Part One – Introduction
Azoospermia affects 1% of all men and accounts for 10-20% of males who present with infertility. It is defined as the complete absence of sperm in the ejaculate. The largest groups are: abnormally descended testes (17%), Klinefelter’s syndrome (14%), infertility of unknown cause (13%) and previous vasectomy (5%). Essential to the workup of male infertility is the semen analysis. According to WHO specimen collection guidelines, two samples (if the first is abnormal) are required. The goals are to determine the underlying cause and subsequently either treat it if possible; or retrieve sperm for assisted reproductive techniques. All investigations and treatment options are available at the Reproductive Health Group or can be organised by our Urologists at nearby hospitals.
The clinician needs to attempt differentiation between obstructive azoospermia (OA) and non-obstructive azoospermia (NOA).
Obstructive (or post-testicular azoospermia, OA) accounts for 40% of azoospermia and can result from a multitude of causes which may be due to a structural (e.g. vasectomy) or functional problem (e.g. failure to ejaculate). Men with OA classically have normal sex hormones (testosterone and FSH), normal testes on clinical examination and normal ultrasound.
NOA can be classified as pre-testicular (the rarer cause; often due to abnormalities of the hypothalamus or pituitary gland in the brain), or testicular; leading to impaired formation of sperm within the testes. Pre and post-testicular azoospermia are often treatable, whereas testicular causes (apart from azoospermia associated with varicocele), are generally not correctable.
Causes of Obstructive Azoospermia (OA)
Iatrogenic / traumatic
- Previous vasectomy (most common cause of OA)
- Inguinal hernia repair (especially with mesh)
- Pelvic or scrotal surgery (e.g. hydrocele repair, orchidopexy)
- Congenital bilateral absence of the vas deferens (CBAVD)
- Young’s syndrome (sinus and chest infections and azoospermia)
- Mullarian or Wolfian duct cyst/ ejaculatory duct cyst
- Chlamydial or gonococcal infection
- Drugs, spinal injury, neurological, previous pelvic or abdominal surgery
Causes of Non-obstructive Azoospermia (NOA)
Pre-testicular (hypogonadotrophic hypogonadism)
- Kallmann’s syndrome (inability to smell, delayed puberty)
- Previous surgery of pituitary gland
- Treatment with testosterone
- Granulomatous illness
- Autoimmune diseases
Testicular (hypergonadotrophic hypogonadism)
- Klinefelter’s syndrome
- Maldescended testes or torsion
- Drugs – steroid abuse, chemotherapy, gonadotoxins
- Infection – mumps
- Idiopathic (i.e. unknown cause)
Part Two – History and Examination
For men referred to the Reproductive Health Group for azoospermia, your Andrologist will carefully explore your medical history and carry out a physical examination as required. Subsequently, various investigation might be required (described in Part 3), before a management plan can be suggested.
History suggestive of Obstructive Azoospermia (OA)
- Previous surgery (vasectomy, inguinal, scrotal, retroperitoneal)
- Genitourinary infection
- Chronic bronchopulmonary infection
- Family history of cystic fibrosis
- Normal libido
History suggestive of Non-Obstructive Azoospermia (NOA)
- Delayed development/ onset of puberty
- History of undescended testes or testicular torsion
- Previous gonadotoxic treatments (including chemotherapy and radiation)
- Environmental exposure to gonadotoxins
- Treatment with (or abuse of) exogenous testosterone
- Visual disturbance
- Pituitary surgery
- Low libido
Examination Findings suggestive of OA
- Normal male characteristics
- Inguinal or scrotal scars
- Normal testis size, consistency and position
- Epididymal fullness or cysts
- Vasa may be absent
- Vasal defect from vasectomy
- (if present assess for position and length of defect and for sperm granuloma)
- Prostatic or midline cyst on digital rectal examination
Examination Findings suggestive of NOA
- Lack of male characteristics
- Small atrophic testes
- Undescended testes
- Gynaecomastia (breast swelling)
- Visual field defects
Part 3 – Investigations
Semen analyses are vital in establishing the quality and quantity of sperm in infertile patients. According to the WHO, at least two evaluations should occur over a two months period.
