Abstract
The aim of this study was to investigate the trend in testicular volume changes after orchiopexy in children with cryptorchidism. The clinical data of 854 children with cryptorchidism who underwent orchiopexy between January 2013 and December 2016 in Shenzhen Children’s Hospital (Shenzhen, China) were retrospectively analyzed. The mean (standard deviation) age of the patients was 2.8 (2.5) years, and the duration of follow-up ranged from 1 year to 5 years. Ultrasonography was conducted preoperatively and postoperatively. The variables analyzed included age at the time of surgery, type of surgical procedure, laterality, preoperative testicular position, preoperative and postoperative testicular volumes, and the testicular volume ratio of them. The average testicular volumes preoperatively and at 1 year, 2 years, 3 years, and 5 years postoperatively were 0.27 ml, 0.38 ml, 0.53 ml, 0.87 ml, and 1.00 ml, respectively (P < 0.001). The corresponding testicular volume ratios were 0.67, 0.76, 0.80, 0.83, and 0.84 (P < 0.001). The mean volume of the undescended testes was significantly smaller than the mean normative value (P < 0.001, lower than the 10th percentile). The postoperative testicular volumes in children with cryptorchidism were generally lower than those in healthy boys but were still greater than the 10th percentile and exhibited an increasing trend. The older the child is at the time of surgery, the larger the gap in volume between the affected and normal testes. Although testicular volume tends to gradually increase after orchiopexy for cryptorchidism, it could not normalizes. Earlier surgery results in affected testicular volumes closer to those of healthy boys.
Keywords: children, cryptorchidism, orchiopexy, testicular volume, trends
INTRODUCTION
Cryptorchidism, known as undescended testis (UDT), is one of the most common congenital abnormalities in boys and is among the few well-known risk factors for testicular cancer.1 In addition to male infertility, which is the most important consequence of cryptorchidism, boys with UDT have a significantly greater risk of developing testicular tumors or testicular torsion. In addition, these boys are also more prone to testicular trauma than boys with normal testicles.2 Cryptorchidism affects 1.0% to 4.6% of full-term neonates and 1.1% to 4.5% of preterm neonates.3 For normal spermatogenesis, the testes should be properly positioned within the scrotum at birth to maintain the necessary temperature. Effective screening and early surgical intervention are crucial for optimizing fertility in adulthood and significantly reducing the risk of testicular cancer. The standard surgical treatment for cryptorchidism is orchiopexy, which improves future fertility prospects and facilitates cancer surveillance.4 The choice of surgical technique, whether open or laparoscopic, primarily depends on the location and accessibility of the undescended testis.5 Given that 80% to 90% of the testis comprises seminiferous tubules, testicular volume is closely linked to the semen profile and testicular function.6 Thus, it is essential to assess testicular volume. However, research on changes in testicular volume after orchiopexy is limited, and the trend of testicular development following orchiopexy remains unclear.
To address this gap, we analyzed preoperative and long-term postoperative testicular volumes in a large cohort and examined trends in testicular volume changes.
PATIENTS AND METHODS
Patients
In this study, we used the clinical data of children who were diagnosed with cryptorchidism and underwent orchiopexy at Shenzhen Children’s Hospital (Shenzhen, China), between January 2013 and December 2016. The inclusion criteria were as follows: (1) a preoperative diagnosis of cryptorchidism confirmed through neurological examination and ultrasonography; (2) age between 0 and 14 years; (3) orchiopexy performed at our hospital; and (4) complete clinical, medical, and surgical records. The exclusion criteria included: (1) a follow-up period less than 1 year; (2) incomplete medical records or follow-up data; or (3) the presence of disorders of sexual development or associated chromosomal or gonadal abnormalities. Additionally, 1607 healthy boys aged 0 to 14 years were studied as a control group.7
Study design
The study indices included age at the time of surgery, surgical approach, laterality of cryptorchidism, preoperative testicular position, preoperative and postoperative testicular volumes, and the testicular volume ratio. We also collected ultrasound data preoperatively and at 1 year, 2 years, 3 years, and 5 years postoperatively and measured the length, width, and height of the testes to calculate testicular volume using the following formula: testicular volume = 0.52 × length × width × height.8 To establish a baseline for comparison, we calculated the median and the 10th and 90th percentiles of testicular volumes for age-matched control groups of healthy boys, allowing us to chart the natural progression of testicular growth relative to age.
