Predicting portal venous anomalies by left-sided gallbladder or right-sided ligamentum teres hepatis: A large scale, propensity score-matched study

BACKGROUND: Right-sided ligamentum teres (RSLT) is often associated with portal venous anomalies (PVA) and is regarded as a concerning feature for hepatobiliary intervention. Most studies consider RSLT to be one of the causes of left-sided gallbladder (LGB), leading to the hypothesis that LGB must always be present with RSLT. However, some cases have shown that right-sided gallbladder (RGB) can also be present in livers with RSLT. AIM: To highlight the rare variation that RSLT may not come with LGB and to determine whether ligamentum teres (LT) or gallbladder location is reliable to predict PVA. METHODS: This study retrospectively assessed 8552 contrast-enhanced abdominal computed tomography examinations from 2018 to 2021 [4483 men, 4069 women; mean age, 59.5 ± 16.2 (SD) years]. We defined the surrogate outcome as major PVAs. The cases were divided into 4 subgroups according to gallbladder and LT locations. On one hand, we analyzed PVA prevalence by LT locations using gallbladder location as a controlled variable (n = 36). On the other hand, we controlled LT location and computed PVA prevalence by gallbladder locations (n = 34). Finally, we investigated LT location as an independent factor of PVA by using propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). RESULTS: We found 9 cases of RSLT present with RGB. Among the LGB cases, RSLT is associated with significantly higher PVA prevalence than typical LT [80.0% vs 18.2%, P = 0.001; OR = 18, 95% confidence interval (CI): 2.92-110.96]. When RSLT is present, we found no statistically significant difference in PVA prevalence for RGB and LGB cases (88.9 % vs 80.0%, P > 0.99). Both PSM and IPTW yielded balanced cohorts in demographics and gallbladder locations. The RSLT group had a significantly higher PVA prevalence after adjusted by PSM (77.3% vs 4.5%, P < 0.001; OR = 16.27, 95%CI: 2.25-117.53) and IPTW (82.5% vs 4.7%, P < 0.001). CONCLUSION: RSLT doesn't consistently coexist with LGB. RSLT can predict PVA independently while the gallbladder location does not serve as a sufficient predictor.