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Page 2 of 8 Imai et al. Mini-invasive Surg 2024;8:2 https://dx.doi.org/10.20517/2574-1225.2023.67

INTRODUCTION
Intestinal obstruction accounts for more than 10% of cases requiring surgical intervention, with over
[1]
300,000 surgeries performed annually in developed countries . The causes of intestinal obstruction include
postoperative adhesions, malignant tumors, Crohn’s disease, nonsteroidal anti-inflammatory drug
[2]
(NSAID)-related enteritis, and radiation-induced enteritis . Moreover, intestinal obstruction has a high
recurrence rate . Postoperative intestinal obstruction recurs in 23% of cases within one year and in 30%
[3]
[4]
within five years .
Over the past 20 years, contrast-enhanced CT has been used to diagnose and treat small bowel obstruction.
It allows the identification of the obstruction site and severity, aiding in treatment decisions, including the
[1]
timing of surgical intervention . However, CT cannot accurately determine the causes of intestinal
obstruction . Conversely, capsule endoscopy enables the direct visualization of the entire small intestine
[6]
[5]
and provides useful information regarding the underlying cause of small intestinal obstruction. To evaluate
the usefulness of capsule endoscopy, we performed a preliminary single-arm prospective observational
study of patients with small intestinal obstruction after the obstruction was relieved.

The objective of this study was to evaluate whether capsule endoscopy can identify the causes of small
intestinal obstruction and to determine the appropriate patient population for capsule endoscopy.

METHODS
Trial design and setting
Between September 2013 and October 2016, we performed a prospective observational study at two centers:
the Graduate School of Medicine, The University of Tokyo and the Japanese Red Cross Medical Center. We
obtained written informed consent from all patients before enrollment. The study protocol was approved by
the institutional review boards of The University of Tokyo (No. 10252) and Japanese Red Cross Medical
Center (No. 487) and registered at UMIN-CTR (UMIN000011831).

Patients
This study included patients aged ≥ 20 years who presented with vomiting, absent bowel movements, or
abdominal pain and were diagnosed with small intestinal obstruction on contrast-enhanced CT. For the
contrast-enhanced CT, 2 mL/kg of iodinated contrast media (370 mg/mL) was administered intravenously.
The arterial- and venous-phase images were obtained after a delay of 30 and 60 s, respectively. Patients with
2
contrast medium allergy or estimated glomerular filtration rate < 45 mL/min/1.73 m underwent
non-contrast CT. The study excluded patients with small intestinal obstruction that was not relieved with
conservative treatment or long tube placement, suspected perforation or peritonitis, Crohn’s disease,
dysphagia, or pacemaker placement.

Variables
We evaluated the age, sex, history of abdominal surgery (colectomy, ovariectomy, hysterectomy,
gastrectomy, appendectomy, cholecystectomy, hepatectomy, or pancreatectomy), regular medication use for
at least 30 days before enrollment (NSAIDs, antiplatelets, anticoagulants, steroids, proton pump inhibitors,
and histamine-2 receptor antagonists), and contrast-enhanced CT findings (such as band adhesions, single
band with length > 1 cm and diameter < 1 cm, matted adhesions, multiple bands with length < 1 cm and
diameter > 1 cm , small intestinal tumors, ischemic enteritis, and Meckel’s diverticulum).
[7]