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Can Urol Assoc J. 2017 Jan-Feb; 11(1-2Suppl1): S34–S39.
PMCID: PMC5332232

Varicoceles in the pediatric population: Diagnosis, treatment, and outcomes

Abstract

Varicocele is commonly encountered in adolescents. There are still many controversies regarding pathophysiology, health effects, clinical significance, and optimum treatment of this condition. This article reviews the current evidence pertaining to children and adolescents with varicocele. This group present a unique and somehow challenging situation, since they are still going through pubertal changes that may confound the effects of the disease and its treatment on the developing testes.

Introduction

Pediatric varicoceles are common, affecting up to 15% of male children and adolescents.1 There is controversy surrounding the urological management of varicoceles in the pediatric population.1,2 Historically, surgical management of pediatric varicoceles was offered in higher grades or those associated with a discrepancy in testicular volume (size is >2 mL or >20% difference on the non-affected side) in order to prevent testicular function decline and infertility.3,4 More recently, the use of surgical repair of varicoceles has been questioned with regard to whether or not it truly leads to improved clinical outcomes. Additionally, advances in surgical and radiological procedures, such as laparoscopic, microsurgical, and sclerotherapy techniques, have altered the landscape of management options for this condition.

Etiology and pathophysiology

A varicocele is the result of an abnormal enlargement of the pampiniform venous plexus, the structure responsible for venous drainage of testicles to the gonadal vein trunci, pudendal and cremasteric veins. Varicoceles are predominantly seen on the left side. Experts believe that anatomical differences in venous drainage of the testicles could be a reason for this discrepancy.5 The left testicular vein enters the renal vein while the right testicular vein enters the inferior vena cava. It was initially postulated there is a difference in hydrostatic pressure between the left and right side accounting for the differences in varicocele formation.6 In particular, the differences in length of the left and right veins and the potential compression of the left testicular vein by the superior mesenteric artery and aorta in what is known as the “nutcracker effect” may lead to increased venous pressure on the left side.7 Varicoceles are significantly more common in adolescents than in children; it is also postulated that the increased arterial blood flow to the testes at puberty exceeds the venous capacity, resulting in pampiniform venous plexus dilatation.8,9

Spermatogenesis is the testicular function most affected by the presence of a varicocele.10 In adolescents with varicoceles, decreased sperm density, increased number of pathological forms, and decreased mobility have been observed, thus, suggesting varicocele-associated reduced fertility.11 There are several postulated mechanisms by which a varicocele alters testicular function and fertility. These are outlined in Table 1. In brief, a combination of hyperthermia, hypoxia, renal and adrenal venous reflux, and increased hydrostatic pressure from the varicocele leads to increased free radicals and endocrine imbalance, and induces autoimmunity mediators that are disruptive to normal testicular function and fertility.12

Table 1.
Pathophysiology of varicocele

Epidemiology

Varicoceles are uncommon in boys under 10 years of age.1 In adolescence, the prevalence of varicoceles typically ranges from of 10–15%.1 In a retrospective review by Raman et al, increased varicocele prevalence was observed in first-degree relatives (particularly brothers) of patients with known varicoceles.13 Up to 40% of adult men with primary infertility have a varicocele and prevalence rises to 81% in men with secondary infertility.14

Diagnosis and evaluation

Varicocele grading

A varicocele can be detected clinically on physical examination with the patient in a standing position. The clinical grading system proposed by Dubin and Amelar is commonly used and consists of the following:15

  • Grade I: Only palpable on Valsalva maneuver.
  • Grade II: Palpable with no Valsalva maneuver.
  • Grade III: Visible with no need for palpation.

With widespread availability and use of ultrasound, the World Health Organization (WHO) has expanded the current grading system to include “subclinical” or Grade 0 (not palpable including during Valsalva) varicocele, which is only detectable by ultrasonography.

The relationship between varicocele grade and ipsilateral testicular hypotrophy is not clear. In a case series published by Kass et al involving 434 boys (age range 6–21 years) with palpable varicoceles, patients with Grade II and III varicoceles had a significantly smaller ipsilateral testicle compared to controls.16 However, other studies have not shown the same correlation.17 Thus, varicocele grade alone should not be used as an indication for surgical repair.

