Abstract
Objectives
Point-of-care ultrasound (POCUS) in the emergency department (ED) may facilitate the diagnosis of nonsurgical sources of abdominal pain after surgical causes are excluded. Identifying mesenteric adenitis is a feasible POCUS application due to its ease of use and speed. However, there are scant data regarding the diagnosis of mesenteric adenitis by POCUS. The objective of this study was to describe the clinical characteristics, outcomes, and interobserver agreement of mesenteric adenitis identified on POCUS in pediatric patients with nonsurgical abdominal pain.
Methods
This was a retrospective review at a tertiary-care, urban pediatric ED. All cases of mesenteric adenitis diagnosed on POCUS from January 2018 to August 2022 were reviewed. Demographics and clinical data, including relevant outcomes, were recorded. All POCUS videos were reviewed by a senior sonologist-physician for determination of mesenteric adenitis in children 21 years and younger with nonsurgical abdominal pain. Interobserver agreement by Cohen κ was calculated between experienced and novice physician sonologists blinded to diagnosis, who reviewed 77 six-second video clips for presence or absence of mesenteric adenitis.
Results
Thirty-three subjects were identified by POCUS to have mesenteric adenitis in the setting of nonsurgical abdominal pain presenting to our ED. Most common indications for POCUS were for suspected appendicitis, suspected intussusception, or undifferentiated abdominal pain. Forty-six percent of patients were male; median age was 9 years (interquartile range, 4–14 years). On 4-week clinical follow-up, 1 patient returned to our ED with a surgical abdomen. Cohen κ values were 0.83 (95% confidence interval, 0.70–0.97) between experienced sonologist-physicians and 0.76 (95% confidence interval, 0.61–.90) between novice and experienced sonologist-physicians.
Conclusions
POCUS can identify mesenteric adenitis, typically a diagnosis of exclusion, in pediatric patients with nonsurgical abdominal pain, both by novice and experienced physician-sonologists. Use of POCUS may help ED clinicians identify a common cause of nonsurgical abdominal pain in children.
Key Words: abdominal pain, mesenteric adenitis, point-of-care ultrasound, extra-pulmonary tuberculosis, COVID-19
Point-of-care ultrasound (POCUS) use in the emergency department (ED) may facilitate the bedside diagnosis of nonsurgical sources of abdominal pain after surgical causes are excluded.1 Identifying mesenteric adenitis is a feasible POCUS application as they are often observed when evaluating suspected surgical causes of abdominal pain.2,3 Probe palpation or “sono-palpation”4 of the source of abdominal pain5 can be integrated by a clinician-sonologist when mesenteric lymph nodes are visualized on ultrasonography in the area of reported pain. However, there are scant data regarding the diagnosis of mesenteric adenitis by POCUS. The objective of this study was to describe the clinical characteristics, outcomes, and interobserver agreement of mesenteric adenitis identified on POCUS in pediatric patients with nonsurgical abdominal pain.
METHODS
This was a retrospective cohort study adhering to the STROBE6 criteria at a single, tertiary-care, urban pediatric ED with affiliated residency, pediatric emergency medicine fellowship, and emergency ultrasound fellowship training programs. All cases of mesenteric adenitis identified on POCUS from January 2018 to August 2022 were independently reviewed by 2 investigators (D.E.S. and J.W.T.). POCUS examinations were performed by emergency medicine residents, pediatric emergency medicine fellows, or endoscopic ultrasonography fellows under the supervision of pediatric emergency ultrasound faculty by saving at least 1 or more 6-second video clips (examples can be accessed at https://youtu.be/99siMfU5xKk; https://youtu.be/dJ0CpaoajFQ; https://youtu.be/-ezSYx38Ll8).
Cases were identified by the senior author using the search function in QpathE (Telexy Healthcare, Maple Ridge, British Columbia, Canada), an image archiving program. Cases were included if mesenteric lymph nodes were identified on POCUS in the area of reported abdominal pain. Cases were excluded if there was a surgical diagnosis or intervention required (appendectomy, air enema, or operative reduction for intussusception) at the time of ED visit. Excluding appendicitis or intussusception in our ED relies on a combination of clinical picture, POCUS for evaluation of appendicitis and intussusception for which we have studied and published on,2,3 when necessary radiology imaging and/or surgical consultation.
Demographic information and clinical data, including presentation (presenting symptoms and signs including abdominal pain, vomiting, diarrhea, and fever), other diagnostic imaging (radiology ultrasound, x-ray or computed tomography [CT] scan), laboratory data (white blood count, viral polymerase chain reaction results, C-reactive protein/erythrocyte sedimentation rate), disposition (discharge or admission), and other patient-specific outcomes (ED revisits or surgical intervention within a month of index ED visit), were independently reviewed by 2 investigators (DES and JWT) and recorded. Likely etiology of mesenteric adenitis was determined by both investigators based on clinical history, laboratory, and all imaging data. As the latter half of the study included the COVID-19 pandemic time period (March 1, 2020, to August 31, 2022), data of children with COVID-19 infection who appeared to have gastrointestinal symptoms including abdominal pain, COVID-19, and other viral testing results were reviewed for presence or absence of COVID-19 infection.
