Abstract Background/Aims Deep enteroscopy is a challenging and time-consuming procedure. Two devices have become the clinical standards for patients: double-balloon enteroscopy (DBE) and motorized spiral enteroscopy (mSPE). Initially, mSPE demonstrated impressive results, with high rates of total enteroscopy, which were superior to those of all other devices. However, for safety reasons, mSPE was withdrawn from the market, and it remains uncertain whether it will return after technical improvements. This prospective randomized trial aimed to compare the DBE and mSPE. Methods Patients indicated for enteroscopy were randomized to undergo either mSPE or DBE. The time to diagnosis or complete enteroscopy was measured, and all complications were recorded. Results A total of 48 enteroscopic procedures were performed, including 23 mSPE and 25 DBE. No significant difference was noted in the procedure time (p=0.212). The mSPE group exhibited a shorter mean procedure time of 54 (range, 15–114; standard deviation [SD], 26) minutes, whereas the DBE group had a mean procedure time of 63 (range, 20–131; SD, 25) minutes. One perforation was seen in the mSPE group. Conclusions DBE and mSPE are both effective enteroscopy methods but showed no significant difference in this randomized trial (German trial registry: DRKS 00025890). Keywords: Double-balloon enteroscopy; Motorized spiral enteroscopy; Small bowel disorders Graphical abstract INTRODUCTION Double-balloon enteroscopy (DBE) has facilitated the deep evaluation of the small intestinal tract since its description by Yamamoto et al. in 2001.1 Enteroscopy has since become established as a safe diagnostic and therapeutic endoscopic procedure. For decades, single-balloon enteroscopy (SBE) has been the primary alternative to DBE, and was first described in 2008.2 Both techniques have been extensively studied for their diagnostic and therapeutic applications. Randomized controlled trials have compared their effectiveness in various clinical settings. In summary, DBE has shown greater efficacy in achieving complete enteroscopy rates as well as diagnostic and therapeutic yield (Fig. 1).3-6 Spiral enteroscopy differs from balloon-based techniques in its applications because it lacks a balloon for anchoring. Instead of relying on a balloon, it uses a spiral overtube that retracts the small bowel over the scope through gentle rotation. The conventional spiral overtube (Spirus Medical Inc.) was introduced in 2007.7 However, this new method failed to establish itself in routine clinical practice, owing to its lack of significant advantages over balloon-assisted methods.8-10 A pivotal development in enteroscopy was the motorization of the conventional spiral by Olympus (Powerspiral; Olympus). The power spiral (PS) demonstrated impressive performance, achieving a total antegrade enteroscopy rate of up to 10%.11 Since then, the PS and DBE have become the preferred devices for deep enteroscopy. The PS was considered to be more effective and faster, leading to its increasing adoption in endoscopy units (Fig. 2). However, significant complications have been reported with the use of PS. For safety reasons, only certified users were permitted to perform interventions using motorized spiral endoscopes. To ensure safe esophageal passage, patients should be intubated before the intervention. In 2023, the PS was withdrawn from the market due to safety concerns. It remains uncertain whether the PS will return after technical improvements or with modified approval. This prospective randomized controlled trial aimed to directly compare DBE with motorized spiral enteroscopy (mSPE). METHODS This was a prospective randomized controlled trial that compared DBE and mSPE. The study was conducted in accordance with Good Clinical Practice and the Declaration of Helsinki, and was registered in the German trial registry (DRKS 00025890). All co-authors had access to the study data and reviewed and approved the final manuscript. The ethics committees at each site approved the study and the patients provided informed consent before participating. Consecutive patients who required small bowel enteroscopy were enrolled from two tertiary centers. The indications for enteroscopy are listed in Table 1. Contraindications for the study included the absence of signed informed consent, age under 18 years or over 99 years, and an inability to discontinue anticoagulation. The participating endoscopists had significant experience in enteroscopy, with at least 250 assisted or performed procedures. Prior to enrollment, randomization was conducted using a computer-generated list. This trial was initiated by clinicians and had no commercial sponsors. All authors had access to the study data and reviewed and approved