Men with certain forms of obstructive azoospermia (OA) may have a reduced ejaculate volume (less than 1.5mL). Obstruction in the prostate will result in low semen volume with low pH and fructose levels. Normal volume implies non-obstructive azoospermia (NOA) or obstruction of both vasa or epididymes.
Follicle stimulating hormone (FSH), luteinising hormone (LH) and early morning testosterone (T) should be measured. OA results in normal hormonal levels, whilst pre-testicular and some testicular abnormalities may have abnormal levels.
Low Testosterone with elevated FSH and LH may be found in primary testicular failure (where the testes have stopped working properly, for unknown reasons). Should there be an abnormality of these hormones, an endocrinology referral should be strongly considered. Pre-testicular infertility (with low Testosterone and low FSH and LH) should be further investigated with prolactin levels and imaging of the pituitary gland (such as a brain MRI).
Genetic testing is an important part of the workup for azoospermia, especially when considering NOA. In these cases, there is an increased frequency of chromosome abnormalities – for example Y-chromosome microdeletions and Klinefelter syndrome.
• Sex chromosome abnormalities
Klinefelter’s syndrome (KS) is the most common chromosomal abnormality (affecting one in 600 males) and accounts for approximately 15% of NOA. The “classical” form (47 XXY) accounts for 80-90% of KS cases. In the remaining 10-20%, so called “mosaics” are found. Clinically, these men have small firm testicles (<5cc) and may demonstrate normal virilisation, but also scant or female hair distribution. Testosterone may be normal or low, whilst FSH is increased.
• Y-chromosome abnormalities
Three microdeletions on the long arm of the Y Chromosome account for about 7% of severe oligospermia/ azoopsermia. AZFc varies between azoospermia and oligospermia. There is a 70% chance of finding sperm with AZFc and thus micro-TESE and ICSI are indicated. If intracytoplasmic sperm injection (ICSI) is utilised, these aberrations will be passed onto male children. In certain countries, pre-implantation sex selection of female embryos may be considered.
With AZFa or AZFb microdeletions, it is highly unlikely that any sperm will be found. Thus, microscopic surgical sperm extraction (micro-TESE) is not indicated and ICSI will fail.
• Autosomal disorders
Cystic fibrosis (CF), an autosomal recessive disorder, is due to a gene mutation. (Children can only develop cystic fibrosis if BOTH parents have the mutation.) It is associated with congenital bilateral absence of the vas deferens (CBAVD), which affects 1% of infertile men. Therefore, in infertile men with no vas on either side, testing for CF in both parents and referral to a genetic counsellor should be offered.
Imaging Options include ultrasound (US), magnetic resonance imaging (MRI) or more invasive methods including vasography.
Scrotal US can verify the size of the testes and look for the absence of structures as well as for evidence of obstruction such as spermatocele or dilatation of vas/ epididymis/ rete testis. It is also useful if the physical examination is suboptimal due to body habitus or testicular pain, or if examination findings are equivocal. In patients with NOA, scrotal US should be strongly considered as there is an increased risk of testicular cancer.
Transrectal US can identify ejaculatory duct obstruction. Aspiration of the seminal vesicles can be performed. Sperm aspirated in such manner can be used for ICSI.
Renal tract Ultrasound
Renal tract US should be performed when unilateral absence of the vas is noted – 20% will have no kidney on the same side.
MRI can be employed to identify ejaculatory duct or prostatic cysts. It enables evaluation of the vas deferens and seminal vesicles and may indicate the site of obstruction.
Vasography is an invasive investigation used to identify the site of obstruction. It is rarely used in purely diagnostic situations and requires microsurgical skills. It is an open procedure, usually undertaken as part of a therapeutic intervention to reconstruct an abnormality.
