A containment vessel for storing and rinsing a medical implant coupled to a delivery system having an outer sheath may include a hollow element having a wall, a proximal end, a distal end, and a lumen extending between the proximal end and the distal end, the lumen of the hollow element being configured and adapted to contain a medical implant in a partially-deployed configuration during storage and rinsing of the medical implant and a proximal end cap including a secondary proximal end cap removably secured to the proximal end cap and configured to reversibly seal the proximal end cap to the outer sheath, thereby establishing a closed fluid connection between the lumen of the hollow element and a lumen of the outer sheath. The proximal end cap may include a sheathing guide configured and adapted to direct the medical implant into the lumen of the outer sheath.