far down the appendicitis pathway as you want, but you will never find the profuse yellow-green discharge and inflamed cervical os if you do not perform the pelvic – and by that time, the patient will have been sitting in the ED for several hours and gotten an expensive, radiating, non-diagnostic CT scan as well. Therefore, as part of the work-up, you perform a pelvic exam and find it unremarkable.

Urine pregnancy test is negative.
Urine dip shows no leukocytes or nitrates.
Basic labs including WBC are unremarkable.

Further Thought Process

At this point, given the initial RLQ tenderness, appendicitis sits atop your differential like it did at the initial presentation. Though some Surgical teams take presumed appendicitis patients to the operating room based on exam alone, this is not common. A diagnostic CT scan is called for most of the time.

These are the obstacles in your mind at this time:

  • Your ED is extremely crowded on this Monday after the holiday weekend.
  • Your team is working hard to manage all of the patients.
  • The patients due for the CT scanner are backed up, not only because of the large queue but because there is less staffing late at night.
  • On that matter itself, the young female has already expressed concern about the effects of radiation on her body.
  • The possible appendicitis patient in front of you has already required multiple rounds of pain medicine, has now spiked a fever, and is looking worse than when she initially came in.
  • You feel like the patient has an inflamed appendix, possibly even rupture. Knowing that the definite therapy is surgical removal, you need to figure out what steps are needed to go from Point A (presumed appendicitis) to Point B (laparoscopic appendectomy).


At that moment, an ultrasound fellowship-trained attending coming in for shift takes sign-out and prints out a few papers for you to scan briefly.

Mallin M, Craven P, Ockerse P, et al. Diagnosis of appendicitis by bedside ultrasound in the ED. Am J Emerg Med. 2015 Mar;33(3):430-2.
Study Design: Prospectively collected US data (by trained residents with attending supervision) for 97 cases of suspected appendicitis, 34 of which were confirmed by surgical or pathology report. Compared with review by fellowship-trained physician.
Results: 67% (24/34) sensitivity, 98% (23/24) specificity. 12% reduction in CT utilization.
Conclusion: Bedside US may be an appropriate initial test to eval patient with suspected appendicitis.

Fox JC, Solley M, Anderson CL, et al. Prospective evaluation of emergency physician performed bedside ultrasound to detect appendicitis. Eur J Emerg Med. 2008 Apr;15(2):80-5.
Study Design: Prospectively enrolled 132 patients with suspected appendicitis. Received work-up as deemed appropriate by attending.
Results: Sensitivity 65%, specificity 90%, PPV 84%, NPV 76%.
Conclusion: Insufficient evidence to support POC US use to rule out appendicitis. However, the high specificity may support US use to rule in the diagnosis.

Elikashvili I, Tay E, Tsung JW. The effect of point-of-care ultrasonography on emergency department length of stay and computed tomography utilization in children with suspected appendicitis. Acad Emerg Med. 2014 Feb;21(2):163-170.
Study Design: Prospective observational convenience sample of children with suspected appendicitis. Of 150 enrolled, 50 had appendicitis (33.3%).
Results: Those who had POC US had a significantly decreased ED length-of-stay compared with those requiring radiology US or CT scan. CT rate decreased during the study from 44 to 27%. For POC US, sensitivity 60% and specificity 94%. For radiology US, sensitivity 63% and specificity 99%. For CT, sensitivity 83% and specificity 98%.
Conclusion: May be feasible to reduce ED length-of-stay and avoid CT scan when using POC US in children with suspected appendicitis. High specificity to rule in appendicitis, similar to radiology US. Safe to use prior to radiology US, as there were no missed cases or negative laparoscopies.

Benefits of Ultrasound for Appendicitis

  • Avoidance of ionizing radiation
  • More readily available and cheaper than CT
  • Quicker than CT (which in many institutions requires a 2+ hour contrast drinking period, which patients often do not tolerate anyway)
  • Faster diagnostic time for Surgeons, who can take patient to OR


  • Lesser diagnostic capability on adults and larger children
  • Excellent specificity to “rule in”, but only moderate sensitivity to “rule out”, thus the patient may end up needing a CT anyway
  • Convincing your hospital’s Surgical team to “buy in” to the idea of appendicitis diagnosis via ultrasound
  • Training emergency physicians in bedside ultrasound for appendicitis rather than having it be performed by the radiology tech or resident
How to Perform the Ultrasound

Courtesy of Ee Tay, MD
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