ASTM F1828-22

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Designation: F1828 − 17 F1828 − 22
Standard Specification for
Ureteral Stents
This standard is issued under the fixed designation F1828; 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 (´) 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
1.1 This specification covers the referee test methods for evaluating the performance characteristics of a single-use ureteral stent
with retaining means at both ends, during short term short-term use for drainage of urine from the kidney to the bladder. These
stents are typically available in diameters of 3.7 Fr to 14.0 Fr, and lengths of 8 cm to 30 cm, and are made of silicone, polyurethane,
and other polymers. They are provided non-sterile for sterilization and sterile for single-use.single use.
1.2 Exclusions—Long-term indwelling usage (over 30 days) is encountered with this product, but not commonly, and is therefore
considered an exception to this specification. Similarly, the use of ureteral stents for non-ureteral applications such as nephrostomy
and ileostomy is excluded from the scope of this specification. Non-sterile ureteral stents are also excluded due to the variability
of hospital sterilization equipment and processes and the resulting effects on ureteral stent characteristics.
1.3 The following precautionary statement pertains only to the test method portion, Section 5, of this specification:
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This specification is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.34 on Urological Materials and Devices.
Current edition approved March 1, 2017Nov. 1, 2022. Published April 2017November 2022. Originally approved in 1997. Last previous edition approved in 20142017
as F1828F1828 – 17. –97 (2014). DOI: 10.1520/F1828-17.10.1520/F1828-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2. Referenced Documents
2.1 ASTM Standards:
D412 Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension
F640 Test Methods for Determining Radiopacity for Medical Use
F748 Practice for Selecting Generic Biological Test Methods for Materials and Devices
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 test media —media—((1)1) saline, an isotonic solution of pH 5.5 to 7.0; (2or ) human urine; or ((2)3 human urine, to be used
for tests of ) artificial urine, a solution of organic and inorganic compounds that closely simulates the chemical and physical
properties of normal human urine. Artificial urine may be used as a substitute for human urine to simulate the effects of human
urine on ureteral stents.
3.1.2 bladder retention means—physical feature of bladder end of stent thethat prevents movement of stent out of bladder.
3.1.3 break strength—peak tensile load required to break stent.
3.1.4 cross section—view of stent tube when cut in a plane perpendicular to length of stent.
3.1.5 distal—situated away from the point of origin. The distal end of a stent is the end that resides in the bladder, also known
as the bladder end.
3.1.6 drainage holes—holes in wall of stent tubing that allow flow of urine into and out of lumen of stent.
3.1.7 dynamic frictional force—resistance to relative motion between two surfaces during motion. This force is defined as the
coefficient of kinetic friction multiplied by the force acting on the surface of the material in a plane perpendicular to the surface.
3.1.8 elongation—expressed as a percent, is equal to the change in length of a sample of tubing at failure divided by its original
length. Stretching of the tubing is produced by tensile loading.
3.1.9 French size—scale used to indicate size of tubular devices, each unit being approximately equal to 0.013 in. or 0.33 mm in
diameter. Typical label French sizes are as follows:
French Size Outside Diameter
in. mm
3.7 0.050, 1.23
4.5 0.060, 1.50
4.7 0.061, 1.57
6.0 0.079, 2.00
7.0 0.092, 2.33
8.0 0.105, 2.67
8.5 0.112, 2.83
10.0 0.131, 3.33
14.0 0.183, 4.66
3.1.10 kidney retention means—physical feature of kidney end of stent that prevents movement of stent out of the kidney.
3.1.11 length—distance between the most proximal portion of the bladder retention means and the most distal portion of the kidney
retention means when the stent is laying on a flat surface with the mainshaft main shaft straight (see Fig. 1Figs. 1 and 2 and Fig.
2).
3.1.12 lumen—channel within a tube.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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FIG. 1 Determination of Stent Length
FIG. 2 Determination of Stent Length (alternative stent anchorage design)
3.1.13 proximal—situated toward the point of origin. In the urinary tract, the kidney is considered to be the point of origin. The
proximal end of a stent is the end that resides in the renal pelvis, also known as the kidney end.
3.1.14 radiopacity—property indicating ability of device to absorb x-rayX-ray energy, allowing device to be seen in a radiograph
or fluoroscopic image.
3.1.15 referee test method—method cited in the published specification for the device. This method will be used when the
performance of the ureteral stent is to be evaluated. The manufacturer need not use this referee test method for inspection and
quality control.
3.1.16 retention strength—force required to overcome the retaining means on a stent.
3.1.17 sterility—state of being free of microorganisms. For purposes of this specification, sterility is defined as freedom from
microorganisms when tested according to the methodology defined by the USP for nonparenteral devices.
3.1.18 tolerances—allowable deviation from a standard size. The tolerance for the length of a ureteral stent is 60.5 cm (0.197
in).in.). The tolerance for the specified French size of a ureteral stent is 60.01 mmcm (0.004 in),in.), or approximately ⁄3
French.-French.
3.1.19 ureteral stent—indwelling tubular device that resides in the kidney, ureter, and bladder containing means for retaining ends
of tube in kidney and bladder.
