Evidence Notes · No. 10
← All notesNo sperm in the ejaculate does not mean no sperm. Where the cause is a blockage, retrieval succeeds almost every time; where the testis is failing, the technique chosen changes the odds substantially.
If you have been diagnosed with azoospermia (the absence of sperm in the ejaculate), being told you have male infertility can be devastating. However, the absence of sperm in the semen does not necessarily mean you are not producing any sperm at all.
For many men, sperm is still being produced inside the testicles but is either blocked from coming out (obstructive azoospermia) or produced in very low, patchy quantities (non-obstructive azoospermia). In these cases, specialists can use surgical sperm retrieval techniques like TESA (Testicular Sperm Aspiration) or Micro-TESE to extract sperm directly for use in IVF.
This guide breaks down the latest medical evidence—including systematic reviews, randomised trials, and clinical studies—to help you understand your options and what to expect.
Surgical sperm retrieval involves extracting sperm directly from the testicles or the epididymis (the tube where sperm matures). The retrieved sperm is then used in conjunction with Intracytoplasmic Sperm Injection (ICSI), an IVF technique where a single healthy sperm is injected directly into an egg.
There are several methods, but the most common include:
In obstructive azoospermia (e.g., after a vasectomy or due to a congenital blockage), sperm production is usually normal. A simple needle aspiration (TESA) works by bypassing the blockage to collect the abundant sperm trapped in the testicles.
In non-obstructive azoospermia (NOA), the testicles are failing to produce normal amounts of sperm. However, sperm production might still be happening in isolated "islands" within the testicle. Micro-TESE works by carefully navigating the testicular tissue under high magnification to locate and extract these rare, microscopic islands of sperm production without removing large amounts of healthy tissue.
Yes, but the success rate depends heavily on the underlying cause of your azoospermia.
The reason is anatomical rather than technical. In non-obstructive azoospermia sperm production is focal — surviving in small islands rather than uniformly — so a blind needle samples wherever it happens to land, while a microscope looks for the right place.13 Observational work agrees with the trial: TESA was positive in 22.2% of a 320-man cohort.14
The honest counterweight. The simpler operation is safer. One comparative study reported complications in 3% after TESA against 21% after micro-TESE, though the micro-TESE group was much smaller;15 in the randomised trial, no complications followed TESA while 6% of micro-TESE patients needed a surgical intervention.11 That trade is real. It is also not a close call in non-obstructive disease, where a failed retrieval usually costs a partner an egg-collection cycle as well as a second operation.
Once the sperm is retrieved, embryological studies show that while surgically retrieved sperm may have slightly lower fertilisation rates than normal ejaculated sperm, the rates of blastocyst (healthy embryo) development and clinical pregnancies are very similar.
Retrieval, obstructive azoospermia
~100%with TESA
A blockage, not a production failure — 82 of 82 men in one series. The simplest scenario in this field.15
Retrieval, non-obstructive
43%vs 22% with TESA
Head-to-head randomised clinical trial, 100 men. Pooled micro-TESE series across 4,895 men give 46.6%.
Why the second number is a range and not a figure Non-obstructive azoospermia is not one condition. Hormone profile, testicular volume, FSH and genetics all move the odds, which is why the assessment beforehand matters more than the technique.
Getting sperm is only the first hurdle; having a baby is the ultimate goal. Studies tracking clinical pregnancies following Micro-TESE and ICSI show that pregnancy outcomes are heavily influenced by two main factors: the quality of the embryos created and the age of the female partner. Evidence suggests that once high-quality embryos are formed using the retrieved testicular sperm (whether used fresh or frozen-thawed), the pregnancy rates are highly encouraging and similar across different causes of infertility.
The surgical retrieval itself is a day-case procedure, taking anywhere from 30 minutes for TESA to a few hours for a complex Micro-TESE.
