Introduction

Vaginally-administered medical devices and drug-delivery devices are used for various clinical indications, complications, and uses relating to women’s health, including pelvic organ prolapse, urinary incontinence, non-hormonal contraception, hormonal contraception, oestrogen replacement therapy, prevention of HIV infection, and diagnostic devices1,2,3,4,5,6. Devices can be broadly classified as drug-free support devices (e.g. ‘vaginal pessaries’), drug-free contraceptive devices (e.g. cervical caps and diaphragms) or drug-releasing vaginal rings (e.g. NuvaRing® and Annovera® for hormonal contraception). Some devices fall into more than one classification; for example, some experimental vaginal pessaries—traditionally used for pelvic organ prolapse—have been modified to release estrogens to treat vaginal atrophy7,8.

The term vaginal pessary is commonly used to refer to devices that are placed into the vagina to provide mechanical support for pelvic organs (bladder, uterus and rectum) that have become displaced and protrude into the vagina4,9,10,11. Such pelvic organ prolapse is due to weakened pelvic floor ligaments and muscles exacerbated by pregnancy/childbirth, age, menopause and being overweight. Certain pessary designs may additionally provide relief for symptoms of urinary incontinence. These devices function by providing structural support, thereby alleviating discomfort, pressure, or leakage of urine. Vaginal pessaries are available in an array of designs and sizes (examples provided in Fig. 1A–E) depending on clinical requirements and vaginal dimensions/shape (due to age, childbirth history and body size), and are commonly manufactured from silicone elastomer, although polyethylene and polyvinylchloride materials are also available4,9.

Fig. 1: Representative photographs of various vaginal pessaries, cervical caps, diaphragms, and drug-releasing vaginal rings.
figure 1

A Donut pessary; B Ring pessary without support; C Gelhorn pessary; D Ring pessary with support; E Cube pessary; F FemCap™ cervical cap; G Caya® diaphragm; H Menstrual cup; I Estring® silicone elastomer vaginal ring, releasing estradiol over 3 months; J Annovera™ silicone elastomer vaginal ring releasing segesterone acetate and ethinyl estradiol over 12 months; K Femring® silicone elastomer vaginal ring, releasing estradiol-3-acetate over 3 months; L NuvaRing® thermoplastic vaginal ring, releasing etonogestrel and ethinyl estradiol over 21 days.

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Drug-free contraceptive devices such as cervical caps and diaphragms (Fig. 1F, G) are barrier-type devices intended for use with a spermicide for the prevention of unintended pregnancy. Importantly, they offer women the option of non-hormonal contraception, although they are generally less effective than hormonal methods, even with perfect use12. Like vaginal pessaries, many caps and diaphragms are available in various designs and sizes, and are commonly fabricated from silicone elastomer1,13. Menstrual cups (which contain no drug actives; Fig. 1H) are fluid collection devices that are becoming increasingly popular as an environmentally friendly alternative to sanitary towels and tampons. They are relatively inexpensive, re-useable, available in a range of shapes and sizes, and most are manufactured from silicone elastomer.

Several drug-releasing vaginal rings are currently marketed (Fig. 1I–L), offering the advantage of sustained or controlled drug release—localised or systemically—over extended time periods for hormonal contraception, estrogen replacement therapy and HIV prevention. Although these drug-releasing rings look like drug-free ring pessaries (Fig. 1B), the polymer selection plays an additional critical role beyond providing mechanical strength—specifically, the polymer also controls the release rate(s) of the incorporated drug active(s). The drug release rate and mechanism are therefore dialled in through judicious design of the device (e.g. matrix vs. reservoir type design) and the choice of polymer through which the drug(s) must diffuse. Five of the seven drug-releasing vaginal rings currently marketed—Estring®, Femring®, Progering®, AnnoveraTM and DapiRing®—are fabricated from silicone elastomer (see examples in Fig. 1I–K); NuvaRing® (Fig. 1L) is manufactured from two different grades of ethylene-vinyl acetate copolymer having different ratios of ethylene and vinyl acetate; and Ornibel® is manufactured from a thermoplastic polyurethane core and an ethylene-vinyl acetate copolymer sheath14,15. These drug-releasing vaginal rings are particularly useful for long-term therapy and in reducing drug dosing compared with oral administration.

The scientific literature around these vaginal devices primarily focuses on formulation development (including drug delivery characteristics) and clinical assessment. Only limited attention has been given to the issue of device appearance and the propensity for vaginal devices to discolour during clinical use2,16,17,18,19,20,21, despite the implications for user acceptability and adherence. Since most vaginal devices require prolonged placement in the vagina, any discolouration or surface staining observed during use was assumed to result from exposure to cervicovaginal fluid, menstrual blood, and/or semen2,16,22. McCoy et al. demonstrated that prolonged exposure to menstrual blood is indeed a major source of surface discolouration observed with drug-releasing vaginal rings16. Highly coloured personal hygiene and cleaning products have also been identified as potential sources of staining for silicone rings16,20, while the coloured pigments produced by many microorganisms during biofilm formation may also be a causal factor14. However, although undesirable and often aesthetically unpleasant (Fig. 2), surface staining does not usually have any deleterious impact on the clinical function of these devices4,20,22. Yet, devices that show significant discolouration during use may cause concern for users and adversely impact user acceptability and behaviours23,24. In this article, we (i) describe the different polymeric materials used to fabricate vaginal devices, (ii) review the scientific literature reporting discolouration of devices, (iii) explore the factors that may contribute to the discolouration of vaginal devices and impact user acceptability and adherence, and (iv) review user opinions and acceptability around discoloured devices, both in the peer-reviewed scientific literature and among users of the social media platform Reddit.