4. Requirements
4.1 Biocompatibility—Ureteral stents shall be tested in accordance with the appropriate biological tests contained in Specifica-
tionPractice F748 or similar guidance established by the U. S. U.S. Food and Drug Administration (FDA) or International
Organization for Standardization (ISO).
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5. Special Precautions
5.1 The following cautionary comments recognize the sensitivity of the materials of construction to potential environmental
conditions. These are outlined here to point out potential situations that could adversely affect the performance of the stent during
testing.
5.1.1 Care should be taken during testing and use to prevent damage to the stents. Such damage can be caused by abrasion and
contact with sharp objects or chemical products.
5.1.2 Stents should be kept away from generators, electric motors, diathermy machines, and fluorescent lights because the ozone
produced may attack elastomeric materials. This applies to both storage and handling.
5.1.3 To help avoid contamination of the stents, proper handling precautions should be observed.
6. Test Methods
6.1 General Guidelines:
6.1.1 Test samples should consist of actual ureteral stents, not material slabs.
6.1.2 Use statistically valid sample sizes in all tests.
6.1.3 Package all stent test samples and sterilize once using the method of sterilization intended to be used for product when it
is sold.
6.1.4 Expose test samples to human urinetest media at 37 6 3°C for a period of 30 days.3 °C for an appropriate duration (for
example, 30 days). When test media is artificial urine, use either of the formulations listed in Annex A1.
6.1.5 Maintain human urine pH pH of test media in the range of 5.5 to 6.5 at all times. Replace human urine Test media should
be replaced weekly.
6.1.6 Perform tests prior to and after soaking for a minimum of 30 days.an appropriate duration (for example, 30 days). For
products with intended chemical/mechanical changes such as softening, swelling, etc., conduct initial mechanical testing only after
sufficient soaking time has elapsed that allowallows such chemical/mechanical changes to occur.
6.1.7 Dynamic frictional force test samples need only be soaked in saline test media for 1 min prior to testing. This test willneed
not be repeated after 30 days.
6.2 Retention Strength:
6.2.1 Scope—This test method measures the ability of a ureteral stent to resist migration. It can be used for testing the proximal
or distal ends of a ureteral stent.
6.2.2 Summary of Test Method:
6.2.2.1 The apparatus is set up as shown in Fig. 3. Clearance between the outside diameter of the stent and inside diameter of the
funnel block hole must be present. (See Note 1#1 in Fig. 3 for a list of appropriate funnel block hole diameters to be used with
stents of different French sizes.)
6.2.2.2 Maintain temperature in the saline test media at 37 6 3°C3 °C by whatever means is available to the test facility. Submerge
the entire funnel block. Set the pull rate through the fixture at a constant 20 in./min or 508 mm/min. in./min. Clean the test bath
and fixture at the beginning of each testing day. The capacity of the load cell used with the tensile testing machine should not
exceed 2 lb.2 lb.
6.2.3 Test Specimen Preparation—The test specimen shall consist of actual sterilized product. The specimen shall be cut to allow
a straight portion of the stent to be inserted upwards through the funnel fixture into the grip of the tensile test machine without
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FIG. 3 Funnel Block for Retention Strength Test
loading the retention mechanism of the stent to be tested. Submerge the test specimen in the saline test media for at least 1 min
to allow it to reach thermal equilibrium. If the material is significantly affected by moisture, allow the specimen to equilibrate for
a minimum of 24 h.
NOTE 1—The portion of the stent held within the gripping mechanism of the tensile testing machine cannot be used for additional testing due to the
potential destructive effects of the gripping mechanism.
6.2.4 Test Procedure:
6.2.4.1 Ensure saline test media is at proper temperature and funnel is submerged. Monitor periodically.
6.2.4.2 When testing a new ureteral stent taken out of its sterile package,package (t=0), straighten retention means with appropriate
guidewire. Insert straight portion of stent through bottom of funnel and into grip. When testing at t=30 days, retention means is
not to be straightened prior to testing.
6.2.4.3 Allow stent to reach thermal equilibrium.
6.2.4.4 Pull specimen up through funnel at 20 in./min. Record maximum force required to pull stent completely through funnel.
6.3 Break Strength:
6.3.1 Break strengthsstrength of test stents will be determined in accordance with Test Method D412, with the following
modifications:
6.3.1.1 Devices used to grip the test specimen in the tensile test machine should be chosen so that the test specimen does not break
at the grip location.
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6.3.1.2 Most stents contain drainage holes. Ideally, these stents should break at a drainage hole. This is how tensile failures
typically occur in vivo. However, stents may break in locations other than drainage holes. This type of failure may be indicative
of potential design or process related problems. In stents without drainage holes, this type of failure is to be expected.
6.3.1.3 Only a segment of the test stent is used for the break strength test. The grippers should be separated by 1 in. This 1 in.
1 in. segment must contain at least one drainage hole (if drainage holes are present) and should contain the section of the stent with
the smallest cross sectional cross-sectional area or weakest point.
6.4 Elongation—The elongation of stent segments separated by 1 in. between the extensometer grips used to hold the segment in
the tensile test machine or two marks placed on the surface of the st
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