There is currently a paucity of available data on the effects of subclinical varicoceles on testicular size or long-term fertility. In a study by Cervellione et al involving 36 children (mean age 12.8 years) with subclinical varicoceles, 10 children (28%) had progressed to a clinically detectable varicocele at four-year followup while 24 (67%) remained unchanged.18 Regular follow may be considered in these patients.

Testicular asymmetry

Testicular asymmetry has generally been accepted as a potential indicator for long-term subfertility and, thus, an indication for treatment of adolescent varicoceles. Testicular size and volume can be estimated in the office with an orchidometer. Some studies have shown accurate correlation between testicular volume measurements from a Prader orchidometer and ultrasonography.19,20 Others, however, support the use of ultrasonography as a more accurate modality to measure testicular volume and follow changes longitudinally.21,22 Testicular volume is often calculated using the Lambert formula (volume=0.71 × length × width × height).21 The accuracy of both the orchidometer and ultrasonography can be influenced by clinician experience and inter-examiner variability. Thus, a decision for surgery should be from several measurements in a consistent manner taken over a period of time.

Abnormal semen parameters have been correlated with testicular volume differentials as low as 10%.23 Currently, threshold values for clinically significant asymmetry range from 10–20% relative difference in volume or an absolute differential of 2–3 mL.23,24 On the other hand, Kolon et al observed that the degree of testicular asymmetry was reduced in up to 80% of adolescents with varicoceles due to catch-up growth of the smaller testicle without any intervention.25 Thus, the challenge lies in selecting patients with testicular asymmetry who are unlikely to have spontaneous catch-up growth of the affected testicle.

Sonographic parameters

Measurement of the peak retrograde venous flow (PRF) in the spermatic cord using Doppler colour flow imaging has emerged as a predictor for progressive testicular asymmetry.26 PRF is measured with the patient performing the Valsalva maneuver in the supine position.26 A retrospective review by Kozakowski et al assessing the PRF in 77 patients (age range 9–20 years) showed that catch-up growth is rare in patients with greater than 20% asymmetry and a PRF of greater than 38 cm/second (mean followup 13 months).27 Poon et al had similar findings in a retrospective review involving 181 patients.28 In patients with a PRF between 30 cm/second and 38 cm/second, data from various series show increased risk for developing progressive testicular asymmetry even when initial testicular asymmetry was less than 15%.27,29,30

Measurement of the maximum vein diameter (MVD) of the pampiniform plexus during Valsalva in adults is a prognosticator for semen parameters following varicocele repair, with an MVD greater than 3 mm preoperatively associated with favourable outcomes.31 However, there is a paucity of evidence with regards to the diagnostic value of MVD in adolescents. MVD does not appear to be a reliable predictor of progression of testicular asymmetry.27

Semen analysis

In a study involving 57 Tanner stage V adolescent males with varicoceles and testicular asymmetry (age range 14–20 years), Diamond et al performed semen analysis that showed decreased sperm concentration and total motile sperm count.23 In a study by Moursy et al, 59 of 60 patients with a varicocele and less than 20% asymmetry managed conservatively were found to have normal semen analysis at age 18 (mean followup 79 months).32 Others have also described normalization of total motile sperm count in two-thirds of Tanner V boys with uncorrected varicocele.33 On the other hand, randomized trials have shown improvement in semen parameters following varicocelectomy (see Treatment and outcomes). There are no standard norms for adolescent semen analysis. Currently, the WHO adult standards are extrapolated to this group. In evaluating the data available thus far, the current role of semen analysis in the evaluation of adolescent varicocele remains unclear.

Endocrine evaluation

The presence of varicocele has been postulated to affect testosterone production and, in turn, the hypothalamic-pituitary-gonadal axis. Multiple studies involving adult men have shown an improvement in testosterone levels post-varicocele repair.34 Although testosterone measurements are affected by multiple factors, such as the assay technique itself, lifestyle factors and age, most recent evidence in adults suggest a positive relationship between varicocele repair and improvement in testosterone levels.34,35 In a recent cross-sectional study by Daamsgard et al involving 7035 men (median age 19 years), 1102 (15.7%) men had a palpable varicocele.36 The presence of a varicocele was associated with higher baseline serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels, and lower serum inhibin B levels, with a trend towards greater deviation from controls as varicocele grade increased.36 There was no difference in baseline serum testosterone levels in those with varicoceles compared to those without.36

There are, however, practical considerations to bear in mind with regards to endocrine evaluation in adolescents. This includes defining standard norms for adolescents with varying tanner stages and the cost of testing and multiple blood draws, especially if done pre- and post-procedure. Taken together, the utility of obtaining baseline hormonal evaluation in identifying adolescents at risk for infertility has not yet been demonstrated and the significance of testosterone change pre- and post-intervention remains unclear.

