ASTM F1828-97

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Designation: F 1828 – 97
Standard Specification for
Ureteral Stents
This standard is issued under the fixed designation F 1828; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The objective of this specification is to describe the test methods used to evaluate the safety and
effectiveness of an indwelling ureteral stent, having retention means at the kidney and bladder ends,
used for urinary drainage of the kidney to the bladder via the ureter.
This specification includes referee test methods that can be used to evaluate the performance
characteristics of ureteral stents. Note that the test methods are not to be construed as production
methods, quality control techniques, or manufacturer’s lot release criteria. The product parameters
addressed by the standard include those determined by the ASTM task group to be pertinent to the
product.
1. Scope D 412 Test Methods for Vulcanized Rubber and Thermo-
plasticRubbersandThermoplasticElastomers—Tension
1.1 This specification covers the referee test methods for
F 640 Test Methods for Radiopacity of Plastics for Medical
evaluating the performance characteristics of a single-use
Use
ureteral stent with retaining means at both ends, during short
F 748 Practice for Selecting Generic Biological Test Meth-
term use for drainage of urine from the kidney to the bladder.
ods for Materials and Devices
These stents are typically available in diameters of 3.7 Fr to
14.0Fr,andlengthsof8cmto30cm,andaremadeofsilicone,
3. Terminology
polyurethane, and other polymers. They are provided non-
3.1 Definitions of Terms Specific to This Standard:
sterile for sterilization and sterile for single-use.
3.1.1 artificial urine—a solution of organic and inorganic
1.2 Exclusions—Long-term indwelling usage (over 30
compounds that closely simulates the chemical and physical
days) is encountered with this product, but not commonly, and
properties of normal human urine.Artificial urine will be used
is therefore considered an exception to this specification.
as a substitute for human urine to simulate the effects of human
Similarly, the use of ureteral stents for non-ureteral applica-
urine on ureteral stents.
tions such as nephrostomy and ileostomy is excluded from the
3.1.2 bladder retention means—physical feature of bladder
scope of this specification. Non-sterile ureteral stents are also
end of stent the prevents movement of stent out of bladder.
excluded due to the variability of hospital sterilization equip-
3.1.3 break strength—peak tensile load required to break
ment and processes and the resulting effects on ureteral stent
stent.
characteristics.
3.1.4 cross section—view of stent tube when cut in a plane
1.3 The following precautionary statement pertains only to
perpendicular to length of stent.
the test method portion, Section 5, of this specification:
3.1.5 distal—situated away from the point of origin. The
1.4 This standard does not purport to address all of the
distal end of a stent is the end that resides in the bladder, also
safety concerns, if any, associated with its use. It is the
known as the bladder end.
responsibility of the user of this standard to establish appro-
3.1.6 drainage holes—holes in wall of stent tubing that
priate safety and health practices and determine the applica-
allow flow of urine into and out of lumen of stent.
bility of regulatory limitations prior to use.
3.1.7 dynamic frictional force—resistance to relative mo-
2. Referenced Documents tion between two surfaces during motion. This force is defined
as the coefficient of kinetic friction multiplied by the force
2.1 ASTM Standards:
acting on the surface of the material in a plane perpendicular to
the surface.
ThisspecificationisunderthejurisdictionofASTMCommitteeF-4onMedical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.34 on Urological Materials and Devices. Annual Book of ASTM Standards, Vol 09.01.
Current edition approved Nov. 10, 1997. Published May 1998. Annual Book of ASTM Standards, Vol 13.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1828
3.1.8 elongation—expressed as a percent, is equal to the 3.1.18 tolerances—the allowable deviation from a standard
change in length of a sample of tubing at failure divided by its size.The tolerance for the length of a ureteral stent is 6 0.5 cm
original length. Stretching of the tubing is produced by tensile (0.197 in). the tolerance for the specified French size of a
loading. ureteral stent is 6 0.01 mm (0.004 in), or approximately 1/3
3.1.9 French size—Scale used to indicate size of tubular French.
devices, each unit being approximately equal to 0.013 in. or 3.1.19 ureteral stent—an indwelling tubular device that
0.33 mm in diameter.Typical label French sizes are as follows: resides in the kidney, ureter, and bladder containing means for
retaining ends of tube in kidney and bladder.
French Size Outside Diameter
in. mm
4. Requirements
3.7 0.050,1.23
4.5 0.060,1.50
4.1 Biocompatibility— Ureteral stents shall be tested in
4.7 0.061,1.57
accordance with the appropriate biological tests contained in
6.0 0.079,2.00
SpecificationF 748orsimilarguidanceestablishedbytheU.S.
7.0 0.092,2.33
8.0 0.105,2.67
Food and Drug Administration or International Organization
8.5 0.112,2.83
for Standardization (ISO).