the final manuscript. (1) Primary endpoint: (i) time to diagnose, (ii) in case of no diagnosis, time for total enteroscopy; (2) secondary endpoints: (i) diagnostic and therapeutic success rate, (ii) complication rate, (iii) complete enteroscopy rate. Statistical calculations Descriptive analyses were conducted using IBM SPSS Statistics for Windows ver. 27 (IBM Corp.) Continuous variables were presented as means, while categorical variables were described as percentages or frequencies. Normal distribution of the data was assessed using the Kolmogorov-Smirnov test. Differences between the two groups were analyzed using either the t-test or the Mann-Whitney U-test, depending on the distribution of the data. Sample size calculation When initiating this study, only one major study on mSPE had been published, making direct comparisons nonexistent. Statistical sample size calculations were performed at the Institute of Biostatistics and Mathematical Modeling, Goethe University Frankfurt, Frankfurt, Germany. The calculation was conducted solely for evaluating the first primary endpoint, “time to diagnose.” We expected the mSPE to be faster than the DBE. Based on the evaluation of published data, we assumed that DBE would achieve diagnostic yield in 25% of cases. In 75% of cases, deep or total enteroscopy would be attempted. The time required to reach this endpoint was estimated to be 120 minutes (standard deviation [SD], 15 minutes) for DBE. For mSPE, the time was estimated similarly but with 60 minutes (SD, 10 minutes) for deep enteroscopy or total enteroscopy. To estimate statistical power, we made the following assumptions: the primary endpoints were hierarchically assessed on both sides at a significance level of alpha=5%. Given the expected non-normal distribution of these endpoints, a nonparametric Mann-Whitney U-test was used for comparison. Complication rates were compared using the Fisher exact test. The total time for both methods was compared using a nonparametric Wilcoxon-Mann-Whitney U-test. Simulations with 10,000 runs each showed that the statistical power was approximately 80% (80.0% with a confidence interval [CI] of 79.2% to 80.8%) when 16 patients per group were included. Procedure and technical equipment 1) Double ballon enteroscopy DBE was performed using EN-580T (center 1) and EN-450P/EN-580T (center 2) endoscopes (Fujifilm). Both endoscopes have a length of 200 cm and a working channel of either 2.2 mm or 3.2 mm. A suitable overtube with an outer diameter of 12.5 mm or 13.5 mm, was employed in all cases. Enteroscopy was performed under deep propofol sedation. The choice of access route was determined based on clinical findings. In the cases of planned total enteroscopy or unclear findings, the oral route was initially preferred. All endoscopists had extensive experience in both the diagnostic and therapeutic applications of the device. 2) Motorized spiral enteroscopy mSPE was conducted using a PS device PSF-1 (Olympus) comprising a PS tube and a control unit. The enteroscope measured 168 cm in length and features a 3.2 mm working channel. The outer diameter of the scope, including the spiral tube, was 18.1 mm. Consequently, all patients were intubated before the antegrade procedure. To ensure safe passage, 18 to 20 mm bougienage was performed before the procedure. The retrograde route is performed under deep sedation or anesthesia. All operators underwent training, possessed routine clinical experience, and had participated in previous PS studies. All enteroscopies were performed in a fluorscopy room (Fig. 3). The procedures were performed using CO2 insufflation as standard practice. IRB approval This study was approved by the ethics committee of Goethe University Frankfurt for both centers (University Hospital Frankfurt and Asklepios Paulinen Klinik) (approval number: DRKS 00025890, 202160). RESULTS The patients were screened for the present study between August 2021 and May 2023. All patients who agreed to participate were included in the study. Forty-eight enteroscopic procedures (23 mSPE and 25 DBE) were performed at two tertiary centers. Table 1 shows the baseline patient characteristics. Primary outcomes The mean procedure time for all patients was 59 minutes (SD, 15–131 minutes), encompassing all study patients regardless of diagnosis. No significant difference was observed in procedure time between the two groups (t-test, p=0.212). The mSPE exhibited a slightly faster mean time of 54 minutes (range, 15–114 minutes; SD, 26 minutes), whereas the DBE had a mean procedure time of 63 minutes (range, 20–131 minutes; SD, 25 minutes). A diagnosis was achieved in 17 patients (68%) undergoing DBE and in 8 patients (35%) undergoing mSPE. The mean time to achieve diagnosis was 33.4 minutes