Treatment and outcomes

Indications for treatment

The diagnostic evaluation of adolescents with varicoceles continues to evolve. Patients should be followed regularly with serial physical examination and assessment of testicular size as the bare minimum.

There continues to be a lack of consensus on the threshold for testicular asymmetry (10%, 15%, or 20%) that warrants varicocele intervention. The decision for surgery should be from several measurements taken over a period of time and in a consistent manner. The effect of ongoing pubertal changes and the possibility of spontaneous catch-up growth should be taken into account.

Ultrasonography is an accurate modality for following testicular size, as it enables clinicians to compare previous images and measurements more precisely. In patients with testicular asymmetry, measurement of the PRF may be helpful in selecting which patients are likely to demonstrate catch-up growth vs. those who may benefit from early intervention. Based on the data available, surgical intervention should be considered in patients with a PRF of greater than 38 cm/second and concurrent testicular asymmetry greater than 20%.

In Tanner V adolescents, semen analysis can be considered as an additional way to assess testicular function. The semen analysis may help the patient and clinician in reaching a decision as to whether an intervention should be performed.

A plethora of different types of interventions to treat varicocele exist in the literature. These range from monitoring to open surgery. The procedural interventions may be divided into open, laparoscopic, and endovascular procedures. All the procedures involve occlusion of the testicular veins or pampiniform plexus. The anatomical site of occlusion varies from distal spermatic cord (low inguinal) to proximal testicular vein (retroperitoneal). Multiple variations in techniques have been reported, primarily to reduce postoperative failures and complications. Examples are arterial-and lymphatic-sparing approaches to reduce the risk of testicular atrophy and hydrocele, respectively.

Our group recently conducted a systematic review of randomized, controlled trials to assess the outcomes of radiological and surgical interventions for varicocele in children and adolescents. We did not include cases series and uncontrolled studies since they tend to overestimate the effect of intervention. In our meta-analysis of nine eligible studies at six months’ followup, we demonstrated an improvement in testicular volume (mean difference 3.18 mL [95% confidence interval (CI) 1.94–4.42]) and in sperm count (mean difference 25.54 × 106 /mL [95% CI 12.84–38.25]) in patients who underwent radiological or surgical treatment as compared to conservative management (Figs. 1 and and2,2, respectively). Morphology and motility parameters were not changed significantly following intervention. Paternity rates following adolescent varicocele repair have not been evaluated in randomized, controlled trials. Nevertheless, Bogaert et al were not able to show any significant difference in paternity in an observational study that followed the participants for over 15 years.54

Fig. 1.
Forest plot of comparison between surgical or radiological intervention to conservative management, outcome: Changes in testicular volume. CI: confidence interval; SD: standard deviation.
Fig. 2.
Forest plot of comparison between surgical or radiological intervention to conservative management, outcome: Sperm concentration. CI: confidence interval; SD: standard deviation.

Lastly, there was no statistically significant difference in other variables, including operating time and length of stay, observed. Varicocele recurrence and hydrocele have been reported with a prevalence of 0–31% and 0–13%, respectively. The quality of the studies is moderate to low.

In conclusion, currently there is a moderate level of evidence that treatment of varicocele in adolescents may improve testicular growth and sperm density.

Footnotes

Competing interests: The authors report no competing personal or financial interests.

This paper has been peer-reviewed.

