Global prevalence of hydrocele in infants and children: a systematic review and meta-analysis

Abstract

Background

Pediatric hydrocele is a congenital pathology commonly diagnosed in newborns. Also, untreated pediatric hydrocele can induce adverse permanent consequences in adulthood. This study aimed to investigate the global prevalence of pediatric hydrocele in infants and children, as a necessary factor for health policymakers.

Methods

Databases of PubMed, Scopus, Web of Science, Embase, ScienceDirect, and Google Scholar search engine were systematically searched for studies reporting the prevalence of pediatric hydrocele in infants and children. The main keywords of “Prevalence”, “Outbreak hydrocele”, “Infant”, and “Child” were used in this regard. Screenings were applied to achieve eligible papers and a quality control process was conducted to select middle to high-quality papers. Finally, the random effect model was used to perform meta-analysis, and heterogeneity was checked by the I² index. Data analysis was applied with CMA (v.2) software.

Results

Following the assessment of 5 eligible studies with a sample size of 70,961 infants (1–2 weeks), the global prevalence of hydrocele in infants was found 0.001% (95%CI:0.00007–0.018, 1 per 1000 live births). In the review of 3 studies with a sample size of 278,597 children (7–12 years), the global prevalence of hydrocele in children was reported 0.0034% (95%CI:0.00004–0.21), 3.4 per 1000 children).

Conclusion

According to the analyzed studies, a relatively high prevalence of hydrocele in infants was reported, globally. Besides, there were undiagnosed or recurrent pediatric hydrocele cases in children which need more precise medical screening. Thus, it is necessary to implement health policies to reduce the prevalence of pediatric hydrocele and associated adverse consequences.

Background

A pediatric hydrocele is a pathologic sac filled with serous fluid beneath the scrotal layer which can develop into both sides of the scrotum, called bilateral hydrocele [1]. Although this type of pathology affects males of all ages, it is also commonly seen in children [2]. Besides, the PH can develop spontaneously in adulthood [3].

There are two types of hydrocele regarding the pathogenesis process; communicating and non-communicating. In the communicating type, the hydrocele is directly in contact with abdominal fluids through the non-closed canal of spermatic cord; besides, the scrotum appears larger or swollen over time [4]. Although the abdominoscrotal passage is blocked naturally in the non-communicating type of hydrocele in infants, some excess abdominal fluid remains in the scrotum surrounding testes [5]. These types of hydroceles could be present at birth or develop for no apparent reason in the future [5]. Non-communicating hydrocele usually remains in the same size or grows slowly over the time [6]. Obstetric testicular edema is usually present at birth and diagnosed in 5% of cases [7]. Premature newborns (≥ 3 weeks) represent a higher risk of hydrocele [8].

Risk factors of PH in children include scrotal damage, inflammation, and infection (such as sexually transmitted infection) [9]. The main symptom of PH is swelling on one or both sides of scrotum [10]. Generally, the hydrocele is not often lethal along with no side-effects on fertility. However, the PH in children reflects an underlying serious disease such as acute infection or the presence of tumors in testis and inguinal canal [11], the associated treatment completely depends on the type and severity of disease. Although medicinal check-ups are necessary, no special treatments are advised in many cases (spontaneous disease disappearance) [2].

In PH cases with severe swelling or an underlying disease (such as a hernia), surgical treatment may be required. Also, in cases with persistent hydroceles, further medical examinations are strictly needed [8]. Since the PH can induce reproductive-associated pathologies, comprehensive health-based planning seems necessary to accelerate early diagnosis and reduce un-detected hydrocele. Thus, this systematic review and meta-analysis study was designed to determine the global prevalence of PH in infants and children.

Methods

In order to collect eligible and extractable data representing the prevalence of pediatric hydrocele in infants and children, a systematic searching was applied in 6 databases of PubMed, Web of Science, Scopus, Embase, ScienceDirect, and Google Scholar using main keywords of “Prevalence”, “hydrocele”, “Infant”, and “Children”. Also, no time restrictions were applied for paper searching (by September 1, 2024). Citation Management Software of EndNote was used for reference arrangement. The references of collected papers were also screened manually to cover the maximum collection of eligible studies. Finally, the searching process was updated on September 16, 2024. Keywords were extracted using the MeSH concept. The search strategy (in each database) was determined using Advanced Searching Mode using (AND) and (OR) operators to reach the maximum combination. For example, the searching strategy in the PubMed database was determined as follows; (((((((Prevalence[Title/Abstract]) AND (hydrocele[Title/Abstract])) OR (Testicular Hydrocele[Title/Abstract])) OR (Scrotal Hydrocele[Title/Abstract])) OR (Vaginal Hydrocele[Title/Abstract])) AND (Infant[Title/Abstract])) OR (Infants[Title/Abstract])) AND (Children[Title/Abstract]))))))).

Inclusion and exclusion criteria

Inclusion criteria were all studies reporting the prevalence of pediatric hydrocele in infants and children, with available full-text, sufficient extractable data, and papers designed in English Language. Besides, all case reports, case series, intervention studies, reviews, and papers with insufficient or unextractable data were excluded.

