
A varicocele is a condition where the veins in the scrotum become enlarged, potentially impacting sperm production and quality. Specifically, a Grade 3 varicocele is a severe case where the enlarged veins are visible to the naked eye. Explaining that sperm count is variable and discussing how a grade 3 varicocele negatively affects sperm count and motility.
The severity of a varicocele can significantly affect sperm count and quality. Research indicates that men with a severe varicocele may experience a decline in sperm count, making it a concern for fertility.
Understanding the impact of a Grade 3 varicocele on sperm count is crucial for men facing fertility issues. This condition can lead to reduced sperm quality and quantity, affecting overall reproductive health.
Key Takeaways
- Varicocele severity can impact sperm count and quality.
- A Grade 3 varicocele is a severe case with visible enlarged veins.
- Men with severe varicocele may experience a decline in sperm count.
- Understanding varicocele’s impact on sperm is crucial for fertility.
- Varicocele can lead to reduced sperm quality and quantity.
Understanding Varicocele and Its Impact on Male Fertility

Understanding varicocele is crucial for addressing its impact on male fertility, as it is a correctable cause of infertility. Varicocele, a condition characterized by the enlargement of the veins within the scrotum, affects a significant portion of the male population.
What is a Varicocele?
A varicocele is essentially a swelling of the veins that drain the testicle, similar to varicose veins in the legs. This condition can lead to a range of complications, including impaired testicular function and reduced sperm quality. The exact cause of varicocele is not always clear, but it is believed to be related to faulty valves within the veins.
How Varicoceles Affect Testicular Health
Varicoceles can have a detrimental effect on testicular health by impairing the testicles’ ability to regulate temperature, a critical factor for sperm production. The pooling of blood due to the enlarged veins can lead to increased testicular temperature, negatively affecting sperm development and quality.
The Connection Between Varicocele and Infertility
The relationship between varicocele and infertility is well-documented, with varicocele being a leading cause of male infertility. The condition can affect sperm count, motility, and morphology, all of which are critical factors in fertility. Addressing varicocele through appropriate medical interventions can potentially improve fertility outcomes.
The Varicocele Grading System Explained

The varicocele grading system is essential for assessing the severity of the condition and understanding its impact on male fertility. This system categorizes varicoceles into different grades based on their severity, which is crucial for understanding the condition’s progression and planning appropriate treatment.
Grade 1 Varicocele Characteristics
A Grade 1 varicocele is the least severe form. It is not visible to the naked eye and can only be detected through a Valsalva maneuver during a physical examination. At this stage, the varicocele is typically small and might not cause significant discomfort or fertility issues.
Grade 2 Varicocele Characteristics
A Grade 2 varicocele is more pronounced than Grade 1 and can be detected without a Valsalva maneuver. It is still not visible to the naked eye but is palpable during a physical examination. Grade 2 varicoceles may start causing some discomfort and could potentially affect fertility.
Grade 3 Varicocele Characteristics
A Grade 3 varicocele is the most severe form and is visible to the naked eye. It represents a significant enlargement of the veins in the scrotum and can cause considerable discomfort. Grade 3 varicoceles are associated with more pronounced fertility issues due to the increased severity of the condition.
Understanding these grades is essential for men to comprehend their condition and the potential impacts on their fertility. The progression from one grade to another can vary, and regular medical check-ups are crucial for monitoring the condition.
Grade3 Varicocele: The Most Severe Form
The most severe manifestation of varicocele is observed in Grade 3, where the enlarged veins are visibly pronounced without the need for any medical maneuver. This advanced stage is characterized by significant testicular volume loss, as indicated by various studies. Understanding the physical characteristics, diagnosis, and symptoms associated with Grade 3 varicocele is crucial for men experiencing fertility issues or testicular discomfort.
Physical Characteristics and Diagnosis
A Grade 3 varicocele is identifiable through its visible enlargement of the veins within the scrotum. Unlike lower grades that may require a Valsalva maneuver for detection, Grade 3 varicoceles are apparent to both the patient and the examining physician. Diagnosis is primarily clinical, supported by physical examination and potentially confirmed through ultrasound imaging.
The physical characteristics of a Grade 3 varicocele include a palpable and visible mass in the scrotum, often described as a “bag of worms.” This description is due to the tortuous and dilated nature of the veins.