All POCUS videos with clinical information were reviewed by a senior sonologist-physician for the presence or absence of mesenteric lymph nodes in children 21 years and younger with nonsurgical abdominal pain. Interobserver agreement by Cohen κ was calculated between experienced and novice sonologist-physicians blinded to diagnosis who reviewed 77 six-second video clips for presence or absence of mesenteric adenitis. Numbers of lymph nodes and mean long-axis and short-axis lymph node sizes were calculated measuring in centimeters from the largest lymph node visualized on the 6-second video from each patient. This study was approved by our institutional review board (#22-0702).
RESULTS
Thirty-three subjects were identified by POCUS to have mesenteric adenitis in the setting of nonsurgical abdominal pain presenting to our ED. Most common indications for POCUS were evaluation of suspected appendicitis, suspected intussusception, or undifferentiated abdominal pain. Demographic and clinical characteristics are presented in Table 1A. Forty-six percent of patients were male. The median age was 9 years old (interquartile range [IQR], 4–14 years) for patients diagnosed with mesenteric adenitis.
TABLE 1A.
Clinical characteristics and demographics.
| Characteristics/Demographics | n = 33 |
|---|---|
| Age, median [IQR], y | 7 [4, 10] |
| Gender, female, % | 52 |
| Abdominal pain, n (%) | 33 (100) |
| Fever, n (%) | 10 (30.3) |
| Vomiting, n (%) | 16 (48.5) |
| Diarrhea, n (%) | 10 (30.3) |
| Symptom duration, median [IQR], d | 2 [1, 4] |
| COVID-19 positive,* n/N = 4/17 | 23.5% |
| ED revisit within 1 mo,† n (%) | 3 (9.1) |
*Polymerase Chain Reaction positive test for COVID-19.
†No ED revisits for missed surgical abdomen requiring laparotomy.
Mesenteric adenitis etiologies are presented in Table 1B. Figure 1 contains images of mesenteric adenitis detected by POCUS. Figure 2 presents radiology imaging and results after POCUS examinations. Based on all clinical, laboratory, and imaging data reviewed by 2 investigators, just under a third of our patients had primary idiopathic mesenteric adenitis. Fewer than half of patients appeared to have viral gastroenteritis associated with their mesenteric adenitis, with 4 of 17 (23.5%) patients having an associated COVID-19 infection (https://youtu.be/-BNy8UDGieo). Two patients in the cohort were found to have extrapulmonary tuberculosis as a cause of the mesenteric adenitis (https://youtu.be/5xilpdZOcgM and https://youtu.be/ukVcoyZzPiI).
TABLE 1B.
Mesenteric adenitis etiology.
| Mesenteric Adenitis Etiology | n = 33 (%) |
|---|---|
| Primary mesenteric adenitis | 12 (36.4) |
| Likely viral illness | 16 (48.5) |
| Extrapulmonary tuberculosis | 2 (6.1) |
| Pneumonia | 1 (3) |
| Pyelonephritis | 1 (3) |
| Strep pharyngitis | 1 (3) |
FIGURE 1.
Mesenteric adenitis.
FIGURE 2.
Radiology imaging after POCUS.
On 4-week clinical follow-up, no patients returned to our ED with a missed surgical abdomen requiring laparotomy. However, there were 3 patients who returned to our ED within 4 weeks from index ED visit for persistent abdominal pain: one who returned a day after the index visit for reevaluation, who had repeat POCUS that confirmed normal appendix and presence of mesenteric adenitis in the area of pain, which was successfully treated with nonopioid auriculotherapy for pain,7 which resolved a few days after the return ED visit. The second patient was diagnosed with mesenteric adenitis from intestinal tuberculosis by POCUS and subsequent CT scan of the abdomen and pelvis and was treated with antituberculosis therapy on the index ED visit, but was diagnosed with bowel perforation on the second ED visit 2 weeks later (not seen on CT scan of the abdomen and pelvis obtained during the index ED visit) and was admitted for laparotomy. The third patient was subsequently diagnosed with pneumonia on the return ED visit.
Mean lymph node long-axis and short-axis measurements and numbers of lymph nodes (with SD and ranges) are presented in Table 2.
TABLE 2.
Lymph node characteristics.
| Mean, SD (Range) | |
|---|---|
| Lymph node long-axis diameter, cm | 1.29 ± 0.35 (0.8–2.2) |
| Lymph node short-axis diameter, cm | 0.63 ± 0.17 (0.4–1.25) |
| No. of lymph nodes, n | 2.69 ± 1.01 (1–5) |
Cohen κ was 0.83 (95% confidence interval, 0.70–0.97) between experienced sonologist-physicians and 0.76 (95% confidence interval, 0.61–.90) between novice and experienced sonologist-physicians.
