ABSTRACT
Objective
This study aimed to assess demographic and sonographic factors associated with successful ultrasound-guided hydrostatic reduction in pediatric patients with intussusception.
Method
This retrospective, single-center study included children with ultrasonographically confirmed intussusception who underwent ultrasound-guided hydrostatic reduction. Demographic characteristics, intussusception location, intussuscepted segment length, mesenteric lymphadenopathy, free intraperitoneal fluid, and increased mesenteric echogenicity were evaluated. The optimal cut-off value for intussuscepted segment length was determined using receiver operating characteristic (ROC) curve analysis.
Results
A total of 132 patients were included; 79 were male (59.8%), and the median age was 2 years. Hydrostatic reduction was successful in 109 (82.6%) patients. No procedure-related perforation or major complication occurred. Surgical treatment was required in 23 patients (17.4%); manual reduction was achieved in 18, whereas 5 patients with bowel ischemia underwent segmental resection and primary anastomosis. The mean intussuscepted segment length was shorter in the successful reduction group than in the failed reduction group (48.4±17.9 mm vs. 68.8±23.4 mm; p<0.001). ROC curve analysis identified 70 mm as the optimal cut-off for predicting failed reduction, with an area under the curve of 0.762. Free intraperitoneal fluid and increased mesenteric echogenicity were associated with failed reduction (p=0.002 and p=0.037, respectively). Age, sex, intussusception location, and lymphadenopathy were not significantly associated with hydrostatic reduction success.
Conclusion
Ultrasound-guided hydrostatic reduction is safe and effective for pediatric intussusception. Longer intussuscepted segment length, free intraperitoneal fluid, and increased mesenteric echogenicity may help predict failed reduction and the need for surgery.
INTRODUCTION
Intussusception is the leading cause of bowel obstruction during infancy and early childhood. Approximately 80% of intussusception cases occur in patients younger than 2 years(1, 2). Intussusception most commonly involves the ileocolic region. Clinical presentation is usually characterized by non-specific symptoms such as vomiting, diarrhea, and fever(2). Given the young age of affected patients, clinical diagnosis may be challenging; therefore, radiological evaluation is frequently required. Diagnosis is usually established by ultrasound (US)(3). Early diagnosis and treatment are important because delays may lead to intestinal ischemia, necrosis, or perforation(4).
Treatment options for intussusception include pneumatic reduction, hydrostatic reduction, and surgery(2, 5). Pneumatic reduction is performed under fluoroscopic guidance, whereas hydrostatic reduction is performed under US guidance. Since pneumatic and hydrostatic reduction techniques are associated with lower morbidity and mortality rates compared to surgery, they are preferred as first-line treatment options. US-guided hydrostatic reduction has been reported to have a higher success rate than pneumatic reduction(6). In addition, because US-guided hydrostatic reduction does not involve ionizing radiation and is easy and inexpensive to perform, it is considered a first-line treatment method(7). The reported success rates of hydrostatic reduction range from 82% to 92.9%(8-10). Surgery is indicated in cases of failed reduction, shock, peritonitis, or intestinal perforation(2).
Clinical factors such as age, time from symptom onset to treatment, presence of rectal bleeding, and vomiting may affect the success of hydrostatic reduction(11, 12). In addition, radiological findings such as intussuscepted segment length, presence of enlarged intra-abdominal lymph nodes, air-fluid levels, and a pathological lead point have also been shown to be associated with procedural success of hydrostatic reduction(13-15).
This study aimed to assess the associations of demographic and sonographic factors with hydrostatic reduction success in pediatric intussusception. Identifying these factors may reduce the need for surgical treatment and the related morbidity and mortality.
MATERIALS and METHODS
Patient Selection
Approval for this retrospective study was obtained from the local ethics committee of University of Health Sciences Türkiye, Dr. Behçet Uz Pediatric Diseases and Surgery Training and Research Hospital with decision no: 2026/05-08, dated: 12.03.2026. The study population included children who were diagnosed with intussusception by US and underwent US-guided hydrostatic reduction at a single tertiary pediatric center between September 2020 and February 2026. In our center, all patients with suspected intussusception were routinely evaluated by US, and US-guided hydrostatic reduction was attempted in all patients when the diagnosis of intussusception was confirmed. No patient was referred directly to surgery without a prior attempted hydrostatic reduction during the study period. Patients with spontaneously reduced intussusception (n=4) and patients who underwent surgery after failed hydrostatic reduction but had no intraoperative evidence of intussusception (n=1) were excluded.
