What are the implications of a testicular biopsy in the contralateral testis of an undescended testis using a 14g Trucut (core biopsy) needle versus fine-needle aspiration cytology (FNAC) on future fertility?

Testicular Biopsy Technique and Fertility Implications in Contralateral Testis

For contralateral testicular biopsy in the setting of undescended testis, use an open incisional biopsy approach rather than 14-gauge Tru-Cut needle or fine-needle aspiration, as guidelines specifically mandate proper tissue handling with Stieve's or Bouin's fixation for accurate detection of testicular intraepithelial neoplasia (TIN), which cannot be reliably achieved with needle techniques. 1, 2

Recommended Biopsy Technique

Open Incisional Biopsy is Standard

• The inguinal approach with early spermatic cord control at the internal inguinal ring is mandatory before any testicular manipulation to prevent tumor spread and ensure proper surgical technique 1, 3
• Open biopsy allows adequate tissue sampling for histological assessment of TIN, which has very high sensitivity and specificity when performed correctly 1
• Tissue must be preserved in Stieve's or Bouin's solution—NOT formalin—for proper TIN detection, which is impossible with needle biopsy techniques that typically use formalin fixation 1, 2

Why Needle Biopsy is Inadequate

• While fine-needle aspiration (FNA) and Tru-Cut needle biopsies can assess spermatogenesis patterns, they cannot reliably detect TIN because they provide insufficient tissue architecture and require specialized fixation 4, 5, 6
• FNA provides cytological assessment and can detect mature sperm, but lacks the histological architecture needed for TIN diagnosis 5, 6, 7, 8
• The primary indication for contralateral biopsy in undescended testis is TIN detection, not spermatogenesis assessment, making needle techniques inappropriate 1

Fertility Implications of Contralateral Biopsy

Risk Profile in Undescended Testis

• Patients with unilateral undescended testis have 3-5% risk of TIN in the contralateral descended testis, with highest risk (≥34%) when testicular volume is <12 ml and age <40 years 1
• The contralateral descended testis in unilateral cryptorchidism may have structural abnormalities including smaller volume, softer consistency, and lower spermatogonia/tubule ratios, indicating baseline impairment independent of biopsy 1
• If untreated, TIN progresses to invasive testicular cancer in 70% of cases within 7 years 1

Direct Fertility Impact of Biopsy

• Open testicular biopsy has minimal direct impact on future fertility when performed properly by experienced surgeons using appropriate technique 4
• The theoretical concern about post-biopsy fibrosis affecting future sperm extraction for ICSI is mentioned but not substantiated with significant clinical evidence 7
• The decision to perform biopsy should be patient-driven, as survival is nearly 100% regardless of whether biopsy or surveillance is chosen 1

Clinical Decision Algorithm

When to Offer Contralateral Biopsy

1. High-risk patients: Testicular atrophy (volume <12 ml) AND age <40 years = ≥34% TIN risk 1
2. Timing: Perform at time of orchiectomy for the undescended testis to avoid second procedure 1
3. Post-chemotherapy: Wait minimum 2 years after chemotherapy before biopsy, as chemotherapy eradicates TIN in two-thirds of patients 1

Patient Counseling Points

• Inform patients that biopsy detection of TIN allows definitive treatment (radiotherapy 20 Gy) but destroys fertility 1
• Surveillance is an acceptable alternative with regular ultrasound monitoring, accepting the risk of delayed cancer detection 1
• Fertility potential is often already compromised in this population independent of biopsy 1
• Paternity rates with unilateral cryptorchidism approach normal, so preserving the contralateral testis function is paramount 1

Critical Pitfalls to Avoid

• Never perform scrotal violation or scrotal approach for biopsy—always use inguinal approach 1, 3
• Never use formalin fixation—only Stieve's or Bouin's solution for TIN detection 1, 2
• Never use 14-gauge Tru-Cut or FNA as substitute for open biopsy when TIN detection is the indication, as these techniques lack the histological architecture and proper fixation required 1, 2, 4
• Do not perform biopsy in patients who have received chemotherapy within the past 2 years 1