Avoiding pitfalls in abdominal ultrasound (aka “tricks of the trade”)

Abstract

I. Getting started. Transducer selection: Choose highest frequency transducer possible. Harmonics: Curved probe if possible. Interact with machine (adjust settings) and the patient (ask questions). II. Positioning patient (3 positions). 1) Right lateral decubitus (intercostal scan, sector transducer). Gas will rise to fundus, and retained gastric fluid will enter antrum/duodenum. This facilitates subsequent visualization of pancreatic head/distal CBD (see position 2). Spleen: Note sagittal image is coronal. Left kidney: Note sagittal image is coronal. Aorta: Coronal images include mid, distal, and bifurcation views. 2) Right posterior oblique (sub-xiphoid/epigastric approach, curved transducer). This position takes advantage of a sub-xiphoid/epigastric approach. As a result of previous scanning in position 1, bowel gas is minimized in these regions. Panc head/body: With transducer over the left lobe, angle caudally. Distal CBD: Begin with transverse scan of uncinate. After determining the course of distal CBD, obtain sagittal images. Left lobe of the liver: Include vasculature and look for dilated bile ducts. Also, image lateral aspect of right hepatic lobe. Gallbladder fundus: Detect subtle gallstones overlooked in LPO position. 3) Left posterior oblique (intercostal scan, sector transducer). CBD: Proximal to mid portion. Measure duct at porta and extrahepatically. Gallbladder: With redundant neck, scan after deep inspiration. Right hepatic lobe: Also evaluate subcostally following deep inspiration. Hepatic veins are best seen using a subcostal oblique approach. IVC and prox aorta: Prox aorta is visible via oblique/coronal scan through right lobe. Right kidney: Use coronal approach for sagittal image. Pancreatic tail: Image transversely through left lobe of liver.