In this retrospective study, we found no significant differences between patients undergoing early versus delayed fluoroscopic reduction of ileocolic intussusception in terms of frequency of successful reduction, need for a surgical intervention after attempted reduction, recurrence of ileocolic intussusception following successful reduction, or hospitalization length after reduction.

Reported success of fluoroscopic reduction of ileocolic intussusception ranges between 74 and 98% [1, 2, 9, 12, 14, 16]. Our fluoroscopic reduction success frequency was in this range for both groups. Ileocolic intussusception can be a serious condition, with mortality approximating 0.2% and about 3.5% of patients requiring an ICU admission in children’s hospitals in the USA [1]. The mortality risk tends to be associated with comorbidities and surgical interventions. Shapkina et al. found a low perforation of 0.4% with fluoroscopic reduction [9]. In our study, a low frequency of adverse events, such as bowel necrosis or resection, was observed. These events occurred in 2% of cases undergoing fluoroscopic reduction between 6 and 12 h and in 2.1% of cases undergoing fluoroscopic reduction less than 6 h from diagnosis.

Our results are concordant with similar research recently published by Williams et al. [13]. Those authors assessed the morbidity and frequency of ileocolic intussusception reduction success rate in patients with different durations of delay between intussusception diagnosis and fluoroscopic enema reduction. In their dataset, 41 patients had a fluoroscopic reduction delay between 3 and 6 h and 11 patients a fluoroscopic reduction delay between 6 and 8 h. There was no significant difference in reduction efficacy or complication frequency.

In a separate study, Lampl et al. compared the time from ileocolic intussusception diagnosis to image-guided reduction between patients that required and did not require surgery. They found that the median time between diagnosis and image-guided reduction was higher in patients who required a surgery (median time 17.9 h) versus patients who did not (median time 7.0 h) [10]. While we observed no significant difference in the need for surgical reduction between our groups, the delayed intervention group in our study had a more similar interval to image-guided intervention as the group that did not go to surgery in the study by Lampl et al. (7:07 h vs. 7 h). This raises the possibility that more prolonged delays (> 12 h) between diagnosis of ileocolic intussusception and initial image-guided intervention may be associated with less good outcomes.

Liu et al. compared patients with a history of symptoms for more than 48 h to patients with symptoms for less than 48 h. They found no differences in success, recurrence, or perforation frequencies. They also found that the presence of bloody stools had a non-significant trend toward less successful reductions [12]. This conflicts with previously published articles. Fike et al. found that failed reduction was more likely if patients had symptoms for more than 24 h before presentation or if patients had bloody stools or lethargy at the time of presentation. They also found that the chances of a successful reduction were also reduced by a more distal colonic extent of the intussusception into the transverse or descending colon [14]. According to Lehnert et al., surgical intervention was more likely in patients presenting after 24 h of symptoms [2]. Zouari et al. found that duration of symptoms longer than 48 h and fever at admission were risk factors for intussusception recurrence [18]. In reviewing approximately 470 charts for this study, we found that it is difficult to assess the precise onset of patients’ symptoms due to the insidious initiation of symptoms. Most patients presenting with ileocolic intussusception tend to be non-verbal or have limited verbal abilities at the typical age of presentation. There is also an association between ileocolic intussusception and other infections (e.g., upper respiratory tract infections) which may act as a confounding variable. For these reasons, we believe it would be difficult to implement a reliable triage of the patients based on duration of symptoms. Further studies are needed to explore the association between early fluoroscopic reduction and outcomes in patients with bloody stools or lethargy at the time of presentation.

While our study demonstrates that a short delay in fluoroscopic reduction of ileocolic intussusception may not significantly negatively impact clinical outcomes, it is important to acknowledge the potential costs and challenges associated with prolonging observation or hospital admission. Delaying the procedure could potentially lead to increased duration of patient discomfort, parental anxiety, and increased healthcare costs related to extended monitoring and hospital stay. These all need to be explored as balancing measures in analyses seeking to optimize staffing for ileocolic intussusception reduction. A short delay to initial fluoroscopic (or US) reduction attempt could have multiple advantages for the planning of care. Even in institutions with 24/7 pediatric radiologist coverage such as ours, we have a single radiologist reading all cases during the night. Having this radiologist perform a procedure delays other patients’ care on the ED and inpatient services. Fluoroscopy technologist coverage is also an issue to consider. In our institution, we are required to call the on-call technologist. In times of short staffing, a lighter call schedule could be beneficial for recruitment and talent retention. It is also worth considering that the surgery and anesthesia teams also have lower resources at certain times of the day, making the response to any possible complication during a fluoroscopic reduction more difficult. Further research is needed to assess the cost-effectiveness and patient satisfaction associated with different timing strategies for ileocolic intussusception reduction, as well as to evaluate the impact on healthcare staff and resource allocation.

Our study found no significant difference in median length of hospitalization after reduction between patients undergoing early versus delayed fluoroscopic reduction of ileocolic intussusception. After reduction, the median stay was around 20 h in both groups. This aligns with previous studies showing that successful reduction allows discharge within 24 h [19]. While some studies suggest that very early reduction within 6 h optimizes outcomes [11], our data provides reassurance that delaying up to 12 h does not negatively impact hospitalization time.

Although there are US findings associated with a lower reduction success frequency [15], such as enlarged mesenteric nodes, ascites, left-sided intussusception, and trapped fluid, it is difficult to predict which cases will have a successful air or contrast reduction based on diagnostic US imaging. Kong et al. found that absent flow on Doppler imaging was associated with a reduced frequency of successful reductions; nevertheless, the reduction attempt was successful in 31% of cases with absent flow [6]. Koumanidou et al. compared the reduction success frequency between patients with enlarged lymph nodes within the intussuscipiens (at least two lymph nodes with one measuring 11 mm or more in the long axis) with patients that did not. They found that reduction was successful in only 46% of patients with enlarged lymph nodes within the intussuscipiens compared to 81% in patients that did not [7]. Even in patients with a known lead point, fluoroscopic intussusception reduction can be used with a success frequency of 60% to temporize the need for emergent surgery [8]. Given the non-negligible frequencies of success in patients with these US findings, for clinical practice, none of these US findings is a true contraindication to attempt a fluoroscopic reduction. In prior studies, spontaneous reduction of intussusception happened in 2.4 to 11% of cases [2, 20].

There are several limitations of this study. Due to the high frequency of reduction success and the rarity of complications with fluoroscopic reduction of ileocolic intussusception, this study is underpowered to detect small differences between the groups. Most cases in the delayed reduction group (6–12-h group) were transferred from outside institutions nearby our main campus which may have unidentified influences on outcomes of interest. It is also important to consider that children who appeared in poorer condition may have had priority or more effort placed by the referring institutions to expedite transportation to our main campus. Thus, prospective research with close follow-up is required to further assess the outcomes of this practice modification.