NxStage Medical, Inc. (NxStage) is a medical device company that develops, manufactures and markets products for the treatment of kidney failure, fluid overload and related blood treatments and procedures. The Company�s primary product is the NxStage System One (System One). It also sells needles and blood tubing sets primarily to dialysis clinics for the treatment of end-stage renal disease (ESRD). It operates in two segments: System One and In-Center. It distributes its products in three markets: home, critical care and in-center. In the System One segment it derives its revenues from the sale and rental of the System One and PureFlow SL equipment, and the sale of disposable products in the home and critical care markets. In the In-Center segment, it derives its revenues from the sale of blood tubing sets and needles for hemodialysis primarily for the treatment of ESRD patients at dialysis centers and needles for apheresis, which is referred to as the in-center market.