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Endoscopic Stricturotomy with Needle Knife in the Treatment of Strictures from Inflammatory Bowel Disease

Lan, Nan MD; Shen, Bo MD

doi: 10.1097/MIB.0000000000001044
Future Directions and Methods in IBD Research

Background: Fibrotic strictures in patients with inflammatory bowel disease (IBD) are often not amenable to medical therapy. Therapy with endoscopic balloon dilation usually requires frequent repeat treatments. Therefore, we developed the novel needle knife stricturotomy (NKSt) for the treatment of strictures in the patients with IBD. The aim of this study was to evaluate the efficacy and safety of NKSt.

Methods: Data of patients with strictures treated with NKSt in our Interventional IBD Unit at the Cleveland Clinic were extracted from the registry. The primary and secondary outcomes were surgery-free survival and procedure-related complications.

Results: A total of 85 patients were included in this study. Multiple strictures were noticed in 30 (35.3%) patients at inception, giving a total of 127 strictures treated. The median length of the treated strictures was 1.5 cm (interquartile range: 1.0–2.0) and 52 (41.6%) were endoscopically nontraversable. The immediate success with passage of the scope through the stricture after NKSt therapy was achieved in all patients. During the median follow-up of 0.9 years (interquartile range: 0.3–1.8) and a median of 2.0 treatment (interquartile range: 1.0–3.0), 13 (15.3%) patients required stricture-related surgery. There were 77 (60.6%) patients who required additional NKSt, endoscopic balloon dilation, or both after the inception of NKSt. In a total of 272 NKSt procedures performed, 10 (3.7%) adverse events occurred, including 9 with delayed bleeding and one hospitalization due to perforation.

Conclusions: Endoscopic NKSt is effective and safe for treating the primary and secondary IBD-related strictures, which may provide an alternative for endoscopic balloon dilation and surgical intervention.

Published online 9 March 2017

Center for Inflammatory Bowel Disease, Digestive Disease and Surgery Institute, The Cleveland Clinic Foundation, Cleveland, Ohio.

Address correspondence to: Bo Shen, MD, The Interventional Inflammatory Bowel Disease (i-IBD) Unit, Digestive Disease and Surgery Institute-A31, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195 (e-mail:

B. Shen is supported by the Ed and Joey Story Endowed Chair.

Presented as a poster at Digestive Disease Week; May 23, 2016; San Diego, CA.

The authors have no conflict of interest to disclose.

Received November 19, 2016

Accepted January 05, 2017

Stricture is a common complication for patients with inflammatory bowel disease (IBD) and its reported frequency varies, depending on the location and nature of the stricture and patient's surgical history.1–3 Etiological factors of stricture include underlying Crohn's disease (CD), the use of nonsteroidal anti-inflammatory drug, anastomotic ischemia after bowel resection, and preoperative radiation.4,5 While strictures were traditionally treated with surgery, various endoscopic approaches such as endoscopic balloon dilation (EBD), stent placement, and topical injection with long-acting corticosteroids have been used.6–9 Extensive studies have been conducted to evaluate the efficacy of EBD in treating strictures of gastrointestinal (GI) tract. Our earlier study showed that the immediate technical success of EBD for treating ileal pouch stricture was achieved in almost all patients with a 5-year pouch retention rate as high as 97%.8 Nevertheless, most patients with IBD strictures required multiple dilations and EBD-related perforation posed an important drawback.10 However, surgical therapy with bowel resection and anastomosis or stricturoplasty can be associated with perioperative and postoperative complications and postoperative disease recurrence.5,7,11 Therefore, the mentality in the management of the stricture is to avoid surgery or at least to space out the need for surgical intervention.

Endoscopic needle knife therapy has been used for the treatment of strictures of the upper GI track, such as biliary tract12,13 and esophagus.14 Our center had previously published a case series stating the feasibility and efficacy of using needle knife stricturotomy (NKSt) for the treatment of ileal pouch-anal anastomosis strictures.8 NKSt was attempted in 10 patients with long, fibrotic strictures refractory to EBD and 6 out 10 managed to maintain a functional pouch. This study is the natural extension of our previous investigation. We hypothesized that NKSt would provide a longer interval to the requirement of further endoscopic intervention than traditional EBD. The aim of this study was to examine the efficacy and safety of NKSt in the treatment of the primary and secondary strictures in patients with IBD.