Study selection

The PRISMA guidelines were totally followed for selection of eligible studies. This protocol was conducted through exclusion of duplicate studies and the selection of eligible investigations based on the inclusion/exclusion criteria. During paper searching, the citations were imported into the Citation Management Software (EndNote). Duplicate papers were selected and merged. During the primary screening, the Title and Abstract of the papers were assessed and irrelevant investigations were excluded. In the secondary screening process, full texts of studies were provided and re-evaluated. Eligible papers with extractable data were considered in this regard. In order to prevent the probable bias, all stages were carried out by two independent researchers. Any potential disagreements regarding the paper’s selection were re-evaluated by the corresponding author.

Qualitative assessment of included papers

To validate the quality of included articles, the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist was used. All aspects of the included papers were assessed including Title, Abstract, Introduction, Statement of the problem, Study objectives, Methods, type of study, statistical population, sampling method, data collection tools, Results, and Discussion. Finally, middle to high-quality papers were included for data extraction. For paper scoring, the values of 1 and 0 were assigned to each approved and rejected item, respectively. The total score was 0–32 on the STROBE checklist. Papers ≥ 16 were considered moderate to high-quality studies (included for data extraction); besides, the articles < 16 were low-quality investigations (excluded) [12].

Data extraction

In this regard, two researchers extracted data using a previously prepared checklist including the “Name of the first author”, “Year of paper publication”, “Country”, “Type of study”, “Sample size”, “Age group”, “Statistics of cases”, “Hydrocele prevalence”, and “Study tools”.

Statistical analysis

Whole statistical analysis was conducted using Comprehensive Meta-Analysis software (v.2). I² test was used to check the heterogeneity and publication bias was assessed using the Egger test. The Funnel plot and Begg and Mazumdar correlation test was used for publication bias. Based on the results of the heterogeneity study, factors such as Sample size and Year of paper publication were detected as effective factors in the heterogeneity index; thus, meta-regression analysis was used to examine in this regard.

Results

Following the databases assessment, a total number of 866 articles were identified. By exclusion of duplicate articles, as well as ineligible papers, 8 eligible studies were selected for data analysis including 5 studies in infants and 3 studies in children (Fig. 1 and Table 1).

Fig. 1

The flowchart of PRISMA reporting the stages of paper selection

Table 1 Static presentation of included papers reporting the prevalence of pediatric hydrocele in infants and children

Global prevalence of hydrocele in infants

Following the assessment of 5 eligible studies with a sample size of 70,961 infants (1–2 weeks), the heterogeneity index was found high (I²:99.3). Thus, a random effect model was used for meta-analysis. The global prevalence of hydrocele in Infants was found 0.001% (95%CI:0.00007–0.018, 1 per 1000 live births) (Fig. 2A). Also, the Begg and Mazumdar correlation test showed no publication bias in eligible studies (p:0.806) (Fig. 2B). The highest prevalence of hydrocele in Infants was reported by Osifo et al. (2008, Nigeria) at 6% (2716 cases with the age of 8.9 ± 4.2 years) [13]. Also, the lowest prevalence of hydrocele in Infants was associated with the study of Yoko Maizumi et al. (1948–1958, Japan) as 0.02% with a sample size of 20,919 participants (Table 1) [14].

Fig. 2

A Forest plot diagram representing the global prevalence of pediatric hydrocele in infants (random effects model). B Funnel plot representing the publication bias in the reviewed studies reporting the prevalence of pediatric hydrocele in infants

Global prevalence of hydrocele in children

In the review of 3 studies with a sample size of 278,597 children (7–12 years), the I² index showed a high heterogeneity level (I²:99.7); accordingly, the random effect model was used to analyze the data. The global prevalence of hydrocele in Children was reported 0.0034% (95%CI:0.00004–0.21, 3.4 per 1000 children) (Fig. 3A). Publication bias was assessed through the Begg and Mazumdar correlation test and no statistical differences were detected in this regard (p:1.000) (Fig. 3B). The highest prevalence of hydrocele in Children was related to the study of Chu et al. (2019, China, 3006 participants) at 6.85% with a mean age of 6.04 ± 4.32 years [16]. Also, the lowest prevalence of hydrocele in Children was reported by Shobha S. Nisale et al. (2016, India) as 0.01% among 274,591 school-age participants (Table 1) [17]. In this regard, another study was associated with Thorat Sukdeo Lingaji et al. (2016) [15].

Fig. 3

A Forest plot diagram representing the global prevalence of pediatric hydrocele in children (random effects model). B Funnel plot representing the publication bias in the reviewed studies reporting the prevalence of pediatric hydrocele in children

In order to investigate the effects of potential factors (sample size and year of the paper publication) affecting heterogeneity index, meta-regression analysis was used. According to Fig. 4, the global prevalence of hydrocele in infants decreased with increasing the sample size (Fig. 4A), this value was also increased following acceleration of study year (Fig. 4B). Also, according to Fig. 5, the global prevalence of hydrocele in children decreased following the increase in sample size (Fig. 5A) and increased with the acceleration of the year of paper publication (Fig. 5B).

