“I wanted to share the good wife is currently 12 weeks pregnant! We appreciate all the dedication and support you and the entire Maze team gave us throughout the process.”
- an ESSM patient from NY

Azoospermia is the term that’s used when a standard semen analysis finds no sperm in the ejaculate. However, a revolutionary new procedure, the Extended Sperm Search & Microfreeze (ESSM), finds and freezes small numbers of sperm in 44% of men with azoospermia. This groundbreaking lab test is performed by dividing the entire semen sample into 5 micro-liter droplets and carefully scanning the drops under a high-powered microscope. Any moving sperm that are located are placed on a specialized device, called a SpermVD, and cryopreserved for future use with in-vitro fertilization and intracytoplasmic sperm injection (ICSI-IVF).

The SpermVD’s innovative design allows individual sperm to be transferred to a microdroplet for freezing. Because the sperm are successfully frozen in such a small quantity of fluid, over 90% of them survive the freeze and thaw process. It also makes them easily found when thawed on the day they are needed to inject into their partner’s egg leading to higher cycle success rates.  

  • This makes it much more likely that sperm will be found than when the sperm are frozen in conventional vials.
  • This makes finding sperm faster, so that they can be injected as soon as possible after the eggs have been retrieved from his partner, which optimizes fertilization and pregnancy outcome rates.

“Using the device was easy… Knowing that there are sperm and that most will survive really takes stress off the lab. The saved time is relieving on a very busy day.”
- Reproductive Specialists of New York


If you’ve been diagnosed with one of the following, you may be a candidate for ESSM:

  • Azoospermia: no sperm observed in the ejaculate in a conventional semen analysis; 44% of azoospermic men will have sperm found and successfully frozen.
  • Cryptozoospermia: where only a very few sperm can be found, even after centrifuging and concentrating the specimen; almost all of these men will have a successful ESSM and be able to proceed with IVF/ICSI.
  • Severe Oligozoospermia: sperm concentration less than 1 million/mL.

Michael Werner, MD, Maze Lab Director and a fellowship trained urologist specializing in male infertility, feels strongly that every man with the diagnosis of azoospermia or cryptospermia should undergo an ESSM prior to considering sperm mapping or testicular sperm extraction (micro-TESE).
ESSM is non-invasive and may be performed as many times as needed. The surgical extraction procedures are invasive and micro-TESE in particular causes some damage to the testicles. 

However, if the ESSM does not find sperm, sperm mapping followed by micro-TESE (if areas of sperm production are found on the sperm mapping) is a viable option and should be strongly considered.

essm combined with Sperm mapping

ESSM does not always find sperm in the ejaculated specimen. We have now pioneered the use of Sperm Mapping in conjunction with ESSM to find and freeze sperm in the least invasive way, called Grid Needle Sperm Extraction and MicroSearch (GN-SEM).

Traditionally, in situations of azoospermia, a micro-TESE is performed.  This involves a surgery in the operating room, where the scrotum is opened, the testicle pushed out, and multiple small pieces of tissue are taken to try to identify sperm.  However, instead of micro-TESE we have traditionally done a sperm mapping first to see if sperm will be found.  If no sperm are found, the man does not need an invasive surgery that can damage the testicles, and the partner does not necessarily need IVF.  However, if sperm are discovered on the sperm mapping, a further procedure is needed to retrieve them.  This can be done through a simple needle biopsy (see below) or a more invasive micro-TESE, depending on the physician and the number and location of sperm found on the sperm mapping.

We have pioneered a method where fine needle aspirates are systematically taken from the testes, following the exact technique used in Sperm Mapping. However, instead of being placed on a slide, the aspirates and sometimes tubules are placed into a medium that is hospitable to sperm, and an ESSM is performed.  Any sperm found are thus immediately frozen on a SpermVD.  These sperm can be easily located and over 90% survive the freezing and thawing process.  They can thus be used to inject into either fresh or frozen eggs.