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Data Sources

All consecutive patients with IBD, which later developed a stricture or strictures and was treated in our Interventional IBD Unit from 2008 to 2016, were identified. This study was approved by the Cleveland Clinic Institutional Review Board (IRB). Informed consent was obtained for the procedures. The clinical data of all patients with strictures who were treated with endoscopy in the interventional IBD Unit were documented in the IRB-approved registry. Demographic, clinical, and endoscopic features together with the management and outcomes were carefully reviewed.

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Inclusion and Exclusion Criteria

The inclusion criteria were: (1) Patients with the primary diagnosis of IBD that developed a primary (disease-related) or secondary (anastomosis-related) fibrotic stricture; (2) the stricture was treated with NKSt with or without prior, concurrent, or subsequent EBD.

Patients who did not carry a primary diagnosis of IBD were excluded from this study. The patients who lacked the documentation of follow-up clinic visit between the inception NKSt and any other subsequent treatments were excluded.

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Data Collection

General demographic information, such as age, sex, ethnicity, and body mass index were extracted from the database. Clinical data were also extracted from the data along with previous surgical history and medical history. Current smoker was defined as consumption of more than 7 cigarettes per week for at least 6 months and ex-smoker was defined as cessation of smoking at least 6 months before data entry. Significant comorbidities were congestive heart disease, coronary bypass surgery, chronic obstructive pulmonary disease, renal stone, or renal insufficiency, non-GI cancer, stroke, and liver failure. Autoimmune diseases were adult onset asthma, type1 diabetes, rheumatoid arthritis, autoimmune thyroid diseases, psoriasis, systemic lupus erythematous, autoimmune hemolytic anemia, vitiligo, celiac disease, pernicious anemia, idiopathic thrombocytopenia purpura, and multiple sclerosis. Family histories of IBD and colorectal cancer recorded were those of the first-degree relatives to the patient. The diagnosis of IBD was classified into CD, Crohn's colitis, and ulcerative colitis. For patients who underwent surgical treatment for their IBD, surgical indications and postoperative neo-bowel configuration were recorded.

The diagnosis of stricture was made based on endoscopy, abdominal imaging, or both, regardless of the presence or absence of stricture-related symptoms. All NKSt procedures were performed by an experienced endoscopist (B.S.). The degree of the strictures was classified into the following, based on the level of resistance when passing the endoscope: 0 = no resistance; 1 = mild resistance; 2 = moderate resistance; 3 = severe resistance and; 4 = not traversable. Multiple strictures were defined as more than one stricture. The locations of the strictures that underwent NKSt were classified as: anastomosis, distal or neoterminal ileum, stoma site, ileocecal valve, colon, and anal canal. For patients with ileal pouch-anal anastomosis, strictures were classified as distal pouch, pouch inlet, afferent limb, and middle of the pouch body. The underlying causes for strictures were classified into the primary and secondary types. The primary strictures were further divided into CD stricture, fecal diversion-related stricture, and pouch inlet stricture. The secondary strictures consisted of anastomotic strictures, inlet or outlet of CD stricturoplasty site, ileal pouch anastomosis, and nipple valve of the Kock pouch.

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Clinical Practice Pattern of NKSt Technique

The selection of the use of EBD, NKSt, or both was based on the clinical discretion of the managing physician (B.S.). In our routine practice, NKSt was considered in patients with refractory strictures who had previously had a poor or partial response to EBD, i.e., the need for frequent EBD less than every 2 to 3 months; refractory or difficult fibrotic strictures with a technical difficulty for EBD; multiple or angulated multiple fibrotic strictures prone to the development of having EBD-associated perforation. In most cases, the strictures treated were clinically symptomatic. However, it is now generally believed that endoscopic recurrence might precede the development of clinical symptoms.15 The severity of symptoms in patients with IBD, especially in those with CD, has been found to be poorly correlated with the objective findings of the disease on endoscopy, imaging, and histology.15 In a recent survey of 116 IBD specialists, gastroenterologists, and surgeons, the investigators reported that 36 (31%) would perform EBD for patients with either symptomatic or asymptomatic strictures.16 Nevertheless, the decision on whether to treat the patients was based on the physician's clinical judgment and the disease presentation of each individual.

The endoscopic stricturotomy was carried out with the use of regular needle knife or needle knife with isolated ceramic tip in the setting of electroincision or electrocauterization at the discretion of the endoscopist. All procedures were performed in an outpatient setting with patients being under conscious sedation.

