Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric appendicitis. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
Module Goals
- Describe the indications for performing point-of-care ultrasound (POCUS) for appendicitis
- Describe the technique for performing POCUS for appendicitis
- Recognize anatomical landmarks for POCUS for appendicitis
- Interpret signs of appendicitis on POCUS
- List the limitations of POCUS for appendicitis
Case Introduction: Child with thigh pain
Mason is an 8-year-old boy who comes to the emergency department for abdominal pain. The pain has been present for 12 hours, started near his belly button, and now has migrated to the lower right side. He describes it as constant and worsening. His parents are concerned because he had a fever to 101F since 2 hours prior to arrival and had 2 episodes of emesis. They deny diarrhea or bloody stool. They gave acetaminophen for fever 2 hours prior to arrival. He has not wanted to eat anything today.
| Vital Sign | Finding |
|---|---|
| Temperature | |
| Heart Rate | 120 bpm |
| Blood Pressure | 106/58 |
| Respiratory Rate | 18 |
| Oxygen Saturation (room air) | 100% |
Why should I perform the appendix POCUS?
- Lack of radiation exposure, lower cost, less patient preparation
- Superior sensitivity and specificity for diagnosing pediatric appendicitis
- POCUS can save ≥2 hours compared to radiology-performed ultrasound
- Can help prioritize radiology studies or expedite surgical consult
Limitations of the appendix POCUS
- Operator dependency and variability in sensitivity
- Difficult visualization of appendix in retrocecal or aberrant locations
- Limitation of visualization dependent on patient body habitus
- Sometimes the appendix cannot be visualized (normal or otherwise)
What are the general principles behind the technique?
- You are using POCUS to look for an abnormal appendix and/or secondary signs of appendicitis.
- It is important to recognize anatomical landmarks.
- The patient should be placed in a supine position.
- Using the linear transducer is appropriate for most pediatric patients, but if the patient has a larger body habitus, the curvilinear transducer may be used (figure 1).
Figure 1. Linear (left) and curvilinear (right) transducer for ultrasonography
- Place the probe over the point of maximal tenderness in the abdominal RLQ.
- Slowly apply increasing gentle pressure (i.e., “graded compression”) to move bowel gas out of the way until able to identify the important landmarks:
- Iliopsoas muscle
- Rectus muscle
- Iliac vessels
- You can also lightly “jiggle” the probe as shown below to help mitigate bowel gas artifact.
Video 1: External view of the RLQ abdomen with the application of graded compression, such that bowel gas is moved out of the way to obtain a view of the desired anatomical structures
Video 2: POCUS clip of the RLQ abdomen demonstrating the application of graded compression and “jiggling” the probe
1. Start in the RLQ Abdomen
Figure 2: Starting in the RLQ abdomen and inferior to the iliac crest, visualize the iliacus muscle and pelvis with no bowel in view. The first bowel you visualize should be the cecum as you scan in a cephalad direction.
Video 3: POCUS clip of the RLQ abdomen showing the cecum coming into view
2. Move the probe more cephalad
Figure 3: Moving the probe in a progressively more cephalad direction, attempt to visualize the iliopsoas, abdominis rectus muscles, and iliac vessels. These anatomic landmarks to help identify the appendix (marked as *) with the CURVILINEAR probe. The appendix may appear in the triangle made by these structures as a blind-ended pouch that does not have peristalsis.[Image courtesy of Dr. Sally Graglia]
Figure 4: Anatomic landmarks to help identify the appendix with the LINEAR probe [image courtesy of Dr. Sally Graglia]
3. Identify the tubular appendix structure
Figure 5: Visualize the appendix in the longitudinal view. In this plane, visualize the end of the pouch to confirm it is a blind-ending tubular structure with no peristalsis that initiates at the cecum. [Image courtesy of Dr. Margaret Martore-Lin]
Figure 6: Visualize the appendix in the transverse view. In this plane, measure the diameter of the appendix from the outer wall to outer wall. An abnormal appendix is >6 mm and non-compressible. [Image courtesy of Dr. Margaret Martore-Lin]
A technique described in Sivitz et al. [1] involves placing the ultrasound probe in a transverse position and starting at the level of the umbilicus. Using compression, move the probe along POCUS-identified anatomical landmarks.