Radiological Evaluation
Diagnosis of intussusception was established using US by a single radiologist. A high-frequency linear probe (Toshiba, Aplio 500) was used for diagnosis and treatment. Cases of intussusception were categorized as ileocolic, ileoileal, or colocolic according to the involved bowel segment. In all US examinations, the length of the intussuscepted segment was measured along the long axis and recorded. The presence of lymphadenopathy, free intraperitoneal fluid, and increased mesenteric echogenicity was also noted. Increased mesenteric echogenicity was defined as subjectively increased echogenicity of the mesenteric fat adjacent to the intussuscepted segment compared with the surrounding mesenteric fat. Mesenteric lymph nodes with a short-axis diameter of 6 mm or greater were considered lymphadenopathy.
Considering transient intussusception as a possibility, patients with an intussuscepted segment length of <20 mm on US were managed conservatively. These patients were observed for 1-6 hours and re-evaluated by US. If the finding persisted, an evacuation enema was performed. These patients then underwent repeat US examinations performed by the same radiologist. Patients in whom reduction was not achieved based on follow-up US images and those with an intussuscepted segment length of ≥20 mm underwent hydrostatic reduction.
Hydrostatic Reduction Procedure
After insertion of a 16-18 Fr catheter in the rectum, the balloon of the catheter was inflated to maintain catheter stability. Saline solution was administered through the catheter by gently compressing the suspended saline bag. During administration of saline solution, colonic distension was monitored simultaneously with US. Colonic expansion was allowed up to a maximum diameter of 40 mm. If the luminal diameter exceeded 40 mm, administration of saline solution was stopped because of the risk of perforation.
Hydrostatic reduction was considered successful when saline solution passage proximal to the intussuscepted segment was observed, at which point the procedure was terminated. If passage of saline solution proximal to the intussuscepted segment was not observed, reduction was attempted with the patient first in the right and then in the left lateral decubitus position. If proximal passage of saline solution still could not be achieved, hydrostatic reduction was considered unsuccessful, and the patient was referred for surgery. The reduction procedure lasted approximately 10 minutes.
All patients who underwent reduction procedures were hospitalized for at least 24 hours and underwent at least one follow-up US examination. Recurrent intussusception was detected in two patients during the 24 hour observation period. Both patients were successfully treated with repeat US-guided hydrostatic reduction. No pathological lead point was suspected on US in either patient.
Surgical Reduction
During intraoperative evaluation, bowel viability was assessed in terms of color, peristalsis, and mesenteric circulation. The bowel and mesentery were explored for a possible pathological lead point, such as an associated mass or space-occupying lesion. Enlarged lymph nodes were resected for sampling.
The primary surgical approach was laparotomy and manual reduction. During this procedure, the intussuscepted segment was gently and carefully reduced from distal to proximal using the milking technique. Manual reduction was adopted as the standard approach because it allows preservation of intestinal continuity. The affected bowel segment was resected, and primary anastomosis was performed when manual reduction failed or when irreversible ischemia, necrosis, or perforation was present. Patients were hospitalized for at least 48 hours postoperatively and underwent US 24-48 hours after surgery to evaluate for complications.
Statistical Analysis
A two-tailed p-value below 0.05 was accepted as indicating statistical significance. Data analyses were conducted with Statistical Package for the Social Sciences (SPSS) software, version 20.0 (IBM Corp., NY, USA).
The association between hydrostatic reduction success and age was evaluated using the Mann-Whitney U test, whereas the association with sex was assessed using the chi-square test. The association between intussusception location and hydrostatic reduction success was analyzed using the likelihood-ratio chi-square test. Preprocedural intussuscepted segment length was compared between the successful and failed reduction groups using the independent-samples t-test. Receiver operating characteristic (ROC) curve analysis was performed to determine the intussuscepted segment length cut-off with the best discriminatory ability for predicting failed reduction. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the area under the ROC curve (AUC) were calculated for the identified cut-off. The associations between hydrostatic reduction success and lymphadenopathy, free intraperitoneal fluid, and increased mesenteric echogenicity were evaluated separately using Fisher’s exact test.