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Outcome Measurements

The primary outcomes were the immediate technical success, which was defined as passage of the gastroscope or pediatric colonoscope without resistance and surgery-free survival. Patients who underwent surgery for their refractory stricture were evaluated in detail. Follow-up time was defined as the time from the first or inception NKSt to the latest GI clinic/telephone follow-up or stricture-related endoscopic therapy or surgery, whichever came first.

The secondary outcomes were the requirement of additional treatment with NKSt or EBD as well as the procedure-related hospitalization and emergency department (ED) visits. Disease-related or NKSt-related hospitalizations and ED visits were also evaluated, and admission for solely for planned surgical purpose were not included as disease-related hospitalizations for analysis purposes. Patient's symptoms presented in the clinical visit immediately before and after the NKSt were compared. The timing and modality of additional treatment that patients underwent before and after the initial NKSt were documented. The interval between EBDs (before the initial NKSt) as well as the interval between the inception NKSt and the first subsequent endoscopic therapy (EBD or NKSt) were calculated and compared.

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Statistical Analysis

Descriptive statistics were computed for all variables. Categorical variables were summarized as percentages. Quantitative variables with a normal distribution were summarized as mean ± standard deviation (SD). Quantitative variable with paranormal distribution were summarized in median and interquartile range (IQR). The interval of treatments needed before and after the initial NKSt was compared with Wilcoxon signed ranks test. The surgery-free survival and risk factors for multiple NKSt were evaluated using Kaplan–Meier curve and log-rank test.

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A total of 85 patients met the inclusion criteria and were therefore included in this study (Table 1).

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Patients were mostly Caucasian (N = 76, 89.4%) and half of them were women (N = 39, 45.9%). The mean age of the whole cohort was 24.4 ± 10.3 years at the time of the primary diagnosis of IBD. There were 50 patients with ulcerative colitis with ileal pouches (58.8%), 32 with Crohn's ileitis (37.6%) and 3 with Crohn's colitis (3.5%). Anti-tumor necrosis factor or anti-integrin biologics were used in 23 (27.1%) patients for their primary underlying diseases.

Seventy-seven patients (90.6%) had had IBD-related surgery before the inception of the endoscopic therapy, and the mean age at the last surgery was 33.5 ± 13.7 years. The 50 patients with underlying ulcerative colitis had restorative proctocolectomy with an ileal pouch, including J pouches in 44 (88.0%), S pouches in 3 (6.0%), and Kock pouches in 3 (6.0%). Of 32 patients with CD, 24 (75.0%) had undergone surgery before the inception NKSt, including 2 (8.3%) with J pouches and remaining 22 (91.7%) with small bowel, large bowel, or both small and large bowel resection (18 [56.2%] with ileocolonic anastomosis, 2 [6.2%] with ileorectal anastomosis, 1 [3.1%] with colo-colonic anastomosis, and 1 [1.6%] with diverted ileostomy). As for the 3 patients with Crohn's colitis, 2 (66.6%) had diverting ileostomies and 1 (33.3%) had J pouch. Of 77 patients who underwent surgery, 28% (3.4%) had antitumor necrosis factor use after the surgery. Among the non-pouch anastomotic strictures, 4 (4.7%) had an end-to-end anastomosis, 12 (14.1%) had a side-to-side anastomosis, 3 (3.5%) had an end-to-side anastomosis and the remaining 2 had an unclear type of anastomosis.

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Characteristics of Stricture

The mean age of patients with strictures diagnosed was 41.9 ± 14.0 years. Apart from the 8 patients who had the primary stricture from CD at the ileocecal valve, the underlying causes of the remaining strictures are shown in Figure 1. A total of 59 patients had the primary strictures, with 41 (69.4%) resulting from CD, 10 (17.0%) from stoma and fecal diversion, and 8 (13.6%) from the pouch inlet. Thirty-three patients had the secondary strictures with 30 (90.9%) being anastomotic strictures and 3 (9.1%) being nipple valve stenosis of a Kock pouch. There were 7 patients who had more than one underlying causes for their strictures. Thirty patients (35.3%) had multiple strictures.

