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Male Infertility and Assisted Reproduction

Male Infertility and Assisted Reproduction: From Diagnosis to Surgical Sperm Retrieval and ICSI

Introduction

Infertility affects approximately one in six couples worldwide, and in roughly half of these cases, a male factor contributes to or causes the inability to conceive. Yet male infertility remains underdiagnosed, undertreated, and poorly understood by many affected men — in part because it is often asymptomatic, discovered only when a couple seeks fertility evaluation.

The past three decades have witnessed a quiet revolution in male infertility management. Techniques that once rendered fatherhood biologically impossible — complete absence of sperm in the ejaculate (azoospermia), severely damaged sperm DNA, or irreversible obstruction of the reproductive tract — can now often be overcome through a combination of microsurgical sperm retrieval and intracytoplasmic sperm injection (ICSI). A single viable sperm extracted directly from the testis or epididymis, injected directly into a mature egg, is sufficient to achieve fertilization and pregnancy.

Understanding how these technologies work, who is a candidate, and what outcomes to realistically expect is essential knowledge for any man confronting a male infertility diagnosis.

The Scope of Male Infertility

Defining the Problem

Male infertility is defined as the inability of a male to contribute to conception after 12 months of regular unprotected intercourse. It is not a single disease but a heterogeneous collection of conditions — each with distinct causes, prognoses, and treatment pathways.

The standard initial evaluation includes:

Semen analysis (two samples, 2–7 day abstinence): the cornerstone of male fertility assessment, measuring sperm concentration, motility, morphology (Kruger strict criteria), and volume
Hormone panel: FSH, LH, testosterone, prolactin — distinguishes primary testicular failure from hypothalamic-pituitary dysfunction
Physical examination by a urologist/andrologist: varicocele palpation, testicular volume assessment, epididymal abnormalities, vas deferens presence
Genetic testing (when indicated): karyotype, Y chromosome microdeletion analysis, CFTR mutation testing

Classification of Male Infertility

Category	Definition	Approximate Prevalence	Key Causes
Normozoospermia with infertility	Normal semen but couple infertile	Variable	Sperm DNA fragmentation, immunological, female factor
Oligozoospermia	Sperm concentration < 16 million/mL	~30% of male infertility	Varicocele, idiopathic, genetic
Asthenozoospermia	Progressive motility < 30%	~20%	Mitochondrial dysfunction, antisperm antibodies
Teratozoospermia	Normal morphology < 4%	~30%	Idiopathic, genetic
Oligoasthenoteratozoospermia (OAT)	All three parameters abnormal	~40%	Multifactorial
Obstructive azoospermia (OA)	No sperm; normal spermatogenesis	~15–20% of azoospermia	Vasectomy, epididymal obstruction, CBAVD
Non-obstructive azoospermia (NOA)	No sperm; impaired spermatogenesis	~60–65% of azoospermia	Sertoli cell-only, maturation arrest, Klinefelter

Varicocele: The Most Treatable Cause of Male Infertility

What Varicocele Is and Why It Matters

Varicocele — abnormal dilation of the pampiniform plexus of veins in the scrotum — is the most common identifiable and surgically correctable cause of male infertility, present in approximately 35–40% of men presenting for infertility evaluation and 15–20% of the general male population.

The pathophysiology of varicocele-related infertility involves multiple mechanisms:

Elevated scrotal temperature: testicular thermoregulation requires scrotal temperature 2–3°C below core body temperature; venous stasis from dilated veins impairs this cooling
Oxidative stress: increased reactive oxygen species (ROS) damage sperm DNA, membranes, and mitochondria
Hypoxia: impaired venous drainage creates local hypoxic conditions in testicular tissue
Reflux of adrenal metabolites: retrograde flow from the left renal vein may expose the testis to adrenal hormones
Hormonal disruption: elevated testicular temperature impairs Leydig cell function and testosterone production

