Testicular Biopsy and Sperm Retrieval

Testicular tissue is sampled for two purposes: diagnostic biopsy (histology in azoospermia, tumour or intersex evaluation) and therapeutic sperm retrieval (harvesting sperm for IVF/ICSI in azoospermia or ejaculatory dysfunction). Both share the same foundations — a spermatic cord block and respect for the testicular vascular anatomy — so they are covered together here. Note that a biopsy is not routine to distinguish obstructive from non-obstructive azoospermia (usually predicted clinically). The evaluation and selection context is covered in the Male Infertility topic; ductal reconstruction on the Vasovasostomy and Vasoepididymostomy page.

Testicular Vascular Anatomy

The testicular artery arises from the anterolateral aorta just below the renal artery and, at the upper pole, divides into internal and inferior testicular branches. The main blood supply enters posteriorly, beneath the epididymis, then bifurcates into subtunical branches that run medially and laterally just deep to the tunica albuginea. These subtunical vessels are end arteries — the sole inflow to their region — so disrupting them causes segmental ischaemia. Consequently, instruments enter the testis anteromedially or anterolaterally to avoid these vessels, never through the well-vascularised anterior surface.

Spermatic Cord Block

Capture the spermatic cord against the scrotal skin at the superiormost scrotum with the non-dominant hand, securing the vas (the most posterior cord structure) within the fingers — a high block spares the epididymis and captures all afferent fibres. Pass a 23–25 gauge, 2-inch needle through the cord, aspirate (to avoid the cord vasculature), inject perivasally first, then deliver the remainder (~10 cc) during slow withdrawal. Typical agent: 5–10 mL of 1% lidocaine or 0.5% bupivacaine, alkalinised 9:1 with 8.4% sodium bicarbonate for office procedures. Because the scrotal skin is innervated separately, add a skin wheal at each biopsy site.

Testicular Biopsy

A diagnostic testicular biopsy is classically indicated in an azoospermic man whose features suggest obstruction (so intact spermatogenesis is expected) rather than spermatogenic failure:

• Normal serum FSH
• At least one palpable vas deferens
• Normal testicular size
• Absence of anti-sperm antibodies

More broadly, biopsy is not routine to distinguish obstructive from non-obstructive azoospermia — the cause is usually predicted clinically (FSH > 7.6 IU/L with a testis < 4.6 cm → ~89% spermatogenic failure; FSH < 7.6 with a testis > 4.6 cm → ~96% obstruction) — so it is reserved for intermediate cases, cryopreserving any sperm found.

• Open (incisional) — through a 1-cm scrotal incision and a 0.5 cm tunica-albuginea incision at the upper medial or lateral pole, seminiferous tubules extrude and are excised with moistened iris scissors using a no-touch technique. Fix in Bouin's, Zenker's, or buffered glutaraldehyde — never formalin (which distorts the histology). Close the tunica albuginea with 5-0 (chromic or polypropylene) and instil 0.25% bupivacaine as a "Marcaine hydrocele" for analgesia.
• Percutaneous core (biopsy gun) — a 14-gauge, 10-cm gun with a short (1-cm) excursion through a skin nick; stabilise the testis and hold the epididymis posteriorly. It gives a small sample and risks unrecognised vessel or epididymal injury.
• Fine-needle aspiration (FNA) — an 18–25 gauge needle passed repeatedly with steady aspiration; less tissue than a core, but adequate for retrieving sperm in obstructive azoospermia.

Postoperative problems: bleeding is the commonest complication; the most serious is an inadvertent biopsy of the epididymis; and an improper fixative or crushed tissue frustrates the pathologist.