Common Symptoms and Discomfort Levels
Men with Grade 3 varicocele often report a range of symptoms, from mild discomfort to significant pain. The discomfort can be exacerbated by standing or physical activity and may be relieved by lying down. Symptoms can include a dull ache, heaviness, or pain in the testicle, which can impact quality of life. “The pain associated with Grade 3 varicocele can be quite debilitating for some men, affecting their daily activities,” as noted in clinical observations.
Progression from Lower Grades to Grade3
The progression from lower grades of varicocele to Grade 3 involves the gradual enlargement of the affected veins over time. Factors influencing this progression include genetic predisposition, hormonal influences, and potentially, lifestyle factors. Monitoring and timely intervention are crucial to prevent the progression to Grade 3, where fertility and testicular health are significantly impacted.
As varicocele progresses, the increased venous pressure and potential testicular atrophy can lead to decreased fertility. Understanding the stages of varicocele progression is vital for early detection and management.
The Relationship Between Varicocele Severity and Sperm Count
Understanding the relationship between varicocele severity and sperm count is essential for diagnosing male infertility. Varicocele, a condition that affects a significant percentage of men, is characterized by the enlargement of veins within the scrotum, potentially impacting sperm production.
Normal Sperm Count Parameters
A normal sperm count is typically considered to be at least 15 million sperm per milliliter of semen. However, the total sperm count, motility, and morphology are also crucial factors in determining fertility. According to the World Health Organization (WHO), a healthy sperm count ranges from 39 million to 928 million per ejaculate.
Normal Sperm Count Ranges:
|
Parameter |
Normal Range |
|---|---|
|
Sperm Concentration |
15 million – 200 million per ml |
|
Total Sperm Count |
39 million – 928 million per ejaculate |
|
Sperm Motility |
32% – 75% progressively motile |
How Varicocele Severity Correlates with Sperm Production
Studies have shown that the severity of varicocele directly impacts sperm production. Men with higher grades of varicocele tend to have lower sperm counts and reduced sperm motility. The exact mechanism is not fully understood, but it’s believed that the increased venous pressure and temperature within the testicles impair spermatogenesis.
“Varicocele is a major cause of male infertility, and its severity is directly correlated with the degree of impairment in sperm production.” –
Temperature Regulation and Sperm Formation
Temperature regulation plays a critical role in sperm formation. The testes are naturally maintained at a temperature slightly lower than the body’s core temperature, which is essential for spermatogenesis. Varicocele can disrupt this delicate temperature balance, leading to impaired sperm production.
The relationship between varicocele severity and sperm count is complex and influenced by multiple factors, including temperature regulation within the scrotum. Understanding these dynamics is crucial for the diagnosis and treatment of male infertility associated with varicocele.
Typical Sperm Count in Men with Grade3 Varicocele
Understanding the effects of Grade 3 varicocele on sperm count is essential for fertility assessments. Men with this condition often face challenges related to reduced sperm production.
Statistical Data on Sperm Count Reduction
Studies have shown that men with Grade 3 varicocele typically experience a significant reduction in sperm count. According to research, the average sperm count in these individuals can be substantially lower than in those without the condition.
|
Varicocele Grade |
Average Sperm Count (million/ml) |
|---|---|
|
No Varicocele |
60-80 |
|
Grade 1 |
50-70 |
|
Grade 2 |
30-50 |
|
Grade 3 |
10-30 |
As shown in the table, the average sperm count decreases as the varicocele grade increases. Men with Grade 3 varicocele often have sperm counts that are significantly lower, typically ranging from 10 to 30 million/ml.
Individual Variation Factors
It’s crucial to note that individual variations exist, and not all men with Grade 3 varicocele will experience the same level of sperm count reduction. Factors such as overall health, lifestyle, and the presence of other fertility issues can influence sperm production.
“The impact of varicocele on sperm count can vary significantly among individuals, highlighting the need for personalized fertility assessments.”
Comparing Sperm Counts Across Varicocele Grades
Comparing sperm counts across different varicocele grades provides valuable insights into the progressive nature of the condition. As varicocele severity increases, sperm count tends to decrease, underscoring the importance of early diagnosis and treatment.
- Grade 1 varicocele: mild impact on sperm count
- Grade 2 varicocele: moderate reduction in sperm count
- Grade 3 varicocele: significant decrease in sperm count
This comparison highlights the correlation between varicocele severity and sperm production, emphasizing the need for timely intervention to preserve fertility.