The primary outcome was testicular volume, and the secondary outcome was the testicular volume ratio. The children with cryptorchidism were categorized into seven age groups according to their age at the time of surgery: 0 to 1 year (0 < age < 1 year), 1 year to 2 years (1 year ≤ age < 2 years), 2 years to 3 years (2 years ≤ age < 3 years), 3 years to 4 years (3 years ≤ age < 4 years), 4 years to 6 years (4 years ≤ age < 6 years), 6 years to 8 years (6 years ≤ age < 8 years), and 8 years to 14 years (8 years ≤ age ≤ 14 years). The testicular volume ratio was defined as the ratio of the volume of the affected testis to that of the contralateral testis.
Statistical analyses
All the statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS, version 29.0.1.0; IBM Corp., Armonk, NY, USA). Statistical data were analyzed using the t-test, Mann‒Whitney U test, or one-way analysis of variance (ANOVA), whereas categorical data were analyzed using the Chi-squared test. One-way ANOVA was conducted to compare the preoperative testicular volumes of children with cryptorchidism to those at 1 year, 2 years, 3 years, and 5 years postoperatively, as well as across different age groups and surgical procedures. We conducted supplementary normality tests for testicular volume and volume ratios via the Kolmogorov‒Smirnov (K‒S) and Shapiro‒Wilk (S‒W) tests. Normally distributed data are presented as the mean (standard deviation [s.d.]), whereas nonnormally distributed data are reported as median (interquartile range [IQR]). P < 0.05 indicated statistical significance.
Ethical approval
This study was approved by the Ethics Committee of Shenzhen Children’s Hospital (Approval No. 202209402). Informed consent for surgery was obtained from all parents or guardians of the participating children. Permission to use publicly available data has been obtained.
RESULTS
Eight hundred and fifty-four children diagnosed with cryptorchidism between January 2013 and December 2016 were included in this study. The observation period was from January 2014 to December 2022. The median follow-up time was 41.0 (range: 12.0–76.0) months. Among them, 311 had left-sided cryptorchidism, 407 had right-sided cryptorchidism, and 136 had bilateral cryptorchidism. Additionally, 118 had low cryptorchidism, 650 had intermediate cryptorchidism, and 86 had high cryptorchidism. Table 1 presents the basic characteristics of all the children with cryptorchidism. A normality distribution test revealed that the testicular volume ratios from the 2nd postoperative year were nonnormally distributed.
Table 1.
Basic characteristics of 854 children with cryptorchidism
| Variable | Case (n) | Age (year), mean | TV (ml), mean±s.d. |
|---|---|---|---|
| Total | 854 | 2.8 | 0.27±0.17 |
| Laterality | |||
| Left side | 311 | 3.0 | 0.27±0.15 |
| Right side | 407 | 2.6 | 0.27±0.18 |
| Bilateral | 136 | 3.1 | 0.29±0.16 |
| Testicular location | |||
| Low | 118 | 3.0 | 0.34±0.17 |
| Median | 650 | 2.7 | 0.26±0.17 |
| High | 86 | 3.4 | 0.29±0.14 |
| Age group | |||
| Age <1 year | 101 | 0.8 | 0.25±0.11 |
| 1 year ≤ age <2 years | 369 | 1.4 | 0.25±0.10 |
| 2 years ≤ age <3 years | 129 | 2.3 | 0.26±0.11 |
| 3 years ≤ age <4 years | 115 | 3.8 | 0.26±0.14 |
| 4 years ≤ age <6 years | 58 | 5.8 | 0.25±0.11 |
| 6 years ≤ age <8 years | 47 | 7.9 | 0.35±0.17 |
| 8 years ≤ age ≤14 years | 35 | 10.8 | 0.66±0.44 |
TV: testicular volume; s.d.: standard deviation
The average age of the patients was 2.8 years. The mean (s.d.) testicular volume on the affected side was 0.27 (0.17) ml preoperatively, 0.38 (0.39) ml at 1 year postoperatively, 0.53 (0.75) ml at 2 years postoperatively, 0.87 (1.50) ml at 3 years postoperatively, and 1.00 (1.62) ml at 5 years postoperatively. The median testicular volume ratios were 0.6 preoperatively, 0.7 at 1 year postoperatively, 0.8 at 2 years postoperatively, 0.8 at 3 years postoperatively, and 0.9 at 5 years postoperatively (Table 2 and Figure 1). The testicular volume was significantly higher after orchiopexy than that before orchiopexy (P = 0.001). These findings indicate that surgical treatment has a definite effect on the development of cryptorchid testes. As the patient grows, the volume of the affected testis becomes closer to the contralateral testis, and the testicular ratios increase (P = 0.001), indicating that with increasing age, the affected testis tends to “catch up” with the contralateral testis.
