Continuing challenges in the diagnosis and management of obscure gastrointestinal bleeding

Recurrence rates and risk factors in obscure gastrointestinal bleeding

Obscure gastrointestinal bleeding (OGIB), defined in 2010, involves bleeding from the GI tract that remains unexplained after standard diagnostic procedures. OGIB, which accounts for about 5% of all GI bleeds, poses diagnostic and management challenges, particularly due to the anatomical features of the small intestine. Advances in capsule endoscopy (CE) and balloon-assisted endoscopy have improved the diagnostic and therapeutic landscape for small intestinal lesions.

Objective

To determine the recurrence rate and identify risk factors for recurrence following diagnostic and therapeutic interventions using CE and balloon-assisted endoscopy in patients with OGIB.

Methods

A retrospective cohort study at Gifu University Hospital analyzed CE procedures for patients with OGIB from 2008 to 2022. Patients underwent CE with subsequent treatments based on the findings. Statistical analyses, including Kaplan-Meier and Cox proportional hazards models, were used to estimate cumulative recurrence rates and identify recurrence risk factors.

Results

Out of 417 patients, 65.2% had positive CE findings, leading to therapeutic interventions in 16.3% of cases. The cumulative recurrence rates at 12, 24, and 36 months were 4.3%, 9.0%, and 13.9%, respectively. Liver cirrhosis (hazard rate: 4.15, 95% confidence interval 1.88-9.18, p < 0.01) was identified as a significant risk factor for recurrence.

Conclusions

A significant recurrence rate in OGIB patients, with liver cirrhosis being a major risk factor. Despite diagnostic and therapeutic advances, a comprehensive approach including careful follow-up and consideration of risk factors is essential for management.

Roles of Capsule Endoscopy and Balloon-Assisted Enteroscopy in the Optimal Management of Small Bowel Bleeding

The small bowel had long been considered a dark unapproachable tunnel until the invention of capsule endoscopy and doubleballoon enteroscopy in the 21st century, which revolutionized the diagnosis and management of small bowel diseases, including bleeding. Various imaging modalities such as computed tomographic enterography, angiography, capsule endoscopy, and balloonassisted enteroscopy play vital roles in the diagnosis and management of small bowel bleeding. The choice of modality to use and timing of application differ according to the availability of the modalities, patient’s history, and physician’s experience. Small bowel bleeding is managed using different strategies as exemplified by medical treatment, interventional radiology, endoscopic therapy, or surgical intervention. Balloon-assisted enteroscopy enables endoscopic interventions to control small bowel bleeding, including electrocautery, argon plasma coagulation, clip application, and tattooing as a prelude to surgery. In this article, we clarify the recent approaches to the optimal diagnosis and management of patients with small bowel bleeding.

Novel experimental and software methods for image reconstruction and localization in capsule endoscopy

BACKGROUND AND STUDY AIMS

Capsule endoscopy (CE) is invaluable for minimally invasive endoscopy of the gastrointestinal tract; however, several technological limitations remain including lack of reliable lesion localization. We present an approach to 3D reconstruction and localization using visual information from 2D CE images.

PATIENTS AND METHODS

Colored thumbtacks were secured in rows to the internal wall of a LifeLike bowel model. A PillCam SB3 was calibrated and navigated linearly through the lumen by a high-precision robotic arm. The motion estimation algorithm used data (light falling on the object, fraction of reflected light and surface geometry) from 2D CE images in the video sequence to achieve 3D reconstruction of the bowel model at various frames. The ORB-SLAM technique was used for 3D reconstruction and CE localization within the reconstructed model. This algorithm compared pairs of points between images for reconstruction and localization.

RESULTS

 As the capsule moved through the model bowel 42 to 66 video frames were obtained per pass. Mean absolute error in the estimated distance travelled by the CE was 4.1 ± 3.9 cm. Our algorithm was able to reconstruct the cylindrical shape of the model bowel with details of the attached thumbtacks. ORB-SLAM successfully reconstructed the bowel wall from simultaneous frames of the CE video. The "track" in the reconstruction corresponded well with the linear forwards-backwards movement of the capsule through the model lumen.

CONCLUSION

 The reconstruction methods, detailed above, were able to achieve good quality reconstruction of the bowel model and localization of the capsule trajectory using information from the CE video and images alone.

Small Intestinal Angioectasia: Characterization, Risk Factors, and Rebleeding

BACKGROUND

Gastrointestinal angioectasias (AEs) represent the most common vascular malformation within the gastrointestinal tract. This study sought to characterize epidemiologic/comorbid risk factors for AEs, rebleeding, and patterns of anatomic distribution within the small intestine.

STUDY

This retrospective observational cohort study included 158 patients with AEs on capsule endoscopy (CE) from 2007 to 2015. Epidemiologic/comorbid data were collected and incorporated into final analysis. Each AE was categorized by location using a small bowel transit time-based quartile system. Rebleeding was evaluated following CE. Multivariate logistic regression was applied to statistically significant factors on univariate analysis to determine independent risk factors for rebleeding.

RESULTS

Most lesions were found in the first quartile (67.1%). Rebleeding occurred in 46 (29.7%) of the 156 patients for whom data were available. Rates of rebleeding were significantly higher among older patients (74.4 vs. 67.7 y, P=0.001), those with active bleeding on CE (41.3% vs. 16.5%, P=0.001), those with a history of aortic stenosis (21.7% vs. 9.2%, P=0.033), and those with AEs presents in quartile 3 (26.1% vs. 8.3%, P=0.003). Age, active bleeding on CE, and AE presence in quartile 3 were independently associated with rebleeding in multivariate analysis (P=0.009, 0.023, and 0.008, respectively).

CONCLUSIONS

These data help improve our knowledge of AEs regarding risk factors for rebleeding, and utilizes a novel small bowel transit time-based quartile localization method that may simplify future research and comparisons of anatomic distribution and behavior of small bowel AEs.

Comparative assessment of feature extraction methods for visual odometry in wireless capsule endoscopy

Wireless capsule endoscopy (WCE) enables the non-invasive examination of the gastrointestinal (GI) tract by a swallowable device equipped with a miniature camera. Accurate localization of the capsule in the GI tract enables accurate localization of abnormalities for medical interventions such as biopsy and polyp resection; therefore, the optimization of the localization outcome is important. Current approaches to endoscopic capsule localization are mainly based on external sensors and transit time estimations. Recently, we demonstrated the feasibility of capsule localization based-entirely-on visual features, without the use of external sensors. This technique relies on a motion estimation algorithm that enables measurements of the distance and the rotation of the capsule from the acquired video frames. Towards the determination of an optimal visual feature extraction technique for capsule motion estimation, an extensive comparative assessment of several state-of-the-art techniques, using a publicly available dataset, is presented. The results show that the minimization of the localization error is possible at the cost of computational efficiency. A localization error of approximately one order of magnitude higher than the minimal one can be considered as compromise for the use of current computationally efficient feature extraction techniques.