Expanding water-absorbing beads: a “growing” problem for the ENT surgeon—a scoping review

Introduction

Water-expanding beads, also known as superabsorbent polymer (SAP) beads, are small, colourful products capable of absorbing many times their weight in water (1). While originally designed for industrial and horticultural use, they are now widely marketed as children’s toys and decorative items. Their bright appearance and soft texture make them particularly appealing to young children, increasing the risk of accidental ear or nasal insertion, inhalation or ingestion.

These incidents present substantial clinical challenges, as serious sequelae such as intestinal obstruction following ingestion, airway compromise from inhalation, or ossicular disruption from otologic insertion frequently necessitate endoscopic or surgical intervention (2-4). Emerging concerns regarding neurotoxicity, related to chemical components such as acrylamide, further underscore the public health implications (5).

Although poison centres and regulatory bodies have raised safety concerns, the clinical literature remains fragmented, with most reports limited to isolated cases or single-centre series. No comprehensive review currently exists to guide early recognition, risk stratification, and escalation of care based on anatomical site or bead characteristics. Given the heterogeneity of data sources, a scoping review methodology was selected to map the extent, range, and nature of reported clinical encounters. The aim of this review is to synthesise existing evidence on the presentation, diagnosis, management, and outcomes of water-expanding bead injuries across all anatomical sites (ingestion, otologic, nasal, and inhalation). Through this synthesis, we aim to identify patterns of clinical significance and propose a practical management algorithm to support timely and effective decision-making in paediatric care. We present this article in accordance with the PRISMA-ScR reporting checklist (available at https://www.theajo.com/article/view/10.21037/ajo-25-65/rc).

Methods

This scoping review aims to (I) characterise all reported injuries associated with SAP bead exposure; (II) map clinical presentations, diagnostic approaches, management strategies and outcomes; and (III) identify evidence gaps to inform a practical, site-specific diagnostic and management framework for clinicians.

This is a scoping review of publicly available data without the collection of any institution-specific patient details; therefore, no human ethics board approval was required. No formal review protocol was registered or published.

Eligibility criteria

Studies were considered eligible if they described human exposures to water-expanding beads via ingestion, nasal or airway insertion, or ear insertions. Both peer-reviewed publications (including case reports, case series, and retrospective reviews) and grey literature sources (such as regulatory bulletins, news articles, and conference abstracts) were included. No restrictions were placed on patient age, publication year, language, or geographical location. Studies were excluded if they investigated non-SAP materials or involved non-human subjects. This broad inclusion ensured comprehensive mapping of all reported exposure contexts.

Search strategy

A comprehensive search was conducted across Embase, PubMed, Web of Science (including MEDLINE), and Google (for grey literature) to identify relevant studies published up to May 24, 2025, with no lower date limit. The search strategy (see Appendix 1) employed a combination of bead-related terms (“water-expanding beads”, “superabsorbent beads”, “polymer beads”, “water beads”, “crystal beads”, “Orbeez”) and injury-related keywords (“ingestion”, “obstruction”, “inhalation”, “aspiration”, “nasal obstruction”, “airway obstruction”, “insertion”, “airway foreign body”, “otic insertion”) using Boolean operators (AND, OR). The grey literature component, though non-systematic, was essential in capturing reports not represented in indexed databases and was limited to the first 50 results on Google. Reference lists of included studies were manually screened to identify additional eligible sources. No language filters or date limits were applied, ensuring reproducibility and completeness of capture.

Study selection

All identified records were screened by the primary author, who assessed titles, abstracts, and full-text articles for eligibility. Discrepancies or uncertainties regarding study inclusion were resolved through iterative re-review. Due to the heterogeneity of included sources and study types, no formal critical appraisal or quality assessment of included studies was conducted, consistent with the aims and methodology of a scoping review. The study selection process is outlined in the PRISMA flowchart (Figure 1).

Figure 1 PRISMA flow diagram for study selection.