Table 2.
Preoperative and postoperative testicular volume and testicular volume ratio in children with cryptorchidism
| Variable | Case (n) | TV (ml), mean±s.d. | TV ratio, median (IQR) | a P | b P |
|---|---|---|---|---|---|
| Preoperative | 854 | 0.27±0.17 | 0.67 (0.28) | 0.001 | 0.001 |
| 1 year after surgery | 854 | 0.38±0.39 | 0.76 (0.40) | ||
| 2 years after surgery | 577 | 0.53±0.75 | 0.80 (0.26) | ||
| 3 years after surgery | 367 | 0.87±1.50 | 0.83 (0.23) | ||
| 5 years after surgery | 401 | 1.00±1.62 | 0.84 (0.26) |
aThe comparison of testicular volume in all stages. bThe comparison of testicular volume ratios in all stages. s.d.: standard deviation; IQR: interquartile range; TV: testicular volume
Figure 1.
Trends in testicular volume and the testicular volume ratio preoperatively and at 1 year, 2 years, 3 years, and 5 years postoperatively in children with cryptorchidism. (a) Trend in testicular volume at different stages. (b) Trend in the testicular volume ratio. Testicular volume ratio: the ratio of the affected testicular volume to the contralateral testicular volume.
In this study, we compared the preoperative and 1-year postoperative testicular volumes of cryptorchid children with those of healthy boys across all age groups. The 1-year postoperative testicular volume was significantly greater than the preoperative testicular volume in all age groups (all P < 0.05; Table 3 and Figure 2). The preoperative testicular volume of patients with cryptorchidism was markedly lower than that of healthy boys and lower than the 10th percentile. One year after orchiopexy, the testicular volume of patients with cryptorchidism was lower than the 50th percentile but was higher than the 10th percentile, close to the average volume of healthy boys. This finding indicates that although the testicular volume increases after surgery, it still does not fully “catch up” to that of healthy boys. However, as surgery was delayed, the volume of the affected testis lagged behind that of healthy boys (Figure 3). The older the child is at the time of surgery, the greater the gap in testicular development between boys with cryptorchidism and healthy boys.
Table 3.
Comparison of preoperative and 1-year postoperative testicular volume across different age groups
| Age group | Case (n) | Preoperative TV (ml), mean±s.d. | TV at 1 year after surgery (ml), mean±s.d. | P |
|---|---|---|---|---|
| Age <1 year | 101 | 0.25±0.11 | 0.32±0.13 | 0.001 |
| 1 year ≤ age <2 years | 369 | 0.24±0.10 | 0.29±0.11 | 0.001 |
| 2 years ≤ age <3 years | 129 | 0.26±0.11 | 0.35±0.36 | 0.004 |
| 3 years ≤ age <4 years | 115 | 0.26±0.14 | 0.39±0.46 | 0.002 |
| 4 years ≤ age <6 years | 58 | 0.25±0.11 | 0.36±0.18 | 0.001 |
| 6 years ≤ age <8 years | 47 | 0.35±0.17 | 0.54±0.37 | 0.001 |
| 8 years ≤ age ≤14 years | 35 | 0.66±0.44 | 1.36±1.01 | 0.001 |
s.d.: standard deviation; TV: testicular volume
Figure 2.
