POCUS biliary and renal — image interpretation viva

Biliary image. Stones + shadowing + wall greater than 3 mm + clinical fever/WCC support cholecystitis; add sonographic Murphy (positive predictive value 72.5% in Ralls' prospective series) to strengthen the rule-in. TG18 needs local + systemic + imaging.^[1][2][6]

Accuracy. Rule-in tool (bedside US sensitivity 87%, specificity 82% for cholecystitis). Negative scan ≠ exclude — escalate to formal imaging if suspicion high. ^[2]

Hydronephrosis. Grade mild/moderate/severe; predicts intervention need but absence does not exclude stone. ^[5]

Aorta 5.8 cm in "renal colic". Treat as symptomatic large AAA until proven otherwise — resus, vascular, theatre pathway; CT only if stable. Always measure aorta on older flank-pain scans. ^[3]

CBD pearl. Age-adjusted MRCP upper limits run to 8 mm under 65 and 11 mm at 65 and over — interpret the duct against age, and over 7 mm with jaundice/fever is obstruction until drained. ^[4]