Fig. 2: Examples of discolouration of drug-releasing vaginal rings and menstrual cups.
figure 2

A 200/320 mg dapivirine + levonorgestrel silicone elastomer ring16; B drug-free silicone elastomer ring16; C Progering® silicone elastomer ring17; D dapivirine silicone elastomer ring20; E dapivirine silicone elastomer ring16; F dapivirine silicone elastomer ring16; G menstrual cup; H menstrual cup (https://lunacup.eu/en-GB/menstrual-cup/blog/post/how-to-clean-the-cup). Vaginal ring images A, B, D were taken following in vitro discolouration studies. Images C, E–H were captured following clinical use. Higher resolution versions of Images E, F are not available.

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Materials used to manufacture vaginal devices

Vaginal devices are manufactured from various non-biodegradable, non-swellable, bioinert polymeric materials, including silicone elastomers, ethylene-vinyl acetate copolymers, thermoplastic polyurethanes, latex, polyethylene and polyvinylchloride. The chemistry and properties of polymers used in drug-releasing rings have been discussed extensively elsewhere6,14,15,25,26. Therefore, only a brief overview of the materials used for vaginal device manufacture is provided here.

Latex

Natural rubber latex is a naturally occurring polymer extracted as a white milky fluid from rubber plants (Hevea braziliensis tree). It is an aqueous dispersion of cis-1,4-polyisoprene particles (25–41%), proteins, carbohydrates, lipids, resins and various minerals27,28. Since liquid latex coagulates rapidly on exposure to air, stabilisation is required prior to transportation and processing. Although once highly favoured for the manufacture of vaginal devices such as the cervical cap, natural rubber latex has largely fallen out of favour due to the risk of allergic reaction from naturally occurring latex proteins present in the rubber and/or the chemical additives required during product manufacture9,10,29. However, latex is still used in the manufacture of certain vaginal pessary devices (e.g. Milex Inflatoball pessary).

Silicone elastomer

Silicone elastomers—prepared by chemical crosslinking of chemically functionalized, linear, polydimethylsiloxane molecules6—are the most common materials used for fabrication of both drug-free and drug-releasing vaginal devices. They offer high flexibility, excellent durability, safety, and biocompatibility26,30. Silicone elastomers that form via an addition-cure reaction are most common, although other curing mechanisms are possible6,15,31,32. Estring®, Femring®, AnnoveraTM and DapiRing® are examples of commercially available drug-releasing vaginal ring products manufactured using medical grade silicone elastomers. Examples of vaginal pessaries produced from silicone include Milex® and Gellhorn pessaries.

Ethylene-vinyl acetate copolymers

Ethylene-vinyl acetate (EVA) copolymers are random copolymers of ethylene (ethene) and vinyl acetate. They have been used extensively in medical and drug-delivery devices due to their hydrophobic and non-biodegradable properties and excellent biocompatibility15,33,34. The thermal, mechanical and drug release properties of these copolymers are dependent upon the molecular weight and vinyl acetate content (typically ranging from 9 to 40%), making it relatively easy to tailor device properties25. NuvaRing® (having a 28% vinyl acetate EVA core and a 9% vinyl acetate EVA sheath) and Ornibel® (28% vinyl acetate EVA sheath and a thermoplastic polyurethane core) are examples of drug-releasing vaginal rings fabricated in whole or in part using EVA35,36,37.

Thermoplastic polyurethanes

Thermoplastic polyurethanes (TPUs) are another versatile group of thermoplastic polymers increasingly used for the fabrication of vaginal devices7,35,38,39. TPUs are copolymers formed by a polymerisation reaction between diisocyanates, short-chain diols, and long-chain diols6. They are available in a range of hydrophilic and hydrophobic grades offering differing mechanical properties, making them ideal for the manufacture of devices having different hardness values and for the delivery of various drug molecules36,37,38. The core of the contraceptive vaginal ring Ornibel® contains etonogestrel and ethinyl estradiol dispersed in a thermoplastic polyurethane37. The Conveen Continence Guard® and the Contrelle Continence Tampon® are examples of drug-free thermoplastic polyurethane vaginal pessaries40. LivRing® is a recently marketed vaginal ring device—made from a hydrophilic polyurethane material and having similar dimensions to NuvaRing®—that slowly releases a glycerine (glycerol) solution for up to seven days for vaginal lubrication41.

