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Page 2 of 21 Tsuboi et al. Mini-invasive Surg 2024;8:26 https://dx.doi.org/10.20517/2574-1225.2023.94

INTRODUCTION
Small-bowel capsule endoscopy (SBCE) was initially introduced in 2000 by Iddan et al. . In recent years,
[1]
it has gained widespread use owing to its minimally invasive nature and diagnostic yield. The
primary indication for SBCE is small-bowel bleeding, and it has been endorsed as the first-line
modality for this condition in the guidelines of reputable organizations, such as the American College of
Gastroenterology (ACG) , European Society of Gastrointestinal Endoscopy (ESGE) , and Japanese
[3]
[2]
[4]
Gastroenterological Endoscopy Society . In Japan, obscure gastrointestinal bleeding (OGIB) is defined
as bleeding from an unknown source, even after esophagogastroduodenoscopy (EGD),
colonoscopy (CS), and, when appropriate, second-look endoscopy. However, with the widespread use
of SBCE, the definition of OGIB has now changed to refer to bleeding from unknown sources even after
enteroscopy. This distinction helps differentiate it from small-bowel bleeding or mid-gut bleeding in
Europe and the United States . Apart from diagnosing small-bowel bleeding, SBCE is also utilized to
[2,3]
evaluate small-bowel tumors, such as Peutz-Jeghers syndrome, familial adenomatous polyposis, and
inflammatory small-bowel diseases such as celiac disease and Crohn’s disease . The first SBCE device,
[3,4]
known as M2A capsule, was developed in 2000 and later renamed PillCam TM[5] . In the mid-2000s, other
capsules such as Endocapsule, MiroCam, and OMOM capsules were introduced. In 2013, CapsoCam
was developed, enabling 360-degree panoramic shots with four small cameras . These devices have
[6]
continued to improve, and various types of SBCEs are currently available.

Furthermore, capsule endoscopy (CE) is useful not only for observation of the small-bowel but also as an
alternative to CS, known as colon capsule endoscopy (CCE). The first-generation CCE was developed in
[7]
2006 . With the development of second-generation devices and improvements in preparation, CCE is now
used for applications ranging from colorectal cancer surveillance to monitoring disease activity in
inflammatory bowel disease.

CE has been developed not only for the colorectal region but also for the upper digestive tract, including the
esophagus and stomach. Esophageal capsule endoscopy (ECE) was first approved by the Food and Drug
Administration (FDA) in the U.S. in 2004 . However, due to the wide anatomical lumen and blind spots in
[8]
the stomach, magnetically controllable CEs have been developed.

With recent advancements in endoscopic technology, the development of artificial intelligence (AI) has
been developed to assist in the reading of CE. Additionally, completely novel concepts such as ultrasound
CE and sampling CE have been introduced in recent years.

The purpose of this paper is to provide an updated overview of the role of CE, including SBCE, CCE, and
magnetically controlled capsule endoscopy (MCCE). A literature search was conducted using PubMed with
the keyword “Capsule endoscopy”. This review aims to provide a comprehensive overview of the current
status and future prospects of CE.

CURRENT POSITIONING OF SBCE
In cases where small-bowel bleeding is suspected as the primary indication for SBCE, studies have reported
a diagnostic yield ranging from 55% to 62% [9-11] .

In prospective studies, SBCE has been consistently shown to demonstrate significantly superior diagnostic
[12]
performance compared to alternative modalities such as computed tomography (CT) enterography and
CT angiography . SBCE exhibits a detection rate for bleeding sources comparable to device-assisted
[13]
enteroscopy (DAE) .
[10]