Beyond Numbers: Sperm Quality Issues in Grade3 Varicocele
Beyond reducing sperm count, Grade3 varicocele compromises various aspects of sperm health. The condition’s impact on sperm quality is multifaceted, affecting not just the quantity but also the overall viability of sperm.
Impact on Sperm Motility
Sperm motility, or the ability of sperm to move properly through the female reproductive tract, is significantly affected in men with Grade3 varicocele. Research indicates that the increased temperature and oxidative stress associated with varicocele can impair sperm motility, making it harder for sperm to reach and fertilize an egg.
Key factors affecting sperm motility in Grade3 varicocele include:
- Increased scrotal temperature
- Oxidative stress and inflammation
- Impaired testicular function
Effects on Sperm Morphology
Sperm morphology, referring to the shape and structure of sperm, is another critical aspect of sperm health impacted by Grade3 varicocele. Abnormal morphology can hinder the sperm’s ability to penetrate the egg, thus affecting fertility.
The relationship between varicocele and sperm morphology is complex, involving factors such as hormonal imbalances and testicular damage. Studies have shown that correcting varicocele can lead to improvements in sperm morphology.
DNA Fragmentation and Genetic Material Integrity
DNA fragmentation, or the breaking or fragmentation of DNA strands within sperm, is a significant concern in men with Grade3 varicocele. High levels of DNA fragmentation can lead to reduced fertility, increased risk of miscarriage, and potential genetic abnormalities in offspring.
The mechanisms behind DNA fragmentation in varicocele involve oxidative stress, which damages the DNA. Assessing DNA fragmentation is crucial for understanding the full impact of Grade3 varicocele on male fertility and for guiding treatment decisions.
Diagnosing a Grade3 Varicocele and Assessing Sperm Health
Diagnosing a Grade 3 varicocele involves a multi-faceted approach that includes physical examination, imaging techniques, and semen analysis. This comprehensive diagnostic process is crucial for understanding the severity of the varicocele and its impact on sperm health.
Physical Examination Techniques
A physical examination is the first step in diagnosing a Grade 3 varicocele. During this examination, the healthcare provider will typically ask the patient to stand and strain, which can help identify the varicocele by feeling the enlarged veins in the scrotum. The varicocele is usually described as feeling like a “bag of worms.”
Ultrasound and Other Imaging Methods
Ultrasound imaging plays a critical role in confirming the diagnosis of a Grade 3 varicocele. It helps to visualize the varicocele and assess its size and severity. Varicocele ultrasound findings can provide detailed information about the condition, including the diameter of the veins and the presence of any reflux.
Comprehensive Semen Analysis Process
A comprehensive semen analysis is essential for assessing the impact of a Grade 3 varicocele on sperm health. This analysis evaluates various parameters, including sperm count, motility, morphology, and DNA fragmentation. The results can help healthcare providers understand the extent to which the varicocele is affecting fertility.
Semen analysis varicocele assessments are critical for determining the best course of treatment and for predicting the likelihood of successful fertility outcomes.
The Progression of Varicocele: From Grade1 to Grade3
Varicocele progression from Grade1 to Grade3 is a complex process that affects male fertility. Understanding this progression is essential for men diagnosed with varicocele, as it can significantly impact their reproductive health.
Timeline of Varicocele Development
The timeline for varicocele development can vary significantly among individuals. Research suggests that varicocele can progress over several years, with some men experiencing a rapid progression from Grade1 to Grade3 within a few years, while others may remain at a lower grade for an extended period.
Factors influencing the timeline include:
- Genetic predisposition
- Lifestyle factors such as diet and exercise
- Presence of other medical conditions
Risk Factors for Progression
Several risk factors can contribute to the progression of varicocele from Grade1 to Grade3. Identifying these factors is crucial for managing the condition effectively.
|
Risk Factor |
Description |
Impact on Progression |
|---|---|---|
|
Age |
Varicocele can progress with age if left untreated. |
Higher risk of progression in younger men |
|
Lifestyle |
Poor diet, lack of exercise, and smoking can exacerbate varicocele. |
Increased risk of progression |
|
Genetics |
Family history can play a role in varicocele severity. |
Higher risk if there’s a family history |
Warning Signs of Worsening Condition
Men with varicocele should be aware of the warning signs that indicate a worsening condition. These include:
- Increased pain or discomfort in the scrotum
- Visible or palpable enlargement of the veins
- Changes in sperm quality or count
Recognizing these signs early can help in seeking timely medical intervention, potentially preventing further progression to Grade3 varicocele.