Gonadal Biopsy for a Disorder of Sex Development

Locate the gonad by laparoscopic exploration and expose it through a labioscrotal or inguinal incision. In a true hermaphrodite (an ovotestis is the commonest gonad; ~half lie in the labioscrotal fold or inguinal canal, the rest retroperitoneally) take a deep, longitudinal biopsy (testicular tissue may lie only near the hilum, and the components are oriented end-to-end). In gonadal dysgenesis, streak gonads of the XX/Turner type carry rare malignancy risk (no excision needed), whereas the XY type has a high (~30%) malignancy risk and requires immediate gonadectomy (excise the entire gonad).

Sperm Retrieval

Retrieval is indicated for azoospermia (obstructive or non-obstructive) or ejaculatory dysfunction. Check a Y-microdeletion first — complete AZFa/AZFb deletions should not undergo TESE (no sperm), whereas AZFc may yield sperm. By cause: obstructive azoospermia — sperm from either the testis or epididymis (equivalent outcomes); non-obstructive azoospermia — micro-TESE (~1.5× more successful than non-microsurgical extraction). Sperm are cryopreserved for later ICSI.

Technique	Site	Access	Best for
PESA	Epididymis	Percutaneous	Obstructive (limited motility, ↑ DNA damage; ~20% failure)
MESA	Epididymis	Microsurgical (open)	Obstructive (large numbers, near-uniform success)
TESA / FNA	Testis	Percutaneous aspiration	Least invasive; obstructive
Percutaneous core	Testis	Biopsy gun (blind)	Obstructive (risks artery/epididymis)
Conventional TESE	Testis	Open	Historic gold standard
Micro-TESE	Testis	Microdissection	Non-obstructive (current gold standard)

Microsurgical Epididymal Sperm Aspiration (MESA)

The preferred epididymal technique for obstructive azoospermia — safe, with near-uniform success and large sperm yields. Deliver the testis, open the tunica vaginalis, and use the operating microscope to identify dilated epididymal tubules; puncture those with clear or white fluid (most likely to hold healthy, motile sperm) — roughly 1 million sperm per microlitre are typically obtained. Close defects with bipolar cautery, close the tunica vaginalis and dartos with 4-0 absorbable monofilament and skin with 5-0 monofilament; avoid chromic sutures (they incite an inflammation mistaken for infection).

Microdissection TESE (micro-TESE)

The gold standard for non-obstructive azoospermia — higher retrieval and less testicular damage than conventional TESE, by targeting the tubules most likely to hold sperm while preserving end arteries with meticulous haemostasis (8–15× magnification far exceeds loupes). Deliver the testis through a median-raphe incision, open the tunica vaginalis, and make a wide equatorial incision with a 15° ultrasharp microknife through an avascular plane (without cutting tubules), then bivalve the testis manually. Survey the parenchyma, preserving the centrifugal vessels; larger-diameter, opaque/whiter tubules most likely contain germ cells. Mince harvested tubules with iris scissors in sperm media, disrupt further by passing through a 24-gauge angiocatheter, and have an embryologist examine them at 100–200× phase contrast. The procedure ends when sperm are found or every tubule of both testes is interrogated; close the tunica albuginea with running 5-0 polypropylene. Up to 60 mL of local is used for a bilateral case.

Other Techniques

• PESA — blind percutaneous epididymal aspiration; retrieves sperm of limited motility with more DNA damage and a ~20% failure rate, and risks the testicular artery (which runs beneath the epididymal head/body — injury can cost the whole testis) or secondary epididymal obstruction, so MESA is generally preferred.
• Conventional TESE / TESA / percutaneous core — open TESE is the historic standard; TESA is the least invasive; a blind percutaneous core risks the artery/epididymis (target the mid-testis).

Complications and Aftercare

• Bleeding/haematoma is the commonest complication of testicular biopsy and retrieval; epididymal injury is the most serious, and disrupting a subtunical end artery (or the testicular artery under the epididymis, as in PESA) risks segmental or whole-testis ischaemia.
• Retrieved sperm are cryopreserved (with FDA-mandated serum testing for banking).
• Anaesthesia combines a cord and skin block with layer-by-layer instillation of local — up to 60 mL for a bilateral micro-TESE.