Testicular biopsy may be helpful in differentiating OA from NOA in men with at least one palpable vas, normal testis size and normal FSH. It is is possible that performing a diagnostic biopsy may reduce the subsequent success rate of sperm retrieval via micro-TESE for NOA because of bleeding, haematoma and fibrosis. Therefore, should testicular biopsy be performed, having the ability to simultaneously cryopreserve sperm for use in ICSI is desirable.
Key Points for Determining the underlying cause of azoospermia
++ Most azoospermia can be determined via history, examination and first-line investigations
++ CFTR mutation should be tested for and genetic counselling offered for men with bilateral absent vasa. The female partners should also be counselled prior to using the sperm of these men
+++ Men with NOA should have genetic counselling with karyotyping and screening for AZF aberrations
+ Transrectal US +/- aspiration of seminal vesicles is important to exclude ejaculatory duct obstruction (EDO), particularly in men with low ejaculate volume
++ If one or both vasa are absent, renal US should be offered
+ Testicular biopsy may help to differentiate between NOA and OA in equivocal cases but has the potential to decrease the chances of sperm retrieval on subsequent Micro-TESE in cases of NOA: hence should be undertaken in units with facility to simultaneously cryopreserve sperm for use in ICSI.
+++ strongly evidence-based
++ less strongly evidence-based
+ not evidence-based but clinically understood / clinical opiniona
Part 4 – Treatment: Reconstruction
Treatment of azoospermia depends on the underlying cause. Essential to determining definitive management is the evaluation of both partners. Female fertility factors (e.g. age, prior fertility, polycystic ovarian syndrome, endometriosis), the number of children desired, success rates of various treatment options, and even financial considerations, may impact the couple’s treatment choice. An understanding that treatments such as vasovasostomy (VV), vasoepididymostomy (VE), and varicocelectomy can take 3-6 months for optimisation of seminal parameters, may also influence a couple’s decision.
Reconstruction for Obstructive Azoospermia (OA)
OA can be overcome by reconstructive surgery, to relieve an obstruction and to restore sperm to the ejaculate. Alternatively, sperm can be harvested from either testis, epididymis or vas, in conjunction with assisted reproductive techniques such as IVF or ICSI.
Reconstruction includes vasovasostomy (VV), vasoepididymostomy (VE), and transurethral resection of the ejaculatory ducts (TURED).
Vasovasostomy (vasectomy reversal)
Despite the numerous factors to be considered, there are no controlled trials investigating whether surgical repair or sperm harvesting with assisted reproduction (AR) provide the better option. However, it appears that unless there are specific dictating female factors, vasovasosotomy provides a more cost-effective option with a higher delivery rate.
This procedure can be achieved by various techniques using an operating microscope or loupes. The principles of repair include a water-tight, end-to-end, tension-free joint with good blood supply.
Although a surgeon may plan for a VV pre-operatively, the decision to undertake VV or VE should be made intra-operatively by analysis of vasal fluid. After prolonged vasal obstruction (longer than 10-15 years), secondary blockage of the epididymis from high pressure can occur, requiring a connection between the vas deferens and the epididymis.
Besides duration since vasectomy, there are several factors that need to be taken into consideration – such as sperm granuloma, length of proximal vas and the microscopic appearance of fluid expressed from the proximal vas (using microscopy).
The following findings will promote VV as the choice of reconstruction:
• Copious clear fluid from the vasal stump on the testicular side
• Motile sperm in this fluid
• Whole sperm or sperm parts in this fluid
• Length greater than 2.7cm
• Sperm granuloma (a small nodule of scar tissue)
If there is absent vasal fluid or the fluid is thick and creamy, VE should be performed regardless of vasal length or presence of sperm granuloma.
An overall VV patency rate has been reported up to 86%, with an average pregnancy rate of 52%. The duration of obstruction and female fertility are important predictive factors in semen return and pregnancy rates.