Treatment Options for Grade3 Varicocele
The treatment of Grade 3 varicocele is multifaceted, involving both traditional surgical methods and modern embolization techniques. Men diagnosed with this condition have several options to consider, each with its benefits and potential outcomes.
Surgical Approaches
Surgical approaches for Grade 3 varicocele involve several techniques, including open varicocelectomy, laparoscopic varicocelectomy, and microsurgical varicocelectomy. These methods aim to repair or remove the varicocele, potentially improving sperm quality and fertility. Microsurgical varicocelectomy is often considered the gold standard due to its high success rate and lower risk of complications.
Embolization Procedures
Embolization is a minimally invasive procedure that blocks the blood flow to the varicocele. It’s performed by inserting a catheter through a vein in the groin or neck and guiding it to the varicocele under imaging guidance. This method is less invasive than surgery and can be effective in reducing symptoms and improving fertility.
Comparing Treatment Effectiveness for Sperm Recovery
Both surgical and embolization treatments have shown effectiveness in improving sperm count and fertility in men with Grade 3 varicocele. However, the choice between them depends on various factors, including the patient’s overall health, the severity of the varicocele, and personal preferences. Studies have shown that successful treatment can lead to significant improvements in sperm parameters and pregnancy rates.
Recovery of Sperm Production After Grade3 Varicocele Treatment
The effectiveness of Grade 3 varicocele treatment in restoring sperm production is well-documented. Studies have shown that treating this condition can lead to significant improvements in both sperm count and quality.
Timeline for Sperm Count Improvement
After treatment, the timeline for observing improvements in sperm count can vary. Generally, men can expect to see changes within 3 to 6 months post-treatment, with some studies indicating continued improvement up to 12 months or more.
Factors Affecting Recovery Speed
Several factors can influence the speed of recovery in sperm production after Grade 3 varicocele treatment. These include:
- Age of the patient
- Pre-treatment sperm count and quality
- Type of treatment received (surgical vs. embolization)
- Presence of other fertility issues
Younger men and those with less severe initial sperm count impairments tend to have faster and more significant recoveries.
Success Rate Statistics and Expectations
Success rates for varicocele treatment in improving sperm count are generally high. A meta-analysis of various studies found that varicocele repair can significantly improve semen parameters in men with clinical varicocele.
|
Treatment Outcome |
Average Improvement |
Range of Improvement |
|---|---|---|
|
Sperm Count |
50% |
20-80% |
|
Sperm Motility |
30% |
10-50% |
|
Pregnancy Rate |
40% |
20-60% |
It’s essential for men undergoing Grade 3 varicocele treatment to have realistic expectations and to discuss their individual prognosis with a healthcare provider.
Grade3 Varicocele and Testosterone Levels
Varicocele, particularly Grade 3, has been linked to alterations in testosterone levels, affecting male fertility. Testosterone is a crucial hormone in males, responsible for sperm production, libido, and overall reproductive health.
How Varicocele Affects Hormone Production
Research suggests that varicocele can impact testosterone production by affecting testicular temperature regulation and blood flow. This can lead to a decrease in testosterone levels, potentially causing issues such as low libido, erectile dysfunction, and infertility.
The exact mechanisms by which varicocele influences hormone production are complex and involve multiple factors, including:
- Impaired testicular function due to increased temperature
- Reduced blood flow and oxygenation to the testes
- Potential oxidative stress and inflammation
Testosterone Restoration After Treatment
Treatment of Grade 3 varicocele can potentially restore normal testosterone levels. Surgical varicocelectomy or embolization procedures aim to correct the varicocele, thereby improving testicular function and hormone production.
Studies have shown that successful treatment can lead to significant improvements in testosterone levels, with some men experiencing:
- Increased libido
- Improved erectile function
- Enhanced fertility
Hormonal Imbalances and Fertility
Hormonal imbalances, particularly low testosterone, can significantly impact fertility. Men with Grade 3 varicocele are at a higher risk of experiencing these imbalances, making timely treatment crucial.