Data extraction and synthesis

Data were manually and independently charted by the primary author using a structured Excel form developed for this review. Extracted data were verified by cross-checking with the original sources to ensure accuracy. Extracted variables (see Table S1) included study characteristics (author, year, country, study type), population data (age, sex, exposure route, number of cases), clinical details (presentation, diagnostic methods, management, outcomes), and exposure site (ear, nasal/airway, gastrointestinal). For large datasets, subgroup information was recorded when available. No imputation of missing data was performed; where data were not reported, it was noted as “not recorded”.

Due to the descriptive and heterogeneous nature of the included evidence, data were synthesised narratively. Findings were grouped by exposure site (ear, nasal/airway, ingestion) and summarised in tables to highlight clinical trends, diagnostic approaches, management strategies, and outcomes. Quantitative synthesis or meta-analysis was not undertaken

Results

This review maps the global literature on SAP bead exposures, encompassing 72 studies and over 13,000 reported cases. The primary search yielded 611 unique records: Web of Science (including MEDLINE) (n=540), Embase (n=50), PubMed (n=19), and Google (n=50). Following screening, 50 case reports, case series, or clinical image reports, 14 retrospective reviews, 6 news articles, and 2 regulatory letters issued by the U.S. Consumer Product Safety Commission were included. Collectively, these sources documented 13,466 exposures, the majority being 98.0% (13,197/13,466) ingestions, followed by 1.4% (188/13,466) ear insertions and 0.6% (81/13,466) nasal insertions or inhalations.

Studies involving multiple exposure types are summarised in Table 1. While ingestion remained the predominant exposure route across all datasets, these larger series provided a more controlled snapshot of exposure patterns. Notably, cases involving other anatomical sites, such as ocular (n=3) and vaginal (n=1) insertions, were reported exclusively in these broader cohort studies and were not included in our review.

A comparison of clinical features, diagnostic approaches, and outcomes across ear, nasal/inhalation, and ingestion cases is summarised in Table 2. While many cases were identified across exposure types during the initial mapping stage, only a smaller subset contained sufficient clinical detail, such as presentation, management, and outcomes, to allow inclusion in the descriptive synthesis. This accounts for the difference between the total number of reports mapped and the more limited number of cases described in detail in the sections that follow.

Ear insertions

Epidemiology

Fifteen cases of ear insertion were identified across four sources (two case series, one case report, and one regulatory letter) as summarised in Table S2. The median age at presentation was 84 months [interquartile range (IQR), 60–84 months]. A male preponderance was observed, with 66.7% (10/15) males and 33.3% (5/15) females; sex was unreported in one case. Laterality was reported in 8 cases. Among these, bead location was right-sided in 50.0% (4/8), left-sided in 25.0% (2/8), and bilateral in 25.0% (2/8). Duration of bead retention was reported in 9 cases, ranging from 5 hours to 10 weeks, with a median duration of 5.5 days (IQR, 2.5–60 days).

Clinical presentation

Clinical symptoms were documented in 33.3% (5/15) of cases. Among symptomatic patients, otalgia occurred in 100% (5/5), otorrhoea in 80.0% (4/5), and low-grade fever in 20.0% (1/5). A history of foreign body exposure was recorded in 33.3% (5/15) of cases. Of these, 40.0% (2/5) had a clearly documented positive history at presentation, contributing to diagnostic delay in the remainder. Initial misdiagnosis as acute otitis media occurred in 20.0% (3/15) of patients, all of whom were treated with otic antibiotic drops. Subsequent bead hydration and expansion occurred in these cases, and 66.7% (2/3) of these patients developed persistent hearing loss.

Diagnosis

Otomicroscopy was the main first-line diagnostic tool, with audiograms (n=2), computed tomography (CT) scans (n=2) and magnetic resonance imaging (MRI) scans (n=1) used in selected cases. In both cases requiring imaging, the patients presented with 10-week and 2-month history of presumed acute otitis media unresponsive to treatment, respectively. Early CT imaging showed erosive changes and well-circumscribed spherical foreign bodies in the middle ear. Whereas follow-up imaging demonstrated secondary complications, including labyrinthitis ossificans and an acquired cholesteatoma respectively, which highlights the progressive and destructive nature of retained beads.