RESULTS
The study included 132 patients, of whom 79 were male (59.8%) and 53 were female (40.2%). The median age was 2 years [interquartile range (IQR), 1-4 years; minimum age, 3 months; maximum age, 12 years]. Intussusception was ileocolic in 117 patients (88.6%), colocolic in 8 patients (6.1%), and ileoileal in 7 patients (5.3%). Intussusception was successfully reduced by hydrostatic reduction in 109 (82.6%) patients. Recurrent intussusception was observed on follow-up US in two patients during the 24-hour observation period after initially successful hydrostatic reduction. Both patients were successfully treated with repeat US-guided hydrostatic reduction. No pathological lead point was suspected or identified in these patients.
Reduction was achieved surgically in 23 (17.4%) patients. Among these 23 patients, successful manual reduction was achieved in 18 patients. Small bowel resection and anastomosis were performed in 5 patients (3.8%) because of irreversible bowel ischemia. A pathological lead point was identified in 8 patients (6.1%): Meckel diverticulum in 3 patients, acute appendicitis in 2 patients, hemangioma in the adjacent mesentery in 1 patient, adenomyoma in 1 patient, and adhesion in 1 patient. Lymph node resection was performed in 9 patients, and all resected lymph nodes were reported as lymphoid hyperplasia. All patients who underwent surgical treatment were discharged without complications. The demographic findings are summarized in Table 1.
In all patients, the mean intussuscepted segment length was 52.0±20.4 mm. Lymphadenopathy was observed in 87 (65.9%), free intraperitoneal fluid in 32 (24.2%), and increased mesenteric echogenicity in 5 (3.8%) patients. The median short-axis diameter of the lymph nodes was 8 mm (IQR, 6-9 mm).
No significant association was found between reduction success and age or sex (p=0.118 and p=0.721, respectively). The reduction success rates were 84.6% for ileocolic, 75.0% for colocolic, and 57.1% for ileoileal intussusceptions. Intussusception location was not significantly associated with reduction success (p=0.213).
The mean intussuscepted segment length was 48.4±17.9 mm in patients who underwent successful reductions and 68.8±23.4 mm in patients with failed reduction. Intussuscepted segment length was significantly associated with hydrostatic reduction success (p<0.001) (Figure 1). ROC curve analysis identified 70 mm as the optimal cut-off for predicting failed reduction. At this cut-off, sensitivity was 60.9%, specificity was 85.3%, PPV was 46.7%, NPV was 91.2%, and the AUC was 0.762.
Lymphadenopathy was observed in 65.1% of patients who underwent successful reduction and in 69.6% of patients in whom reduction attempts failed. The association between lymphadenopathy and successful hydrostatic reduction was not significant (p=0.81). Free intraperitoneal fluid was more frequent in the failed reduction group than in the successful reduction group (52.2% vs. 18.3%) and was significantly associated with failed hydrostatic reduction (p=0.002). Increased mesenteric echogenicity was also more common in the failed reduction group (13.0% vs. 1.8%) and was significantly associated with failed hydrostatic reduction (p=0.037) (Figure 2). The comparative statistical results are summarized in Table 2.
DISCUSSION
In this study, we evaluated demographic and sonographic factors associated with hydrostatic reduction success in pediatric intussusception. The hydrostatic reduction success rate was 82.6%, and no complications occurred during the procedure. The likelihood of successful hydrostatic reduction decreased as intussuscepted segment length increased. The optimal cut-off value for the length of the intussuscepted segment in terms of differentiating successful and failed reduction attempts was calculated as 70 mm. In addition, free intraperitoneal fluid and increased mesenteric echogenicity were significantly associated with failed reduction.