References

1. Akbay E, Cayan S, Doruk E, et al. The prevalence of varicocele and varicocele-related testicular atrophy in Turkish children and adolescents. BJU Int. 2000;86:490–493. https://doi.org/10.1046/j.1464-410X.2000.00735.x. [PubMed]
2. Meacham RB, Townsend RR, Rademacher D, et al. The incidence of varicoceles in the general population when evaluated by physical examination, gray scale sonography, and colour Doppler sonography. J Urol. 1994;151:1535–8. [PubMed]
3. Pintus C, Rodriguez Matas MJ, Manzoni C, et al. Varicocele in pediatric patients: Comparative assessment of different therapeutic approaches. Urology. 2001;57:154–7. https://doi.org/10.1016/S0090-4295(00)00859-1. [PubMed]
4. Baazeem A, Belzile E, Ciampi A, et al. Varicocele and male factor infertility treatment: A new meta-analysis and review of the role of varicocele repair. Eur Urol. 2011;60:796–808. https://doi.org/10.1016/j.eururo.2011.06.018. [PubMed]
5. Waalkes R, Manea IF, Nijman JM. Varicocele in adolescents: A review and guideline for the daily practice. Archivos Espanoles de Urologia. 2012;65:859–871. [PubMed]
6. Paduch DA, Skoog SJ. Diagnosis, evaluation and treatment of adolescent varicocele. ScientificWorldJournal. 2004;4(Suppl 1):263–78. https://doi.org/10.1100/tsw.2004.76. [PubMed]
7. Stassen CM, Weil EH, Janevski BK. Left renal vein compression syndrome (“nutcracker phenomenon”) RoFo. 1989;150:708–10. https://doi.org/10.1055/s-2008-1047107. [PubMed]
8. Green KF, Turner TT, Howards SS. Varicocele: Reversal of the testicular blood flow and temperature effects by varicocele repair. J Urol. 1984;131:1208–11. [PubMed]
9. Nagler HM, Lizza EF, House SD, et al. Testicular hemodynamic changes after the surgical creation of a varicocele in the rat. Intravital microscopic observations. J Androl. 1987;8:292–8. https://doi.org/10.1002/j.1939-4640.1987.tb00964.x. [PubMed]
10. Micic S, Illic V, Isvaneski M. Correlation of hormone and histologic parameters in infertile men with varicocele. Urologia Internationalis. 1983;38:187–90. https://doi.org/10.1159/000280888. [PubMed]
11. Paduch DA, Niedzielski J. Semen analysis in young men with varicocele: Preliminary study. J Urol. 1996;156:788–90. https://doi.org/10.1016/S0022-5347(01)65816-6. [PubMed]
12. Naughton CK, Nangia AK, Agarwal A. Pathophysiology of varicoceles in male infertility. Hum Reprod Update. 2001;7:473–81. https://doi.org/10.1093/humupd/7.5.473. [PubMed]
13. Raman JD, Walmsley K, Goldstein M. Inheritance of varicoceles. Urology. 2005;65:1186–9. https://doi.org/10.1016/j.urology.2004.12.057. [PubMed]
14. Gorelick JI, Goldstein M. Loss of fertility in men with varicocele. Fertil Steril. 1993;59:613–6. https://doi.org/10.1016/S0015-0282(16)55809-9. [PubMed]
15. Dubin L, Amelar RD. Varicocele size and results of varicocelectomy in selected subfertile men with varicocele. Fertil Steril. 1970;21:606–9. https://doi.org/10.1016/S0015-0282(16)37684-1. [PubMed]
16. Kass EJ, Stork BR, Steinert BW. Varicocele in adolescence induces left and right testicular volume loss. BJU Int. 2001;87:499–501. https://doi.org/10.1046/j.1464-410X.2001.00144.x. [PubMed]
17. Alukal JP, Zurakowski D, Atala A, et al. Testicular hypotrophy does not correlate with grade of adolescent varicocele. J Urol. 2005;174:2367–70. https://doi.org/10.1097/01.ju.0000180418.23208.1d. [PubMed]
18. Cervellione RM, Corroppolo M, Bianchi A. Subclinical varicocele in the pediatric age group. J Urol. 2008;179:717–9. https://doi.org/10.1016/j.juro.2007.09.095. [PubMed]
19. Goede J, Hack WW, Sijstermans K, et al. Normative values for testicular volume measured by ultrasonography in a normal population from infancy to adolescence. Horm Res Paediatr. 2011;76:56–64. https://doi.org/10.1159/000326057. [PubMed]
