Varicocele

A varicocele is an abnormal dilation and tortuosity of the pampiniform plexus veins draining the testis, most commonly on the left, diagnosed on ultrasound by a pampiniform plexus vein diameter greater than 2–3 mm that further dilates or shows venous reflux lasting more than 1–2 seconds with Valsalva. It affects up to 15% of the general male population and up to 35–40% of men presenting with primary infertility, making grayscale and color/spectral Doppler ultrasound of the scrotum the reference-standard imaging study for detection, classification, and surgical planning.

Quick Reference

• Diagnostic threshold: largest pampiniform plexus vein >2–3 mm in diameter (supine or standing), with increased diameter or reflux >1 second on Valsalva
• Reflux duration cutoff: transient reflux <1 sec = physiologic; ≥1–2 sec = pathologic; persistent reflux throughout Valsalva = most severe
• Side: left >> right (left testicular vein drains at a right angle into the left renal vein); isolated right-sided varicocele is atypical and should prompt evaluation for retroperitoneal mass or situs anomaly
• ESUR-SPIWG ultrasound grades:
  • Subclinical — visible only with color Doppler/Valsalva, no palpable veins
  • Grade 1 — palpable only with Valsalva
  • Grade 2 — palpable without Valsalva
  • Grade 3 — visible through the scrotal skin
• Physical exam (Dubin-Amelar) grading: Grade I (palpable only with Valsalva), Grade II (palpable at rest), Grade III (visible at rest)
• Color Doppler ultrasound performance: sensitivity ~97%, specificity ~94% for clinically evident varicocele
• Testicular volume: should be measured (Lambert’s formula) bilaterally — ipsilateral testicular hypotrophy supports treatment in adolescents
• Report essentials: largest vein diameter (supine + standing), reflux duration and pattern, laterality, testicular volumes, and any secondary retroperitoneal finding
• Management trigger: abnormal semen parameters + clinically palpable varicocele in a man attempting conception, or progressive ipsilateral testicular hypotrophy in an adolescent

Background

Varicocele results from incompetence or absence of valves within the internal spermatic (testicular) vein, allowing retrograde venous flow into the pampiniform plexus surrounding the spermatic cord. The left testicular vein empties directly into the left renal vein at a right angle, versus the right testicular vein’s oblique, low-pressure entry into the inferior vena cava — an anatomic asymmetry that accounts for the marked left-sided predominance of varicocele (Alsaikhan et al., 2016). Left renal vein compression between the aorta and superior mesenteric artery (“nutcracker” physiology) can produce or exacerbate a left varicocele and should be considered, particularly in adolescents or lean patients, when the varicocele is large, of sudden onset, or does not decompress with recumbency (Guerroumi & Benslima, 2021).

Varicocele is the most common surgically correctable cause of male infertility. Proposed mechanisms of testicular injury include elevated intratesticular and scrotal skin temperature (reported increases of roughly 2.5°C from venous stasis, disrupting the tightly temperature-regulated process of spermatogenesis), retrograde reflux of adrenal and renal metabolites, testicular hypoxia, and oxidative stress with elevated reactive oxygen species (Agarwal et al., 2011; Pastuszak & Wang, 2015). No single mechanism fully explains the variable clinical impact, and genetic and lifestyle factors likely modulate individual susceptibility.

Imaging Anatomy

The relevant venous anatomy is the pampiniform plexus, a network of veins surrounding the testicular artery and vas deferens within the spermatic cord, coalescing cranially into the internal (testicular) spermatic vein. Key structures to interrogate and localize on ultrasound include:

• Pampiniform plexus veins — superior to and surrounding the testis within the scrotal sac and along the spermatic cord, best assessed with the patient supine and then standing
• Inguinal/supratesticular spermatic cord — dilated veins are typically most prominent here and may extend down along the posterolateral aspect of the testis
• Left renal vein and its aortomesenteric segment — relevant when nutcracker physiology is suspected as a secondary cause
• Testis parenchyma and volume — assessed in three orthogonal dimensions for Lambert’s formula (length × width × height × 0.71) to detect ipsilateral hypotrophy from chronic venous congestion
• Intratesticular veins — a less common site of dilation (intratesticular varicocele), usually contiguous with an extratesticular varicocele and to be distinguished from an intratesticular cystic mass

Imaging Findings

Ultrasound (grayscale and color/spectral Doppler)

Ultrasound is the imaging modality of choice for varicocele, though historically there has been no single universally agreed technique; the ESUR-SPIWG guidelines now standardize this (Freeman et al., 2020; Lorenc et al., 2020).

