Varicocele
Varicocele - Summary
A varicocele is a scrotal swelling consisting of a collection of dilated veins of the pampiniform plexus in the spermatic cord. About 95% of varicoceles occur on the left side because of the difference in drainage routes of the right and left spermatic veins.
Varicoceles generally become noticeable at puberty due to testicular growth and increased testicular blood flow.
Varicoceles occur in about 15% of men in the general population.
The man may present with concern about scrotal swelling or scrotal pain, or a varicocele may be an incidental finding on physical or ultrasonographic examination.
A varicocele is usually asymptomatic, but 2–10% of affected men may have vague dragging or heavy sensations and aching pain in the scrotum or groin.
A varicocele presents characteristically as a 'bag of worms' within the spermatic cord above the testis on the left side of the scrotum. It is more easily palpated with the man standing, especially when the Valsalva manoeuvre is performed.
In most men a varicocele does not require any treatment; however, some cases may need to be referral to secondary care:
Urgent referral to a urologist to exclude a tumour, should be done if a varicocele appears suddenly, especially if the man is older than 40 years of age and the varicocele remains tense when lying down, and if there is a solitary right-sided varicocele.
Referral to a urologist is indicated if there is uncertainty about the nature of a scrotal swelling.
Routine referral to a urologist for consideration of varicocele ablation, is indicated if it is causing distress or embarrassment, or if there is pain or discomfort.
Adolescents with a varicocele should be referred to a urologist if there are concerns about reduced ipsilateral testicular volume or if the boy or parents/guardians are concerned by appearance or symptoms and cannot be fully reassured in primary care.
Men with a left-sided varicocele should not be routinely referred for ultrasonography to look for an underlying tumour.
If referral is not indicated:
The man should be reassure that, in most men, the varicocele does not require any treatment and is not likely to cause any symptoms or long-term complications.
Associated discomfort should initially be managed by recommending supportive underwear and simple analgesia.
If relevant it should be explained that although varicoceles may be associated with fertility problems, nearly two-thirds of men who have a varicocele have no difficulty in fathering children.
For men with fertility problems, it should be explained that available evidence does not support the use of varicocele ablation to improve pregnancy rates.
Have I got the right topic?
This CKS topic covers the management of varicocele in primary care.
This CKS topic does not cover the secondary care management of varicocele.
There are separate CKS topics on Infertility and Scrotal swellings.
The target audience for this CKS topic is healthcare professionals working within the NHS in the UK, and providing first contact or primary health care.
How up-to-date is this topic?
How up-to-date is this topic?
Changes
October 2012 — reviewed. A literature search was conducted in September 2012 to identify evidence-based guidelines, UK policy, systematic reviews, and key RCTs published since the last revision of the topic. No changes to clinical recommendations have been made.
Previous changes
July to November 2008 — this is a new CKS topic. The evidence-base has been reviewed in detail, and recommendations are clearly justified and transparently linked to the supporting evidence.
Update
New evidence
Evidence-based guidelines
No new evidence-based guidelines since 1 September 2012.
HTAs (Health Technology Assessments)
No new HTAs since 1 September 2012.
Economic appraisals
No new economic appraisals relevant to England since 1 September 2012.
Systematic reviews and meta-analyses
No new systematic review or meta-analysis since 1 September 2012.
Primary evidence
No new randomized controlled trials published in the major journals since 1 September 2012.
New policies
No new national policies or guidelines since 1 September 2012.
New safety alerts
No new safety alerts since 1 September 2012.
Changes in product availability
No changes in product availability since 1 September 2012.
Goals and outcome measures
Goals
Making an accurate diagnosis
Appropriate treatment in primary care settings
Appropriate referral to secondary care or other specialist service
Providing appropriate advice to patients
Background information
Definition
What is it?
A varicocele is a scrotal swelling consisting of a collection of dilated veins of the pampiniform plexus in the spermatic cord. It may be caused by incompetent or absent valves in the testicular (spermatic) vein or, rarely, may be secondary to a tumour or other pathological process obstructing the spermatic vein [Pugh, 2000; Ellis et al, 2006; El-Saeity and Sidhu, 2006].
Varicoceles generally become noticeable at puberty due to testicular growth and increased testicular blood flow [Sandlow, 2004].
Prevalence
How common is it?
Varicoceles occur in about 15% of men in the general population [Diamond, 2007; Kroese et al, 2012].
