Safety of motorized spiral enteroscopy: is what we know today enough?

Over the last 20 years, we have seen a fantastic evolution in small-bowel endoscopy, first with small-bowel capsule endoscopy and subsequently with device-assisted enteroscopy (DAE), including double-balloon enteroscopy (DBE), single-balloon enteroscopy (SBE), and manual spiral enteroscopy. Motorized spiral enteroscopy (MSE) represents the latest innovative advancement in enteroscopy [1]. MSE appears to offer several advantages compared with conventional DAE, which include: shorter procedure times, an apparently fast learning curve [1] [2] [3], and high total enteroscopy rates [4]. Of note, the rate of total enteroscopy through only an antegrade approach can be as high as 31.1 % [2]. The diagnostic yield is comparable to DAE. However, as with all new technologies, to allow for its widespread application in clinical practice, the most recent must not be inferior to the methods already available and, most importantly, it must have a comparable, or even a more favorable, safety profile.

The DAE techniques available so far have proven their value and safety in large cohort studies. Results from large prospective registries and systematic reviews including more than 10 000 procedures have shown that the overall DAE-related major complication rate is around 1 % [5]. Conversely, MSE safety data are still scarce. The evidence on the safety of MSE in unselected populations is still based on a limited number of patients, approximately 750 from seven studies to date [1] [2] [3] [4] [6] [7] [8]. For MSE, minor adverse events (AEs), such as superficial mucosal tears, submucosal hematomas, and throat discomfort, are to be expected in about a quarter of patients [1] [2] [3] [4] [6] [7]. Two serious adverse events (SAEs; 1.5 %) were recorded in one study (one delayed bowel perforation and one bleed from a Mallory–Weiss lesion) [1], and one case of pancreatitis was reported in a case series of 14 patients [6]. In addition, information on the impact of prior major abdominal surgery on the safety of MSE is still currently limited to approximately 60 patients from two studies that included patients with altered gastrointestinal (GI) anatomy [3] [8]. It would therefore be useful to create large prospective MSE complication registries, as was done for DBE [9], that can provide more robust data on how the procedure performs in the true real-life setting, outside of a clinical study.

In this issue of Endoscopy, Beyna et al. report on their prospective multicenter observational study of 298 patients (median age 68 years) [8]. Safety analysis, as measured by SAEs, was chosen as the primary end point of the study. The study enrolment was divided into two phases: a training phase (47 patients) and a core phase that included the remaining 251 patients, some of whom had undergone major abdominal surgery and had altered GI anatomy. Their overall SAE rate was 2.3 % in the per-patient analysis: 2.0 % in the core group and 4.3 % in the training group; it was not increased after abdominal surgery (1.9 %). All but one SAE occurred during an antegrade MSE procedure, with SAEs including one delayed perforation and one premature disassembly of the spiral overtube during the withdrawal phase. Interestingly, only one SAE (0.9 %) occurred at a center already experienced in MSE, whereas the overall SAE rate was 3.3 % at new MSE centers. The SAE rates were 0.8 % and 3.5 % for diagnostic procedures and when therapeutic interventions were performed, respectively.

“The accumulating evidence from the numerous ongoing trials will provide a more accurate understanding of the potential complications related to MSE, their actual frequency, and the predisposing risk factors that can help to minimize their incidence.”

The authors have to be commended for the effort to set up a study specifically aimed at assessing the safety issue in a clinical practice setting. However, although the SAE rates were below the thresholds proposed by the ESGE guideline of 1 % and 5 % for diagnostic and therapeutic procedures, respectively [10], as correctly pointed out by the authors, the study was not adequately powered for these subgroup analyses. Furthermore, the study was conducted in endoscopy tertiary referral centers with endoscopists who were already experienced in deep enteroscopy using standard DAE and, notably, approximately 40 % of the procedures were performed at two highly experienced MSE centers. Therefore, the results still have to be interpreted with caution and cannot be generalized.

In addition, some intrinsic features related to MSE, with a potential influence on safety, must also be taken into consideration. The premature disassembly of a spiral overtube has been reported in this study [8] and in two recent case reports [11] [12]. Although an uneventful resolution of this peculiar SAE has been described for these cases, clinicians should be alerted to this potential risk. In addition, all this emphasizes that MSE should be performed in high volume centers, by skilled and well-trained endoscopists who are ready to face and solve unexpected and potentially dangerous situations. There is probably still room to further refine the technique (and perhaps the device) in order to reduce these SAEs, as well as the spiral-related injuries to the GI mucosa that are particular to this type of procedure.

Adequate sedation of the patient during enteroscopy is highly advantageous. Nevertheless, sedation safety should remain paramount, because sedation-related complications have been reported in up to 0.5 % of the 2245 patients collected in a prospective DBE database [9]. It is not yet fully understood what the ideal sedation regimen is for MSE, especially for the cumbersome antegrade procedure. General anesthesia with endotracheal intubation has been used as per protocol in most MSE studies. Notably, prophylactic esophageal bougie dilation has been performed in clinical studies to aid passage of the endoscope through the upper esophageal sphincter but the real-world necessity of this step remains unknown. One study reported mild cardiopulmonary AEs related to general anesthesia in 3/132 patients (2.3 %) [1]; in their series, Beyna et al. reported two SAEs related to sedation/anesthesia [8]. Interestingly, Al-Toma et al. performed 92 % of MSEs in their study with only propofol sedation, with no adverse events related to sedation reported [3]. Although the choice of sedation is usually governed by procedure complexity, clinical factors, and local organizational protocols [5], future studies will have to clarify which is the most appropriate and safest sedation for antegrade MSE.

In conclusion, the results of the current study are promising but will need to be further validated in randomized studies comparing against established alternative approaches, such as DBE. The accumulating evidence from the numerous ongoing trials will provide a more accurate understanding of the potential complications related to MSE, their actual frequency, and the predisposing risk factors that can help to minimize their incidence.

Publication History

Article published online:
20 July 2022

• References

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