However, achieving a pregnancy takes longer. The retrieved sperm is processed immediately in the lab on the same day as your partner's egg retrieval, or it is frozen for a future IVF cycle. The entire IVF/ICSI process usually spans several weeks or months.
Because the underlying cause of the infertility (such as testicular failure or a missing vas deferens) is not being cured, you will still have azoospermia after the procedure. However, the sperm retrieved can often be frozen. If the lab retrieves enough healthy sperm, it can be separated into multiple small vials and frozen for several future IVF attempts, meaning you may only need to undergo the surgery once to have multiple children.
If TESA or Micro-TESE is unsuccessful, or if you use all your frozen sperm and wish to have another child, you may need a repeat procedure. However, if a thorough Micro-TESE finds absolutely no sperm, doctors generally advise against repeating the surgery, as the chances of finding sperm on a second attempt are extremely low. In such cases, using donor sperm or considering adoption are the next steps.
Surgical sperm retrieval is a low-risk operation, but as with any surgery there are risks:
A crucial concern for many men is how this surgery affects testosterone (the male hormone produced in the testicles) and erections.
Because sperm retrieval removes small amounts of testicular tissue, it can temporarily lower testosterone levels. A 2021 study on the endocrine follow-up of men post-TESE noted that patients can experience temporary hypogonadism (low testosterone). Symptoms might include fatigue, reduced sex drive, and temporary erectile dysfunction.
Fortunately, for the vast majority of men, testosterone levels recover to their pre-surgery baseline within 12 months. Doctors recommend a "watchful waiting" approach and regular hormone blood tests for the first year after surgery to ensure your levels return to normal.
Testosterone can fall after retrieval, and with it energy, libido and erections. For the great majority it returns to baseline within twelve months — which is why hormone testing through that first year is part of the plan, not an afterthought.
You are a good candidate for TESA if you have obstructive azoospermia (e.g., previous vasectomy, cystic fibrosis gene mutations).
You are a candidate for Micro-TESE if you have non-obstructive azoospermia. However, doctors will run blood tests (FSH, Testosterone, Inhibin B) and genetic tests before surgery.
Worth asking in clinic
The evidence guiding surgical sperm retrieval is strong. The superiority of Micro-TESE over TESA for non-obstructive azoospermia is backed by randomised clinical trials and rigorous meta-analyses. The guidelines provided by the European Association of Urology also strongly support these pathways, emphasising comprehensive genetic and urological testing before surgery to optimise outcomes and check for other men's health issues.
TESA succeeds in close to 100% of cases. The sperm is there; the problem is the plumbing.
Randomised clinical trials and meta-analyses agree. This is the clearest finding in the field.
Around 40–60% with Micro-TESE. Wide, because the underlying causes differ greatly.
Fertilisation may be slightly lower than with ejaculated sperm; blastocyst development and clinical pregnancy rates are similar.
Temporary hypogonadism can occur; levels return to baseline within twelve months for the large majority.
AZFa and AZFb microdeletions carry virtually no chance of retrieval, and surgery is strongly discouraged. An AZFc deletion is different — pooled analysis still gives around 40%.16
If there is no sperm in the ejaculate, biological fatherhood is still possible. Where the cause is a blockage the sperm are there, and retrieval succeeds in close to every case. Where the testicle itself is not producing, micro-TESE gives the best chance of finding the few that exist, because the tubules are examined under the microscope rather than sampled blindly, and it takes less tissue than the older techniques. Success is not guaranteed, and an AZFa or AZFb deletion makes it close to futile. Have the hormone profile and the genetic tests done, and get a realistic figure for your own situation, before agreeing to an operation.
Every figure on this page is traceable to one of these. Where a study is small, unrandomised or industry-sponsored, that is stated in the text rather than left in the footnote.
Where this leaves you
Hormone profile, testicular volume and genetic testing all shape whether retrieval is worth attempting and which technique to use. Some genetic findings make surgery inadvisable, and that is worth knowing beforehand.