Pathophysiology
What is the pathophysiology?
About 95% of varicoceles occur on the left side because of the difference in drainage routes of the right and left spermatic veins [Cuschieri et al, 1996; Dasgupta and Tiptaft, 2005; El-Saeity and Sidhu, 2006]:
A varicocele drains into the testicular vein within the inguinal canal on each side.
The left testicular vein then drains vertically into the left renal vein, and increased pressure in the vertical column of blood can lead to the dilation of the pampiniform plexus.
The right testicular vein drains at an oblique angle into the inferior vena cava, which gives it some protection.
Bilateral varicoceles may occur from cross-circulation from the left to right pampiniform plexus.
Diagnosis
Diagnosis of varicocele
Diagnosis
How do I know my patient has a varicocele?
The man may present with concern about scrotal swelling or scrotal pain, or a varicocele may be an incidental finding on physical or ultrasonographic examination.
A varicocele is usually asymptomatic, but 2–10% of affected men may have vague dragging or heavy sensations and aching pain in the scrotum or groin.
A varicocele presents characteristically as a 'bag of worms' within the spermatic cord above the testis on the left side of the scrotum:
The scrotum on the side of the varicocele may be seen to hang lower than on the normal side.
Dilation and tortuosity of the veins is increased on standing and is usually decreased when the man lies down. The varicocele cannot usually be palpated lying down.
Performing the Valsalva manoeuvre whilst standing increases dilation.
There may be a cough impulse.
If there is uncertainty about the diagnosis, see the CKS topic on Scrotal swellings.
Basis for recommendation
Basis for recommendation
The basis for these recommendations is expert opinion in textbooks [Schwartz, 1999; Russell et al, 2004; Sandlow, 2004; Sweetland and Conway, 2004; Browse et al, 2005; Dasgupta and Tiptaft, 2005], review articles [Junnila and Lassen, 1998; Kass, 2001], and guidelines on male infertility from the European Association of Urology [Dohle et al, 2007].
Management
Management
Scenario: Management: covers the management of men and boys (10 years of age or older) with varicocele.
Scenario: Management
Scenario: Management of varicocele
Referral
Who should I refer?
Refer urgently to a urologist to exclude a tumour:
If a varicocele appears suddenly, especially if the man is older than 40 years of age and the varicocele remains tense when lying down.
If there is a solitary right-sided varicocele.
Refer to a urologist if there is uncertainty about the nature of a scrotal swelling.
Refer routinely to a urologist for consideration of varicocele ablation:
If it is causing distress or embarrassment.
If there is pain or discomfort.
Refer adolescents with a varicocele to a urologist:
If there are concerns about reduced ipsilateral testicular volume.
If the boy or parents/guardians are concerned by appearance or symptoms and cannot be fully reassured in primary care.
Do not routinely refer men with a left-sided varicocele for ultrasonography to look for an underlying tumour.
If a varicocele is found in the male partner of an infertile couple, see the CKS topic on Infertility for more information on assessment and when to refer. The National Institute for Health and Clinical Excellence recommends that men should not be offered surgery for varicoceles as a form of fertility treatment because it does not improve pregnancy rates.
Basis for recommendation
Basis for recommendation
Most varicoceles are idiopathic without underlying malignancy. Available evidence does not support referral for ultrasonography to exclude a renal tumour in men presenting with a scrotal varicocele.
Rare serious underlying causes include impairment of venous drainage due to venous thrombosis, tumour invasion, or extrinsic compression by an intra-abdominal tumour. A varicocele (whether acute, symptomatic, or an incidental finding) will rarely be the sole feature of a renal or retroperitoneal tumour:
If an older man (> 40 years of age) presents with a newly symptomatic varicocele, especially one that does not empty on lying down, an advanced renal tumour is possible, although other clinical signs and symptoms pointing to the underlying cause are likely to be present [Cuschieri et al, 1996; Junnila and Lassen, 1998; Russell et al, 2004; Dasgupta and Tiptaft, 2005; El-Saeity and Sidhu, 2006].
When a varicocele develops only on the right side, vena caval obstruction from a renal carcinoma or other retroperitoneal tumour should be excluded [Junnila and Lassen, 1998; Dasgupta and Tiptaft, 2005].