- Move laterally to identify the lateral border of the ascending colon.
- Move down the lateral border to the end of the cecum.
- Move medially across the psoas and iliac vessels.
- Move down the border of the cecum.
- Move up the border of the cecum.
- Rotate the probe into a sagittal position and identify the end of the cecum in the long axis and move medially across the psoas.
Figure 7: The Sivitz et al technique for identifying the appendix on POCUS
Sometimes there is a suboptimal view of the anatomy landmarks on POCUS. The following are troubleshooting tips that may be useful:
- Perform graded compression to displace bowel gas that may be obscuring your view.
- Apply posterior manual compression to the right lower back in an anteromedial direction of the ultrasound probe. This is usually done with the POCUS operator’s opposite hand (Figure 7).
Figure 8: Posterior manual compression technique to assist with POCUS visualization of the appendix
- Position the patient in the left lateral decubitus position to help visualization of a retrocecal appendix.
- Administer analgesia before starting and distraction (videos, smartphone) during the exam to reduce patient movement.
- Position the patient with knees flexed, which can relax the abdominal wall musculature.
- Use a high-frequency linear probe to improve the resolution of regional structures and anatomy (although a curvilinear probe should be used if increased depth is required for a larger body habitus).
Figure 9: Normal appearing appendix on POCUS [Image courtesy of Dr. Will Shyy]
Ultrasonography Signs of Acute Appendicitis
- Enlarged appendix >6 mm (Figure 10)
- Noncompressible (although can be compressible if perforated appendix)
Figure 10: Enlarged appendix measuring 1.36 cm (>6 mm is abnormal) with hyperechoic fat concerning for inflammation [Image courtesy of Dr. Will Shyy]
Secondary Ultrasonographic Signs of Appendicitis
- Peri-appendiceal free fluid
- Hyperechoic mesenteric fat
- Appendicolith
- Increased blood flow (“ring of fire”) surrounding the appendix on Doppler color mode
- Complex right lower quadrant mass, suggestive of ruptured appendix
| Secondary Sign of Appendicitis | Ultrasound View |
|---|---|
| Peri-appendiceal free fluid secondary to inflammatory edema or perforation. You may also see an abscess that appears as a complex mass and is a sign of a ruptured appendicitis. |
 Figure 11. Appendix with peri-appendiceal fluid collection [image by Dr. Will Shyy] |
| Hyperechoic mesenteric fat as a sign of inflammation visible (also see figure 10) |
 Figure 12: Appendicolith (A) within the lumen of the appendix in addition to hyperechoic fat (arrows) concerning for inflammation [image courtesy of Dr. Will Shyy]  Figure 13. Appendicitis with hyperechoic fat suggestive of inflammation Video 4: POCUS clip of a pediatric patient with appendicitis. Notice the hyperechoic fat surrounding the appendix, visible in transverse as a tubular structure at the bottom of the screen. |
| Appendicolith: A hyperechoic structure within the appendiceal lumen has a dark, clean acoustic shadow, similar to the appearance of a gallstone. | Figure 12 above |
| “Ring of Fire”, or increased blood flow surrounding the appendix: Using the color Doppler mode on the ultrasound, the appendix in transverse view will appear hyperemic, suggestive of appendiceal inflammation. |
 Figure 14. “Ring of fire” appendiceal hyperemia using the color Doppler mode on ultrasound [image by Dr. Will Shyy]  Figure 15. Cross-sectional image of appendicitis with hyperemia |
| Complex RLQ mass: A ruptured appendicitis may appear as a complex right lower quadrant mass, where the appendix itself may be difficult to visualize. It can be difficult to distinguish this from other pathologies, such as intussusception or ruptured Meckel’s diverticulitis. |
Video 5: POCUS clip of ruptured appendicitis, appearing as a complex right lower quadrant mass Figure 16. Close-up POCUS view of the appendix from video 5 |
Benefits of Appendix POCUS
An appendix POCUS benefits children with suspected appendicitis, as demonstrated in the literature:
- Decrease in CT scan utilization [2-4]
- Decrease in lengths of Emergency Department stay [3, 4]
- Tsung et al, Critical Ultrasound J, 2014 [4]: There was a shorter ED length of stay (LOS) with mean LOS reported for the following modalities:
- POCUS: 154 minutes
- Radiology US: 288 minutes
- CT scan: 487 minutes
- Tsung et al, Critical Ultrasound J, 2014 [4]: There was a shorter ED length of stay (LOS) with mean LOS reported for the following modalities:
Equivocal Findings on POCUS
- Oftentimes an appendix cannot be visualized on both POCUS and radiology-performed ultrasound, especially in patients with higher BMI [5].