Polyvinyl chloride

Polyvinyl chloride (PVC) is a linear thermoplastic polymer that is used extensively in industrial and healthcare applications. Its physical, mechanical, and thermal properties depend upon its molecular weight and the addition of various modifying agents such as heat stabilisers, lubricants, processing aids, pigments, and plasticisers42,43. PVCs are broadly classified as either flexible or rigid43, with soft, flexible, medical-grade materials normally favoured for the fabrication of vaginal pessaries (e.g. Balance PVC Ring Pessary®). However, use of PVC for vaginal devices is declining, due to concerns over leaching of plasticisers and other excipients, and relatively poor biocompatibility compared to other materials.

Polyethylene

Polythene (PE) is a low-cost, chemically resistant, thermoplastic polymer. It can be produced in both linear and branched forms and is classified according to type: (i) low-density PE, (ii) linear low-density PE, (iii) ultra-low-density PE, (iv) high-density PE, and (v) ultra-high molecular weight PE44,45. Although rarely used for drug-releasing devices (due to relatively poor drug permeation characteristics), PE is used for the manufacture of certain drug-free vaginal pessaries, e.g. the Portia Rigid Polythene Pessary®. While many vaginal pessaries are designed to have some degree of flexibility, rigid pessaries fabricated from PE are preferred in cases of severe organ prolapse (https://www.ukcs.uk.net/resources/Documents/Pessary 2021/UK Pessary Guideline final April21.pdf). However, the increased rigidity and improved support offered by these rigid devices is often accompanied by difficulties or discomfort during placement, removal or use.

Discolouration of vaginal devices during clinical use

While information around discolouration of vaginal devices is sparse, information and advice are reported in patient information leaflets, manufacturers’ guidance notes, original research articles and online discussion forums2,4,16,17,20,22,46,47 (https://personalmed.com/wp-content/uploads/2022/03/Use-and-Care-of-Pessaries.pdf). Here, we provide descriptions of the various types of vaginal devices and discuss literature reports of their discolouration.

Vaginal pessaries

Vaginal pessaries are offered in a variety of designs (ring, donut, cube, dish, shelf and Gellhorn) and sizes and are broadly classified as either support pessaries or space-filling pessaries (Fig. 1A–E)4,9,48. (https://thepogp.co.uk/_userfiles/pages/files/resources/uk_pessary_guideline_final_april21.pdf; https://personalmed.com/wp-content/uploads/2022/03/Use-and-Care-of-Pessaries.pdf). Most modern pessaries are fabricated from either PVC or silicone elastomer, although PE and latex devices are also available4,9,49,50. Duration of wear depends upon the pessary type and medical condition being treated. Some pessaries, such as the ring pessary, are worn for several months at a time, while others, such as the cube pessary, need to be removed and cleaned daily9 (https://www.iuga.org/spotlight-v16-1/expert-opinion-vaginal-pessaries-in-the-management-of-pelvic-organ-prolapse). Most pessary patient information leaflets, clinician guidance notes and healthcare websites mention discolouration as a normal consequence of prolonged product use. For example, an educational leaflet for the EvaCare® silicone ring pessary (Personal Medical Corp. USA) states that pessaries have a long usage life and can remain in place for 8 to 12 weeks. A slight discolouration of the pessary is normal. (https://personalmed.com/wp-content/uploads/2022/03/Use-and-Care-of-Pessaries.pdf). Discolouration of pessaries has also been reported in the scientific literature4,5,22,49,51. Menstruating women reported discolouration of their pessaries occurring more quickly than non-menstruating women, causing some users to remove their pessary during menstruation22,52. In general, changes in pessary colour have been attributed to contact with vaginal fluids and/or blood52 and, while unsightly, they do not harm the user or negatively affect the clinical performance of the device4. For this reason, replacement of a pessary due to staining is unnecessary unless it is accompanied by evidence of damage or loss of supportive function4,22,52 (https://www.iuga.org/spotlight-v16-1/expert-opinion-vaginal-pessaries-in-the-management-of-pelvic-organ-prolapse; https://www.ukcs.uk.net/resources/Documents/Pessary 2021/UK Pessary Guideline final April21.pdf).

Cervical caps

Cervical caps (Fig. 1F) are small dome or thimble-shaped contraceptive barrier devices designed to fit tightly over the cervix3,53,54. They are placed in combination with a spermicidal lubricant before sexual intercourse and can be worn for up to 48 h13,53 (https://cervicalbarriers.org/wp-content/uploads/2019/12/contraception_report_dia.pdf). Historically, latex rubber—and more recently silicone elastomers—have been used to manufacture cervical caps13,53,55,56. Popularity of the cervical cap has decreased steadily since the introduction of the contraceptive diaphragm, the oral contraceptive pill, and intrauterine devices, and with the withdrawal of devices such as Lea’s Shield in 2008 and the Prentif cap in 2005. Femcap™—made from soft silicone elastomer—is currently the only cervical cap available for use in the US, UK and Europe1,3,57.