Although experts suggest referral for consideration of ablation if the man has pain or discomfort [Junnila and Lassen, 1998], there is no good evidence to guide management. BMJ Clinical Evidence found no comparative studies of sufficient quality to guide the choice among expectant management, surgery, embolization, or sclerotherapy to relieve pain and discomfort caused by a varicocele [Shekhar Biyani et al, 2009]. However, for men with bothersome symptoms, discussion of likely benefits and possible risks of alternative management options is warranted. Most urologists accept discomfort as a valid indication for treatment [Dohle et al, 2007].
It is reasonable to counsel all adolescents with a varicocele, and their families, that the effects on future fertility are impossible to predict with absolute certainty but that the risk of infertility is probably small [Kass, 2002]. Most CKS expert reviewers believe that it is currently appropriate to manage most adolescents with a varicocele by observation and monitoring of testicular size (either by the adolescent or the clinician). Varicocele ablation should be considered for those with abnormal testicular volume [Diamond, 2007], as improvements in sperm parameters and testicular volume have been demonstrated after varicocelectomy [Okuyama et al, 1988; Laven et al, 1992].
Available evidence in a Cochrane review suggests that men should not be offered surgery for varicocele as a form of fertility treatment because it does not improve pregnancy rates. The National Institute for Health and Clinical Excellence have based their recommendation on this review, but commented that until a full report of the World Health Organization multicentre trial is published on the effect of varicocele repair on pregnancy rates, the effectiveness of varicocele repair in men with abnormal semen remains uncertain [National Collaborating Centre for Women's and Children's Health, 2004].
Advice
What advice should I give to someone who has a varicocele?
Reassure that, in most men, the varicocele does not require any treatment and is not likely to cause any symptoms or long-term complications.
Initially, manage associated discomfort by recommending supportive underwear and simple analgesia.
If relevant, explain that although varicoceles may be associated with fertility problems, nearly two-thirds of men who have a varicocele have no difficulty in fathering children.
For men with fertility problems, explain that available evidence does not support the use of varicocele ablation to improve pregnancy rates.
If varicocele ablation is being considered, explain that the urologist will fully discuss the risks and benefits of both surgical and percutaneous embolization procedures and that complications are infrequent and mild. Options for varicocele ablation include:
Surgery either by retroperitoneal, inguinal, subinguinal, or laparoscopic approaches.
Percutaneous radiographic retrograde embolization via the femoral vein.
Percutaneous antegrade embolization via the scrotum.
Basis for recommendation
Basis for recommendation
No evidence supports the wearing of close-fitting underwear, and the recommendation is based on expert advice in textbooks [Russell et al, 2004; Ellis et al, 2006].
Although varicoceles are present in many men who father children [Sandlow, 2004], evidence indicates that they are also associated with reduced fertility [Johnson et al, 1970; Kroese et al, 2012]. However, at present, the available evidence does not support the use of varicocele ablation to improve pregnancy rates.
A report from the Practice Committee of the American Society for Reproductive Medicine states that only larger varicoceles which are typically easily palpable have been clearly associated with infertility [American Society for Reproductive Medicine, 2006].
Varicocele surgery carries a small risk of wound infection, hydrocele, persistence or recurrence of the varicocele and, rarely, testicular atrophy. There may be scrotal numbness and persistent pain. Intraperitoneal complications (e.g. injury to the bowel, bladder, or major blood vessels) are uncommon. Surgery successfully eliminates more than 90% of varicoceles [American Society for Reproductive Medicine, 2006].
Percutaneous embolization may be associated with less pain, but results are variable and the spermatic vein cannot be accessed in some men [American Society for Reproductive Medicine, 2006].
Evidence
Evidence
Supporting evidence
Investigation of men with a varicocele
Evidence on investigation of men with a varicocele
Available evidence from case reports and case series does not support further investigation to look for a tumour in men presenting with a varicocele.
A systematic review investigated the evidence base for the common practice in UK radiology departments of performing an extended ultrasonographic examination to exclude a renal and/or retroperitoneal tumour if a varicocele was found on scrotal ultrasonography [El-Saeity and Sidhu, 2006]:
Medline and Embase were searched for all articles, case series, and case reports on varicocele and renal tumours and varicocele and/or retroperitoneal tumours. The bibliographies of relevant textbooks were also searched. The authors found ten case reports, two case series, and four articles.
Only 2.3% of people with a renal tumour in one case series presented with a varicocele.
