# Computer-Aided Bleeding Detection Algorithms for Capsule Endoscopy: A Systematic Review
###### Abstract  
Capsule endoscopy (CE) is a widely used medical imaging tool for the diagnosis of gastrointestinal tract abnormalities like bleeding. However, CE captures a huge number of image frames, constituting a time-consuming and tedious task for medical experts to manually inspect. To address this issue, researchers have focused on computer-aided bleeding detection systems to automatically identify bleeding in real time. This paper presents a systematic review of the available state-of-the-art computer-aided bleeding detection algorithms for capsule endoscopy. The review was carried out by searching five different repositories (Scopus, PubMed, IEEE Xplore, ACM Digital Library, and ScienceDirect) for all original publications on computer-aided bleeding detection published between 2001 and 2023. The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) methodology was used to perform the review, and 147 full texts of scientific papers were reviewed. The contributions of this paper are: (I) a taxonomy for computer-aided bleeding detection algorithms for capsule endoscopy is identified; (II) the available state-of-the-art computer-aided bleeding detection algorithms, including various color spaces (RGB, HSV, etc. ), feature extraction techniques, and classifiers, are discussed; and (III) the most effective algorithms for practical use are identified. Finally, the paper is concluded by providing future direction for computer-aided bleeding detection research. bleeding classification; bleeding detection; bleeding recognition; bleeding segmentation; capsule endoscopy; wireless capsule endoscopy +
Footnote †: journal: Sensors  
0000-0001-6000-0001-6000][PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Computer-Aided Bleeding Detection Algorithms for Capsule Endoscopy: A Systematic Review. Sensors 2023  
intestine is encompassed in the system. The capsule is propelled by peristaltic movement when it goes through the SB. While moving along the GI tract, images are captured at a fixed frame rate (2 frames per second, fps), although the newest model of CE manufactured by Given Imaging (PillCam SB 3 capsule) is able to achieve a frame rate of 2-6 fps based on the capsule speed as it travels through the SB [2]. These images are transferred to a data recorder worn on a belt outside the patient's body, and about eight hours after swallowing, the patient returns to the clinic where the data and images are downloaded. Within 24-48 h, the capsule is passed through the patient's stool. CE is considered a first-line examination tool for diagnosing various kinds of diseases, including ulcers, polyps, bleeding, and [PERSON]'s disease [3]. A single scan may include up to 10,000 images of the GI tract for each patient, but evidence of abnormalities may appear in only a few of them. A very common abnormality found in the GI tract is bleeding [4]. To detect this, many researchers have contributed high-performance classifiers. Detection of bleeding at an early age is critical since it is a precursor for inflammatory bowel diseases such as [PERSON]'s disease and ulcerative colitis (UC). Bleeding is not only limited to the stomach; it can occur anywhere in the GI tract [5]. It is considered to be a common abnormality detected by CE and is often defined as \"bleeding of unknown origin that recurs or persists or is visible after an upper endoscopy and/or negative endoscopy result\" [6]. The major challenge is that residual traces and blood spots do not have typical shapes or textures, and their colors can range from light red to dark intense red and brown, making it difficult to distinguish blood from other digestive contents. This diversity of color might depend on the position of the camera, the bleeding timing [7], and the neighboring conditions of the intestinal content [8]. Bleeding is not a single pathology, and it may be caused by a variety of small intestinal diseases, such as open wounds, vascular lesions, angiodysplasia, ulcers, [PERSON]'s disease, and tumors.