Discolouration of cervical caps with prolonged use was reported as early as 1953 by Lehfeldt and Liebmann; the authors stated that “while some discolouration of the plastic material may occur with prolonged use, the same cap can be used for several years”58. Similarly, the author of a 1984 thesis assessing the efficacy of the latex Prentif-rim cap reported that “cap users found that their cervical caps cracked and discoloured over time (23% at 1 month vs 56% at over 1 year)”59. Manufacturers of FemCap™ and Lea’s Shield (both silicone elastomer devices; the latter has been discontinued) also referred to device discolouration in their physicians’ labelling leaflets. Unlike some vaginal pessaries, cervical caps are not designed to be worn during menstruation, and users are instructed to wash the devices after each use. This suggests that exposure to menstrual blood may not be the primary cause of staining for these devices. Instead, cap manufacturers and prescribing clinicians comment that discolouration of cervical caps is the result of frequent contact with cervicovaginal fluids and that discolouration does not compromise the function, effectiveness or lifespan of the device unless accompanied by other signs of damage or deterioration4,58 (https://www.nhs.uk/conditions/contraception/contraceptive-diaphragm-or-cap).

Diaphragms

Contraceptive diaphragms are flexible, shallow dome or cup-shaped, reusable devices with a flexible rim (Fig. 1G) and can be used with or without a spermicide for the prevention of unintended pregnancy. They are generally classified according to spring type—coil spring, flat spring, or arching spring—and range in size from 50–105 mm. Silicone elastomer and latex are the most common materials for their fabrication53. Although duration of use varies, it is generally recommended that diaphragms remain in place for at least 6 hr after intercourse and not longer than 24 h in a single use13,53,60. All diaphragms are designed to be removed, washed, dried, and stored after each use. Although diaphragm use during menstruation is not generally recommended53, discolouration is commonly reported, as noted in patient information leaflets, patient guidance notes, and in several scientific articles16,60,61. For example, Behets et al. reported discolouration of a silicone Wide-Seal Arching Diaphragms (Milex Products, Chicago, USA) during an 8-week acceptability and feasibility study60. Discolouration was also reported in a 1981 US patent describing a silicone elastomer contraceptive device. Interestingly, the inventors of this device suggested that an interaction between the tin catalyst present in the condensation-cure silicone elastomer material and components of vaginal fluid was responsible for discolouration of the diaphragm61. However, similar discolourations have been observed for vaginal devices fabricated from silicone elastomers that do not use tin-catalysed silicone elastomers16,60 (https://uhs.berkeley.edu/sites/default/files/diaphragm.pdf), suggesting the cure chemistry is not the primary contributing factor. As with other vaginal devices, discolouration of diaphragms does not affect device integrity or necessarily indicate the presence of infection60.

Menstrual cups

Menstrual cups are pliable, bell-shaped or V-shaped devices (Fig. 1H) for the collection of menstrual blood. They are typically fabricated from silicone elastomer or thermoplastic polymers. The cups range in size, shape and colour, and are designed to remain in place for up to 12 h, collecting between 10–38 mL of menstrual blood62. The typical shelf-life of a menstrual cup varies between 2 and 4 years, depending upon frequency of use and the cleaning regime used62. Almost all cups show surface staining over time. As with other vaginal devices, the extent of staining of menstrual cups varies depending upon the user (the amount of menstrual blood and duration of bleed varies among women63,64,65), and the device type (e.g. choice of polymer material, design of device, etc.) and generally ranges in colour from light to dark brown (Fig. 2G, H)66,67. While aesthetically unpleasant, staining does not affect the effectiveness of the cup. In fact, in one observational study involving Kenyan school girls, monitoring of menstrual cup colour changes from clear-white to yellow-brown proved useful as an indicator of actual rather than self-reported use67.

Drug-releasing vaginal rings

Marketed drug-releasing vaginal rings are flexible, single-sized (outer diameter 54–56 mm) torus-shaped polymeric devices (Fig. 1I–L)14,15. All products are either opaque white or partially/fully colourless and transparent, although a recent study has reported women’s preferences around alternative colour options, including darker colours such as black and red (which would mask discolouration)68. During the 1970s and 1980s, vaginal ring devices were initially developed to provide sustained or controlled release of progestogens and/or estrogens to the vagina for hormonal contraception and treatment of menopausal symptoms. In recent years, vaginal rings have been developed to release other therapeutic agents, most notably antiretrovirals for pre-exposure prophylaxis of sexual acquisition of human immunodeficiency virus (HIV) and combinations of drugs as multipurpose prevention technology (MPT) products69,70,71,72. Marketed vaginal rings are mostly made from silicone elastomers and ethylene-vinyl acetate copolymers6,15.