Data from ten case reports and one case series suggest that a varicocele may present at a late stage of the disease in people with a renal tumour.
The authors concluded that a retroperitoneal tumour will manifest in other ways before a varicocele develops. A young man with a varicocele will almost never have a retroperitoneal tumour, and further investigation is warranted only when a varicocele develops in an older man (> 40 years of age). This will be rare, and there will most likely be other clinical manifestations of the primary tumour.
Association of varicocele with reduced fertility
Evidence on association of varicocele with reduced fertility
Varicocele has been associated with infertility, although the mechanism by which fertility is affected has not been determined.
The exact association between reduced male fertility and the presence of a varicocele is not known [Dohle et al, 2007]. In a large study of infertile couples (n = 9034 men), the prevalence of a varicocele was 12% in men with normal semen analysis and 25% in men with abnormal semen analysis [WHO, 1992]. Varicoceles are associated with:
Decreased testicular volume on the same side [WHO, 1992; Zini et al, 1997].
Increased scrotal temperature [Zorgniotti and Macleod, 1973].
Impaired semen quality; typically oligozoospermia. The total sperm count was significantly lower in men with varicoceles than in those without (p = 0.01) [WHO, 1992].
The mechanism by which fertility is affected has not been explained satisfactorily. It is possible that spermatogenesis is affected by impaired blood drainage from the testis, leading to increased scrotal temperature, hypoxia, increased testicular pressure, and reflux of adrenal metabolites [American Society for Reproductive Medicine, 2006; Kroese et al, 2012].
Surgery for varicocele as a form of fertility treatment
Evidence on the results of surgery for varicocele as a form of fertility treatment
Limited available evidence suggests that men should not be offered surgery for varicoceles as a form of fertility treatment because it does not improve pregnancy rates.
A Cochrane review attempted to evaluate the effect of varicocele treatment on pregnancy rates in men from subfertile couples [Kroese et al, 2012]:
The authors searched the Cochrane Menstrual Disorders and Subfertility Group trials register (12 September 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2004), Medline (January 1966 to May 2004), Embase (January 1985 to May 2004), and reference lists of articles. They also hand-searched 22 relevant specialist journals from their first issue until 2004, checked cross-references and references from review articles, and contacted researchers.
Randomized controlled trials were included if they reported pregnancy rates as an outcome measure and if they reported data in treated (surgical ligation or radiological embolization of the internal spermatic vein) and control groups.
One of the nine studies that met the inclusion criteria was an extension of a previously published study; this left eight studies for analysis (n = 682). All eight only included men from couples with subfertility problems. One study excluded men with sperm counts less than 5 million/mL, and one excluded men with sperm counts less than 2 million/mL and/or progressive motility less than 10%. Two trials involving clinical varicoceles included some men with normal semen analysis. Three studies specifically addressed only men with subclinical varicoceles.
The combined Peto odds ratio (OR) of the eight studies was 1.10 (95% CI 0.73 to 1.68), indicating no overall statistical benefit of varicocele treatment over expectant management in subfertile couples in whom varicocele in the man is the only abnormal finding.
Only three studies in this Cochrane review [Madgar et al, 1995; Nieschlag et al, 1998; Krause et al, 2002] included men with clinical varicoceles and abnormal semen. However, these studies had methodological flaws, including a high drop-out rate, small size, insufficient power, and exclusion of men with low sperm counts.
The authors concluded that there was no evidence that the treatment of varicocele in men from couples with unexplained fertility improves the couple's chances of conception. They state that it was not appropriate to include the results of the World Health Organization (WHO) multicentre study without full access to its scientific details, but the WHO data will be added to their review if and when they become available.
The National Institute for Health and Clinical Excellence have based their recommendation on this Cochrane systematic review but acknowledged that the exclusion of the WHO data could have made a difference to the conclusions of the review [National Collaborating Centre for Women's and Children's Health, 2004].
Not all experts agree that it was acceptable to base guideline recommendations on the Cochrane review and have challenged the decision to combine the studies in a meta-analysis, as they were heterogeneous in terms of inclusion criteria and clinical characteristics of participants [Ficarra et al, 2006]. The Cochrane review also included men with normal semen for whom varicocele repair is not recommended [American Society for Reproductive Medicine, 2006].
