My testicles have suddenly descended and appear smaller; what are the possible causes and do I need urgent urologic evaluation?

Sudden Testicular Descent and Apparent Size Reduction

If your testicles have suddenly descended lower and appear smaller, this warrants urgent evaluation with scrotal ultrasound to rule out testicular torsion or other acute pathology—do not delay seeking medical attention.

Immediate Triage: Is This an Emergency?

The sudden change in testicular position and appearance requires rapid assessment because certain conditions can cause irreversible damage within 6 hours. 1

Red Flags Requiring Emergency Department Evaluation:

• Acute scrotal pain accompanying the change—testicular torsion typically presents with abrupt pain, though pain can sometimes be mild or absent in partial torsion 1
• Nausea or vomiting associated with testicular symptoms 1
• Firm, tender, or abnormally positioned testis on self-examination 1
• Sudden onset (within hours to days) rather than gradual change 1

If any of these features are present, proceed immediately to an emergency department for scrotal Doppler ultrasound. 1, 2, 3

Understanding "Sudden Descent" and Apparent Size Change

Normal Anatomical Variation vs. Pathology:

The scrotum's position varies with temperature, cremasteric muscle tone, and body position—this is physiologic. However, sudden persistent change accompanied by apparent size reduction suggests pathology rather than normal variation. 1

Most Likely Causes by Clinical Context:

If Accompanied by Pain (Even Mild):

• Testicular torsion—the spermatic cord twists, cutting off blood supply; the affected testis may appear higher initially but can hang abnormally as swelling develops, and may look smaller due to ischemia 1, 2
• Epididymitis/epididymo-orchitis—infection causes swelling that can alter testicular position; the testis itself may appear relatively smaller compared to the enlarged, inflamed epididymis 1
• Torsion of testicular appendages—more common in prepubertal boys but can occur in adults; causes localized pain and swelling 1

If Painless or Minimally Symptomatic:

• Testicular atrophy—volumes below 12 mL are considered atrophic and associated with impaired spermatogenesis, hormonal dysfunction, or prior injury 4
• Chronic conditions becoming apparent—longstanding atrophy from prior cryptorchidism, varicocele, or hormonal disorders may suddenly become noticeable 1, 4
• Hydrocele or fluid accumulation—can make the testis appear to hang lower and seem relatively smaller within the enlarged scrotum 2, 3

Diagnostic Approach

First-Line Imaging:

Scrotal Doppler ultrasound is mandatory to determine the cause of sudden testicular changes. 1, 2, 3

• Sensitivity of 91.7% and specificity of 99.2% for detecting testicular torsion when combined with clinical assessment 1
• Identifies the "whirlpool sign" (twisted spermatic cord) with 96% sensitivity for torsion 1
• Assesses testicular perfusion via color Doppler—absent or decreased flow indicates torsion 1
• Measures testicular volume accurately using the Lambert formula (Length × Width × Height × 0.71) 4
• Distinguishes intratesticular from extratesticular pathology with 98-100% accuracy 5

Key Ultrasound Findings to Correlate:

• Testicular volume <12 mL is definitively atrophic and warrants further workup 4
• Size discrepancy >2 mL or 20% between testes requires investigation for underlying pathology 4
• Heterogeneous echotexture suggests nonviable testis or tumor 1
• Absent or reversed diastolic flow on spectral Doppler indicates torsion 1

Conditions Associated with Testicular Atrophy

If ultrasound confirms reduced testicular volume (<12 mL), consider these etiologies: 4

Primary Testicular Dysfunction (Elevated FSH):

• Klinefelter syndrome (47,XXY)—most common genetic cause of primary testicular failure 4
• History of cryptorchidism—especially if uncorrected or corrected late; increases atrophy and cancer risk 1, 4
• Prior chemotherapy or radiation—causes irreversible testicular damage 4
• Autoimmune orchitis—can produce painless bilateral atrophy 4
• Myotonic dystrophy—associated with primary gonadal failure 4

Secondary Testicular Dysfunction (Low/Normal FSH):

• Anabolic steroid or exogenous testosterone use—suppresses spermatogenesis and causes atrophy that can persist for months to years after cessation 4
• Chronic opioid use—suppresses GnRH secretion 4
• Hyperprolactinemia—from pituitary adenoma or medications 4

Systemic Conditions:

• Type 2 diabetes/metabolic syndrome—linked to functional hypogonadism 4
• Chronic liver disease (cirrhosis)—contributes to secondary hypogonadism 4
• Chronic kidney disease—associated with decreased testosterone production 4

Recommended Workup Algorithm

Step 1: Urgent Scrotal Doppler Ultrasound

Obtain within hours if any concern for torsion; within days if painless but sudden change. 1, 2, 3

Step 2: If Ultrasound Shows Atrophy (Volume <12 mL):

Obtain morning serum hormones (08:00-10:00 h) on two separate occasions: 4

• FSH, LH, total testosterone—to differentiate primary from secondary hypogonadism 4
• Prolactin—to exclude hyperprolactinemia 4
• Karyotype analysis—if FSH elevated and volume <12 mL, to screen for Klinefelter syndrome 4

Step 3: Assess Cancer Risk

Men under 30-40 years with testicular volume <12 mL have ≥34% risk of intratubular germ cell neoplasia (TIN) if testicular cancer develops. 4

High-risk features requiring urology referral: 4

• Age <30-40 years with volume <12 mL
• History of cryptorchidism
• Presence of any testicular mass
• Rapid progressive atrophy

If untreated, 70% of TIN-positive testes progress to invasive cancer within 7 years. 4

Step 4: Fertility Assessment

• Semen analysis—testicular volume <12 mL strongly correlates with impaired spermatogenesis, reduced sperm count, and decreased concentration 4
• Discuss sperm banking before any intervention or testosterone therapy 4
• Repeat semen analysis every 6-12 months to monitor for declining parameters 4

Critical Management Pitfalls to Avoid

• Never assume a sudden testicular change is benign without imaging confirmation—even small, mobile masses require ultrasound 5
• Never delay ultrasound for suspected torsion—irreparable damage occurs within 6 hours 1
• Never start testosterone replacement without clarifying fertility intentions—exogenous testosterone causes azoospermia that may take months to years to recover 4
• Never perform scrotal-approach biopsy for suspected tumor—this violates lymphatic drainage patterns; radical inguinal orchiectomy is the standard approach 5

When to Refer to Urology

Urgent (Within 24-48 Hours):

• Any solid intratesticular mass detected on ultrasound 5
• Testicular volume <12 mL in men <30-40 years, especially with cryptorchidism history 4
• Rapid progressive atrophy 4

Routine (Within 2-4 Weeks):

• Confirmed testicular atrophy (volume <12 mL) with elevated FSH 4
• Infertility concerns with abnormal semen analysis 4
• Size discrepancy >2 mL or 20% between testes 4

Patient Counseling Points

• Teach testicular self-examination—monthly palpation to detect masses or further changes 4
• Avoid exogenous testosterone or anabolic steroids—these will worsen atrophy and suppress fertility 4
• Monitor for symptoms of hypogonadism—decreased libido, erectile dysfunction, fatigue, loss of muscle mass 4
• Discuss fertility preservation options if testicular volume is borderline or declining 4