• Technique: high-frequency linear transducer (≥7.5 MHz), patient examined supine and then standing/upright, with and without Valsalva maneuver; color and spectral Doppler applied to the largest visualized vein
• Grayscale appearance: multiple anechoic, serpiginous, tubular structures ≥2–3 mm in diameter superior to and posterolateral to the testis, increasing in caliber with Valsalva or upright positioning
• Color Doppler: spontaneous or Valsalva-induced retrograde (reversed) flow filling the dilated venous channels; color flash extending toward the transducer during Valsalva confirms reflux
• Spectral Doppler: reflux duration is timed from the onset of the Valsalva-induced flow reversal; brief reflux (<1 second) is a normal variant, while reflux ≥1–2 seconds, especially if sustained through the Valsalva maneuver, is considered pathologic and correlates with more severe disease (Bagheri et al., 2018)
• Reflux pattern grading: patterns have been further subclassified (e.g., transient vs. persistent, wave morphology) as an ultrasound-based predictor of varicocele severity and its downstream effect on semen parameters
• Testicular parenchyma: usually normal echotexture; look for ipsilateral volume loss relative to the contralateral testis as a marker of chronic hemodynamic injury, particularly relevant in adolescents being considered for early repair

Other modalities

CT and MRI are not first-line for varicocele itself but may incidentally demonstrate dilated pampiniform plexus/spermatic cord veins on pelvic or retroperitoneal studies, and are useful when working up a suspected secondary cause — e.g., a retroperitoneal or renal mass causing tumor thrombus or extrinsic venous compression, or characterizing nutcracker anatomy with cross-sectional angulation and pressure gradient assessment across the aortomesenteric left renal vein segment. Venography (retrograde or antegrade spermatic venography) is now reserved largely for planning or performing percutaneous venographic embolization rather than for primary diagnosis.

Grading and Classification

Two grading systems are in routine use and should not be conflated in a report:

System	Basis	Grades
Dubin-Amelar (clinical/physical exam)	Palpation ± Valsalva	I: palpable only with Valsalva; II: palpable at rest; III: visible at rest
ESUR-SPIWG (ultrasound)	Grayscale/Doppler appearance	Subclinical; Grade 1: color Doppler/Valsalva only; Grade 2: palpable without Valsalva; Grade 3: visible through skin

The ESUR-SPIWG consensus recommends that every report explicitly state the largest vein diameter in both supine and standing positions, the presence, duration, and pattern of reflux in both positions, laterality, and bilateral testicular volumes — this standardized dataset is what drives clinical and surgical decision-making (Freeman et al., 2020).

Differential Diagnosis and Pitfalls

• Hydrocele — anechoic but non-tubular, non-compressible fluid collection surrounding the testis rather than serpiginous vascular channels; absent Doppler flow
• Epididymal cyst/spermatocele — discrete anechoic cystic structure, typically at the epididymal head, without flow and without change with Valsalva
• Inguinal hernia — bowel gas/peristalsis or omental fat tracking into the inguinal canal/scrotum, distinguishable from vascular channels on grayscale and lack of venous Doppler signal
• Isolated right-sided varicocele — uncommon and should prompt a search for a retroperitoneal or pelvic mass causing venous obstruction, IVC thrombus, or situs inversus
• Missed reflux from inadequate Valsalva — a poorly performed Valsalva maneuver can under-diagnose or under-grade a varicocele; technique standardization (upright positioning, adequate strain, sufficient observation time) is essential
• Intratesticular varicocele — can mimic a hypoechoic intratesticular lesion on grayscale; color Doppler demonstrating venous flow that augments with Valsalva, and its contiguity with an extratesticular varicocele, confirms the diagnosis and avoids unnecessary biopsy or orchiectomy

