In many healthcare systems, transabdominal ultrasound (US) is still the only morphologic evaluation performed before ERCP, despite its uncertain stand-alone diagnostic value. In settings where access to further imaging may delay care, determining when US alone is sufficient becomes clinically relevant. Whether US can independently justify ERCP in clinically and biochemically suggestive choledocholithiasis remains unclear. We aimed to determine the real-world accuracy of US as the sole pre-ERCP imaging tool and to identify actionable ultrasound criteria that can safely streamline the diagnostic pathway.

All ERCPs performed for suspected CBD stones between 2016–2024 were retrospectively analyzed. Eligible patients had an evocative clinical presentation, a cholestatic profile, and an interpretable pre-ERCP US. US was considered positive when stones were explicitly described; CBD diameter was recorded. The reference standard was cholangiographic stone visualization, stone retrieval, or confirmed complete duct clearance. Diagnostic accuracy parameters were calculated, and CBD diameter cut-offs were evaluated.

Among the 1,092 ERCPs performed for suspected CBD stones during the study period, 837 procedures in 515 patients fulfilled inclusion criteria. Choledocholithiasis was confirmed in 510 patients (99.0%). US identified stones in 74.0%. Direct stone visualization yielded a sensitivity of 73.7% and a positive predictive value of 99.1%. No true negative case was observed, resulting in a specificity and negative predictive value of 0%. In the subgroup with measurable CBD diameter (n = 421), a threshold of 8 mm achieved a sensitivity of 94.7% and a positive predictive value of 98.7%, clearly outperforming direct stone detection.

In clinically and biologically suggestive choledocholithiasis, US used as the sole imaging modality consistently confirmed—but never excluded—the diagnosis. A positive US—either via direct stone detection or a CBD ≥ 8 mm—strongly supported proceeding directly to ERCP, enabling timely therapeutic management while avoiding delays linked to additional imaging. In contrast, a negative US remained unsafe and systematically required complementary imaging. These data refine the practical role of ultrasound in the diagnostic algorithm and provide robust real-life evidence relevant to everyday endoscopy practice, particularly in resource-limited settings.