Management

Only 13.3% (2/15) of insertions were successfully managed in the outpatient setting. The remaining cases required examination under anaesthetic (EUA) and/or definitive surgical intervention. Among the 13 cases requiring operative management, intraoperative findings were documented in 7 cases and included tympanic membrane perforation in 57.1% (4/7), ossicular erosion in 28.6% (2/7), and acquired cholesteatoma in 14.3% (1/7). Surgical management included tympanoplasty and ossicular reconstruction when indicated.

Outcomes

Follow-up data were available for 53.3% cases (8/15). Of these, 62.5% (5/8) achieved full recovery. Complications occurred in 37.5% (3/8), comprising mild-to-moderate conductive hearing loss in 25.0% (2/8) and profound sensorineural hearing loss (SNHL) in 12.5% (1/8). The patient who experienced profound SNHL had a pure tone average (PTA) of 113 db, on the background of the water bead being in situ for 10 weeks, initially treated with otic antibiotic drops with significant hypotympanic, otic capsule and ossicular chain erosion found intra-operatively. Overall, delayed diagnosis and prolonged bead hydration were associated with a higher risk of complications and surgical complexity.

Nasal insertions and inhalations

Epidemiology

A total of 19 cases were identified across five sources (two case reports, one case series, one conference abstract, and one regulatory letter), of which 78.9% (15/19) were nasal insertions and 21.1% (4/19) inhalation events, as summarised in Table S3. Age was reported in 16 cases, with a median age of 36 months (IQR, 36–48 months). Sex was reported in 17 cases, with 70.6% (12/17) male and 29.4% (5/17) female patients. Among nasal insertions with laterality reported (12/15 cases), right-sided insertions were more common at 66.7% (8/12) compared to left-sided insertions at 33.3% (4/12). All inhalation events with localisation data (3/4 cases) involved the left bronchial tree, including one in the left mainstem bronchus (1/3) and two in the left lung (2/3).

Clinical presentation

Symptom severity for nasal insertions was closely associated with bead retention time, which ranged from 4 hours to 7 days (data available in 12 cases). 33.3% (4/12) of beads were retained for <1 day, all with patient or caregiver-reported insertion, and were associated with nasal congestion and rhinorrhoea. A proportion of 25.0% (3/12) of beads were retained for 1–3 days, none with reported insertion history, and resulted in more severe symptoms, including nasal pain, snorting, agitation, and feeding refusal. 41.7% (5/12) of beads were retained for 3–7 days (41.7%, 5/12) and led to systemic escalation, with fever in 80.0% (4/5) and epistaxis in 40.0% (2/5).

In the two inhalation cases with data on clinical features, there was one asymptomatic patient (incidental finding) and one with recurrent lower respiratory tract infections, cough, and respiratory distress requiring multiple hospitalizations.

Diagnosis

Diagnosis was made clinically or via nasal endoscopy, with CT used in select cases. Two patients underwent chest CT after prolonged bead retention (≥1 year). Imaging demonstrated significant parenchymal sequelae, including multiple cystic changes of the left lower lobe in a patient with recurrent lower respiratory tract infections, and atelectatic collapse of the left lung in an incidentally detected case initially noted as unilateral lung opacification on chest X-ray. In a further inhalation case reported in a conference abstract, chest X-ray demonstrated left lung atelectasis.

Management

Of the 15 nasal insertions, 20.0% (n=3/15) were resolved without general anaesthesia, including two removals at home and one outpatient removal. Of the remaining 12 nasal cases, 11 required endoscopic removal under general anaesthesia. In six cases, the beads had expanded and fragmented, necessitating repeated suctioning to achieve complete retrieval. In one case, despite endoscopic examination, the bead could not be visualised or retrieved and was presumed to have been ingested and passed spontaneously without complication.

Among the four inhalation cases, management details were reported in 75.0% (3/4). All three underwent bronchoscopy, performed using rigid (1/3), flexible (1/3), or unspecified techniques (1/3). One patient developed fibrotic tissue and bronchial erosion requiring complex fragment removal. Another exhibited granulation tissue and bronchiectasis changes on follow-up.

Outcomes

All patients with nasal insertions achieved complete clinical recovery, except for one case complicated by nasal adhesions, which required reoperation under general anaesthesia and resolved by 9 months.