for DBE (range, 4–70 minutes; SD, 23 minutes) and 19.4 minutes for mSPE (range, 9–44 minutes; SD, 12 minutes). Diagnostic results after enteroscopy are listed in Table 2. Total enteroscopy rate During all the procedures, the depth of insertion was estimated by the examiner. The total length of the small intestine, excluding previous surgical alterations, was 500 cm. In DBE, the mean estimated insertion depth was 234 cm (range, 10–500 cm; SD, 145 cm). Complete oral panenteroscopy was defined as passing the ileocecal valve via the oral route. In two cases (mSPE group), endoscopic passage of the ileocecal valve was not possible. Administering a contrast agent under X-ray confirmed the position. These cases were considered complete enteroscopies. Total enteroscopy via the retrograde route was confirmed when the previously placed ink markings were reached. The complete enteroscopy rate for DBE was five patients (20%), with total enteroscopy achieved via the antegrade route alone in two patients (8.0%). Because enteroscopy is usually completed after diagnosis or successful intervention, the total enteroscopy rate should be evaluated in relation to the number of patients for whom complete enteroscopy is desired, which was 12 patients (48%). In these cases, the total enteroscopy rate was five (41.7%), with two achieved via the antegrade route alone (16.7%). For mSPE, the estimated insertion depth was 227 cm (range, 10–500 cm; SD, 186 cm). Complete enteroscopy was achieved in seven patients (30.4%), with total antegrade enteroscopy possible in five of these patients (21.7%). In 17 patients undergoing mSPE with the intention of total enteroscopy, five (29,4%) achieved it via the antegrade route. Overall, seven out of 17 patients (41.1%) underwent total enteroscopy. No significant differences were observed in the depth or total enteroscopy rates between the two endoscopic techniques (Table 3). Diagnostic and therapeutic yield The enteroscopic procedure was successful in all the patients included in this study. A diagnosis was made or confirmed in 25 of the 48 patients. The diagnostic yield for mSPE was 35%, significantly lower than the 68% yield in the DBE group. No statistical correlation was seen between previous abdominal surgeries and diagnostic yield (Kolmogorov-Smirnov test, p=0.125). Complications No severe sedation-related complications were observed during the procedure. All the patients were successfully intubated and ventilated as intended. Furthermore, no complications were associated with bouginage performed using oral mSPE. Three cases of desaturation occurred during DBE, all of which were managed conservatively. Endoscopic intervention achieved 100% technical success. No statistical correlation was observed between previous abdominal surgeries and adverse events (Kolmogorov-Smirnov test, p=0.79). However, one major complication occurred in the mSPE group. One patient underwent argon plasma coagulation during the procedure to treat angiodysplasia. Deep enteroscopy was performed without any immediate concerns, and the patient was discharged the following day without any signs of abdominal trauma. However, the patient was readmitted to hospital on the second night with abdominal pain. A computed tomography revealed free abdominal air, and a subsequent laparotomy identified a small perforation, which was surgically sutured. Given the clinical situation and localized perforation, this event was classified as a procedure-related serious adverse event (SAE). Smaller mucosal lacerations were recorded in both groups, with four in the DBE group and seven in the mSPE group. All the patients were discharged the following day. Longer hospital stay was consistently associated with additional diagnostic procedures and necessary interventions. DISCUSSION Entering the small bowel for diagnostic or therapeutic procedures is challenging and time consuming. New endoscopic techniques should prioritize patient safety and ease of use. A rapid and efficient approach is required to achieve complete enteroscopy of the small bowel. The PS system was designed to meet these needs, but its effectiveness in randomized trials has not been compared with that of DBE. mSPE aims to overcome drawbacks, such as time-consuming procedures and incomplete enteroscopy. An initial clinical feasibility study reported that mSPE was remarkably fast, with a median insertion time of 25 minutes across 140 procedures.11 However, a significant limitation of this study is the exclusion of patients who had undergone prior abdominal surgery. Among patients with a history of abdominal surgery, the insertion time increased from 29 to 38 minutes (p=0.642), which was still shorter than the typical DBE procedure times of 80 to 90 minutes.3,12,13 A