Key factors affecting fertility in men with hormonal imbalances include:
- Reduced sperm count and quality
- Impaired sperm motility and morphology
- Decreased libido and sexual function
In conclusion, Grade 3 varicocele can have a profound impact on testosterone levels and overall male fertility. Understanding the relationship between varicocele and hormone production is essential for developing effective treatment strategies.
Living with Untreated Grade3 Varicocele
Living with an untreated Grade3 varicocele can have significant implications on a man’s fertility and overall well-being. The condition, characterized by the enlargement of the veins within the scrotum, can lead to a variety of health issues if not addressed.
Progressive Fertility Decline Risks
One of the most significant risks associated with untreated Grade3 varicocele is the progressive decline in fertility. Studies have shown that varicocele can lead to a decrease in sperm count, motility, and morphology, making it challenging for couples to conceive.
The exact mechanism by which varicocele affects fertility is not fully understood, but it is believed that the pooling of blood in the scrotum leads to an increase in testicular temperature, which can impair sperm production.
|
Varicocele Grade |
Impact on Sperm Count |
Fertility Implications |
|---|---|---|
|
Grade 1 |
Minimal impact |
Less likely to affect fertility significantly |
|
Grade 3 |
Significant reduction |
Higher risk of infertility |
Pain Management Strategies
Managing pain associated with untreated Grade3 varicocele is crucial for maintaining quality of life. Several strategies can be employed, including:
- Over-the-counter pain relief medications
- Supportive underwear to reduce discomfort
- Avoiding heavy lifting or strenuous activities
In some cases, more invasive treatments may be necessary to alleviate pain and address the underlying condition.
Quality of Life Considerations
Living with untreated Grade3 varicocele can have broader implications on a man’s quality of life, beyond just fertility and pain. It can affect daily activities, emotional well-being, and overall health.
Men with untreated Grade3 varicocele should be aware of these potential impacts and discuss their options with a healthcare provider to determine the best course of action.
Fertility Preservation Options for Men with Grade3 Varicocele
Fertility preservation is a critical consideration for men with Grade3 varicocele. The condition’s impact on sperm quality and quantity necessitates proactive measures to safeguard reproductive potential.
Sperm Banking Considerations
Sperm banking, or cryopreservation, is a widely accepted method for fertility preservation. It involves freezing sperm samples for potential future use in assisted reproductive technologies.
The process begins with a semen analysis to assess sperm quality and quantity. Men with Grade3 varicocele may have compromised sperm parameters, making it essential to discuss the viability of their sperm with a fertility specialist.
Key considerations for sperm banking include:
- Initial sperm quality and quantity
- Potential for future improvement with treatment
- Cost and storage implications
- Legal and ethical considerations regarding stored sperm
Assisted Reproductive Technologies
Assisted reproductive technologies (ART) offer hope for men with Grade3 varicocele to father children. These technologies include in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).
|
ART Method |
Description |
Relevance to Grade3 Varicocele |
|---|---|---|
|
IVF |
Involves fertilizing an egg with sperm outside the body |
Can be used with compromised sperm quality |
|
ICSI |
Involves injecting a single sperm into an egg |
Particularly useful for severe male factor infertility, such as in Grade3 varicocele |
Timing of Intervention for Optimal Results
The timing of fertility preservation and intervention is crucial for men with Grade3 varicocele. Early consideration of sperm banking and ART can significantly improve outcomes.
Men should consult with fertility specialists to determine the best course of action based on their individual circumstances, including the severity of their varicocele and overall reproductive health.
Preventive Measures and Lifestyle Modifications
Managing Grade 3 varicocele effectively requires a combination of preventive measures and lifestyle modifications. By adopting certain changes, individuals can potentially alleviate symptoms and improve their testicular health.
Activities to Avoid with Grade 3 Varicocele
Certain activities can exacerbate the condition of Grade 3 varicocele. It is advisable to avoid heavy lifting, as it can increase abdominal pressure and worsen the varicocele. Similarly, standing for long periods can also have a negative impact. Regular breaks and positional changes can help mitigate these effects.
Activities that involve straining or bending, such as weightlifting, should be approached with caution. If these activities are unavoidable, wearing supportive clothing can provide some relief.