In this way, we are taking men with azoospermia (including on an ESSM) and with a very non-invasive procedure (needle aspiration), retrieving sperm that can be used to create an embryo…all in one relatively non-invasive step!

Essm on surgically retrieved sperm (Srs) specimens

Many men with azoospermia will have low levels of sperm production in the testes. Sperm are retrieved in various ways. Traditionally, this tissue will be sent to an embryology lab at an IVF center to identify sperm.  These sperm can be injected into either fresh or frozen eggs (or both) for future use.

However, now we can perform an ESSM on these specimens.  This typically yields better results, because:

  1. We can spend much longer looking through this tissue for individual sperm (6-8 hours) than is available at a typical IVF lab.  
  2. The isolated sperm are placed on SpermVD’s, which allows them to be:
    1. Found more easily.
    2. Survive freezing and thawing at a dramatically higher rate than conventionally freezing and thawing.
  3. We can often coordinate the ESSM with the day of egg retrieval so fresh sperm can be used with fresh eggs.
    1. Sperm can be frozen on SpermVD’s, again allowing for good thaw rates and easy location.

Surgical attempts at retrieving these sperm are performed in several ways:

  • Micro-TESE: sperm are taken directly from the testis, which has been opened in the operating room.
  • Grid Needle Sperm Extraction and MicroSearch (GN-SEM): sperm are aspirated in a pattern from the testicles.
  • Microscopic Epididymal Sperm Aspiration (MESA): sperm are taken from the epididymis in the operating room. This is usually performed on men who have a blockage of sperm rather than low production.
  • Men undergoing testicular removal for cancer can have part of the testicle sent to a lab to look for sperm.
  • Trans-women undergoing gender affirming surgery can have the removed testicles evaluated for sperm using ESSM.


If you believe you're an appropriate candidate for the ESSM procedure, we encourage you to contact us as soon as possible. A phone consultation will be conducted to discuss the procedure in detail, answer any questions you may have, make sure you are an appropriate candidate for ESSM and if so, schedule the appointment. You will then be required to send your records to Dr. Werner for review.

ESSM Testimonials

Dr. Werner found another way for us with ESSM to get the best of the best.

I want to say a special thank you to you and the team. Chaya, both you and Dr. Werner were so patient with my husband.

We started our journey in the fall of 2018  and you guys have been there all the way. He gave up on having children since he was over 50, but the team was always giving me hope. Even when we received zero sperm from a regular donation. Dr. Werner found another way for us to use the extended sperm search method and found the best of the best. Now we are here holding our precious gift. Here is our munchkin… 4.2.2023.

A million thanks are only the tip of the iceberg. THANK YOU SO MUCH!!!!

NY, 50

We were at the end of the road before we came to Maze.

We have been trying to conceive for over ten years now and honestly we were close to the end of the road before we came to Maze. I have done sperm analyses over fifteen times in four different countries. All with the same disappointing result; azoospermia. After every test I took I would wish for at least one sperm to be found just as a sign of hope but I was always told there is nothing. I have been to the top urologist in this country and their only solution would be a surgery. My wife and I were against the surgery unless we have exhausted all other options.

I say faith brought us to you. I did the test in the morning in Manhattan and was expecting a call the next day or two as usual with the usual disappointing news of azoospermia. I remember getting a call later that evening from a New York number and did not even think it was you. I answered that call that changed our life for the better. I remember you telling me that, “I have good news for you, we were able to freeze over 40 sperm.” and I could not believe my ears. I remember asking you if you’re sure you called the right person!!! It was the greatest news I had ever received in my life to say the least. I did a few more tests with positive results to ensure we have enough just as a safety net even though you told me it’s enough to conceive.

I’m glad to announce that this year we had a beautiful baby boy after a few failed IVF procedures who is the center of our lives now. I ultimately hope that you are able to reach as many people as possible with your innovative techniques and dedication to your skills. Your emotional support was beyond what we expected and much appreciated. This is only a fraction of our gratitude for you and your facility for everything you have done for my family.
Thank you from the bottom of our hearts…

 FK, 37 

ESSM test finds sperm in azoospermic patient, yielding 7 healthy embryos.

