„... not seen due to overlying gas and fluid“. How often is abdominal ultrasound imaging impaired?

Aim: To examine the frequency of abdominal ultrasound examinations with reduced diagnostic information due to bowel and gastric gas or intraperitoneal fluid.

Methods and materials: We retrospectively reviewed reports of abdominal ultrasound examinations from 622 patients (368 men-254 women, aged 15–92 years) who presented in our hospital's emergency department. All patients were examined by a 3–5 year radiology Resident or a Consultant radiologist. We assessed the sonographer's ability to adequately examine all solid organs (right and left lobe of the liver, portal vein, gallbladder, head, body and tail of the pancreas, kidneys, spleen). We examined in how many patients at least one part of solid abdominal organs was not adequately visualised because of gas in the stomach and bowel or peritoneal fluid.

Results: Gastric and transverse colon gas (95 patients) obscured the body and tail (75) or the whole pancreas (20 patients). Distended large bowel loops minimised imaging of the right lobe of the liver (16) or spleen (7). In 51 patients some fluid was present in one or more peritoneal spaces (Morrison's or Douglas pouch, perihepatic and perisplenic spaces, paracolic gutters). In 17 of these patients at least one part of the solid organs was not visualised: left lobe of the liver (8 patients), portal vein (5), spleen (4). Altogether, gas (118) or fluid (17) obscured imaging in 135/522 (25.86%) patients.

Conclusion: Gas or fluid collections in the abdomen frequently inhibit adequate imaging. Sonographers should be aware of this limitation in order to avoid diagnostic pitfalls.