Preoperative and 1-year postoperative testicular volume in children with cryptorchidism, categorized by age group. Age group 1: age <1 year; 2: 1 year ≤ age <2 years; 3: 2 years ≤ age <3 years; 4: 3 years ≤ age <4 years; 5: 4 years ≤ age <6 years; 6: 6 years ≤ age <8 years; 7: 8 years ≤ age ≤14 years.
Figure 3.
Comparison of testicular volume between cryptorchid patients and normal boys. Red curve: preoperative testicular volume of cryptorchid patients. Pink curve: postoperative testicular volume (1 year postoperatively) in the same cohort. P10: the 10th percentile of testicular volume in normal boys; P50: the median testicular volume in normal boys; P90: the 90th percentile of testicular volume in normal boys.
DISCUSSION
This is a large-scale clinical study of postoperative testicular volume changes in children with cryptorchidism and a long follow-up period. Our study revealed that the preoperative testicular volume in patients with cryptorchidism was significantly lower than that in healthy boys. Postoperatively, the testicular volume of the affected side tended to “catch up” but did not reach the normal volume in healthy boys. Age at the time of surgery is a critical factor influencing postoperative testicular development. Earlier surgery results in testicular volumes closer to those of healthy boys, whereas delayed surgery results in a larger gap between the affected and normal testicular volumes.
Decreased testicular volume due to atrophy impacts future fertility and hormonal function, especially when orchiopexy is delayed. Given this, incorporating preoperative volume measurements as a baseline could strengthen the model’s predictive accuracy. A recently article on laparoscopic orchiopexy indicates that testicular volume recovery can signify successful intervention and improved vascularization postoperatively.9 Therefore, using testicular volume as both a prognostic marker and an indicator of model effectiveness could enhance patient monitoring protocols. In this study, we observed that the testicular volume and testicular volume ratio increased following orchiopexy, indicating that the volume of the affected testis tended to “catch up” with the volume of contralateral healthy testis after the operation. Ajiki et al.10 studied 93 children with cryptorchidism and reported that the post-orchiopexy testicular volume on the cryptorchid side was significantly greater than the preoperative volume. Tseng et al.11 included 182 children with cryptorchidism, with a median follow-up of 34 months, and most children had good postoperative testicular growth. Similarly, Marret et al.12 investigated 55 children and reported that surgical treatment led to good testicular development. Another study also reported significantly increased testicular volumes after orchiopexies. In that study, the testicular growth rate was higher than normal.13 Histological analysis revealed that the increase in testicular development after orchiopexy was due to an increase in the number of germ cells per tubule and interstitial cells.14,15 Laparoscopic orchidopexies were associated with a lower risk of complications such as testicular atrophy and wound infection and greater success in maintaining the position of the testicle in the middle or lower part of the scrotum without subsequent retraction.2 Therefore, orchiopexy positively affects testicular development in children with cryptorchidism, and the change in testicular volume during the follow-up period is one of the most important criteria for surgical success.16,17,18,19
We observed that the preoperative testicular volume in children with cryptorchidism was lower than that in healthy boys. Although the testicular volume tended to “catch up” after orchiopexy, it remained lower than that in healthy boys, and this disparity did not normalize by the end of the study’s observation period. This phenomenon may be related to cryptorchidism. Testicular hypoplasia, characterized by reduced size due to poor testicular development and a decrease in or absence of germ cells, is a known consequence of this condition.20 Tasian et al.15 studied the relationship between histopathological changes in the testes and reduced fertility potential in children with cryptorchidism. They reported that each additional month of undescended testes was associated with a significant reduction in germ cells and mesenchymal stromal cells, which are often moderate to severe. Additionally, undescended testes are prone to severe germ cell depletion, which may be exacerbated by elevated temperatures in the inguinal canal that increase the levels of reactive oxygen species, promote germ cell apoptosis, and reduce testicular weight.21,22 Early orchiopexy in children with cryptorchidism may help reduce the risk of testicular cancer, preserve fertility, and improve testicular development.23