Several scientific articles have reported discolouration of vaginal rings, and mostly those fabricated from silicone elastomers2,16,17,18,19,20,21,46. In one respect, this is not entirely surprising, as a greater number of marketed ring products are silicone-based (although NuvaRing® and its generic forms for hormonal contraception outsell the drug-releasing silicone rings by some margin). However, silicone elastomers may be inherently more prone to surface staining compared to thermoplastic polymers, due to their relatively large size and surface area, the relative softness of the material, and their higher porosity due to the relatively large free volume between the siloxane chains6,73. Vaginal ring staining is reported as yellow (most common), brown, or dark staining16,17,18,21. Burton et al. reported brown surface discolouration of silicone rings containing either progesterone, d-norgestrel or norethindrone following clinical use19; these rings were manufactured using a tin-catalysed condensation-cure silicone elastomer, like that used in Femring®. As all rings used in the study were sterilised post-manufacture using ethylene oxide, the discolouration observed on the rings was most likely attributed to clinical use rather than microbial contamination introduced during manufacture19. The authors also commented that “the discolouration appeared to be subject-related rather than related to the period of in vivo use”19. Variability in ring discolouration between users has also been documented in more recent articles2,21,74. In a Phase 1 clinical study of a dapivirine-releasing ring (for HIV prevention), nine out of twenty-four devices showed yellow discolouration, and three out of 24 showed much darker yellow or brown staining74. Discolouration was observed for both placebo (drug-free) and drug-loaded rings, suggesting that exposure to menstrual blood rather than the drug component in the rings was the probable cause of discolouration74. Interestingly, these early dapivirine-releasing rings, formulated using a condensation-cure silicone elastomer75,76,77, showed similar discolouration patterns to the addition-cure dapivirine-releasing silicone ring recently approved for HIV prevention in African countries16,78, supporting the hypothesis that differences in silicone elastomer curing chemistries do not play a significant role in staining.

With the development of longer-acting vaginal rings—such as the 1-year contraceptive Annovera™—there is an increased likelihood that users will observe significant discolouration of their rings due to prolonged exposure to cervicovaginal fluids, menstrual blood, and personal care products. During a 90-day clinical study, users of a dapivirine+levonorgestrel ring reported a high frequency of unscheduled bleeding79, and discolouration was observed on the surface of some rings returned to the clinic after use16. Also, a study evaluating adherence amongst users of Progering®—a 3-month silicone progesterone-releasing ring for post-partum contraception6—reported discolouration of rings returned to the clinic varying from pale yellow to dark brown17. Progestins such as levonorgestrel and progesterone are known to increase unscheduled bleeding80,81, and it is this increased intensity and duration of bleeding in combination with the longer duration of use that explains the increased staining observed with longer use of progestin-releasing rings.

Although it had been widely assumed that the staining observed on vaginal rings was due to exposure to cervicovaginal fluid and/or menstrual blood17,21,82, no confirmatory evidence had been reported until recently. McCoy et al. demonstrated that exposure of drug-free and drug-loaded (dapivirine and dapivirine + levonorgestrel) silicone elastomer vaginal rings to simulated menstrual fluid caused yellow surface discolouration with dark spots and markings, like the discolourations observed in rings following clinical use16. The intensity of yellow staining was shown to increase with the duration of exposure to the simulated fluid, and microscopic analysis identified blood debris on the surface of the rings as the cause of dark marks and spots. The similarity in staining across all formulations led the authors to conclude that the type and loading of drug(s) in the rings did not significantly influence the extent of discolouration.

While yellow, brown or dark brown discolouration is most common, more unusual colours have also been reported16,20. Murphy et al. reported that the non-natural pink surface colour observed on some dapivirine-releasing vaginal rings was consistent with the use of highly coloured personal care products by some clinical trial participants. The authors determined that the surface staining caused by these personal care products did not impact drug assay values or induce drug degradation20. Separately, McCoy et al. reported that various highly coloured synthetic dyes could produce significant staining of both the surfaces and the interiors of silicone rings16. The staining patterns observed were consistent with those observed for clinical rings exposed to highly coloured personal care and cleaning products16,20.

Discolouration of vaginal devices tested in non-human animals

Vaginal device discolouration has also been observed in non-human animal studies. For example, a study investigating the formation of microbial biofilm on vaginal rings worn by macaques (a non-human primate species) noted that two out of six rings recovered from the test animals were discoloured with “low and copious amounts of brown residue”. Residue was observed on both a drug-loaded and drug-free control ring, indicating that staining was not associated with the active substance in the rings but rather the result of exposure to menstrual bleeding82, like findings reported for human clinical studies16.

User opinions and acceptability around discoloured devices

Many studies report high user acceptability and satisfaction with vaginally-administered medical devices and drug-releasing vaginal rings24,46,83,84,85,86,87,88,89. Even though device discolouration does not negatively affect function or lifespan, users may be concerned about staining/discolouration, and it can impact acceptability and adherence23,24,85,90. Some participants in a Phase 1 adherence and acceptability study of dapivirine and/or maraviroc vaginal rings observed staining of their rings21. The discolouration was attributed to menstruation, with several trial participants indicating that “they would prefer to remove the ring during their menses because it felt dirty”. This concern has been echoed in other studies, including a clinical trial of a three-month tenofovir+levonorgestrel ring in which participants expressed concerns regarding the trade-off required between the convenience of a longer use product and the potential for enhanced levels of staining because of the ring remaining in place during menses82. In general, women appear to have a strong preference for the removal and cleaning of rings after menstrual bleeding21,82,83,90,91. However, these unplanned and unnecessary removals for cleaning can reduce adherence and efficacy. Of course, hygiene concerns are not the only reason for ring removal; some studies report women removing rings for fear of it blocking menstrual flow, being expelled with blood, increased pain/discomfort when wearing the ring during menses, being removed during tampon removal, and perceptions of “vaginal overload” (concurrent ring, tampon, and IUD use)23.