“I was told I was azoospermic after going to several well-known fertility centers in the tri-state area. I then came to Maze Laboratories for a standard semen analysis, which also showed zero sperm count. However, after having Maze’s ESSM lab test, 42 sperm were recovered and safely stored. In collaboration with the IVF lab, my wife and I are happy to say that 7 healthy embryos were developed!”

– J, 37 –


We have healthy embryos ready for transfer thanks to ESSM.

Had a diagnosis of cryptozoospermia, so was optimistic about the likelihood of success with having a testicular biopsy on the day of egg retrieval. Unfortunately, there was no sperm found in the tissue, and his partner froze her eggs. His urologist referred him to Maze. ESSM identified sperm in every sample, and they now have healthy embryos ready for transfer.

C (39, NY)

Maze's ESSM identified 10 times more sperm, consistently on multiple visits.

Had multiple semen analyses in multiple centers, all of which showed azoospermia. He had an extended sperm search at another center (using a different protocol). On only one occasion they found small numbers of sperm, that he was told were too poor quality for ICSI. ESSM identified 10 times more sperm, consistently on multiple visits. K is now the father of a beautiful baby boy. 

K (36, NJ)

Now planning IVF in NY with the sperm identified and frozen in ESSM.

Had two TESEs and in both cases was told there was no sperm. He came to NY for a second opinion and was referred to Maze for ESSM as a prerequisite to considering additional surgery. He is now planning IVF in NY with the sperm identified and frozen in ESSM. 

F (35, Canada)

Transwoman was able to freeze adequate sperm to move on with her transition. 

A transwoman who wanted to consider fertility preservation before surgery. Uncomfortable with stopping hormones completely, she worked with her doctor to lower her doses and come in for ESSM. She was able to freeze adequate sperm to move on with her transition. 

G (27, CA)

M is now the father of a beautiful little girl.

He was frustrated- there was always sperm in his semen analysis, but no motility. While he worked with Dr Werner to try and improve his overall reproductive health, he wasn’t able to move on with IVF. ESSM was able to identify very small numbers of moving sperm that the semen analysis didn’t, and isolate them for IVF. M is now the father of a beautiful little girl.

M (52, NY)

ESSM recovered 5 times more sperm per vial, enough for 5 sperm per egg.

He had some vials of frozen TESE, but there were so few sperm in each vial that it took hours for the IVF lab to find enough for ICSI. They referred him for ESSM in hopes of finding enough to be able to choose the best quality sperm for ICSI, instead of the only one they could find. ESSM recovered 5 times more sperm per vial, enough for 5 sperm per egg.

R (36, NY)

published studies & articles

  1. A New Procedure Could Expand Reproductive Choices for Transgender Women with NYTIMES (October 2022) Read Now.
  2. Dr. Michael Werner shares background & results for Extended Sperm Search & Microfreeze, with A Time. (March 2021) Read Article
  3. Fertility Outcomes - Extended Sperm Search
  4. Microfreeze- A Novel solution for freezing small numbers of spermatozoa
  5. ESSM & a Transgender Female (Abstract)
  6. Utilization of ESSM in Severe Oligospermia
  7. Sperm Mapping and Sperm Vitrification to Minimize Testicular Biopsy
  8. Senior Andrologist, Chaya Rothschild, presents “Vitrification of Sperm- Sounds like a Plan” in the "Fertilization- What Matters? Filtering Out the Noise," webinar sponsored by ZyMōt Fertility Inc.

* The Extended Search procedure, which was developed and is performed in Israel by MFC Labs, is exclusively performed in the U.S. by Maze Health. Special thanks to Mordechai Koenig, and ATIME for notifying us about this groundbreaking technique.

Last Updated: February 2024