- In situations with an experienced sonographer, where the appendix is not visualized and there are no secondary signs on radiology-performed ultrasound, patients are at low risk for appendicitis with a negative predictive value in the 80’s% [6, 7].
- Serial ultrasound has been recommended in equivocal ultrasound cases as ultrasound’s sensitivity increases with length of pain [8].
- For POCUS for appendicitis, non-visualized appendix studies continue to represent a diagnostic dilemma [1, 9]. For more on this topic, read a deeper-dive on this topic in a PEM Pearls post.
The studies below examine the sensitivity and specificity of appendix POCUS for identification of appendicitis in patients of any age with the exception of Sivitz et al., which specifically studied pediatric patients only. (Table 1).
| Study | N | Patient Age | Sensitivity | Specificity | Comments |
|---|---|---|---|---|---|
| Sivitz et al., 2014 [1] | 264 | Pediatric |
85%
(95% CI: 75-95%)
|
93%
(95% CI: 85-100%)
|
In this study, pediatric emergency medicine ultrasonographers were able to visualize the appendix in 71% of patients. Gold standard was either pathologic review, telephone follow-up to 6 months, or electronic medical records review up to 1 year, if unable to reach the patient.
|
| Fields et al., 2017 [9] | 6,636 | Pediatric | 89%
(95% CI: 47–99%) |
97%
(95% CI: 84–99%) |
These test characteristics were derived from a pediatric-only sub-analysis of a larger systematic review and meta‐analysis study across all ages to identify the test characteristics of the appendix POCUS, performed by emergency physicians. The overall test characteristics across all ages was 91% (95% CI: 83–96%) sensitivity and 97% (95% CI: 91–99%) specificity. |
| Chen et al., 2000 [10] | 317 | Any age | 85% | 98% | After a 5-day intensive training course in abdominal ultrasound, emergency physician-performed POCUS was compared to surgeon’s clinical impression in diagnosing acute appendicitis, as confirmed by pathological reports. Ultrasonography performed better than surgeon clinical impression and resulted in a high sensitivity and specificity. |
| Fox et al., 2008 [11] | 132 | Any age | 65%
(95% CI: 52-76%) |
90%
(95% CI: 81-95) |
Emergency physicians performed a 5-minute appendix POCUS for patients with a clinical suspicion for acute appendicitis. The gold standard confirmation was either pathology specimens from appendectomy surgery or telephone follow-up. |
Table 1. Published studies evaluating the sensitivity and specificity of appendix POCUS
Case Resolution
The patient has a leukocytosis with a WBC 13.3 x 109/L and an absolute neutrophils count (ANC) 10.3 x 109/L but otherwise unremarkable labs. His final Pediatric Appendicitis Score (PAS) is 8. You decide to incorporate appendix POCUS to your evaluation. You place a linear, high-frequency transducer on the patient and visualize his appendix. You observe the following:
Video 6. An appendix POCUS, demonstrating appendicitis.
Figure 17: Enlarged appendix measuring 1.36 cm in diameter (>6 mm is abnormal)
Normal anatomy for comparison:
Video 7: Appendix POCUS clip showing normal anatomy including the psoas muscle, vasculature, and a small, compressible appendix.
ED Course
The patient receives IV morphine and is made NPO. The general surgeon on call is consulted and agrees with the plan for an appendectomy.