A total of 127 strictures were treated in this 85-patient cohort, and the characteristics of the strictures are listed in Table 2. The stricture length was recorded in 122 strictures, with a median length of 1.5 (IQR: 1.0–2.0) cm. Eight (6.4%) patients had the primary stricture at ileocecal valve. In pouch patients, strictures were found in the pouch inlet (N = 22, 17.3%), afferent limb (N = 25, 19.7%), middle of the pouch body (N = 3, 2.4%), and pouch anastomosis (N = 24, 18.9%). In addition, there were also 2 (1.6%) patients with strictures found at the nipple valve of a Kock pouch. The other 5 (3.9%) strictures were found at the anal canal, and 1 (0.8%) was found in the middle colon. All other strictures were found in the surgical anastomotic site (N = 25, 19.7%) and distal ileum (N = 12, 9.4%). Approximately, half of strictures were in level 4 (N = 54, 42.5%), meaning that the lumen was not traversable to an endoscope.

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Treatment and Outcomes

A total of 127 strictures were treated with endoscopic NKSt, and each patient received a median of 2.0 (IQR: 1.0–3.0) treatments. Before NKSt, 69 (54.3%) of 127 strictures had been treated with EBD. The mean interval between the EBD sessions was 6.5 ± 5.2 months. There were also 14 (11.0%) strictures that were treated with concurrent EBD during the first NKSt. A total of 53 patients had an immediate clinical follow-up after the initial NKSt treatment, of whom 29 (54.7%) claimed to experience symptom improvement. Clinic follow-up between the inception NKSt and additional treatment, if any, was not available for the remaining 32 patients, and they were therefore excluded for the longitudinal comparison.

The median duration of follow-up after the initial NKSt was 0.9 (IQR: 0.3–1.8) years for the whole cohort. A total of 77 (60.6%) strictures required multiple treatments after the initial NKSt. There were 57 (44.9%) strictures, which required a subsequent NKSt, and 14 (11.0%) strictures that needed a combined subsequent therapy for NKSt and EBD (Fig. 2). Additional 29 (22.8%) strictures were also treated with EBD after the inception NKSt treatment. The mean interval between the initial NKSt, and the first subsequent therapeutic endoscopic intervention was 7.0 ± 6.8 months.

There were a total of 48 strictures that had received EBD therapy both before and after the inception NKSt and the interval of the treatments before and after were compared. There was a numerical difference in the mean intervals between the pre-NKSt EBDs (4.8 ± 3.7 months) and the mean interval between the inception NKSt and subsequent treatment needed (6.8 ± 7.2 months) (P = 0.08). Univariate analysis using log-rank test showed that patients with length of stricture longer than 4 cm (P = 0.04) were more likely to receive multiple NKSt, and patients with a degree1 stricture were more likely to require only one session (P = 0.01) (Table 3 and Figure 3).

Subsequent surgical intervention was needed in 13 patients (15.3%) (Table 4). Five of the 13 patients (38.5%) required diverting loop ileostomy (4 with a J pouch and 1 with an S pouch), of whom 3 eventually had ileostomy closure and 3 remained diverted up to the latest follow-up. Two (15.4%) patients had a pouch resection and redo pouch. Five patients (38.5%) had partial colectomy for anastomotic strictures. The last patient underwent ileostomy revision for nipple valve stenosis of a Kock pouch.

A total of 11 (12.9%) patients visited the ED because of one or more of the following stricture- or disease-related symptoms: 11 with abdominal pain and 5 with nausea and vomiting, 4 with dehydration, and 1 with severe malnutrition. Eight of the 11 patients who visited ED were eventually admitted in hospital. In addition, another 10 patients were admitted to hospital directly giving a total of 18 hospitalized patients due to stricture-related presentations. The causes for hospitalization were examination under anesthesia (EUA) to evaluate the stricture (N = 7, 38.9%), bowel obstruction due to stricture (N = 11, 61.1%), failure to thrive and malnutrition (N = 2; 11.1%).

Kaplan–Meier analysis was conducted to evaluate the surgery-free survival. For patients undergoing NKSt, the cumulative 3-year surgery-free survival was 62.0%. Univariate analysis showed significant risks for surgery in patients with a higher baseline body mass index and stricture-related hospitalizations, especially in those with obvious obstructive symptoms and malnutrition (Table 5).

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A total of 272 NKSt procedures were performed for the 85 patients. Most patients tolerated the procedure well, and procedure-associated complications were not common. There were a total of 10 (3.7% per procedure-based) adverse events in 9 (10.6%) patients. One patient (0.4% per procedure based) had perforation which required hospitalization and urgent exploratory laparotomy with extensive lysis of adhesions and loop ileostomy. The patient with CD-associated refractory anastomotic stricture was treated with a total of 7 sessions of EBD and concurrent use of adalimumab before the inception NKSt. Nine patients (3.3% per procedure) experienced a postprocedural bleeding, resulting in ED visits, and 5 were eventually hospitalized. All but one bleeding patients were stable when admitted, and 10 units of blood transfusion was given to that patient. There was no mortality associated with NKSt.