10.0 0.131,3.33
14.0 0.183,4.66
5. Special Precautions
3.1.10 kidney retention means—physical feature of kidney
5.1 The following cautionary comments recognize the sen-
end of stent that prevents movement of stent out of the kidney.
sitivity of the materials of construction to potential environ-
3.1.11 length—length of stent is defined as the distance
mental conditions. These are outlined here to point out poten-
between the most proximal portion of the bladder retention
tialsituationsthatcouldadverselyaffecttheperformanceofthe
means and the most distal portion of the kidney retention
stent during testing.
means when the stent is laying on a flat surface with the
5.1.1 Care should be taken during testing and use to prevent
mainshaft straight. (See Fig. 1).
damage to the stents. Such damage can be caused by abrasion
3.1.12 lumen—the channel within a tube.
and contact with sharp objects or chemical products.
3.1.13 proximal—situated toward the point of origin. In the
5.1.2 Stents should be kept away from generators, electric
urinary tract, the kidney is considered to be the point of origin.
motors,diathermymachines,andfluorescentlightsbecausethe
The proximal end of a stent is the end that resides in the renal
ozone produced may attack elastomeric materials. This applies
pelvis, also known as the kidney end.
to both storage and handling.
3.1.14 radiopacity—property indicating ability of device to
5.1.3 To help avoid contamination of the stents proper
absorb x-ray energy, allowing device to be seen in a radiograph
handling precautions should be observed.
or fluoroscopic screen.
3.1.15 referee test method—the method cited in the pub-
6. Test Methods
lished specification for the device. This method will be used
when the performance of the ureteral stent is to be evaluated. 6.1 General Guidelines:
The manufacturer need not use this referee test method for 6.1.1 Test samples should consist of actual ureteral stents,
not material slabs.
inspection and quality control.
3.1.16 retention strength—force required to overcome the 6.1.2 Use statistically valid sample sizes in all tests.
6.1.3 Package all stent test samples and sterilize once using
retaining means on a stent.
3.1.17 sterility—the state of being free of microorganisms. the method of sterilization intended to be used for product
For purposes of this specification, sterility is defined as when it is sold.
freedom from microorganisms when tested according to the 6.1.4 Expose test samples to artificial urine at 37 6 3° C for
methodology defined by the USP for nonparenteral devices. a period of 30 days. Use either of the two artificial urine
FIG. 1 Determine of Stent Length.
F 1828
formulations listed inAnnexA1. In situations where testing in 6.2.3 Test Specimen Preparation—The test specimen shall
artificial urine is not practical, distilled water may be used. consist of actual sterilized product. The specimen shall be cut
6.1.5 Maintain artificial urine pH in the range of 5.5 to 6.5
to allow a straight portion of the stent to be inserted upwards
at all times. Replace urine should be weekly. through the funnel fixture into the grip of the tensile test
6.1.6 Performtestspriortoandaftersoakingforaminimum
machine without loading the retention mechanism of the stent
of 30 days. For products with intended chemical/mechanical
to be tested. Submerge the test specimen in the water bath for
changes such as softening, swelling, etc., do initial mechanical
at least 1 min to allow it to reach thermal equilibrium. If the
testing only after sufficient soaking time has elapsed that allow
material is significantly affected by moisture, allow the speci-
such chemical/mechanical changes to occur.
men to equilibrate for a minimum of 24 h. Use distilled water,
6.1.7 Dynamic frictional force test samples need only be
if possible.
soakedindistilledwaterfor1minpriortotesting.Thistestwill
NOTE 1—The portion of the stent held within the gripping mechanism
not be repeated after 30 days.
of the tensile testing machine cannot be used for additional testing due to
6.2 Retention Strength:
the potential destructive effects of the gripping mechanism.
6.2.1 Scope—This test method measured the ability of a
ureteral stent to resist migration. It can be used for testing the 6.2.4 Test Procedure:
proximal or distal ends of a ureteral stent.
6.2.4.1 Ensure test bath is at proper temperature and funnel
6.2.2 Summary of Test Method:
is submerged. Monitor periodically.
6.2.2.1 TheapparatusissetupasshowninFig.2.Clearance
6.2.4.2 When testing a new ureteral stent taken out of its
between the outside diameter of the stent and inside diameter
sterile package, (t=0), straighten retention means with appro-
of the funnel block hole must be present. (See Note 1 in Fig. 2
priateguidewire.Insertstraightportionofstentthroughbottom
for a list of appropriate funnel block hole diameters to be used
of funnel and into grip. When testing at t=30 days, retention
with stents of different French sizes.)
means is not to be straightened prior to testing.
6.2.2.2 Maintain temperature in the water bath at 376 3°C
6.2.4.3 Allow stent
...