LUQ US findings

This patient's US showed small bowel obstruction without features of complication such as perforation or ischaemia. The diagnosis could be made at the bedside with management such as NGT insertion, analgesia and surgical referral and admission soon after initial consultation.

SMALL BOWEL ULTRASOUND

Just placing the abdominal transducer gently anteriorly on the abdomen of a patient with SBO will reveal dilated loops of bowel with absent peristalsis. You can translate the transducer superiorly and inferiorly and medically and laterally to look for a transition point. However, this is a bit of a waste of time as it is seen easier on CT. 

It's a better use of time to look for features of complications like perforation or bowel ischaemia which would lead to antibiotics and expedited CT/ theatre. 

Small bowel can be differentiated from large by its smaller caliber (normally 2-3cm vs 6cm) and the presence of valvular conniventes which extend across the lumen. Fanning through the bowel will demonstrate this. 

Small intestine is also usually fluid filled and has less gas than large intestine. Fluid will be anaechoic on US. However with time, the contents of the obstructed small intestine become "faecalised" or thicker and will appear on US like a hypoechoic hetogenous/ homogenous mass. 

SMALL BOWEL OBSTRUCTION

US has sensitivity and specificity in the 90s for SBO (1,2).

Features of SBO:

1. Dilated loops of SI >2.5cm

2. Washing machinging (to and fro movement of contents) or static contents

ISCHAEMIC BOWEL

Features of bowel ischaemia (3) are:

1. gas in the bowel wall (hyperechoic locules with reverberation artefact.

2. thickened bowel wall (>2mm) - late stage ischaemia may have thin walls 

3. free fluid between the bowel loops (suggesting perforation)

REFERENCES

1. Rosano N, Gallo L, Mercogliano G, Quassone P, Picascia O, Catalano M, Pesce A, Fiorini V, Pelella I, Vespere G, Romano M, Tammaro P, Marra E, Oliva G, Lugarà M, Scuderi M, Tamburrini S, Marano I. Ultrasound of Small Bowel Obstruction: A Pictorial Review. Diagnostics (Basel). 2021 Mar 30;11(4):617. doi: 10.3390/diagnostics11040617. PMID: 33808245; PMCID: PMC8065936.

2. Lin YC, Yu YC, Huang YT, Wu YY, Wang TC, Huang WC, Yang MD, Hsu YP. Diagnostic accuracy of ultrasound for small bowel obstruction: A systematic review and meta-analysis. Eur J Radiol. 2021 Mar;136:109565. doi: 10.1016/j.ejrad.2021.109565. Epub 2021 Jan 23. PMID: 33516142.

3.Reginelli A, Genovese E, Cappabianca S, Iacobellis F, Berritto D, Fonio P, Coppolino F, Grassi R. Intestinal Ischemia: US-CT findings correlations. Crit Ultrasound J. 2013 Jul 15;5 Suppl 1(Suppl 1):S7. doi: 10.1186/2036-7902-5-S1-S7. Epub 2013 Jul 15. PMID: 23902826; PMCID: PMC3711730.