DISCUSSION
In the absence of readily available imaging data, mesenteric adenitis was customarily taught as a diagnosis of exclusion. With the growing availability of POCUS and the ability to visualize the presence or absence of mesenteric adenitis and integrate the location of abdominal pain while evaluating for surgical diagnoses, it is now feasible to make the diagnosis of mesenteric adenitis with surgical diagnoses excluded in the ED. Little information is available regarding the clinical characteristics of pediatric ED patients with nonsurgical abdominal pain from mesenteric adenitis visualized on POCUS; however, it must be stressed that surgical causes of abdominal pain must be excluded before the diagnosis of mesenteric adenitis can be considered.8–11 Furthermore, research by Gross et al11 suggests that lymph node size does not appear to differentiate mesenteric adenitis associated with appendicitis compared with mesenteric adenitis from nonsurgical causes. In our limited retrospective series, we demonstrate that POCUS diagnosis of mesenteric adenitis can be made without any significant missed surgical diagnoses.
Our ED catchment area includes recent arrivals of children or adolescents from high-prevalence areas for tuberculosis, for which 2 patients in our retrospective cohort were diagnosed with tuberculous mesenteric adenitis, which has important implications from a global health perspective. A POCUS protocol for detecting extrapulmonary tuberculosis designed for high-prevalence areas with HIV and tuberculosis, named FASH (focused assessment for HIV-associated tuberculosis) examination, includes detecting pericardial effusion, pleural effusion, retroperitoneal or mesenteric lymphadenopathy, splenic microabscesses, and ascites.12 Mesenteric adenitis is a key and only finding in the FASH examination in our 2 patients who were both HIV negative; a 21-year-old male patient with multiple lower abdominal mesenteric lymph nodes and bowel wall thickening and positive interferon gamma release assay who subsequently developed bowel obstruction and a 10-year-old with a mass of right-lower-quadrant mesenteric lymph nodes that was biopsied to rule out malignancy that showed necrotizing granulomas consistent with tuberculous mesenteric adenitis. Mesenteric adenitis from tuberculosis in children identified by POCUS has been sporadically reported in the medical literature.13
The radiology literature cites cutoff values for enlarged mesenteric lymph nodes (>4 mm to 2 cm), but these have been found in more than a quarter of asymptomatic children on CT or ultrasound imaging.14 We would note that our mesenteric lymph node measurements in symptomatic children overlap the lymph node measurements noted in asymptomatic children.14
As part of the study time period in this retrospective cohort study included the COVID-19 pandemic, it is notable that a few patients in this cohort had acute COVID-19 infection (no criteria for Mulitsystem Inflammatory Syndrome in Children [MIS-C]) as manifested by abdominal pain from mesenteric adenitis visualized on POCUS. Nearly a third to a half of the patients in the cohort complained of vomiting or diarrhea presumably from viral gastrointestinal infection in addition to abdominal pain from mesenteric adenitis. We also note mesenteric adenitis found on POCUS in cases of abdominal pain associated with pneumonia and streptococcal pharyngitis.
The study is limited by the small cohort and retrospective design as it is certain that not all patients with nonsurgical mesenteric adenitis were captured when POCUS faculty were not available to scan all children with abdominal pain. Our cohort size is likely too small to generate generalizable epidemiologic statistics regarding the diagnosis of mesenteric adenitis on POCUS relative to that of radiology ultrasound or CT scans or alternate diagnoses such as appendicitis or intussusception; however, we note that presence or absence of mesenteric adenitis was inconsistently reported on radiology imaging reports and with no report of localization of pain. In our limited retrospective cohort, we can report there were no surgical diagnoses missed within 4 weeks of follow-up. However, the danger of making the diagnosis of mesenteric adenitis is the potential diagnostic error of “satisfaction of search”15 and not excluding a surgical cause of abdominal pain. As emergency physicians become skilled at finding normal appendix or excluding intussusception on POCUS, the diagnosis of mesenteric adenitis can be made when mesenteric lymph nodes are visualized in an area of reported abdominal pain.
CONCLUSIONS
Mesenteric adenitis, typically a diagnosis of exclusion, can be identified reliably by POCUS in pediatric patients with nonsurgical abdominal pain, both by novice and experienced sonologist-physicians. Use of POCUS may help ED clinicians identify a common cause of nonsurgical abdominal pain in children.
Footnotes
Disclosure: J.W.T. has served as a paid consultant to DIA Imaging Analysis, Ltd, an artificial intelligence ultrasound imaging company. The authors declare no conflict of interest.
AI Statement: Generative artificial intelligence was not used in the drafting of this article.
The authors are responsible for the reported research. All authors have participated in the concept and design of the study, analysis and interpretation of data, and drafting and revising of the manuscript, and all authors have approved the manuscript as submitted.
This was presented as an oral abstract at the American College of Emergency Physicians Scientific Assembly annual meeting, San Francisco, CA, in October 2022.
Contributor Information
Dana E. Stone, Email: dana.elizabeth.stone@gmail.com.
Jennifer E. Sanders, Email: jenny.sanders@gmail.com.
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