A catheterization apparatus comprising a containing catheter for facilitating sequential treatment operations and an elongated inner catheter, (310, 510, 710), said containing catheter (100, 750) of said catheterization apparatus (300, 500, 700) comprising: a median portion comprising an elongated, substantially tubular member, having a main lumen therein extending between a proximal end and a distal end of said tubular member, thereby providing fluid communication between said proximal end and said distal end of said tubular member; a distal portion, comprising a distal stiff member extending between a stiff member proximal end and a stiff member distal end, and comprising: a proximal opening located at said stiff member's proximal end, and comprising a mating surface of a sealed joint, a distal opening, and a stiff member void inside said stiff member, configured to provide fluid communication between said proximal opening and said distal opening; wherein said distal portion is physically associated with said median portion so that said stiff member void of said distal stiff member is in fluid communication with said main lumen, and wherein said elongated inner catheter is insertable into said main lumen of said containing catheter, having a cross-section dimension smaller than a cross-section dimension of said main lumen, thereby forming a gap between said inner catheter and an inner surface of said tubular member when said elongated inner catheter is inserted into said tubular member, said elongated inner catheter extending between an inner catheter proximal end and an inner catheter distal end, having a length greater than a length of said median portion of said containing catheter, and wherein said elongated inner catheter is hollow, having an inner catheter channel between a catheter proximal opening and a catheter distal opening and wherein said elongated inner catheter distal end is blind and comprises an inner catheter mating surface configured to fit said mating surface of said proximal opening at said stiff member proximal end, and said distal catheter opening is proximal to said inner catheter distal end and facing said gap between said elongated inner catheter and said inner surface of said tubular member, so that, when said elongated inner catheter is inserted into said containing catheter and pressed onto said distal stiff member, a sealing joint is formed between said inner catheter distal end and said proximal opening at said stiff member proximal end, thereby preventing fluid flow through said proximal opening of said distal stiff member, and fluid communication is provided between said inner catheter channel and said gap through said inner catheter distal opening. a median portion comprising an elongated, substantially tubular member, having a main lumen therein extending between a proximal end and a distal end of said tubular member, thereby providing fluid communication between said proximal end and said distal end of said tubular member; a distal portion, comprising a distal stiff member extending between a stiff member proximal end and a stiff member distal end, and comprising: a proximal opening located at said stiff member's proximal end, and comprising a mating surface of a sealed joint, a distal opening, and a stiff member void inside said stiff member, configured to provide fluid communication between said proximal opening and said distal opening; wherein said distal portion is physically associated with said median portion so that said stiff member void of said distal stiff member is in fluid communication with said main lumen, and a proximal opening located at said stiff member's proximal end, and comprising a mating surface of a sealed joint, a distal opening, and a stiff member void inside said stiff member, configured to provide fluid communication between said proximal opening and said distal opening; wherein said elongated inner catheter is insertable into said main lumen of said containing catheter, having a cross-section dimension smaller than a cross-section dimension of said main lumen, thereby forming a gap between said inner catheter and an inner surface of said tubular member when said elongated inner catheter is inserted into said tubular member, said elongated inner catheter extending between an inner catheter proximal end and an inner catheter distal end, having a length greater than a length of said median portion of said containing catheter, and wherein said elongated inner catheter is hollow, having an inner catheter channel between a catheter proximal opening and a catheter distal opening and wherein said elongated inner catheter distal end is blind and comprises an inner catheter mating surface configured to fit said mating surface of said proximal opening at said stiff member proximal end, and said distal catheter opening is proximal to said inner catheter distal end and facing said gap between said elongated inner catheter and said inner surface of said tubular member, so that, when said elongated inner catheter is inserted into said containing catheter and pressed onto said distal stiff member, a sealing joint is formed between said inner catheter distal end and said proximal opening at said stiff member proximal end, thereby preventing fluid flow through said proximal opening of said distal stiff member, and fluid communication is provided between said inner catheter channel and said gap through said inner catheter distal opening.