This study verified the usefulness of POCUS performed by pediatric emergency physicians by applying criteria set to lower standards for detecting intussusception at an early stage. Our results demonstrated a relatively short symptom duration of 11.7 hours in intussusception cases, excellent performance outcome of POCUS, and the limitations of clinical features for distinguishing the intussusception and non-intussusception groups.
In this study, POCUS performed by pediatric emergency physicians seemed highly reliable (sensitivity, 100%; specificity, 95.6%; and accuracy, 97.8%) and useful (positive likelihood ratio, 23.0; and negative likelihood ratio, 0) in detecting intussusception. A previous study also showed a high degree of accuracy with 100% sensitivity and 94% specificity, even though it enrolled only 49 patients, which was a relatively small number . Among the 92 patients with “suspicious” POCUS results in this study, 22 were confirmed as false positives, with a relatively low positive predictive value of 76.1%. This might be because the intussusception reduced spontaneously in 6 patients with edematous ileocecal valves, given the time interval between performing POCUS and RADUS. Moreover, the uncertain cases, wherein the patients were not definitely concluded as having no intussusception, were interpreted as indicating “suspicious” POCUS results; thus, the low positive predictive value was expected. In the ED setting, a missed diagnosis of intussusception possibly leads to serious consequences; therefore, the interpretation criteria of POCUS should be strict regarding the exclusion of intussusception as the diagnosis. In this study, RADUS was preferably requested in cases of “suspicious” POCUS results for confirming the diagnosis, as well as for evaluating reducibility or the possible presence of a pathologic lead point in cases of definite intussusception. We intended to use POCUS primarily as a utility for screening suspected intussusception rather than for confirming an exact diagnosis in the ED.
Proactively performing POCUS by applying criteria set to lower standards seems to facilitate the detection of intussusception at an early stage. Accordingly, this study aimed to perform POCUS by applying criteria set to lower standards in patients showing any one of the following symptoms: intermittent abdominal pain/irritability, bloody stool, two or more causes of nonspecific abdominal pain/irritability, abdominal mass/distension, vomiting, or lethargy. Consequently, the enrolled patients with intussusception were considered to be in the early stage, which presented symptoms for a much shorter mean duration of 11.7 hours instead of a duration of over 18.5 hours reported in previous studies [12-14]. The favorable treatment outcome in 97.1% of patients with successful air enema reduction also indirectly indicates that the patients were in early stages of intussusception; only 2 patients required surgical reduction. Moreover, the intussusception group in this study presented a lower prevalence of vomiting (37.1%) and bloody stool (21.4%) than did those in previous studies, which reported vomiting in 85% and bloody stool in up to 65% of patients . According to the clinical course of intussusception, as intestinal obstruction progresses, abdominal pain appears first, followed by vomiting and bloody stool [3, 11]. Thus, our findings indicated that most patients with intussusception were in the early stage and had not yet developed vomiting.
Compared with the non-intussusception group, the intussusception group presented more intermittent abdominal pain (P < 0.001), but less vomiting (P = 0.001); however, the other clinical features were not significantly different. Only intermittent abdominal pain/irritability (58.6%) seems helpful in distinguishing intussusception in the early stages in a clinical setting, and this may suggest that detecting intussusception would still be challenging without performing POCUS.
This study has several limitations owing to its retrospective design. Most of the patients with “negative” POCUS results were not confirmed to have intussusception using RADUS; thus, the possibility of false-negative results exists. However, we strictly ruled out patients without intussusception, and none of them were proven to have intussusception within 48 hours of ED discharge. Moreover, defining the onset of intussusception on the basis of the duration of symptoms determined by the parents might be incorrect. However, we double-checked the presumed time in order to reduce any recall bias. We also did not consider the individual POCUS experience of pediatric emergency physicians, cost-effectiveness of POCUS, and satisfaction of the children or parents. Further prospective studies are required to address these issues.
In conclusion, POCUS may be performed by pediatric emergency physicians to detect intussusception. Furthermore, performing POCUS by applying criteria set to lower standards in the ED could help detect intussusception at an early stage, which may present with obscure clinical symptoms.