Fig. 4

Meta-regression analysis of the effect of sample size (A) and year of studies (B) on global prevalence of hydrocele in infants

Fig. 5

Meta-regression of the effect of sample size (A) and year of studies (B) on global prevalence of hydrocele in children

Discussion

Pediatric hydrocele (PH) is a curable pathology which can lead to early treatment and complete removal of complications following on-time diagnosis by an experienced delivery team [18]. Untreated hydrocele can eventually lead to infertility [19]. Currently, there are no single global statistics available regarding the prevalence of pediatric hydrocele; thus, it seems that presentation of a valid report in this regard causes the awareness of medical staff and health policymakers. This study was designed to present the global prevalence of PH in two groups of infants and children. The results of this meta-analysis study (statistical population of 349,558 cases) showed that the global prevalence of this disease in infants and children is 1 per 1000 and 3.4 per 1000, respectively. The findings showed that by the age (from infancy to childhood), the rate of pediatric hydrocele increases. This finding represented late or no diagnosis of PH pathology during labor or a few days post-labor. It is also suggested that multiple environmental factors can lead to the occurrence of PH in the post-infant period [20].

Provision of health solutions for early diagnosis of PH pathology seems a critical approach. Hydrocele in infants is a benign condition commonly disappears with no treatment [2]. However, in persistent cases beyond infancy, careful screening is essential to determine the need for surgical intervention. The exact report of hydrocele’s prevalence and ongoing management strategies emphasizes the importance of pediatric surveillance in early childhood health care. The studies conducted by Osifo and Osaigbovo [13] and Imaizumi et al. [14] provided important insights regarding the prevalence and special characteristics of hydrocele in infants, albeit from different geographical and clinical contexts. Osifo and Osaigbovo [13] in a study entitled “Congenital hydrocele: prevalence and outcome among male children who underwent neonatal circumcision in Benin City, Nigeria” found that among 2,715 male neonates circumcised, 4.7% were diagnosed with hydrocele. This study highlighted that 83.4% of the diagnosed cases resolved spontaneously by the age of 18 months, with peak resolution occurring between 4–6 months.

According to this study, it is suggested that neonates with congenital hydrocele should be monitored for spontaneous resolution for at least 18 months before surgical intervention, as no hydrocele-associated complications were observed during follow-up period [13]. In contrast, the study conducted by Imaizumi et al., [14] entitled “The prevalence at birth of congenital malformations at a maternity hospital in Osaka City, 1948–1990” provided a broader epidemiological perspective on congenital malformations, including hydroceles. In this study, no special focus on hydrocele outcomes or management strategies was considered. While this study documented various congenital conditions over several decades, it lacked detailed findings on hydroceles and prevalence rates or resolution outcomes like those reported by Osifo and Osaigbovo [13].

Totally, while Osifo and Osaigbovo’s research [13] offered specific insights into the prevalence and management of hydrocele in a Nigerian context, Imaizumi et al. contributed to a general understanding of congenital malformations without delving deeply into hydrocele specifics [14]. The studies by Lingaji et al., [15], Chu et al., [16], and Nisale [17] provided valuable insights into the prevalence and management of hydrocele and hernia among children, highlighting different aspects of these conditions. Lingaji and Sambhus Dilip [15] reported a prevalence rate of 2.5% for hydroceles among the surveyed school children. Their findings indicated that hydrocele is often associated with inguinal hernias, emphasizing the need for comprehensive screening in pediatric populations [15].

In contrast, the study by Chu et al. focused on the management of inguinal hernias rather than hydroceles specifically [16]. This research analyzed data from 3,006 cases and found that individualized treatment strategies significantly reduced recurrence rates in adolescents. While this study not directly address hydrocele, it underscored the importance of tailored surgical approaches in managing related conditions, given that hydroceles can occur alongside hernias [16]. Nisale’s study reported a prevalence of 1.7% for hydroceles in their cohort study. This study highlighted the significance of early detection and intervention for both hernias and hydroceles to prevent complications and improve outcomes in pediatric patients [17].

Overall, while Lingaji and Sambhus Dilip emphasized the prevalence of hydrocele in a specific population [15], Chu et al. provided insights into surgical management strategies for hernias which may also relate to cases involving hydrocele, and Nisale and Warad contributed additional prevalence data supporting the need for vigilant screening in school-aged children [17].

Limitations

Among the most important limitations of the present study, is the limited number of investigations conducted in infants and children was noticed causing higher confidence limits with higher heterogeneity. Also, most of the studies were conducted in Asia and Africa, and no studies were found in Europe or America causing reduced geographical diversity.

Conclusion

This study reported pediatric hydrocele disease with the prevalence of 1 and 3.4 per 1000 cases for infants and children, respectively. Findings can be useful in health policies of societies and accurate statistics lead to the improvement of health standards. The prevalence of pediatric hydrocele can lead to the prevention of acute disease conditions and rapid diagnosis with early treatment.