If the female partner is aged 35 to 39, pregnancy rates are reported as 54%. However, once aged 40 years or older, these rates dramatically reduce to 14%.
Vas reversal outcomes
|Obstructive Interval (years)||Return of sperm rate||Pregnancy rate|
VE is indicated for epididymal obstruction with patency rates of up to 80%, and pregnancy rates of 13-56% being reported. This procedure is technically very challenging and time-consuming. Use of an operating microscope is essential.
Transurethral resection of the ejaculatory duct (TURED)
TURED is a procedure which opens an obstructive midline cyst in the prostate or resects part of the prostate itself, dis-obstructing the ejaculatory ducts. The procedure can be performed at the same time as vasography (cannulation of the vas and injection of a dye). Once the duct is adequately resected, a tinge of dye can be seen emerging in the prostate.
The procedure improves sperm numbers in 50% of previously azoospermic men, yielding a pregnancy rate of 25%. Complications include re-obstruction, rectal injury, retrograde ejaculation into the bladder and urine reflux, which may affect sperm quality and cause infections.
Part 5 – Treatment: Sperm harvesting, varicocele, hormonal optimisation
Sperm harvesting for obstructive and non-obstructive azoospermia (OA and NOA)
Several targets for sperm retrieval are possible – testis, epididymis or the vas. There are also different methods of harvesting sperm from these areas. It can be undertaken percutaneously (aspiration or biopsy) and with an open technique (with or without the operating microscope). The choice about which area to target and the means by which this is done is based on clinical presentation, available equipment and the skills of the surgeon.
Some options include:
- Testicular sperm aspiration (TESA)
- Conventional testicular sperm extraction (C-TESE)
- Microsurgically assisted TESE (Micro-TESE)
- Percutaneous epididymal sperm aspiration (PESA)
- Microsurgical epididymal sperm aspiration (MESA)
For men with OA, reconstruction may be possible and this should be considered. Without reconstruction, sperm retrieval is necessary to use with IVF/ICSI to achieve a pregnancy. Most men with OA have normal sperm production capabilities. Thus, any approach to the testis, epididymis or vas should yield sufficient numbers of sperm.
TESA may be all that is necessary. However, although a simple procedure, it yields the lowest sperm numbers which, and may not retrieve enough motile sperm for IVF. In these cases, a PESA or MESA can be utilised.
PESA involves percutaneous passage of a fine needle through the epididymis whilst applying negative pressure through a syringe. It is simpler and more accessible than MESA, as it does not require microsurgical training. However, it is not as precise, resulting in lower retrieval rates. Complications are usually minor, but can include haematoma, spermatocele and fibrosis and scarring at the injection site. PESA may therefore potentially compromise future reconstruction attempts.
MESA can procure sperm in OA in 90% of cases and pregnancy rates range from 40% to 60%. MESA has the advantage of being able to accurately target the epididymal tubules which, under the operating microscope appear favourable for containing motile sperm. Reconstruction might be possible at the same setting.
There is conflicting evidence as to the best choice for sperm retrieval techniques for OA. The American Urological Association (AUS) Best Practise Statement suggests there is no difference in outcome for IVF or ICSI in relation to the method of sperm harvest and therefore the choice of method is dependent on local facility and surgeon factors. The American Society for Reproductive Medicine guidelines suggest that MESA yields the best pregnancy rates in OA, but requires microsurgical expertise so cannot be recommended for all cases.
Non-obstructive azoospermia (NOA)
Depending on the underlying pathology, up to 70% of men with NOA, will harbour sperm within the testes and, if found on harvesting, live births can result in 30% to 50% of such couples. In men with NOA, the AUA Best Practice Statement recommends open surgical testicular sperm retrieval with or without microscopic magnification for patients with NOA. Cryopreservation of sperm should be offered at the time for use with ICSI.