Further primary research to clarify the effect of varicocele treatment on pregnancy rates seems unlikely, as intracytoplasmic sperm injection is now available and no evidence suggests that spermatozoa from men with varicoceles are less likely than those from men without varicocele to achieve fertilization and embryo development in vitro [Templeton, 2003]. Further research is needed comparing the effectiveness of varicocele ligation or embolization with in vitro fertilization, taking into consideration the person's preference and the cost effectiveness of these procedures [National Collaborating Centre for Women's and Children's Health, 2004].
Search strategy
Scope of search
A literature search was conducted for guidelines and systematic reviews on the primary care management of varicocele.
Search dates
June 2008 - September 2012
Key search terms
Various combinations of searches were carried out. The terms listed below are the core search terms that were used for Medline and these were adapted for other databases. Further details are available on request.
exp varicocele/, varicocele.tw
Table 1. Key to search terms.| Search commands | Explanation |
|---|---|
| / | indicates a MeSh subject heading with all subheadings selected |
| .tw | indicates a search for a term in the title or abstract |
| exp | indicates that the MeSH subject heading was exploded to include the narrower, more specific terms beneath it in the MeSH tree |
| $ | indicates that the search term was truncated (e.g. wart$ searches for wart and warts) |
Topic specific literature search sources
American Urological Association
European Association of Urology
American Society for Reproductive Medicine
Sources of guidelines
National Institute for Health and Clinical Excellence (NICE)
Scottish Intercollegiate Guidelines Network (SIGN)
Royal College of General Practitioners
National Guidelines Clearinghouse
Guidelines International Network
NHS Scotland National Patient Pathways
Agency for Healthcare Research and Quality
Institute for Clinical Systems Improvement
National Health and Medical Research Council (Australia)
Royal Australian College of General Practitioners
British Columbia Medical Association
University of Michigan Medical School
Michigan Quality Improvement Consortium
National Resource for Infection Control
UK Ambulance Service Clinical Practice Guidelines
RefHELP NHS Lothian Referral Guidelines
Medline (with guideline filter)
Driver and Vehicle Licensing Agency
NHS Health at Work (occupational health practice)
Sources of systematic reviews and meta-analyses
Systematic reviews
Protocols
Database of Abstracts of Reviews of Effects
Medline (with systematic review filter)
EMBASE (with systematic review filter)
Sources of health technology assessments and economic appraisals
NIHR Health Technology Assessment programme
NHS Economic Evaluations
Health Technology Assessments
Canadian Agency for Drugs and Technologies in Health
International Network of Agencies for Health Technology Assessment
Sources of randomized controlled trials
Central Register of Controlled Trials
Medline (with randomized controlled trial filter)
EMBASE (with randomized controlled trial filter)
Sources of evidence based reviews and evidence summaries
Central Services Agency COMPASS Therapeutic Notes
Sources of national policy
Health Management Information Consortium (HMIC)
Patient experiences
Patient.co.uk - Patient Support Groups
Sources of medicines information
The following sources are used by CKS pharmacists and are not necessarily searched by CKS information specialists for all topics. Some of these resources are not freely available and require subscriptions to access content.
British National Formulary (BNF)
electronic Medicines Compendium (eMC)
European Medicines Agency (EMEA)
References
American Society for Reproductive Medicine (2006) Report on varicocele and infertility. Fertility and Sterility 86(Suppl 4), S93-S95.
Browse, N.L., Black, J., Burnand, K.G. and Thomas, W.E.G. (Eds.) (2005) Varicocele. In: Browse's introduction to the symptoms and signs of surgical disease. 4th edn. London: Hodder Arnold. 350.
Cuschieri, A., Hennessy, T.P.J., Greenhalgh, R.M. et al. (Eds.) (1996) Varicocele. In: Clinical surgery. Oxford: Blackwell Science. 416.
Dasgupta, P. and Tiptaft, R.C. (2005)
Diamond, D.A. (2007) Adolescent varicocele. Current Opinion in Urology 17(4), 263-267. [Abstract]
Dohle, G.R., Jungwirth, A., Colpi, G. et al. (2007) Guidelines on male infertility. ..European Association of Urology.www.uroweb.org [Free Full-text]
Ellis, H., Calne, R. and Watson, C. (Eds.) (2006) Varicocele. In: Lecture notes: general surgery. 11th edn. Oxford: Blackwell Publishing. 383.
