A Day in the IVF Lab


Most people call  our embryology laboratory an IVF lab (in vitro fertilization lab), but it’s technically an embryology lab and there’s a separate andrology lab where semen is collected and analyzed. An egg, sperm and embryo cryopreservation area is adjacent to the embryology lab in University of Colorado Hospital.

The Advanced Reproductive Medicine (ARM) team of embryologists, physicians, nurses and others gave a behind-the-scenes look at a typical day in their lab.

Meet our Team


Prepping for the day

IVF Lab Table | Fertility Lab Tour
The day starts around 7 a.m. as embryologist Melissa Rosario opens up and staff members begin to arrive and prepare for a full day of IVF work. Today it’s two egg retrievals, four embryo transfers, two semen collections and sample preps to go along with the egg retrievals, two intracytoplasmic sperm injections (ICSIs) and the normal lab activities of analysis, testing, embryo evaluation, monitoring, shipping and receiving to genetics labs and much more.

The first egg retrieval of the day

Egg Retrieval Lab Table | Fertility Clinic Tour

The dual console lab table is IVF-central for Rosario and fellow embryologist David Russell. Two embryology lab stations have built in microscopes, special heated surfaces and chambers to keep the embryos and eggs happy when they are out of the incubator.

The stations are adjacent to an operating room with pass-thru windows connecting the two rooms. The incubators are within reach of the embryologists at the lab tables. The physician and a hopping crew begin the first egg retrieval in OR 1. The female patient is sedated but conscious as the doctor goes for the egg follicles guided by an ultrasound image. About the size of a grape, the first follicle’s fluid is aspirated and placed in a tube that is passed to David. “Number one,” he announces through the window to the OR team, meaning he has found the first viable egg. The team retrieves more follicles in the course of about 15 minutes and David finds 10 eggs, the number they predicted from earlier ultrasounds. He uses a microscope to evaluate the cells of each egg’s encircling cumulus cloud. “How do they look?” asks the doctor, and David replies they look good. “You always say that,” she says. David replies that he always likes to add to the positive atmosphere —and these eggs are good. David places them in the incubator where the pH of the culture media is maintained similar to the pH of a womb, and the temperature is held at about 37degrees Celsius (body temperature). The eggs await preparation for fertilization later in the day.

Chain of custody

Nurses & Embryologists at CU Advanced Reproductive Medicine Lab Throughout the day’s procedures and movements of eggs, sperm and embryos, the entire team takes meticulous care to identify every item and match it with the right patient. These protocols include verbal, visual and written confirmations, double-checked by different staffers. Everything is labeled and number coded before being used in a procedure or being stored in incubators and the nearby cryopreservation tanks holding sperm, eggs and embryos.

Frozen embryo prep and implantation

Frozen embryo transplant prep | Infertilty Lab TourAt 9:30 a.m., Melissa prepares a frozen embryo to be implanted in a couple of hours. Vitrified embryos are flash frozen, and Melissa needs to (and does) know exactly how this was done in order to un-vitrify it properly, which they call “warming.” Using a series of warming solutions Melissa carefully warms and rehydrates the embryo. Once the embryo is successfully warmed, it goes in the incubator until the recipient mother is ready for transfer. Melissa begins warming another embryo for later transfer. Its quality isn’t very good and she thinks the chances of pregnancy are decreased, but she has seen embryos of this quality make babies before. At 11:07 a.m., the OR team has the first mom ready to receive her embryo (embryo transfer). Melissa loads the embryo into a long thin soft flexible plastic tube known as a catheter, and walks it into the OR. The doctor guides the catheter into the uterus using ultrasound to visualize the uterine cavity. Melissa returns to the microscope to confirm the embryo did not get stuck in any mucus that may be present on the catheter. “All clear!” she calls out through her window to the OR. And the procedure is done. Of the four embryo transfers on this day, three were with previously frozen embryos and one was considered a fresh embryo transfer 5 days after the egg retrieval. Three patients chose to include acupuncture in the process, which can improve blood flow that can help create a more embryo-receptive environment in the uterus. Acupuncture’s stress-reducing properties are also welcome during infertility treatments.

ICSI, or “sperm wrangling”

David finishes prepping the sperm for one of the two ICSIs (intracytoplasmic sperm injections) being done in an hour. The sample collected early this morning has about 3,000 sperm, a far cry from the 38,000,000 the patient had in his sample only months before. The patient was called back to the lab to collect a second sample. At that point, Melissa and David found out he recently started taking a “fitness supplement” that contained testosterone which severely impacted his sperm production.  ICSI will give these sperm a big assist in finding the target by injecting a single healthy sperm into each of the female partner’s eggs. At the inverted microscope/ICSI station, Melissa looks at the magnified round up of five eggs in the drops surrounding the sperm sample in the middle. She’s having to hunt for one of the 3,000 sperm, sees one moving past, and pins it down by the tail. “They’re very durable,” she says, as she flips the sperm around with her microscopic glass needle and sucks it up tail first. She moves one of eggs around looking for the right spot to enter, holds it in place with another glass tool, then pokes through the egg’s outer shell (zona pellucida) with the needle and injects the sperm into the cytoplasm center of the egg. This is where fertilization takes place.

At the end of the day

Because maturing embryos and women ready to ovulate do not take weekends off, David and Melissa often need to do something in the lab every day of the week. “Embryologists never know what they’ll be doing until about two days beforehand,” says Melissa. So the lab crew finishes up the day’s work and preps for the next, diligently cultivating and sustaining the eggs, sperm and embryos in ARM’s care, and keeping this very important part of fertility treatment operating smoothly.