recent prospective trial investigated the performance of mSPE in patients who had undergone prior abdominal surgery. The authors concluded that prior surgery led to a significantly longer procedure time.13 In the present study, 29.2% of patients had a history of abdominal surgery, with a mean insertion time of 54 minutes for mSPE and 63 minutes for DBE (p=0.212). The insertion time varies depending on the indication. To compare these two techniques better, the rate of complete enteroscopy can serve as a more suitable metric. Two recent meta-analyses examining over 460 and 876 patients undergoing mSPE found that the total enteroscopy rate was between 43% and 51%, with a wide range among the studies (95% CI 30–75; 95% CI, 24.7–62.5).14,15 In the present study, the total enteroscopy rate when intended was relatively low, at 41.2% for mSPE and 41.7% for DBE comparing other publications. The comparatively low rates of total enteroscopy may be explained by the variations in patient characteristics among the studies included in the meta-analysis. Previous studies predominantly included patients without prior abdominal surgery. DBE studies report total enteroscopy rates ranging from 18% to 66%.3-5 The first clinical trial exploring mSPE showed promising results for complete enteroscopy using the antegrade approach. Total panenteroscopy is possible in 10% to 21% of cases.11,16 Our data showed comparable results with 29.4% for mSPE and 16.7% for DBE. Complete antegrade enteroscopy with DBE is relatively rare, suggesting that the reported rates may have been overestimated. Both the mSPE and DBE have been extensively investigated; however, no direct randomized controlled trials have compared them. In a prospective randomized trial of 125 patients with Crohn's disease, mSPE demonstrated a higher rate of complete enteroscopy compared to SBE (78% vs. 11%).17 In the present investigation, mSPE showed higher effectiveness and decreased the investigation time, but without any significant difference. The presented data must be viewed from the perspective that both centers are tertiary. Moreover, one of the two centers is internationally known for its expertise in small bowel enteroscopy. This led to the selection of difficult patients for inclusion in the trial. Extensive experience in the field of DBE might create an advantage in favor of DBE. Patients presenting at a tertiary center more often fail enteroscopy in other units and are sent to undergo a specific examination. This cohort was not eligible for randomization and was excluded. Therefore, trials with consecutive patients are preferable. Both methods are generally safe for diagnostic and therapeutic enteroscopies. Nonetheless, there was one reported perforation during the study period. One patient experienced acute abdominal pain after mSPE and argon plasma coagulation for angiodysplasia, which led to localized peritonitis due to a small perforation. Although studies generally report low rates of major adverse events (0% to 2.3%), some significant events like “deep laceration” with “prolonged hospital stay” have not always been classified as SAEs,12,18,19 as noted by Despott and Murino in 2022.20 This could partly explain why serious complications resulted in the withdrawal of PS from the market in 2023. DBE has been intensively studied in recent years and shows a high safety profile with a perforation rate of 0.4% in over 2,478 examinations at nine United States centers, as well as in the German DBE registry.21,22 A review of published data revealed that the most SAEs occurred in high-risk patients who underwent the antegrade approach. Using mSPE only in the retrograde approach can reduce the risk of severe injuries to the esophagus and pylorus. This would also eliminate the need for prior intubation and bougienage in most cases, potentially allowing for complete enteroscopy via the retrograde route.23 This study had some limitations. The diagnostic yield and total enteroscopy rate were lower than those reported in other studies. Moreover, the diagnostic yield was twice as high (68%) in DBE group to the mSPE group (35%). This suggests that mSPE underperformed in our cohort, whereas DBE showed above-average results. Consequently, DBE may be a viable alternative, particularly because mSPE is not currently available. In spite of these limitation, this study is the first and only randomized comparison of DBE and mSPE. Currently, there are very few prospective studies on the double-balloon technique, and this study demonstrates that high rates of complete enteroscopy can be achieved by experienced surgeons. We expect that the motorized spiral might return to a modified version by other companies because the technique is too interesting to be kept off the market.