Learn More…
References
- Sivitz AB, Cohen SG, Tejani C. Evaluation of acute appendicitis by pediatric emergency physician sonography. Ann Emerg Med. 2014;64(4):358-364.e4. doi:10.1016/j.annemergmed.2014.03.028. PMID: 24882665
- Doniger SJ, Kornblith A. Point-of-Care Ultrasound Integrated Into a Staged Diagnostic Algorithm for Pediatric Appendicitis. Pediatr Emerg Care. 2018;34(2):109-115. doi:10.1097/PEC.0000000000000773. PMID: 27299296
- Elikashvili I, Tay ET, 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;21(2):163-170. doi:10.1111/acem.12319. PMID: 24673672
- Tsung JW, Tay ET, Elikashvili I. The effect of point-of-care ultrasonography on emergency department length of stay and CT utilization in children with suspected appendicitis. rit Ultrasound J 6, A32 (2014). https://doi.org/10.1186/2036-7902-6-S1-A32
- Abo A, Shannon M, Taylor G, Bachur R. The influence of body mass index on the accuracy of ultrasound and computed tomography in diagnosing appendicitis in children. Pediatr Emerg Care. 2011;27(8):731-736. doi:10.1097/PEC.0b013e318226c8b0. PMID: 21811194
- Cohen B, Bowling J, Midulla P, et al. The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study?. J Pediatr Surg. 2015;50(6):923-927. doi:10.1016/j.jpedsurg.2015.03.012. PMID: 25841283
- Ly DL, Khalili K, Gray S, Atri M, Hanbidge A, Thipphavong S. When the Appendix Is Not Seen on Ultrasound for Right Lower Quadrant Pain: Does the Interpretation of Emergency Department Physicians Correlate With Diagnostic Performance?. Ultrasound Q. 2016;32(3):290-295. doi:10.1097/RUQ.0000000000000214. PMID: 27082937
- Bachur RG, Dayan PS, Bajaj L, et al. The effect of abdominal pain duration on the accuracy of diagnostic imaging for pediatric appendicitis. Ann Emerg Med. 2012;60(5):582-590.e3. doi:10.1016/j.annemergmed.2012.05.034. PMID: 22841176
- Matthew Fields J, Davis J, Alsup C, et al. Accuracy of Point-of-care Ultrasonography for Diagnosing Acute Appendicitis: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(9):1124-1136. doi:10.1111/acem.13212. PMID: 2846445
- Chen SC, Wang HP, Hsu HY, Huang PM, Lin FY. Accuracy of ED sonography in the diagnosis of acute appendicitis. Am J Emerg Med. 2000;18(4):449-452. doi:10.1053/ajem.2000.7343. PMID: 10919537
- Fox JC, Solley M, Anderson CL, Zlidenny A, Lahham S, Maasumi K. Prospective evaluation of emergency physician performed bedside ultrasound to detect acute appendicitis. Eur J Emerg Med. 2008;15(2):80-85. doi:10.1097/MEJ.0b013e328270361a. PMID: 18446069
Additional Reading
- Benabbas R, Hanna M, Shah J, Sinert R. Diagnostic Accuracy of History, Physical Examination, Laboratory Tests, and Point-of-care Ultrasound for Pediatric Acute Appendicitis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(5):523-551. doi:10.1111/acem.13181. PMID: 28214369
- Estey A, Poonai N, Lim R. Appendix not seen: the predictive value of secondary inflammatory sonographic signs. Pediatr Emerg Care. 2013;29(4):435-439. doi:10.1097/PEC.0b013e318289e8d5. PMID: 23528502Lin-Martore M, Kornblith AE. Diagnostic Applications of Point-of-Care Ultrasound in Pediatric Emergency Medicine. Emerg Med Clin North Am. 2021 Aug;39(3):509-527. doi: 10.1016/j.emc.2021.04.005. PMID: 34215400
- Vasavada P. Ultrasound evaluation of acute abdominal emergencies in infants and children. Radiol Clin North Am. 2004;42(2):445-456. doi:10.1016/j.rcl.2004.01.003. PMID: 15136027
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