Among inhalation cases, clinical stabilisation occurred in all patients, although persistent structural lung disease was noted in 25.0% (n=1/4), manifesting as ongoing bronchiectasis and atelectasis at follow-up.

Ingestions

Epidemiology

Sixty-one sources reported ingestion, accounting for 98.0% of cases (n=13,197/13,470) as summarised in website: https://cdn.amegroups.cn/static/public/10.21037ajo-25-65-1.xlsx. The median age was 14 months (IQR, 11–19 months). A slight male predominance was observed, with 52.7% (6,664/12,639) males and 47.3% (5,975/12,639) females among cases with sex reported. Additionally, two adult cases were reported in the literature, including a fatal accidental exposure in a 76-year-old woman with dementia.

Clinical presentation

76.3% of children were asymptomatic (6,472/8,484). Among symptomatic cases, nausea/vomiting occurred in 2.5% (297/11,880), abdominal pain in 1.0% (123/12,300), constipation in 0.7% (81/11,571), and fever in 0.4% (51/12,750), noting that denominators varied due to incomplete symptom reporting across studies. Less frequently, patients reported seizures (n=4), likely due to hyponatremia from hyperemesis and neurotoxicity (n=1) from acrylamide exposure.

The time between ingestion and the onset of symptoms was reported in only 10 cases, with a median delay of 24 hours (IQR, 24–72 hours). The largest study reporting this latency period identified a range from 6 hours to 5 days (1).

Hospital presentation often occurred days later, particularly when the ingestion was unwitnessed, with a median delay of 2 days (IQR, 1–4 days). In a case series by Mehmetoğlu et al. involving 21 patients, the interval from ingestion to hospital presentation ranged from 30 minutes to 5 days (10).

Diagnosis

Ultrasound was the most reliable imaging modality, with a 77.1% (37/48) detection rate, with 10.8% (4/37) of cases being misdiagnosed as duplication cysts. Whereas X-rays often failed to visualise beads directly at only 12.7% (7/55), they were more successful at detecting signs of obstruction at 77.4% (41/53). CT had variable success at 38.9% (7/18) but was used less frequently and often for preoperative planning. Beads were found throughout the small bowel, most often in the jejunum and terminal ileum.

Management

Most cases (84.4%, 357/423) were managed conservatively with observation. Endoscopy was used infrequently at 2.7% (26/963), and only 1.3% (99/7,615) of reported cases required surgical intervention for obstruction or perforation.

Outcomes

Recovery was reported in 654 of 658 patients (99.4%). Three deaths were noted in the review. Two were clearly described in the literature and occurred following significant delays in surgical intervention: 25 and 7 days, respectively. Both patients developed serious postoperative complications, including anastomotic leak, sepsis, and multiorgan failure. In one of these cases, concurrent Salmonella infection may have exacerbated bowel wall necrosis.

A third paediatric death, reported in the media, lacked clinical detail. There was additionally a fourth, non-paediatric death documented involving an elderly woman with dementia who was inadvertently exposed to multiple SAP sachets while waiting in an emergency department. She developed fatal oropharyngeal obstruction within 30 minutes; postmortem findings confirmed mechanical asphyxiation due to rapid gel expansion in the upper airway.

Severe non-fatal outcomes included one case of suspected acrylamide-associated encephalopathy and another requiring long-term enteral feeding following gastrointestinal damage secondary to infection. Despite these rare complications, the overall prognosis remained favourable in most cases.

Discussion

Summary of key findings

This scoping review synthesised 72 studies reporting 13,466 cases of SAP bead exposure. While ingestion was most common, ear or nasal insertions and inhalation were disproportionately associated with complications requiring general anaesthesia or surgery. Across all exposure routes, delayed presentation and diagnostic uncertainty contributed to poorer outcomes.

Interpretation and clinical relevance

Outpatient removal was rarely successful beyond 24–72 hours post-exposure. Insertion-related cases frequently required operative intervention, particularly where beads had expanded or fragmented in situ. Ingestion cases were largely asymptomatic and managed conservatively; however, a subset developed life-threatening complications, often due to delayed diagnosis or concurrent infections.