Possible factors contributing to the postprocedure adverse events were listed in Table 6. Patients who developed the complications were older (50.2 ± 15.3 years) at the inception for NKSt. Eight (88.8%) had the primary strictures from underlying CD. The use of systemic corticosteroids was found in 4 (44.4%) patients and the use of antitumor necrosis factor was found in 5 (55.5%) patients. None of the patients who developed complications had concurrent fistula, abscess, or sinus. Six of the 9 patients (66.6%) had multiple strictures with a total of 18 strictures treated. The locations of strictures in those patients were ileocolonic anastomosis (N = 8, 44.4%), pouch inlet (N = 5, 27.8%), afferent limb of the pouch neoterminal ileum (N = 5, 22.2%), and the nipple valve of a Kock pouch (N = 1, 5.6%). The average length of the strictures was 2.1 ± 0.8 cm; and 9 strictures had a severity score ≥3.

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In this historical cohort, we evaluated 85 patients with IBD with strictures who were treated with NKSt. Patients with these strictures would normally need surgical intervention. The strictures mostly occurred at the anastomotic site and most of the strictures were nontraversable to an endoscope. The immediate technical success of NKSt was achieved in all patients (Fig. 4; See video, Supplemental Digital Content, During a median follow-up of 0.9 years, 13 (15.3%) patients required stricture-related surgery. The overall complication rate was 3.7% based on the number of procedures with 1 (0.4%) who had severe complication (perforation) that required hospitalization and surgery and 1 (0.4%) who had 10 units of blood transfusion.

The management of IBD strictures has been challenging. These strictures were classified into the primary (from underlying disease) and secondary (from surgical anastomosis) in nature.17 Underlying diseases that cause the primary strictures include CD, tuberculosis, malignancy, radiation, and medications.7,18,19 CD can be classified into 3 clinical phenotypes: nonstricturing nonpenetrating (B1), stricturing (B2), and penetrating (B3), based on the Montreal Classification.20 It was reported that only around 10% or less patients presented with stricturing disease at diagnosis.21,22 As disease progresses, disease phenotype often shifts from B1 to B2 or B3, resulting in approximately 20% to 30% B2 patient in the second decade after the initial diagnosis.19,20

Mechanical complications such as strictures often require surgical treatment. It was estimated that 80% of patients with CD would undergo at least 1 surgical resection within the first 10 years of diagnosis.23 However, disease recurrence is common after bowel resection and anastomosis or stricturoplasty. Studies from our group showed a recurrence rate of 37% after surgery, whereas the indication for 92% of reoperation was obstruction.24 A meta-analysis of 23 studies showed a comparable postoperative recurrence rate of 23%.25 The reported frequencies of the secondary or anastomotic strictures ranged from 3% to 30%, depending on underlying diseases, type of surgical procedure, and the site of anastomosis.18,19 Regardless of various surgical techniques developed, the recurrence rate of stricture even after stricturoplasty remains to be high.26

Although surgery has been a standard therapy for treatment of IBD-related strictures, endoscopic approaches have emerged as a valid treatment option. The main goal of the endoscopic therapy is to avoid or space out the need for subsequent surgery. The treatment of IBD-related GI tract strictures with EBD has been extensively studied. Our group had previously published several studies on the efficacy and safety of EBD in treating ileal pouch strictures.7–9 There is a potential in EBD with an acceptable short and long-term outcomes for short strictures.27,28 However, approximately half of patients with CD with the primary strictures required more than one session of EBD.29,30 In a study of 185 patients with CD treated with EBD, our group reported that 66 (35.7%) would eventually need subsequent salvage surgery,10 which is similar to that of a meta-analysis of 13 studies with a reported surgery-free rate of 67%.31 Purported risk factors for surgical intervention in those patients were anastomotic strictures,32,33 long strictures (>4–5 cm)29,31, and history of smoking.34 Despite few small series reporting unexpected high complication rate of more than 10%.35,36 In larger cohorts, the reported perforation rate is approximately 2% to 3% per patient.27,31 The overall recurrence rate of treated stricture was comparable between those with upfront surgery and with failed-EBD-then-surgery.26 For those who were not mentally and medically ready for surgery, EBD seems to be a reasonable alternative.37