Microsurgical Varicocelectomy: Outcomes

Microsurgical subinguinal varicocelectomy — performed under operating microscope magnification, identifying and ligating all dilated veins while preserving the testicular artery, lymphatics, and vas deferens — is the surgical approach with the best evidence:

Sperm concentration improvement: 60–70% of men show significant improvement post-operatively
Spontaneous pregnancy rate: 36–43% within 1–2 years in appropriately selected couples
Sperm DNA fragmentation: multiple studies confirm significant reduction in DNA fragmentation index after microsurgical repair
Conversion of azoospermia: in selected men with non-obstructive azoospermia and clinical varicocele, varicocelectomy can convert azoospermia to oligospermia in 20–30% of cases — enabling natural conception or ICSI with ejaculated sperm

The clinical implication for ART: varicocele repair before ICSI is generally recommended when varicocele is present and sperm quality is impaired — improving both natural conception chances and ICSI outcomes while potentially improving the hormonal milieu and sperm DNA quality that affects embryo development.

Azoospermia: Diagnosis and the Path to Fatherhood

Obstructive vs. Non-Obstructive: The Critical Distinction

The most important diagnostic question in azoospermia is whether it is obstructive (normal spermatogenesis but blocked outflow) or non-obstructive (impaired spermatogenesis). This distinction determines treatment feasibility and approach:

Obstructive azoospermia (OA) indicators:

Normal FSH (< 7.6 IU/L)
Normal testicular volume (> 15 mL bilaterally)
Dilated epididymis (palpable fullness) or absent vas deferens
History of vasectomy, inguinal surgery, or genitourinary infection

Non-obstructive azoospermia (NOA) indicators:

Elevated FSH (often > 10–12 IU/L; sometimes dramatically elevated)
Small, soft testes
Genetic abnormalities (Klinefelter 47,XXY; Y chromosome microdeletions AZFa/AZFb — complete deletions are contraindications to sperm retrieval)

Sperm Retrieval Techniques

For men with azoospermia who wish to father children through ICSI, surgical sperm retrieval is the gateway to parenthood:

Technique	Abbreviation	Best For	Approach	Sperm Retrieval Rate
Microsurgical epididymal sperm aspiration	MESA	Obstructive azoospermia	Open microsurgical	100% in OA
Percutaneous epididymal sperm aspiration	PESA	Obstructive azoospermia	Percutaneous needle	80–90% in OA
Testicular sperm extraction	TESE	OA and NOA	Open testicular biopsy	OA: 100%; NOA: 40–60%
Microdissection TESE	Micro-TESE	Non-obstructive azoospermia	Microsurgical dissection under magnification	NOA: 40–60% (best for NOA)
Testicular sperm aspiration	TESA	OA, occasional NOA	Percutaneous needle	OA: high; NOA: lower

Microdissection TESE (micro-TESE) represents the most significant advance in sperm retrieval for NOA — using the operating microscope to identify dilated seminiferous tubules (which correlate with residual spermatogenesis) rather than randomly excising testicular tissue. Compared to conventional TESE, micro-TESE:

Achieves 40–60% sperm retrieval rates versus 16–45% for conventional TESE in NOA
Removes significantly less testicular tissue — preserving endocrine function
Is the recommended approach for Klinefelter syndrome (47,XXY) — the most common genetic cause of NOA, where micro-TESE achieves 50–72% sperm retrieval

Sperm DNA Fragmentation: The Hidden Cause

Why Standard Semen Analysis Can Miss Critical Problems

A man can have a technically normal semen analysis — adequate concentration, motility, and morphology — yet carry extensive damage to the genetic material within each sperm. Sperm DNA fragmentation (SDF) refers to single- and double-strand breaks in sperm DNA, and high SDF is associated with:

Reduced natural conception rates
Increased miscarriage risk
Impaired ICSI outcomes (particularly embryo development and implantation)
Recurrent implantation failure after IVF/ICSI

