Where should a filter be placed in a patient with a circumaortic left renal vein?
If unrecognized, a circumaortic left renal vein may provide a collateral pathway for a clot to circumnavigate a filter and embolize to the lungs. If the filter is placed above the posterior segment, a clot may travel up the posterior segment to the anterior segment that is above the filter and then pass on to the lungs. The filter should therefore be placed below the lowest renal vein. This placement ensures that a clot would encounter the filter as it travels centrally.