MEDICAL DILATOR WITH ECHOGENETIC MARKER

1 . A method for creating a dissected tissue space in a human subject by using ultrasonic guidance, the method comprising:

a. inserting a distal end of a dilator assembly into a tissue space of a subject, the dilator assembly comprising:

i. a medical dilator comprising a beveled distal section and an elongate cylindrical section proximally abutting the beveled section, and

ii. a dilator-sheath arranged to coaxially surround at least a portion of the cylindrical section of the dilator, the dilator-sheath comprising a hyperechoic marker having an acoustic impedance at least twice that of an outer cylindrical surface portion of the dilator-sheath adjacent to the marker, at least a portion of the hyperechoic marker being proximally displaced from a distal end of the dilator-sheath and distally displaced from a proximal end of the dilator-sheath;

b. causing and regulating distal movement of the dilator assembly, the causing and regulating including:

responsively to receiving an ultrasound image indicating that the hyperechoic marker has reached a target marker-location in the tissue space, ceasing the distal movement; and

c. subsequent to the cessation of the distal movement, deploying an inter-tissue or inter-organ spacer in the tissue space so as to separate a first tissue from a second tissue, or a first organ from a second organ, wherein at least a portion of the spacer is deployed beyond the target marker-location.

2 . The method of claim 1 , wherein substantially all of the spacer is deployed beyond the target marker-location.

3 . The method of claim 1 , wherein a distance from the hyperechoic marker to the distal end of the dilator-sheath matches a length of the deployed spacer.

4 . (canceled)

5 . The method of claim 1 , wherein the first organ is the subject's prostate, and the second organ is the subject's rectum.

6 . The method of claim 1 , wherein the first organ is the subject's cervix, and the second organ is the subject's rectum.

7 . (canceled)

8 . The method of claim 1 , wherein the first organ is the subject's liver or pancreas or head of the pancreas, and the second organ is the subject's duodenum or small intestine.

9 - 16 . (canceled)

17 . The method of claim 1 , wherein during the inserting the dilator assembly is arranged to surround a portion of a guide needle.

18 - 20 . (canceled)

21 . The method of claim 1 , additionally including hydro-dissecting the first tissue from the second tissue, or the first organ from the second organ, before the hyperechoic marker has reached a target marker-location.

22 - 24 . (canceled)

25 . A method for creating a dissected tissue space between a prostate and a rectal wall of a human subject, the method comprising:

a. inserting, through an incision in the subject's perineum, a distal end of a dilator assembly, the dilator assembly arranged to surround a portion of a guiding element penetrating the perineum, the guiding element being one of a guidewire and a guide-needle, the dilator assembly comprising:

i. a distally-beveled dilator, and

ii. a sheath arranged to coaxially surround a portion of the dilator that excludes a distal tip of the dilator, the sheath comprising a hyperechoic marker having an acoustic impedance at least twice that of an outer cylindrical surface portion of the sheath adjacent to the marker, at least a portion of the hyperechoic marker being disposed between 4 and 5 cm from a distal end of the sheath;

b. causing and regulating distal movement of the dilator assembly, the causing and regulating including:

i. responsively to the distal tip of the dilator reaching a first surface of the rectal wall, withdrawing the guiding element, and

ii. responsively to receiving an image from a transrectal ultrasound probe indicating that the hyperechoic marker is parallel to an apex of the prostate, ceasing the distal movement;

c. subsequent to the cessation of the distal movement and while the hyperechoic marker is parallel to the apex of the prostate, (i) withdrawing the dilator, (ii) inserting a deflated tissue-dissection balloon through an interior lumen of the sheath until a distal end of the deflated balloon is aligned with a distal end of the sheath, and (iii) withdrawing the sheath to expose the balloon; and

d. inflating the balloon to cause thereby a separation of the prostate from the rectal wall.

26 . The method of claim 25 , wherein substantially all of the balloon is deployed beyond the target marker-location.

27 . The method of claim 25 , wherein a distance from the hyperechoic marker to the distal end of the dilator-sheath matches a length of the balloon

28 . The method of claim 27 , wherein the distance is from an edge of the hyperechoic marker or from another echogenically distinguishable portion thereof.

29 . The method of claim 25 , additionally including hydro-dissecting the first tissue from the second tissue, or the first organ from the second organ, before the hyperechoic marker has reached a target marker-location.

30 - 33 . (canceled)

34 . A medical dilator kit for an ultrasound-guided tissue dissection, the kit comprising:

a. a beveled-tip medical dilator comprising (i) a conical frustum section formed in a distal portion of the dilator, (ii) a cylinder section formed proximally to the conical frustum portion to abut the base thereof, and

b. a dilator-sheath having an internal diameter greater than or equal to an external diameter of the dilator, the sheath comprising a hyperechoic marker having an acoustic impedance at least twice that of an outer cylindrical surface portion of the dilator-sheath adjacent to the marker, at least a portion of the hyperechoic marker being proximally displaced from a distal end of the dilator-sheath and distally displaced from a proximal end of the dilator-sheath.

35 . The dilator kit of claim 34 , wherein the at least a portion of the hyperechoic marker is displaced at least 3 cm and not more than 6 cm from the distal end of the dilator-sheath.

36 . The dilator kit of claim 35 , wherein the at least a portion of the hyperechoic marker is displaced at least 4 cm and not more than 5 cm from the distal end of the dilator-sheath.

37 . The dilator kit of claim 34 , wherein a distal-tip section of the dilator-sheath includes a beveled circumference.

38 . The dilator kit of claim 37 , wherein a beveling angle of the distal-tip section of the dilator-sheath is greater than a slant angle of the conical frustrum section of the dilator.

39 . The dilator kit of claim 34 , wherein the hyperechoic marker is attached to the outer cylindrical surface portion of the dilator-sheath or formed in the outer cylindrical surface portion of the dilator-sheath.

40 - 42 . (canceled)

43 . The dilator kit of claim 34 , additionally comprising an inter-tissue or inter-organ spacer.

44 - 51 . (canceled)