Clinical Impact and Management

Ultrasound-diagnosed varicocele correlates with abnormal semen analysis: men with a varicocele have been reported to have normal semen parameters in only about 14% of cases versus roughly 31% in men without one, with bilateral varicoceles associated with a further reduction in normal semen parameters. Reflux duration greater than 2 seconds on Doppler has been associated with greater likelihood of semen parameter improvement after varicocelectomy, making the ultrasound report directly actionable for urology. In adolescents, serial ultrasound documentation of testicular volume is used to decide whether ipsilateral hypotrophy warrants earlier surgical or percutaneous treatment rather than watchful waiting. For the report, radiologists should explicitly state laterality, vein diameter in both positions, reflux duration/pattern, and testicular volumes so referring clinicians can apply guideline-based (e.g., ESUR-SPIWG) treatment thresholds without needing to re-scan the patient.

FAQ

What ultrasound findings confirm a varicocele?

A varicocele is confirmed when the largest pampiniform plexus vein measures greater than 2–3 mm in diameter and shows an increase in diameter or venous reflux lasting at least 1–2 seconds on color/spectral Doppler during a Valsalva maneuver, ideally assessed with the patient both supine and standing.

Why do varicoceles occur almost exclusively on the left?

The left testicular vein drains into the left renal vein at a right angle, creating higher outflow resistance and turbulence, whereas the right testicular vein enters the inferior vena cava obliquely at lower pressure; left renal vein compression (nutcracker physiology) can further contribute to left-sided varicocele.

What does a right-sided-only varicocele suggest?

An isolated right varicocele is atypical and should raise concern for a retroperitoneal or pelvic mass, IVC thrombus, or situs anomaly causing venous obstruction, warranting cross-sectional imaging of the abdomen and pelvis.

How is varicocele severity graded on ultrasound?

The ESUR-SPIWG system grades varicoceles as subclinical (color Doppler/Valsalva only), Grade 1 (palpable only with Valsalva), Grade 2 (palpable without Valsalva), or Grade 3 (visible through the scrotal skin), based on ultrasound and correlated physical findings.

Does varicocele grade or reflux duration predict fertility outcomes?

Longer, more persistent venous reflux (particularly reflux sustained beyond 1–2 seconds) and higher-grade varicoceles correlate with worse semen parameters, and reflux duration greater than 2 seconds has been associated with a greater likelihood of semen improvement following varicocelectomy.

Can an intratesticular varicocele be mistaken for a testicular mass?

Yes — on grayscale it can resemble a hypoechoic intratesticular lesion, but color Doppler showing venous flow that augments with Valsalva, along with continuity with an extratesticular varicocele, establishes the correct diagnosis and avoids unnecessary biopsy.

References

1. Pauroso S, Di Leo N, Fresilli D, et al. Varicocele: ultrasonographic assessment in daily clinical practice. J Ultrasound. 2013. PMID: 23396816
2. Freeman S, Bertolotto M, Richenberg J, et al. Ultrasound evaluation of varicoceles: guidelines and recommendations of the European Society of Urogenital Radiology Scrotal and Penile Imaging Working Group (ESUR-SPIWG) for detection, classification, and grading. Eur Radiol. 2020. PMID: 31332561
3. Lorenc T, Krupski W, et al. Ultrasound evaluation of varicoceles: systematic literature review and rationale of the ESUR-SPIWG guidelines and recommendations. J Ultrason. 2020. PMID: 32720266
4. Alsaikhan B, Alrabeeah K, Delouya G, Zini A. Epidemiology of varicocele. Asian J Androl. 2016. PMID: 26763551
5. Agarwal A, Deepinder F, Cocuzza M, et al. Varicocele-induced infertility: newer insights into its pathophysiology. Indian J Urol. 2011. PMID: 21716891
6. Pastuszak AW, Wang R. Varicocele and testicular function. Asian J Androl. 2015. PMID: 25926610
7. Guerroumi H, Benslima N. Left varicocele revealing a nutcracker phenomenon. Pan Afr Med J. 2021. PMC: PMC8418162
8. Bagheri SM, Khajehasani F, Iraji H, Fatemi I. A novel method for investigating the role of reflux pattern in color Doppler ultrasound for grading of varicocele. Sci Rep. 2018. PMC: PMC5916946