Notably, ring users are less concerned about ring discolouration when it is explained to them prior to first use. One participant of a study exploring ring use in India stated, “as long as there is prior information and we know why it is getting discoloured, it is fine…nothing to worry about.”83. This was also true for NuvaRing® users, who appeared unconcerned by the discolouration of ring devices when they had been informed in advance about potential colour changes46. This highlights the importance of good clinical guidance and patient education as tools to allay women’s concerns about ring discolouration and improve adherence24,46,83,92.

Social media commentary around discoloured devices

Social media platforms—such as Facebook, Twitter, Reddit, and others—are proving increasingly useful in providing insights into various aspects of healthcare93,94,95. The open-access social media platform Reddit hosts communities (known as ‘subreddits’) where individuals share personal experiences, symptoms, treatments, and coping mechanisms related to various health conditions. Many Reddit communities and subreddits focus on clinical indications or topics (e.g. women’s health, birth control, NuvaRing, menopause, etc.) that are not extensively covered in more traditional forums. Most importantly, anonymity on Reddit encourages users to share genuine, unfiltered insights and experiences. We have noted increased commentary (e.g. queries, opinions, discussions and perspectives) among users of drug-releasing vaginal rings on Reddit. We recognise that Reddit is not a curated source and that Reddit users might not represent the broader population. The data collected may therefore be skewed by selection bias, demographic constraints, and limited regional representativeness, and the absence of detailed demographic information may restrict the generalisability of the study outcomes. Nonetheless, we believe that valuable insights into various aspects of women’s healthcare can be gleaned from Reddit posts.

We conducted a search of Reddit posts for references to colour/colour, staining, discolour/discolour and at least one of the following terms—vaginal ring, NuvaRing, Annovera, Estring, menstrual cup, contraceptive ring or vaginal pessary. Thematic analysis of fifty-six de-identified Reddit posts (and responses) identified five broad themes: device discolouration (Theme 1), unexpected staining causes concern (Theme 2), lack of understanding about what is normal (Theme 3), advice and reassurance (Theme 4) and cleaning (Theme 5). Illustrative quotations have been provided to support interpretations; each post was assigned a unique identifying code, e.g. P01, where ‘P’ refers to ‘post’ and the two-digit number indicates the order in which posts were saved.

Theme 1–Device discolouration

Reddit contributors reported discolouration of their vaginal rings, menstrual cups and menstrual discs. Device staining varied in colour (brown, yellow, black and grey), with brown the most frequently reported:

“… The cup has recently become very brown and discoloured…” (P18)

“…the ring is brown/grey…” (P48)

The amount and pattern of discolouration also varied among Reddit contributors, with staining described as complete, faint, a darkening in colour, spots and even holes:

“… The holes aren’t completely black, just a little black colouring…” (P08)

“…and the whole ring is completely stained brown…” (P25)

“…faint but noticeable spots…” (P36)

Theme 2—Unexpected staining causes concern

Reddit contributors expressed feelings of fear and concern when faced with unexpected and unexplained colour changes to their devices. It appears that a lack of understanding of the natural processes that cause staining/discolouration left device users feeling scared and confused, which in turn resulted in a reluctance among some users to keep using the device:

“… it’s again turning a little brown. It’s very scary…” (P12)

“… I have no clue what happened. I don’t feel comfortable putting it back in.” (P48)

Several Reddit contributors felt that stained devices were dirty, disgusting, or reflected badly on their personal hygiene:

“… the ring gets stained and looks gross…” (P45)

“… It wipes off and actually looks like dirt, but I’m very clean…” (P48)

Theme 3—Lack of understanding about what is normal

A significant number of Reddit contributors wanted to know if staining of their vaginal devices was 'normal' and if other users had experienced similar discolouration. Queries were posted by both inexperienced users and long-term users who had experienced an unexpected change to their device appearance. These posts suggest a lack of easily accessible information for users regarding the propensity for vaginal devices to stain, particularly with prolonged use:

“I’ve had the ring for three months now… […] When taking it out today and it was fully brown… […] Has anyone else had the same experience?” (P30)

“Don’t know if it’s normal or not, but mine was also a bit more yellow tinted when I switched my rings…” (P02)

“… it was light yellow/brown? I’ve been using it for almost 8 years and never had this happen…” (P04)

Several Reddit contributors sought advice on how to prevent the discolouration from happening again:

“… Does the colour change mean anything?… […] and how can I prevent that from happening again??” (P01)

Theme 4—Advice and reassurance

Many responses to posts from concerned users provided reassurance that any staining observed, whilst unsightly, was nothing to be concerned about:

“I’ve always heard that stains were just cosmetic and not a problem…” (P24)

“Discolouration doesn’t mean that the cup is dirty or unsafe or not working appropriately…” (P19)

In general, blood (menstrual bleeding, spotting, withdrawal discharge) and normal vaginal secretions were highlighted by responders as the primary causes of device discolouration:

“It’s normal, you probably had a slight withdrawal discharge and it will stain the ring when you leave it in. It’s still fine and will work fine…” (P31)

“Brown stains are usually blood stains. Even though sometimes you might not feel or see spotting, your ring is coming into contact with all types of fluids…” (P51)

Some responders described personal experiences of device staining and highlighted the fact that discolouration had not caused any unpleasant side effects or adverse health issues:

“Mine is stained from spotting, but hasn’t caused any issues.” (P39)

“For anyone concerned about discolouration, my cup looks like this [photograph of stained device provided by Reddit contributor not included in this article] and is fine.” (P05)

These personal accounts appeared to be sufficient to allay the fears of some concerned Reddit contributors:

“… Glad I’m not the only one though cause I was worried!” (P53)

However, when someone appeared to be particularly anxious or device staining was accompanied by other medical symptoms, responders tended to err on the side of caution and recommended seeking medical advice:

“It’s probably just dried blood/normal vaginal secretions. Still, you might want to call your doctor to be sure it’s safe.” (P49)

Theme 5—Cleaning

In addition to reassurances that discolouration is perfectly normal, many responders provided suggestions for cleaning stained devices. Menstrual cup users largely favour the use of hydrogen peroxide solutions. However, exposure to sunlight and the use of baby wipes were also suggested. Contraceptive ring users were more cautious, preferring to use warm water with or without soap, and in some cases, manual abrasion:

“You can remove stains with hydrogen peroxide. Or a lot of sunlight if your cup is silicone.” (P55)

“… I’ve tried washing but doesn’t come off completely. I have to use my nails to kind of scrape it off.” (P45)

Some ring users voiced concerns about harsh or unusual cleaning methods reducing the effectiveness of their devices:

“I tried washing and it won’t come off and I don’t want to wash it too much to decrease it’s effectiveness…” (P33)

“So, I took my ring out and it was stained a little so I wiped it with an alcohol wipe. Is that okay? Will it cause it to not work?” (P43)

Users should be informed that attempting to remove any discolouration using abrasive techniques (scratching with nails or using cleaning devices) can damage the membrane on certain contraceptive devices used to control the rate of hormone release. Most patient information leaflets advise cleaning with cold or lukewarm (not hot)—in some instances using mild soap—and optionally drying with a clean cloth towel or paper towel (https://annovera.com/Annovera-Patient-Information.pdf; https://www.medicines.org.uk/emc/files/pil.6449.pdf).

Device colour and the freedom to choose preferred colours appear to be important to users. For menstrual cup users who disliked or were worried about the presence of staining, responders suggested that coloured cups are a better choice since they show less obvious staining:

“… one of the biggest complaints is the ring being WHITE considering we’re gonna see everything…” (P51)

“I really like that my new cups I got to choose colours I like, …” (P55)

“Stains show a lot less on warm tones in my experience…” (P54)

Contraceptive ring users often recognised that cleaning could improve the overall appearance of the ring, but most rings would not return to their original colour:

“My ring also had some staining as well, if you kind of scrub it with a wash cloth it will come off but it never really looked perfectly white again.” (P52)

Patient information leaflets for most drug-releasing rings, including contraceptive rings, explicitly state that rings may be rinsed with cool to lukewarm—but not hot—water. While no explanation is provided, these constraints are likely to avoid drug degradation, drug extraction, distortion of the ring shape, and/or disruption of the rate-controlling polymer membrane. No clinical studies have formally investigated the washing of drug-releasing vaginal devices by users.

Reddit posts provided interesting insights into the concerns that some vaginal device users experience when their contraceptive rings and menstrual cups become discoloured. In general, vaginal device users—both new and experienced—found unexpected discolouration of their vaginal devices unsettling and looked to their peers for similar experiences, advice, and, importantly, reassurance that the changes they were observing were normal. This emphasises the need for prescribing clinicians and device manufacturers to provide appropriate, easily understood information around the potential for vaginal devices to become discoloured during normal use. The fact that women are reaching out to peers on social media fora for information and reassurance raises questions about the quality of patient information currently available to vaginal device users and/or highlights that users do not read the supplied information96.

In addition to improved information for users, strategies to reduce or mask vaginal device discolouration, such as the inclusion of coloured dyes, may be helpful in allying women’s concerns around device appearance and hygiene. However, women’s opinions on an acceptable vaginal device colour are highly personal and vary considerably21,68. Some women prefer white rings because they look plain and 'medical' while others prefer coloured rings as they appear 'less sterile', more natural or more 'feminine'21. A recent study by Zhao et al. reported that while vaginal ring colour was important for many women, others felt that safety, comfort, and product efficacy were more important factors68. Safety concerns regarding the addition of coloured chemicals and their potential to cause health issues such as vaginal irritation was also raised by a small number of women21,68. Although colouring may help mask some vaginal device discolouration, anecdotal evidence from Reddit users suggests that coloured vaginal devices, such as menstrual cups, still display discolouration that is easily apparent to the user. Alternative strategies to reduce rather than simply mask device discolouration should be explored.