20. Schiff JD, Li PS, Goldstein M. Correlation of ultrasonographic and orchidometer measurements of testis volume in adults. BJU Int. 2004;93:1015–7. https://doi.org/10.1111/j.1464-410X.2003.04772.x. [PubMed]
21. Sakamoto H, Saito K, Oohta M, et al. Testicular volume measurement: Comparison of ultrasonography, orchidometry, and water displacement. Urology. 2007;69:152–7. https://doi.org/10.1016/j.urology.2006.09.012. [PubMed]
22. Diamond DA, Paltiel HJ, DiCanzio J, et al. Comparative assessment of pediatric testicular volume: Orchidometer vs. ultrasound. J Urol. 2000;164:1111–4. https://doi.org/10.1016/S0022-5347(05)67264-3. [PubMed]
23. Diamond DA, Zurakowski D, Bauer SB, et al. Relationship of varicocele grade and testicular hypotrophy to semen parameters in adolescents. J Urol. 2007;178:1584–8. https://doi.org/10.1016/j.juro.2007.03.169. [PubMed]
24. Skoog SJ, Roberts KP, Goldstein M, et al. The adolescent varicocele: What’s new with an old problem in young patients? Pediatrics. 1997;100:112–21. https://doi.org/10.1542/peds.100.1.112. [PubMed]
25. Kolon TF, Clement MR, Cartwright L, et al. Transient asynchronous testicular growth in adolescent males with a varicocele. J Urol. 2008;180:1111–4. https://doi.org/10.1016/j.juro.2008.05.061. [PubMed]
26. Cimador M, Castagnetti M, Gattuccio I, et al. The hemodynamic approach to evaluating adolescent varicocele. Nat Rev Urol. 2012;9:247–57. https://doi.org/10.1038/nrurol.2012.41. [PubMed]
27. Kozakowski KA, Gjertson CK, Decastro GJ, et al. Peak retrograde flow: A novel predictor of persistent, progressive and new onset asymmetry in adolescent varicocele. J Urol. 2009;181:2717–22. https://doi.org/10.1016/j.juro.2009.02.038. [PubMed]
28. Poon SA, Gjertson CK, Mercado MA, et al. Testicular asymmetry and adolescent varicoceles managed expectantly. J Urol. 2010;183:731–4. https://doi.org/10.1016/j.juro.2009.10.028. [PubMed]
29. Korets R, Woldu SL, Nees SN, et al. Testicular symmetry and adolescent varicocele — does it need followup? J Urol. 2011;186:1614–8. https://doi.org/10.1016/j.juro.2011.03.068. [PubMed]
30. Van Batavia JP, Badalato G, Fast A, et al. Adolescent varicocele — is the 20/38 harbinger a durable predictor of testicular asymmetry? J Urol. 2013;189:1897–1901. https://doi.org/10.1016/j.juro.2012.11.011. [PubMed]
31. Schiff JD, Li PS, Goldstein M. Correlation of ultrasound-measured venous size and reversal of flow with Valsalva with improvement in semen-analysis parameters after varicocelectomy. Fertil Steril. 2006;86:250–2. https://doi.org/10.1016/j.fertnstert.2005.12.038. [PubMed]
32. Moursy EE, ElDahshoury MZ, Hussein MM, et al. Dilemma of adolescent varicocele: Long-term outcome in patients managed surgically and in patients managed expectantly. J Ped Urol. 2013;9:1018–22. https://doi.org/10.1016/j.jpurol.2013.01.017. [PubMed]
33. Kolon TF. Evaluation and management of the adolescent varicocele. J Urol. 2015;194:1194–201. https://doi.org/10.1016/j.juro.2015.06.079. [PubMed]
34. Fisch H, Hyun G. Varicocele repair for low testosterone. Curr Opin Urol. 2012;22:495–8. https://doi.org/10.1097/MOU.0b013e328358e0fb. [PubMed]
35. Trost LW, Mulhall JP. Challenges in testosterone measurement, data interpretation, and methodological appraisal of interventional trials. J Sex Med. 2016;13:1029–46. https://doi.org/10.1016/j.jsxm.2016.04.068. [PubMed]
36. Damsgaard J, Joensen UN, Carlsen E, et al. Varicocele is associated with impaired semen quality and reproductive hormone levels: A study of 7035 healthy young men from six European countries. Eur Urol. 2016. [Epub ahead of print]. https://doi.org/10.1016/j.eururo.2016.06.044. [PubMed]
