I would guess that a chronically swollen liver could push other organs to the left and cause such an anomaly. The liver is a large, firm organ and might cause that kind of distension as it crowds other softer organs out for additional space. Of course, that's just a possible theory on my part. I have been flushing for two yeas and passed over 6000 stones of all sizes. I passed another 200 small stones this morning. Yet I have never had that kind of imbalance in my ribcage.