Role of physicochemical properties

SAP beads are designed to absorb hundreds of times their weight in water, expanding rapidly in aqueous environments such as nasal mucus, middle ear exudate, bronchial secretions, or gastrointestinal fluid. Expansion kinetics vary by product size and composition: standard beads typically reach maximal diameter (0.9–1.7 cm) within 4–12 hours, while jumbo variants may continue expanding for up to 96 hours, reaching diameters of 6 cm or more (11-13).

This progressive hydration explains the characteristic delay in symptom onset, particularly in ingestion cases where obstruction often arises 6–96 hours post-exposure. It also informs the clinical trajectory of retained beads in the ear, nose, or airway, where retained fragments can continue expanding, causing pressure necrosis, erosion, or obstruction.

Diagnostic and therapeutic implications

This review introduces a critical clinical insight: the physicochemical properties of SAPs may inform the duration of post-exposure monitoring. Because significant expansion may not occur immediately, especially with larger “jumbo” beads, an observation/monitoring period of up to 96 hours may be warranted in suspected cases, even if the patient is initially asymptomatic. For standard-sized beads, maximal growth is typically reached within 4 to 12 hours, which may align with the time frame in which obstruction is most likely to develop (13). Where possible, knowledge of the bead’s type and brand should inform clinical risk stratification and the intensity of monitoring. To our knowledge, this 96-hour window has not been previously proposed in the literature and represents a novel contribution to the management of these exposures, particularly in paediatric settings where premature discharge may result in missed evolving pathology.

Furthermore, the material properties of these beads also pose challenges to diagnosis, as their friable consistency and radiolucency limit detection on standard imaging modalities such as X-rays. Ultrasound, though more successful in visualizing hydrated beads, requires high clinical suspicion and targeted application. However, ultrasound may underestimate bead burden relative to endoscopy and carries the risk of misidentifying the lesion as an enteric duplication cyst (14). Such diagnostic confusion may lead to unnecessarily invasive procedures, including bowel resection, rather than a more conservative enterotomy for foreign body extraction.

Diagnostic and management algorithm

Given the spectrum of clinical presentations and the site-dependent risks associated with SAP bead exposure, a stratified diagnostic and management algorithm is essential, as summarised in Figure 2. These cases often present non-specifically, particularly in younger children, and SAP bead exposure should be included early in the differential diagnosis for unilateral otorrhea, nasal discharge, chronic cough, or unexplained abdominal symptoms. A collateral history that includes potential access to water beads, bead size and colour, product branding, and timing of exposure can significantly expedite diagnosis.

Figure 2 Flowchart for the diagnosis and management of water-expanding bead injuries. EUA, examination under anaesthetic; US, ultrasound.

Ear insertions

For suspected otologic insertions, otomicroscopy is the first-line diagnostic modality, enabling detailed visualisation and, in some cases, safe outpatient removal. However, the friable, translucent, and expansile nature of SAP beads significantly limits success with awake removal. In published series, the vast majority (87%) of patients required removal under general anaesthesia (4,15,16). Once hydrated, the beads are not only difficult to visualise but also highly slippery and prone to fragmentation, increasing the risk of canal wall trauma, tympanic membrane perforation, and middle ear extension.

A low threshold for EUA is therefore warranted, particularly in cases involving prolonged bead retention, limited visualisation, or an uncooperative child. Early EUA allows for controlled removal under magnification, minimising the risk of iatrogenic injury and incomplete extraction. Importantly, irrigation may need to be avoided, as it accelerates bead expansion (16). Post-removal audiometry may be considered for patients with prolonged in situ duration or persistent hearing symptoms.

Nasal insertions and inhalation

Nasal insertions, especially in toddlers, are frequently misdiagnosed due to their radiolucency and overlap with common paediatric conditions such as rhinitis or upper respiratory tract infection (URTI). Beads expand within nasal secretions, and cases retained >72 hours are more likely to present with epistaxis and fever (17). In 73% of reported cases, removal required general anaesthesia, with endoscopic retrieval as the mainstay. Outpatient was only feasible when the bead was in situ for <24 hours.

