Point-of-care Ultrasound to Screen for Gastrointestinal Dysfunction: Image Acquisition and Interpretation

Summary

Screening for gastrointestinal (GI) dysfunction using point-of-care ultrasound (POCUS) has been reported but remains underutilized. This manuscript reviews the relevant literature and describes a protocol that permits POCUS screening for dilation/dysfunction of the small bowel and/or stomach, which can arise as the final common pathway of various GI pathologies.

Abstract

A major cause of morbidity and healthcare resource utilization is gastrointestinal (GI) dysfunction. Although GI symptoms are frequently evaluated with computed tomography (CT), this modality subjects patients to ionizing radiation, high costs, and high resource utilization (including sometimes inter-facility transfers from non-hospital settings). Thus, alternative methods of screening for GI dysfunction that do not subject patients to radiation and transport risk are highly desirable. One such emerging option that may help with bedside decision-making is GI point-of-care ultrasound (POCUS). However, utilization of GI POCUS is limited by a lack of training of providers and standardization in image acquisition and interpretation. To address this unmet need, we propose an evidence-based image acquisition protocol using point-of-care ultrasound to screen for two important types of GI dysfunction: ileus or obstruction. This protocol includes guidance on probe selection, patient positioning, and image acquisition sequence. Further, we review image interpretation and the limitations of this protocol.

Introduction

Gastrointestinal dysfunction is a common cause of significant morbidity and mortality^1,2. Abdominal pain alone contributes to close to 18 million emergency department visits annually, and total healthcare expenditures related to GI pathology are conservatively estimated at $119.6 billion annually³. Computer tomography, which is often the imaging modality of choice for gastrointestinal concerns, is associated with ionizing radiation, increasing the lifetime risk of malignancy⁴. Moreover, many causes of GI dysfunction can be addressed conservatively if surgical or ....

Protocol

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Illustrative images were obtained from a de-identified educational database devoid of protected health information. Inclusion criteria: any patient with suspected GI dysfunction or healthy volunteers with presumed normal bowel function. Exclusion criteria: patient refusal.

1. Transducer selection

1. Select a low-frequency (1-5 MHz), large footprint (i.e., ....

Results

Differentiating normal versus abnormal gastrointestinal function is best performed using a multi-parameter model. The model that has been the most robustly tested includes the following criteria, sometimes referred to as "diagnostic criteria": 1) bowel diameter ≥ 2.5 cm and abnormal peristalsis. Additional criteria, sometimes referred to as "staging criteria" vary in the literature, but those commonly used and easily identifiable on bedside ultrasound include interloop free fluid and bowel wall edema⁸

Discussion

The proposed GI POCUS image acquisition protocol has several key steps. First, given the irregular orientation and dynamic location of the bowels in the body, it is important to have a systematic image acquisition approach. Specifically, the "lawnmower" technique allows for systematic visualization of the abdominal cavity and identification of optimally localized loops of bowel.

Second, although the optimal criteria for identifying intestinal dysfunction with ultrasound remain under ac.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CX50	Philips	n/a	Used to obtain a subset of the Figures & Videos
Edge 1	Sonosite	n/a	Used to obtain a subset of the Figures & Videos
Epic 7C	Philips	n/a	Used to obtain a subset of the Figures & Videos
HS60	Samsung	n/a	Used to obtain a subset of the Figures & Videos
Logiq E10	GE	n/a	Used to obtain a subset of the Figures & Videos
LX	Sonosite	n/a	Used to obtain a subset of the Figures & Videos