The optimal age for surgical intervention in children with cryptorchidism remains debated, with current recommendations suggesting surgery between 6 months and 12 months or up to 18 months after birth.14,23,24,25 The evidence increasingly suggests the benefits of early surgery for promoting testicular health and fertility.26 Despite early diagnosis in many cases, most children are referred for surgery after their 1st year.27 In our study, most children underwent surgeries between 1 year and 2 years of age, and many patients were still older than 2 years, possibly because their parents lacked medical knowledge or because they did not pay attention to the disease. We categorized children into age groups on the basis of their age at surgery and revealed that earlier surgery was associated with a smaller difference in testicular volume between boys with cryptorchidism and healthy boys in the same age group. Conversely, later surgery resulted in a more pronounced difference. These findings suggest that early surgery is crucial for promoting optimal testicular development in children with cryptorchidism. Kollin et al.28 compared the growth of testes in children with spontaneously descending cryptorchidism to that of normal and surgically treated testes. They reported that, compared with their scrotal counterparts, spontaneously descending testes were growth impaired from birth. The longer the testes remained untreated, the more significant the growth impairment was. Tseng et al.25 studied 134 children with unilateral cryptorchidism, with a median follow-up of 3.9 years. They reported that testicular growth was more rapid in children who underwent surgery before 1 year of age, suggesting that orchiopexy be performed within the 1st year after birth. Conversely, another study by Tseng et al.11 analyzed 183 children with cryptorchidism, with a median follow-up of 34 months, suggesting that performing surgery before 2 years of age is associated with an increased risk of postoperative testicular atrophy. These conflicting conclusions from the same center may be due to variations in the criteria for postoperative testicular comparisons and potential biases in case data. Similarly, Marret et al.12 examined 55 children with cryptorchidism to assess the incidence of testicular atrophy following surgery before 1 year of age and concluded that orchiopexy before 1 year did not increase the risk of testicular atrophy and was associated with improved testicular development. However, Niedzielski et al.29 concluded that there were significant increases in testicular volume and reductions in testicular atrophy indices across all treatment modalities, with no significant differences between age groups or treatment types.
This study has several advantages. First, the patients’ testicular volumes were accurately measured using ultrasound, which is more objective and precise than assessing testicular volume through physical examination. Second, this study included a long and regular postoperative follow-up period. The follow-up time in most studies is approximately 1 year after orchiopexy. Our extended follow-up provides more comprehensive data for assessing the growth trends of testicular volume.
There are some limitations in this study. First, despite our efforts to collect comprehensive data, some information was missing, leading to the exclusion of patients with incomplete data. Additionally, variations in the experience levels of ultrasonographers and pediatric urologists and differences in technique standardization may have introduced variability. Furthermore, we recognize that because the study was conducted in a single center, the generalizability of the findings may be limited. A multicenter study would provide a more comprehensive view and findings with broader applicability. We will consider this for future research to strengthen the external validity and influence of our study.
CONCLUSIONS
The testicular volume in children with cryptorchidism tends to increase after orchiopexy but could not actually normalizes. The age at the time of surgery is a critical factor influencing postoperative testicular development. Earlier surgery results in affected testicular volumes closer to those of healthy boys.
AUTHOR CONTRIBUTIONS
YYH and ZLY designed this study. YYH and ZCK acquired, analyzed, and interpreted the data and drafted the manuscript. YYH, HJG, PLZ, SLL, and PYC recorded and checked the data. ZCK, WHX, and FHS performed the follow-up procedures. ZLY revised the manuscript. All authors read and approved the final manuscript.
COMPETING INTERESTS
All authors declare no competing interests.
ACKNOWLEDGMENTS
This study was funded by the Guangdong High-level Hospital Construction Fund and Shenzhen Fund for Guangdong Provincial High-level Clinical Key Specialties (SZXK035). We appreciate all the doctors and nurses in the Urology Department of Shenzhen Children’s Hospital (Shenzhen, China) for their contributions and thank all the children who were enrolled in this study.