Another approach for lower GI strictures is the use of self-expandable metal stents (SEMS).37,38 It seems that SEMS has a poorer efficacy in benign colorectal strictures.37 The complication rate of using SEMS in treating large bowel obstruction was reported to be as high as 71%.39 SEMS has been reported for the treatment of CD-related strictures.40 However, the lack of a long-term efficacy and stent migration limit its applicability.40 Topical injection of long-acting corticosteroids after EBD was reported to prolong the interval for redilation41,42 and even surgery-free survival.41 The benefit of intralesional injection of long-acting corticosteroids after EBD is controversial. It may be more applicable in the prevention of esophageal stricture after submucosal dissection for esophageal cancer.43,44

Endoscopic needle knife therapy had previously been used for the treatment of strictures in the biliary system,45 esophagus,46 and stomach.47 Needle knife biliary sphincterotomy and stricturotomy are routinely used in both diagnostic and therapeutic endoscopic retrograde cholangiopancreatography.48,49,50 NKSt was first reported in our previous study for the treatment of long fibrotic strictures of the ileal pouch which had been refractory to multiple EBD therapy.8 Out of the 10 patients who underwent NKSt in combination with sequential EBD for their refractory strictures, 6 managed to maintain their functional pouches. Subsequently, we reported 2 cases in which we used NKSt in treating nipple valve stenosis of a continent ileostomy48 and outlet stricture of diverted colon.51 In our study, we confirmed that NKSt was applicable to various forms of strictures in patients with IBD. Although most patients still needed additional treatment, the interval of between the inception NKSt and additional endoscopic treatments was more spaced out than the EBD approach, before the NKSt treatment. In broad sense endoscopic NKSt is considered a part of endoscopic stricturotomy. Endoscopic stricturotomy can be carried out by various tools ranging from needle knife, needle hook knife to needle knife with an isolated ceramic tip. The setting of stricturotomy can be electroincision or electrocauterization.

The results of this study have several clinical implications. The results elaborate that NKSt is an effective way of treating strictures in IBD.8 There were only 10 (11.8%) patients who eventually had to undergo surgery during the follow-up period, making NKSt with or without EBD an effective way to space out the need for surgery or even avoid surgery. The rate of requirement for subsequent surgery after NKSt with/without EBD seems to be lower than the historical rate of EBD reported in literature. The reported rate of surgical intervention for patients with CD treated with EBD ranged from 28% to 47%.10,17,52–54 Like EBD, the major concern for NKSt has been the risk of perforation and excessive bleeding. We believe that EBD may have a higher risk for perforation because of the radial and blind force exerted equally on asymmetric stenosis. In contrast, NKSt provides a more localized and directed target of treating the stricture that may reduce the risk for perforation in experienced hands. Although several occasions of excessive late-onset bleeding after NKSt necessitating ED visits, hospitalization, or both were noted in our series, but no blood transfusion was needed. Therefore, patients undergoing NKSt therapy should be monitored closely. It should be pointed out that the best treatment option should be individualized. One of the key techniques in NKSt is the full control of the motion of the tip of the endoscopy. The endoscopist should always anticipate perforation or bleeding and be ready when it occurs. The backup plan, such as endoscopic clipping or surgical intervention, should be readily available whenever needed. We recommend that NKSt be a valid alternative to surgery, for patients with a straight stricture less than 4 cm that were refractory to EBD.

There are limitations to the study. Despite being the largest case series of NKSt in patients with IBD, the patients' underlying disease conditions and history of IBD-related surgery varied, making it difficult to control all confounding factors for the disease course. There might have been referral and selection bias as our interventional IBD Unit is subspecialized in managing complex cases with skilled endoscopist and supporting personnel. Moreover, almost half of the patients underwent EBD before or after NKSt, indicating that most of the patients had a short-lasting response to EBD therapy alone. However, the benefits of EBD might have also contributed to the patient's treatment process. Last, the sample size was still small and the follow-up time was short. Further controlled studies with a longer follow-up in direct comparison between NKSt and EBD approaches are needed.

In conclusion, patients with IBD with strictures can be effectively and safely treated by NKSt. The proper use of this technique may prolong the need for or avoid stricture-related surgical intervention.

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Crohn's disease; electroincision; endoscopy; gastrointestinal tract; needle knife; stricture; stricturotomy

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