Inhaled beads, while less common, present unique challenges. They may remain occult for extended periods and are often diagnosed incidentally or after prolonged respiratory symptoms. Complications include bronchiectasis, fibrotic erosion, and segmental atelectasis (18). Rigid or flexible bronchoscopy is both diagnostic and therapeutic. Bead fragmentation is common during retrieval, and complete clearance may require suctioning and basket retrieval, with follow-up imaging if indicated to exclude retained fragments (18).

Ingestion

Ingestion represents the most frequent exposure route but is often asymptomatic at presentation. Due to the physicochemical properties of SAP beads, including delayed and progressive expansion within gastrointestinal fluids, symptom onset may be delayed by up to 96 hours. Obstruction typically occurs in the small bowel and may only become evident days after exposure.

Conservative management is appropriate for asymptomatic patients with no signs of obstruction, and the majority recover without intervention (19). However, escalation to imaging (preferably ultrasonography) is indicated for persistent symptoms or when ingestion timing is unclear (20). In cases with concerning findings or non-progression of material, endoscopy or surgical intervention (typically via enterotomy) may be required. Gastrografin may be considered in select cases to reduce bead volume and promote passage (21,22).

Public health

In Australia, there is no mandatory safety standard for SAP beads, but the Australian Competition and Consumer Commission (ACCC) has encouraged businesses to stop marketing them as toys since 2015 (23). Additionally, between 2018 and early 2019, the ACCC oversaw two recalls of specific water bead products (23). Although beads that fail the small parts test cannot legally be marketed to children under three, they continue to be sold as sensory toys for older children, without requirements for detailed warning labels other than choking and size-associated risks (24). Moreover, regulatory gaps remain because these products are still widely available online and are also marketed for non-toy uses as decorative items, watering products for plants, and absorbents in diapers. Hence, there is a case for further regulations or public awareness campaigns on the subject, given the magnitude of the issue.

Strengths and limitations

This is the first comprehensive synthesis of SAP bead-related injuries across multiple anatomical sites. By including grey literature and regulatory reports, it captures a broader spectrum of clinical severity than case series alone.

However, limitations include heterogeneous data from case reports, poison centre data, news articles, and safety bulletins, which lack standardized reporting, hindering comparisons. Publication bias and underreporting likely underestimate incidence, overrepresenting severe cases. Long-term outcomes are underreported, and grey literature often lacks clinical detail, adding uncertainty. Variability in water bead composition and market changes (e.g., product recalls after severe cases) confound outcomes. Biases further affect its validity, including challenges related to the use of deidentified patient data and the potential overlap of patients across studies. Time-lag and recall biases risk missed diagnoses, particularly in unwitnessed settings.

Future directions

Further research is needed to quantify risk based on bead type and duration in situ, assess long-term outcomes, and evaluate the effectiveness of public health interventions. Prospective data collection and standardised reporting across poison centres and emergency departments are warranted.

Conclusions

Water-expanding beads represent an underrecognised but increasingly common source of paediatric foreign body injury, capable of causing serious complications including bowel obstruction, mucosal necrosis, hearing loss, and airway damage. Their friable, radiolucent, and expansile properties create diagnostic and therapeutic challenges—particularly when exposure is unwitnessed and symptoms are nonspecific.

This review highlights key clinical patterns and outlines a site-specific, risk-stratified management approach. Most ingestion cases can be managed conservatively, but a 96-hour observation period may be warranted due to delayed expansion kinetics. For nasal and otologic insertions, early otolaryngology involvement and a low threshold for EUA are critical. Inhaled beads, while rare, may require bronchoscopy and carry risk for long-term pulmonary sequelae.

Clinicians should maintain a high index of suspicion and routinely include SAP beads in the differential diagnosis for unilateral otorrhea, nasal discharge, cough, or unexplained gastrointestinal symptoms in young children. Standardised guidelines and public health interventions are urgently needed to mitigate preventable harm from these widely available products.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the PRISMA-ScR reporting checklist. Available at https://www.theajo.com/article/view/10.21037/ajo-25-65/rc

Peer Review File: Available at https://www.theajo.com/article/view/10.21037/ajo-25-65/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://www.theajo.com/article/view/10.21037/ajo-25-65/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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