The capsule endoscopy “suspected blood indicator” (SBI) for detection of active small bowel bleeding: no active bleeding in case of negative SBI

Abstract

Objective. Capsule endoscopy (CE) is the gold standard to diagnose small bowel bleeding. The “suspected blood indicator” (SBI) offers an automated detection of active small bowel bleeding but validity of this technique is unknown. The objective was to analyze specificity and sensitivity of the SBI using the second small bowel capsule generation for the detection of active bleeding. Methods. This is a retrospective analysis of all patients (199) who attended our clinic for CE from June 2008 through March 2013. The second-generation PillCam SB 2 capsule was used for detection of (1) luminal blood content and (2) potentially responsible small bowel lesions. The findings of an independent investigator were correlated to SBI findings and a number of SBI markings were analyzed by a receiver operating characteristic (ROC). Results. In 157/199 cases, no sign of active bleeding or altered blood was detected. One hundred and thirty-seven of these 157 cases provided at least one SBI marking and a mean of 18.4 positive SBI markings per record were found. In 20 cases, neither SBI nor the human investigator detected abnormalities. Thirteen patients showed investigator-detected minor bleeding with mean SBI findings of 36 positive screenshots per record. When major bleeding was diagnosed by the investigator (n = 29), SBI detected a mean of 46.6 SBI-positive markings. SBI turned positive in 179 patients, whereas the investigator detected active bleeding in 42 cases. All patients with active bleeding were detected by SBI (sensitivity 100%, specificity 13%). ROC analysis revealed 51.0 SBI markings being the optimal cutoff for active versus no bleeding (sensitivity 79.1%, specificity 90.4%, misclassification of 15.3%). Conclusion. The new SBI software is a reliable tool to exclude active bleeding and/or major lesions but analysis of the CE video by a trained investigator is still important for the detection of lesions responsible for past bleeding.

Key Words::

• capsule endoscopy
• endoscopy
• intestinal bleeding
• small bowel capsule endoscopy
• suspected blood indicator

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.