REFERENCES
- 1.Gurney JK, McGlynn KA, Stanley J, Merriman T, Signal V, et al. Risk factors for cryptorchidism. Nat Rev Urol. 2017;14:534–48. doi: 10.1038/nrurol.2017.90. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Anand S, Krishnan N, Pogorelic Z. Utility of laparoscopic approach of orchiopexy for palpable cryptorchidism:a systematic review and meta-analysis. Children (Basel) 2021;8:677. doi: 10.3390/children8080677. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Riedmiller H, Androulakakis P, Beurton D, Kocvara R, Gerharz E. EAU guidelines on paediatric urology. Eur Urol. 2001;40:589–99. doi: 10.1159/000049841. [DOI] [PubMed] [Google Scholar]
- 4.Xie X, Hu J, Liu L, Lei P, Zhang P, et al. Bibliometric analysis of scientific publications on cryptorchidism:research hotspots and trends between 2000 and 2022. Heliyon. 2023;9:e19722. doi: 10.1016/j.heliyon.2023.e19722. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Ashley RA, Barthold JS, Kolon TF. Cryptorchidism:pathogenesis, diagnosis, treatment and prognosis. Urol Clin North Am. 2010;37:183–93. doi: 10.1016/j.ucl.2010.03.002. [DOI] [PubMed] [Google Scholar]
- 6.Bahk JY, Jung JH, Jin LM, Min SK. Cut-off value of testes volume in young adults and correlation among testes volume, body mass index, hormonal level, and seminal profiles. Urology. 2010;75:1318–23. doi: 10.1016/j.urology.2009.12.007. [DOI] [PubMed] [Google Scholar]
- 7.Yang ZL, Ke ZC, Li SL, Zhou W, Zhou GL, et al. [Ultrasound measurement of the testis volume of 0-14 years old Chinese boys. Zhonghua Nan Ke Xue. 2020;26:1083–6. [Article in Chinese] [PubMed] [Google Scholar]
- 8.Lin CC, Huang WJ, Chen KK. Measurement of testicular volume in smaller testes:how accurate is the conventional orchidometer? J Androl. 2009;30:685–9. doi: 10.2164/jandrol.108.006460. [DOI] [PubMed] [Google Scholar]
- 9.Pogorelic Z, Situm J, Baric T, Situm M. The safety and effectiveness of single-stage, vessel-preserving, laparoscopic orchiopexy for intra-abdominal testes in pediatric patients:a 10-year single-center experience. J Clin Med. 2024;13:2045. doi: 10.3390/jcm13072045. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Ajiki J, Narukawa T, Naitoh Y, Inoue Y, Fujihara A, et al. Factors affecting testicular volume after orchiopexy for undescended testes. J Med Ultrason (2001) 2023;50:493–9. doi: 10.1007/s10396-023-01329-4. [DOI] [PubMed] [Google Scholar]
- 11.Tseng CS, Huang KH, Kuo MC, Hong CH, Chen CH, et al. The impact of primary location and age at orchiopexy on testicular atrophy for congenital undescended testis. Sci Rep. 2019;9:9489. doi: 10.1038/s41598-019-45921-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Marret JB, Ravasse P, Boullier M, Blouet M, Dolet N, et al. Surgery for no palpable testis before the age of one year:a risk for the testis?J Pediatr Urol. 2019;15:377, e1–6. doi: 10.1016/j.jpurol.2019.03.019. [DOI] [PubMed] [Google Scholar]
- 13.Al Hindi S, Khalaf Z. The outcome of laparoscopic assisted orchidopexy in very young children:a single hospital experience. J Pediatr Urol. 2021;17:536.e1–7. doi: 10.1016/j.jpurol.2021.03.004. [DOI] [PubMed] [Google Scholar]
- 14.Park KH, Lee JH, Han JJ, Lee SD, Song SY. Histological evidences suggest recommending orchiopexy within the first year of life for children with unilateral inguinal cryptorchid testis. Int J Urol. 2007;14:616–21. doi: 10.1111/j.1442-2042.2007.01788.x. [DOI] [PubMed] [Google Scholar]
- 15.Tasian GE, Hittelman AB, Kim GE, DiSandro MJ, Baskin LS. Age at orchiopexy and testis palpability predict germ and Leydig cell loss:clinical predictors of adverse histological features of cryptorchidism. J Urol. 2009;182:704–9. doi: 10.1016/j.juro.2009.04.032. [DOI] [PubMed] [Google Scholar]
