We present the case of a newborn female patient with a suspected right hypoplastic lung who was referred to our Service to perform a perfusion lung scintigraphy. The tracer (99mTc-albumin microspheres) was injected with a central catheter through the umbilical vein. The lung scan showed abnormal extrapulmonary activity that was attributed to an erroneous canalization (catheter in Arantius duct). A new study, with injection through the peripheral vein, showed the lung perfusion, with a global decrease of activity in the right lung. This case demonstrates a cause of abnormal extrapulmonary perfusion tracer uptake, verifying that using the correct access route is mandatory.