Conclusions

This broad overview of the literature and the Reddit social media platform reveals that all vaginal medical devices—including drug-releasing vaginal rings—are prone to discolouration following prolonged exposure to cervicovaginal fluid and/or menstrual blood, particularly when used during menses, irrespective of design or material used for their manufacture. Although discolouration can be aesthetically unpleasing, it is generally acknowledged not to adversely affect device integrity, clinical function, or lifespan. However, it often has a negative effect on user behaviour and willingness to continue use of the devices. As such, more clinical research is needed to evaluate the impact of device discolouration on user behaviour. Strategies to reduce discolouration (by modifying the surface properties of the devices97,98,99) or mask discolouration (including the use of darker-coloured devices99) may prove useful, although care must be taken to ensure the biocompatibility of the polymer material.

To the best of our knowledge, there is no ongoing innovation in materials science to prevent or reduce discolouration of vaginal devices/vaginal rings, likely due to concerns around tinkering with the well-established medical grade polymer systems used to fabricate such devices. Changes to the bulk or surface chemistry of the polymers could impact biocompatibility, drug release characteristics, mechanical characteristics, polymer-drug interactions, manufacturability, and supply chain. Adding a separate coating layer to reduce/prevent discoloration would be equally challenging, introducing issues around adhesion, durability, drug permeability, biofilm/antifouling performance, and manufacturing control. Nonetheless, our hope is that this article will stimulate further consideration and research around this important topic.

Methods

This article contains two distinct parts—a narrative review and a thematic analysis of Reddit posts. Methodologies for both components are provided below.

Narrative review

The narrative review component of this article was conducted to provide an exhaustive search and critical synthesis of the literature around the discolouration of vaginal devices during use in humans. Literature searches were performed using PubMed, Web of Science and Google Scholar, covering publications from January 1950 to May 2024. We also used Google Scholar to obtain information from product patient information leaflets (patient package inserts), medication guides, and manufacturers’ guidance, etc. While vaginal pessaries for pelvic organ prolapse (POP) and contraceptive barrier methods have a long history and date back to ancient Egypt and Greece, the first polymer devices—as distinct from earlier materials like metal, ivory, or natural substances—were mostly introduced in the mid-20th century following the advent of synthetic polymers and advances in materials science. Similarly, the first polymeric drug-releasing vaginal rings were reported in the late 1960s following the development of medical-grade silicone rubber. Thus, we deemed it prudent to begin our literature search in 1950. Search terms included combinations of relevant keywords, including

'vaginal', 'intravaginal', 'ring', 'pessary', 'diaphragm', 'colour', 'discoloured', 'discolouration', 'Estring', 'NuvaRing', 'Femring' and 'Annovera'. Boolean operators (AND/OR) were used to combine search terms appropriately. Articles were included if they were published in English and even briefly reported or discussed the topic of discolouration of a vaginal device. Given the relatively small number of search hits, the full texts of all articles were reviewed for eligibility. Reference lists of key papers were also screened to identify additional relevant publications. Data were extracted and organised thematically to enable narrative synthesis. Themes were identified inductively based on recurring concepts across the literature.

Analysis of Reddit posts

We searched Reddit, a popular social media platform (https://www.reddit.com), to gain insight into the personal experiences of vaginal device users around device discolouration. According to the Reddit privacy policy (https://www.reddit.com/policies/privacy-policy), Reddit considers its site to be a public platform and provides a public content policy. The Research Governance, Ethics and Integrity Team at Queen’s University Belfast reviewed the manuscript and determined the study exempt from ethical review under the QUB policies and procedures. Reddit posts, from date of inception of the Reddit website (2005) to the search date (May 2024), were searched using relevant keywords including 'Annovera', 'colour/colour', 'contraceptive ring', 'discolour/discolour', 'Estring', 'menstrual cup', 'NuvaRing', 'stain', 'vaginal pessary', 'vaginal ring'. The search terms were informed by the expertise of members of the research team. The authors did not create posts or contact any users of the platform. All posts and associated responses were copied verbatim into a Microsoft Excel spreadsheet and screened for relevance. Posts were included if they were related to users’ discussions about their opinions and/or their acceptability of discoloured vaginal devices. Posts unrelated to the discolouration of vaginal devices were excluded. Relevant posts and responses were imported into Microsoft Word, and an inductive thematic analysis was conducted100. Initial coding was undertaken by a single researcher, with independent coding of a subsample of posts (60%) undertaken by a second researcher to identify potential coding discrepancies. Codes were aggregated into broader themes, which were then discussed and agreed within the research team. Illustrative quotations were used to support interpretations; each post was assigned a unique identifying code, e.g. P01, where ‘P’ refers to ‘post’ and the two-digit number indicates the order in which posts were saved.