37. Zorgniotti AW. Testis temperature, infertility, and the varicocele paradox. Urology. 1980;16:7–10. https://doi.org/10.1016/0090-4295(80)90321-0. [PubMed]
38. Hienz HA, Voggenthaler J, Weissbach L. Histological findings in testes with varicocele during childhood and their therapeutic consequences. Eur J Ped. 1980;133:139–46. https://doi.org/10.1007/BF00441582. [PubMed]
39. Garolla A, Torino M, Miola P, et al. Twenty-four-hour monitoring of scrotal temperature in obese men and men with a varicocele as a mirror of spermatogenic function. Hum Reprod. 2015;30:1006–13. https://doi.org/10.1093/humrep/dev057. [PubMed]
40. Paick JS, Park K, Kim SW, et al. Increased expression of hypoxia-inducible factor-1alpha and connective tissue growth factor accompanied by fibrosis in the rat testis of varicocele. Actas Urologicas Espanolas. 2012;36:282–8. https://doi.org/10.1016/j.acuro.2011.07.022. [PubMed]
41. Goren MR, Kilinc F, Kayaselcuk F, et al. Effects of experimental left varicocele repair on hypoxia-inducible factor-1alpha and vascular endothelial growth factor expressions and angiogenesis in rat testis. Andrologia. 2016. [Epub ahead pf print]. https://doi.org/10.1111/and.12614. [PubMed]
42. Netto NR, Jr, Lemos GC, De Goes GM. Varicocele: Relation between anoxia and hypospermatogenesis. Int J Fertil. 1977;22:174–8. [PubMed]
43. Camoglio FS, Zampieri N, Corroppolo M, et al. Varicocele and retrograde adrenal metabolites flow. An experimental study on rats. Urologia internationalis. 2004;73:337–42. https://doi.org/10.1159/000081595. [PubMed]
44. Mali WP, Oei HY, Arndt JW, et al. Hemodynamics of the varicocele. Part II. Correlation among the results of renocaval pressure measurements, varicocele scintigraphy, and phlebography. J Urol. 1986;135:489–93. [PubMed]
45. Mali WP, Arndt JW, Coolsaet BL, et al. Hemodynamic aspects of left-sided varicocele and its association with so-called right-sided varicocele. Int J Androl. 1984;7:297–308. https://doi.org/10.1111/j.1365-2605.1984.tb00787.x. [PubMed]
46. Sweeney TE, Rozum JS, Gore RW. Alteration of testicular microvascular pressures during venous pressure elevation. Am J Physiol. 1995;269:H37–45. [PubMed]
47. Gat Y, Zukerman Z, Chakraborty J, et al. Varicocele, hypoxia, and male infertility. Fluid mechanics analysis of the impaired testicular venous drainage system. Hum Reprod. 2005;20:2614–9. https://doi.org/10.1093/humrep/dei089. [PubMed]
48. Santamaria L, Martin R, Nistal M, et al. The peritubular myoid cells in the testes from men with varicocele: An ultrastructural, immunohistochemical, and quantitative study. Histopathology. 1992;21:423–33. https://doi.org/10.1111/j.1365-2559.1992.tb00426.x. [PubMed]
49. Romeo C, Santoro G. Free radicals in adolescent varicocele testis. Oxid Med Cell Longev. 2014;2014:912878. https://doi.org/10.1155/2014/912878. [PMC free article] [PubMed]
50. Jarow JP, Sanzone JJ. Risk factors for male partner antisperm antibodies. J Urol. 1992;148:1805–7. [PubMed]
51. McFadden MR, Mehan DJ. Testicular biopsies in 101 cases of varicocele. J Urol. 1978;119:372–4. [PubMed]
52. Hadziselimovic F, Leibundgut B, Da Rugna D, et al. The value of testicular biopsy in patients with varicocele. J Urol. 1986;135:707–10. [PubMed]
53. Alkaram A, McCullough A. Varicocele and its effect on testosterone: Implications for the adolescent. Transl Androl Urol. 2014;3:413–7. [PMC free article] [PubMed]
54. Bogaert G, Orye C, De Win G. Pubertal screening and treatment for varicocele do not improve chance of paternity as adult. J Urol. 2013;189:2298–303. https://doi.org/10.1016/j.juro.2012.12.030. [PubMed]

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