Conflicts of Interest

The authors have no potential conflicts of interest.

Funding

None.

Author Contributions

Data curation: LW, GD, IAM; Formal analysis: EH; Investigation: MH, JW, GD, IAM; Project administration: MK, MH; Software: EH; Resources: SZ, AM; Supervision: SZ, AM; Writing–original draft: MK; Writing–review & editing: all authors.

Fig. 1.

Double-balloon-enteroscopy after preparation.

Fig. 2.

Motorspiral enteroscope reaching a small bowel metastasis from malignant melanoma.

Fig. 3.

X-ray showing deep enteroscopy by double balloon.

Table 1.

The baseline patients characteristics

Characteristic Double-balloon enteroscopy Motorized spiral enteroscopy Total no. of patients  Female 11 9  Male 12 11 Mean age (yr) 59 66 Prior abdominal surgery  Cholecystectomy 2 2  Hernia 0 2  Pancreatectomy 1 2  Gastrectomy 2 0  Appendectomy 1 0  Small bowel resection 2 0 Anticoagulation  Asprin 4 5  Antiplatelet agent 0 0  Asprin+antiplatelet agent 0 3  Oral anticoagulation 3 0 Indication for enteroscopy  Anemia 11 12  Crohn's disease 4 3  Polyps 2 2  Acute bleeding 2 0  Tumor/lymphoma 2 1  Stenosis 3 2 Table 2.

The diagnostic results after enteroscopy

Diagnosis Double-balloon enteroscopy Motorized spiral enteroscopy Angiodysplasia 3 3 Tumor/lymphoma 3 1 Stenosis 5 1 Ulcer 2 0 Crohn's disease 1 1 Polyps 2 2 Dieulafoy bleeding 1 0 No diagnose 8 15 Table 3.

The most significant results and complications of this trial

Double-balloon enteroscopy Motorized spiral enteroscopy Wilcoxon-Mann-Whitney U-test Antegrade approach 21 11 Retrograde approach 4 12 Time to diagnosis (range, SD; min) 33.4 (4–70; SD 23) 19.4 (9–44; SD 12) 0.11 Diagnostic yield (%) 68 34.8 Total procedure time (range, SD; min) 63 (20–131; SD 25) 54 (15–114; SD 26) 0.212 Total enteroscopy rate (n, %) 5/25 (20.0) 7/23 (30.4) 0.409  When intended 5/12 (41.7) 7/17 (41.2) 0.979  On oral route alone 2/12 (16.7) 5/17 (29.4) 0.797 Time to total enteroscopy (range, SD; min) 51 (40–51; SD 13) 36 (22–48; SD 11) 0.23 Complications  Adverse events 4 7  Serious adverse events 0 1 REFERENCES 1. Yamamoto H, Sekine Y, Sato Y, et al. Total enteroscopy with a nonsurgical steerable double-balloon method. Gastrointest Endosc 2001;53:216–220.ArticlePubMed 2. Kawamura T, Yasuda K, Tanaka K, et al. Clinical evaluation of a newly developed single-balloon enteroscope. Gastrointest Endosc 2008;68:1112–1116.ArticlePubMed 3. 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Seung Min Hong, Dong Hoon Baek
Clinical Endoscopy.2025; 58(4): 546.     CrossRef