Dietary and Supplement Recommendations
A diet rich in antioxidants can help improve overall testicular health. Foods high in vitamins C and E, such as citrus fruits and nuts, are beneficial. Including foods with zinc, like oysters and beef, can also support sperm health.
Certain supplements may also be beneficial. For instance, vitamin D supplements have been linked to improved sperm quality. However, it’s crucial to consult with a healthcare provider before adding any supplements to your regimen.
|
Nutrient |
Food Sources |
Benefits |
|---|---|---|
|
Vitamin C |
Citrus fruits, strawberries |
Antioxidant properties |
|
Zinc |
Oysters, beef, chicken |
Supports sperm health |
|
Vitamin E |
Nuts, seeds |
Antioxidant properties |
Stress Management and Testicular Health
High levels of stress can negatively impact testicular health and sperm quality. Engaging in stress-reducing activities such as meditation, yoga, or deep breathing exercises can be beneficial. Regular exercise, such as walking or jogging, can also help manage stress levels.
Ensuring adequate sleep is also crucial. Aim for 7-8 hours of sleep per night to help regulate stress hormones and support overall health.
Conclusion: Managing Expectations with Grade3 Varicocele
Managing grade 3 varicocele requires a comprehensive understanding of its impact on male fertility and the available treatment options. As discussed, a Grade 3 varicocele can significantly affect sperm count and quality, leading to potential fertility issues.
Understanding varicocele treatment expectations is crucial for individuals diagnosed with this condition. Treatment can improve sperm production and overall fertility, but the recovery timeline varies among individuals.
Grade 3 varicocele recovery expectations should be managed based on individual health, the severity of the condition, and the chosen treatment approach. With proper management and timely intervention, many men can experience improvements in their fertility.
It’s essential for individuals with Grade 3 varicocele to consult healthcare professionals to determine the best course of treatment and to discuss their specific varicocele treatment expectations and grade 3 varicocele recovery expectations.
FAQ
What is a Grade3 varicocele and how does it affect sperm count?
A Grade3 varicocele is the most severe form of varicocele, characterized by a significantly enlarged and visible vein. It can lead to a substantial decrease in sperm count due to impaired testicular function and temperature regulation.
How does varicocele severity impact sperm production?
Varicocele severity is directly correlated with sperm production. As the varicocele progresses from Grade1 to Grade3, sperm production is increasingly impaired, leading to reduced sperm count and quality.
What are the typical sperm count parameters for men with Grade3 varicocele?
Men with Grade3 varicocele often have significantly reduced sperm counts, typically below the normal range of 15 million to 200 million sperm per milliliter.
Can Grade3 varicocele cause sperm motility issues?
Yes, Grade3 varicocele can lead to sperm motility problems due to the impaired testicular environment and increased oxidative stress.
How is Grade3 varicocele diagnosed?
Diagnosis of Grade3 varicocele involves physical examination, ultrasound, and semen analysis to assess the severity of the condition and its impact on sperm health.
What are the treatment options for Grade3 varicocele?
Treatment options for Grade3 varicocele include surgical approaches, such as varicocelectomy, and embolization procedures, which aim to restore normal testicular function and improve sperm count and quality.
How long does it take for sperm count to improve after Grade3 varicocele treatment?
The timeline for sperm count improvement after treatment varies, but significant improvements can be seen within 6-12 months after successful treatment.
Can Grade3 varicocele affect testosterone levels?
Yes, Grade3 varicocele can impact testosterone production, leading to hormonal imbalances that may affect fertility and overall health.
What are the risks of living with untreated Grade3 varicocele?
Untreated Grade3 varicocele can lead to progressive fertility decline, increased risk of testicular atrophy, and chronic pain, significantly impacting quality of life.
Are there any preventive measures that can help manage Grade3 varicocele?
While there are no guaranteed preventive measures, lifestyle modifications, such as avoiding heavy lifting, maintaining a healthy diet, and managing stress, can help alleviate symptoms and support testicular health.
Can men with Grade3 varicocele preserve their fertility?
Yes, men with Grade3 varicocele can preserve their fertility through sperm banking and assisted reproductive technologies, such as IVF or ICSI, which can help achieve successful pregnancies.
National Center for Biotechnology Information. Evidence-Based Medical Insight. Retrieved from https://pubmed.ncbi.nlm.nih.gov/21620978/