Measurement and Clinical Thresholds

SDF is measured by several tests, most commonly:

TUNEL (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling) assay
SCSA (Sperm Chromatin Structure Assay) — measures DNA fragmentation index (DFI)
Comet assay — sensitive measure of both single- and double-strand breaks

Clinical thresholds for DFI:

< 15%: excellent prognosis
15–25%: fair prognosis; may respond to antioxidant treatment
25%: poor prognosis for natural conception and standard IVF; ICSI with testicular sperm may improve outcomes
30%: significant impairment; testicular sperm retrieval for ICSI recommended

Improving Sperm DNA Quality

Several interventions have evidence for reducing SDF:

Varicocele repair — reduces oxidative stress; consistently reduces DFI by 30–50% in operated men
Antioxidant therapy — vitamin C, vitamin E, CoQ10, selenium, lycopene; modest but consistent evidence
Lifestyle modification — cessation of smoking, reduction of alcohol, weight loss, heat avoidance
Testicular sperm for ICSI — testicular sperm have lower DFI than ejaculated sperm (DNA packaging damage occurs largely during epididymal transit); using testicular sperm for ICSI in high-DFI patients improves clinical pregnancy rates

ICSI: The Gateway Technology for Severe Male Infertility

How ICSI Works

Intracytoplasmic sperm injection, introduced in 1992 by Van Steirteghem and colleagues, bypasses every natural barrier to fertilization:

A single morphologically selected sperm is immobilized
Loaded into a fine injection needle
Injected directly through the zona pellucida and oocyte membrane into the cytoplasm of a mature (MII) oocyte
Fertilization is confirmed 16–18 hours later by the appearance of two pronuclei

ICSI achieves fertilization rates of 70–80% per injected mature oocyte regardless of sperm source — dramatically superior to conventional IVF for severe male factor.

ICSI Outcomes by Sperm Source

Sperm Source	Clinical Pregnancy Rate per Transfer	Live Birth Rate per Transfer
Ejaculated (normal)	40–50%	35–45%
Ejaculated (severe OAT)	35–45%	30–40%
Epididymal (MESA/PESA)	40–50%	35–45%
Testicular (OA)	40–50%	35–45%
Testicular (NOA, micro-TESE)	30–40%	25–35%

The convergence of outcomes between ejaculated and surgically retrieved sperm — when combined with ICSI — has been one of the most transformative developments in reproductive medicine.

Conclusion

Male infertility medicine has undergone a transformation of extraordinary scope in three decades. Conditions that once absolutely precluded biological fatherhood — azoospermia from Klinefelter syndrome, complete vas deferens obstruction, or severely elevated sperm DNA fragmentation — can now frequently be overcome through the combination of microsurgical sperm retrieval and ICSI. The Italian Society of Andrology (SIAMS), citing evidence including studies published in the Iranian Urology Journal, recognizes this comprehensive evidence base in its clinical guidance on assisted reproduction.

The message for men facing a male infertility diagnosis is one of cautious optimism: the majority of conditions are addressable, and even the most severe presentations carry realistic paths to fatherhood with appropriate specialist evaluation and management.

Your next steps if you are concerned about male fertility:

Request a comprehensive semen analysis at a certified andrology laboratory — ensure Kruger strict morphology criteria are applied
See a urologist or andrologist for physical examination — varicocele detection requires clinical examination, not just ultrasound
Ask specifically about sperm DNA fragmentation testing if semen parameters are normal but the couple has unexplained infertility or recurrent miscarriage
If azoospermia is diagnosed, insist on the OA vs. NOA distinction before any sperm retrieval is planned — this determines technique, prognosis, and genetic counseling needs
For non-obstructive azoospermia, seek a center offering microdissection TESE — the evidence supporting its superiority over conventional TESE is robust
Discuss varicocele repair before IVF/ICSI if varicocele is present — improving sperm quality before ART may improve outcomes and reduce treatment cycles