Hydrostatic reduction is a first-line treatment option for pediatric intussusception. In the meta-analysis by Kim et al.(9), the pooled reduction success rate was 82%. In the large series of 543 patients reported by Ntoulia et al.(10), the reduction success rate was 86.7%, and 72 patients required surgery. Among the surgically treated patients, spontaneous or manual reduction was achieved in 68%, whereas small bowel resection and ileocecal resection were performed in 19.4% and 12.5%, respectively. A pathological lead point was identified in 25% of patients requiring surgery, including lymphoid hyperplasia (9.7%), Meckel diverticulum (4.2%), Burkitt lymphoma (4.2%), enteric duplication cyst (2.8%), juvenile polyp (2.8%), and adenoviral appendicitis (1.4%)(10). In the series by Yang et al.(16), which included 3086 pediatric patients treated using two different protocols, surgical treatment was required in 19.9% of patients, and bowel resection was performed in 2.6% of all patients. In the meta-analysis by Sadigh et al.(5), the perforation rate during hydrostatic reduction was 0.43%. In our study, 17.4% of patients required surgery after failed hydrostatic reduction. Manual reduction was achieved surgically in 13.6% of patients, whereas small bowel resection was performed in 3.8% because of irreversible bowel ischemia. A pathological lead point was identified in 6.1% of patients, with Meckel diverticulum being the most common finding (2.3%). No perforation occurred during hydrostatic reduction in any patient.
Pediatric intussusception reduction success may be affected by demographic and clinical factors. In the study by Zhuang et al.(11), clinical, laboratory, and imaging parameters were evaluated together, and a nomogram was developed to estimate the need for surgery. Symptom duration, bloody stool, white blood cell count, creatine kinase isoenzyme (CK-MB), intussuscepted segment length, and mental status were identified as independent risk factors(11). In the series of 290 patients reported by Alsinan et al.(12), female sex, age younger than 1 year, and symptom duration longer than 48 hours were associated with failed reduction. That study included patients aged between 1 and 36 months. Similarly, Elrouby et al.(17) reported that younger age, low body mass index, longer symptom duration, bloody stool, a palpable abdominal mass, left-sided intussusception, and increased air-fluid levels on radiography were associated with failed reduction. However, that study included only patients aged between 6 months and 3 years(17). In the review by Hwang et al.(18), left-sided colocolic intussusceptions were suggested to have a lower likelihood of successful reduction. In our study, neither age nor sex was significantly associated with hydrostatic reduction success. The success rates were 84.6% for ileocolic, 75.0% for colocolic, and 57.1% for ileoileal intussusceptions. Although the success rate appeared higher for ileocolic intussusceptions, intussusception location was not significantly associated with reduction success. The differences between our findings and those reported in previous studies may partly reflect the relatively small number of patients, particularly in the failed reduction group.
Several sonographic findings have been reported to be associated with hydrostatic reduction success in pediatric patients. In the study by Gondek et al.(13), which included only patients with ileocolic intussusception, free intraperitoneal fluid and absence of Doppler vascularity in the intussuscepted segment were associated with failed reduction. Ayana et al.(14) reported that intussusceptions shorter than 35 mm were more likely to be successfully reduced. In the series by Wondemagegnehu et al.(15), which included 174 children, free intraperitoneal fluid was observed in 21.8% of patients and enlarged lymph nodes in 54.6%. The mean intussuscepted segment length was 52 mm. In that study, free intraperitoneal fluid and the presence of a pathological lead point or associated mass were significantly associated with reduced treatment success(15). In our study, the likelihood of successful hydrostatic reduction decreased significantly as intussuscepted segment length increased. A cut-off of 70 mm showed 60.9% sensitivity and 85.3% specificity for predicting failed reduction. Free intraperitoneal fluid and increased mesenteric echogenicity were also significantly associated with failed reduction.
Study Limitations
This study has several limitations. First, because of its retrospective and single-center design, the possibility of selection bias cannot be completely excluded. Second, the relatively small number of patients in the failed hydrostatic reduction group may have reduced statistical power, particularly in subgroup analyses. Therefore, the findings should be confirmed in larger patient cohorts. Third, because sonographic evaluations were performed by a single radiologist, interobserver variability analysis could not be performed, which may have made the results operator-dependent. Finally, because the interval between symptom onset and treatment was inconsistently documented in the medical records, symptom duration could not be analyzed in a standardized manner. This represents an important limitation because symptom duration may affect reduction success, bowel ischemia, the need for bowel resection, and the decision to proceed with surgery. In addition, free intraperitoneal fluid was evaluated only as a binary variable according to its presence or absence; its amount and distribution were not analyzed.
CONCLUSION
In conclusion, hydrostatic reduction of pediatric intussusception can be performed safely and successfully under US guidance. The likelihood of successful reduction decreases as intussuscepted segment length increases. Pre-reduction US assessment of intussuscepted segment length, free intraperitoneal fluid, and increased mesenteric echogenicity may be useful for predicting failed reduction and identifying patients who may require surgery.