Micro-TESE involves the use of a surgical microscope at 15x to 20x magnification, targeting larger and more opaque testicular tubules. This improves sperm retrieval rate. The majority of studies show statistically better retrieval rates ranging from 45% to 57% for micro-TESE compared with conventional TESE. Micro-TESE appears to claim a lower complication rate compared with conventional TESE, and there is a smaller volume of testicular tissue removed.
Conventional-TESE involves opening of the testois and excision of several tubules, often from several regions of the testis. The specimen is then sent for processing and immediate microscopic evaluation. Complications include haematoma whilst large volume TESE can result in permanent reduction in testosterone levels.
TESA involves percutaneous aspiration of sperm from the testis with a needle and syringe. Multiple passes are made. The benefits include no need for microsurgical training, rapidity and non-invasiveness. Retrieval rates range from 10-30%. It appears likely that TESA have sperm retrieval rates that are inferior to that obtained with TESE.
(For hypergonadotropic hypogonadism and subsequent sperm retrieval)
There have been several publications suggesting that optimisation of the hormonal environment improves sperm retrieval rates in patients with NOA. These studies are particularly applicable to patients with Klinefelter’s Syndrome but may also be applied to non-Klinefelter’s patients. Different protocols have been suggested and may include consideration of testosterone to oestradiol ratios, or improvement of FSH levels. The most common drugs used are Clomiphene Citrate, Anastrazole, Tamoxifen and/or hCG for 3-6 months prior to attempted sperm retrieval.
Risks of AR techniques
Whilst IVF and ICSI are available, there appear to be slight additional risks to both mother and child. The risks of pre-term labour (10% versus 8%), low birth weight (7% versus 4.7%) and birth defects (5% versus 4%) is higher in babies born following IVF compared with naturally conceived babies.
Key points for sperm harvesting
- The type of azoospermia and surgeon preferences determines the method choice ++
- OA should be treated if possible; simple sperm retrieval techniques can be employed +
- NOA usually requires open surgical sperm retrieval with micro-TESE having the highest sperm retrieval rates ++
- Repeated biopsies may reduce subsequent sperm retrieval rates ++
- AR may incur slight absolute increases in major birth defects ++
- heavily evidence-based +++
- less substantively evidence-based ++
- not evidence-based but are clinically understood +
Recent data suggests a benefit for treating varicoceles in patients with abnormal semen parameters and a clinical varicocele. In patients with a clinical varicocele and NOA, the main potential benefit is for motile sperm to be detected in the ejaculate which may obviate the need for a (micro) TESE. Return of sperm into the ejaculate has been reported in 12 studies and range from 21-56% of azoospermic men post varicocele repair. However, these studies are retrospective and uncontrolled. Furthermore, most men still require a micro-TESE to retrieve adequate sperm for ICSI despite a varicocele repair. The absence of a varicocele may enhance spermatogenesis and improve the success rate at micro-TESE.
The choice of treatment of a varicocele is based on the skill set of the treating doctor, but based on two meta-analyses, microsurgical varicocelectomy has demonstrated the highest success rates with the lowest recurrence and complication. This has led some authors to suggest that a microsurgical varicocelectomy is currently the gold standard for varicocele repair.
Treatment of pre-testicular infertility
For these conditions, referral to an endocrinologist is recommended. In hypogonadotrophic hypogonadism, there are some effective medical treatments including androgen replacement and human chorionic gonadotrophin (hCG) combined with follicle-stimulating hormone (FSH). Pulsatile gonadotrophin releasing hormone may be used if there is a pituitary cause. Whilst testosterone replacement is justified for other symptoms (such as low energy levels and libido), there is no role for this to improve fertility. Exogenous testosterone can reduce gonadotrophin levels and hence impair spermatogenesis; and should be ceased during fertility treatment. Prolactin producing pituitary adenomas can be treated medically (microadenomas) or surgically (larger adenomas).