- 16.Sato Y, Kirihana Y, Meguro S, Tanji R, Onagi A, et al. Evaluation of testicular stiffness in boys with unilateral cryptorchidism after orchiopexy by ultrasound strain elastography. Fukushima J Med Sci. 2024;70:57–64. doi: 10.5387/fms.2023-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.van der Plas EM, Zijp GW, Froeling FM, van der Voort-Doedens LM, Meij-De Vries A, et al. Long-term testicular volume after orchiopexy at diagnosis of acquired undescended testis. J Urol. 2013;190:257–62. doi: 10.1016/j.juro.2013.02.004. [DOI] [PubMed] [Google Scholar]
- 18.Echeverría Sepúlveda MP, Yankovic Barceló F, López Egaña PJ. The undescended testis in children and adolescents part 2:evaluation and therapeutic approach. Pediatr Surg Int. 2022;38:789–99. doi: 10.1007/s00383-022-05111-4. [DOI] [PubMed] [Google Scholar]
- 19.Jiang DD, Acevedo AM, Bayne A, Austin JC, Seideman CA. Factors associated with delay in undescended testis referral. J Pediatr Urol. 2019;15:380.e1–6. doi: 10.1016/j.jpurol.2019.03.029. [DOI] [PubMed] [Google Scholar]
- 20.Slowikowska-Hilczer J, Szarras-Czapnik M, Wolski JK, Oszukowska E, Hilczer M, et al. The risk of neoplasm associated with dysgenetic testes in prepubertal and pubertal/adult patients. Folia Histochem Cytobiol. 2015;53:218–26. doi: 10.5603/FHC.a2015.0021. [DOI] [PubMed] [Google Scholar]
- 21.Imamoğlu M, Bülbül SS, Kaklikkaya N, Sarihan H. Oxidative, inflammatory and immunologic status in children with undescended testes. Pediatr Int. 2012;54:816–9. doi: 10.1111/j.1442-200X.2012.03695.x. [DOI] [PubMed] [Google Scholar]
- 22.Liu F, Huang H, Xu ZL, Qian XJ, Qiu WY. Germ cell removal after induction of cryptorchidism in adult rats. Tissue Cell. 2012;44:281–7. doi: 10.1016/j.tice.2012.04.005. [DOI] [PubMed] [Google Scholar]
- 23.Hadziselimovic F, Herzog B. The importance of both an early orchidopexy and germ cell maturation for fertility. Lancet. 2001;358:1156–7. doi: 10.1016/S0140-6736(01)06274-2. [DOI] [PubMed] [Google Scholar]
- 24.Ritzén EM. Undescended testes:a consensus on management. Eur J Endocrinol. 2008;159(Suppl 1):S87–90. doi: 10.1530/EJE-08-0181. [DOI] [PubMed] [Google Scholar]
- 25.Tseng CS, Chiang IN, Hong CH, Lu YC, Hong JH, et al. Advantage of early orchiopexy for undescended testis:analysis of testicular growth percentage ratio in patients with unilateral undescended testicle. Sci Rep. 2017;7:17476. doi: 10.1038/s41598-017-17825-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Pakkasjärvi N, Taskinen S. Surgical treatment of cryptorchidism:current insights and future directions. Front Endocrinol (Lausanne) 2024;15:1327957. doi: 10.3389/fendo.2024.1327957. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Nah SA, Yeo CS, How GY, Allen JC, Jr, Lakshmi NK, et al. Undescended testis:513 patients’ characteristics, age at orchidopexy and patterns of referral. Arch Dis Child. 2014;99:401–6. doi: 10.1136/archdischild-2013-305225. [DOI] [PubMed] [Google Scholar]
- 28.Kollin C, Granholm T, Nordenskjöld A, Ritzén EM. Growth of spontaneously descended and surgically treated testes during early childhood. Pediatrics. 2013;131:e1174–80. doi: 10.1542/peds.2012-2902. [DOI] [PubMed] [Google Scholar]
- 29.Niedzielski J, Kucharski P, Slowikowska-Hilczer J. The volume of unilaterally undescended testis after hCG therapy compared to orchidopexy and combined methods. Andrology. 2018;6:742–7. doi: 10.1111/andr.12507. [DOI] [PubMed] [Google Scholar]