El-Saeity, N.S. and Sidhu, P.S. (2006) "Scrotal varicocele, exclude a renal tumour." Is this evidence based? Clinical Radiology 61(7), 593-599. [Abstract]
Ficarra, V., Cerruto, M.A., Liguori, G. et al. (2006) Treatment of varicocele in subfertile men: the Cochrane Review–a contrary opinion. European Urology 49(2), 258-263. [Abstract]
Johnson, D.E., Pohl, D.R. and Rivera-Correa, H. (1970) Varicocele: an innocuous condition? Southern Medical Journal 63(1), 34-36.
Junnila, J. and Lassen, P. (1998) Testicular masses. American Family Physician 57(4), 685. [Abstract] [Free Full-text]
Kass, E.J. (2001) Adolescent varicocele. Pediatric Clinics of North America 48(6), 1559-1569. [Abstract]
Kass, E.J. (2002) The adolescent varicocele: treatment and outcome. Current Urology Reports 3(2), 100-106. [Abstract]
Krause, W., Muller, H.H., Schafer, H. and Weidner, W. (2002) Does treatment of varicocele improve male fertility? Results of the 'Deutsche Varikozelestudie', a multicentre study of 14 collaborating centres. Andrologia 34(3), 164-171. [Abstract]
Kroese, A.C.J., de Lange, N.M., Collins, J. and Evers, J.L.H. (2012) Surgery or embolization for varicoceles in subfertile men (Cochrane Review). .Issue 10.John Wiley & Sons, Ltd.www.thecochranelibrary.com [Free Full-text]
Laven, J.S., Haans, L.C., Mali, W.P. et al. (1992) Effects of varicocele treatment in adolescents: a randomized study. Fertility and Sterility 58(4), 756-762. [Abstract]
Madgar, I., Weissenberg, R., Lunenfeld, B. et al. (1995) Controlled trial of high spermatic vein ligation for varicocele in infertile men. Fertility and Sterility 63(1), 120-124. [Abstract]
National Collaborating Centre for Women's and Children's Health (2004) Fertility: assessment and treatment for people with fertility problems (full NICE guideline) [Replaced by clinical guidance 156]. .Clinical guideline 11.Royal College of Obstetricians and Gynaecologists.www.rcog.org.uk [Free Full-text]
Nieschlag, E., Gertle, L., Fischedick, A. et al. (1998) Update on treatment of varicocele: counselling as effective as occlusion of the vena spermatica. Human Reproduction 13(8), 2147-2150. [Abstract] [Free Full-text]
Okuyama, A., Nakamura, M., Namiki, M. et al. (1988) Surgical repair of varicocele at puberty: preventive treatment for fertility improvement. Journal of Urology 139(3), 562-564. [Abstract]
Pugh, M. (Ed.) (2000) Stedman's medical dictionary. 27th edn. Baltimore, MD: Lippincott Williams & Wilkins.
Russell, R.C.G., Williams, N.S. and Bulstrode, C.J.K. (Eds.) (2004) Varicocele. In: Bailey & Love's short practice of surgery. 24th edn. London: Arnold. 1407
Sandlow, J. (2004) Pathogenesis and treatment of varicoceles. British Medical Journal 328(7446), 967-968. [Free Full-text]
Schwartz, S.I. (Ed.) (1999) Varicocele. In: Principles of surgery. 7th edn. New York: McGraw-Hill. 1761.
Shekhar Biyani, C., Cartledge, J. and Janetschek, G. (2009) Varicocele. Clinical Evidence..BMJ Publishing Ltd.www.clinicalevidence.com [Free Full-text]
Sweetland, H. and Conway, K. (Eds.) (2004) Scrotal problems. In: Crash course: surgery. 2nd edn. Edinburgh: Mosby. 198-200.
Templeton, A. (2003) Varicocele and infertility. Lancet 361(9372), 1838-1839.
WHO (1992) The influence of varicocele on parameters of fertility in a large group of men presenting to infertility clinics. Fertility and Sterility 57(6), 1289-1293. [Abstract]
Zini, A., Buckspan, M., Berardinucci, D. and Jarvi, K. (1997) The influence of clinical and subclinical varicocele on testicular volume. Fertility and Sterility 68(4), 671-674. [Abstract]
Zorgniotti, A.W. and Macleod, J. (1973) Studies in temperature, human semen quality, and varicocele. Fertility and Sterility 24(11), 854-863.