How you store period blood depends entirely on why you’re saving it. People collect menstrual blood for stem cell banking, diagnostic testing, DNA preservation, and personal or spiritual practices. Each purpose calls for different methods, temperatures, and timelines. Here’s what works for each scenario and what happens to menstrual blood when it’s stored under various conditions.
Collecting Menstrual Blood Cleanly
A menstrual cup is the most common collection method, whether you’re saving blood for personal use or contributing to a medical study. Cups collect blood directly without absorbing it into fibers, which gives you a cleaner, more concentrated sample. Research comparing menstrual cups, tampons, and pads for donation found that cups yielded the most usable material. Tampons and pads absorb much of the fluid and mix it with cotton or synthetic fibers, making extraction harder.
If you’re collecting for any kind of testing or banking, empty the cup into a clean glass or sterile container. Wash your hands first and avoid touching the inside of the container. For personal use where sterility isn’t critical, any clean jar with a lid works.
Short-Term Storage: Refrigerator vs. Room Temperature
Temperature makes a dramatic difference in how quickly menstrual blood degrades. At room temperature (roughly 18°C to 25°C), the living cells in blood deteriorate fast. Studies on blood stem cells show that at room temperature, only about 45% of viable stem cells remain after 24 hours, dropping to 19% by 48 hours and essentially zero by 72 hours. The blood’s ability to form new cell colonies disappears completely within 48 hours at room temperature.
Refrigeration at around 4°C changes the picture significantly. At that temperature, about 97% of viable stem cells survive the first 24 hours, 87% remain at 48 hours, and even at 96 hours (four days), roughly 78% are still intact. If you’re storing menstrual blood for any biological purpose, getting it into the refrigerator quickly is the single most important step you can take.
For simple personal storage with no medical or testing goals, refrigeration still slows bacterial growth and keeps the blood from breaking down as fast. Expect the color to darken and some separation to occur regardless of temperature.
Preventing Clotting
Menstrual blood clots naturally, and if you want to keep it in liquid form, you’ll need an anticoagulant. In laboratory settings, EDTA is commonly used at a concentration of about 4 millimolar (0.15% by weight). Heparin is another option, though it can cause platelet clumping and alter the appearance of white blood cells.
For home storage without lab-grade chemicals, some people stir the blood immediately after collection to break up clots mechanically, or add a small amount of saline. These methods won’t prevent clotting as effectively as chemical anticoagulants, but they can slow the process. If you’re storing blood for a commercial testing kit, follow the kit’s instructions exactly, as many include their own preservative solutions in the collection tube.
Long-Term Storage: Freezing and Cryopreservation
For storage beyond a few days, freezing is necessary. How you freeze matters.
For personal storage or DNA preservation, a standard home freezer works. Forensic research shows that freezing at around -30°C is one of the two best methods for preserving DNA integrity, alongside air-drying. Frozen samples yielded the highest DNA recovery rates and produced the most complete genetic profiles when tested later. Pour the blood into a freezer-safe container, leave a small gap at the top for expansion, seal it tightly, and freeze it as soon as possible after collection.
For stem cell banking, the process is more involved. Clinical-grade protocols use controlled-rate freezing with a cryoprotectant solution, typically 10% DMSO mixed with 90% serum. The cells are frozen gradually using specialized equipment and then stored in liquid nitrogen. This isn’t something you can replicate at home. Companies that offer menstrual stem cell banking provide collection kits and handle the freezing process at their facility. If you’re interested in this, the key on your end is getting the sample refrigerated and shipped to the lab as quickly as possible.
Preserving DNA From Menstrual Blood
If your goal is to preserve genetic material for future testing, you have two reliable options: freezing or air-drying. Both methods consistently outperform other storage approaches in forensic studies. Air-drying is surprisingly effective. Letting menstrual blood dry on a clean surface (a cotton swab, filter paper, or even fabric) at room temperature preserves DNA well enough for later extraction and genetic profiling.
Dried samples are also easier to store long-term. They don’t need refrigeration, take up less space, and are more stable at room temperature than liquid blood. If you’re storing blood specifically for genetic information, letting it dry on a clean piece of cotton or paper and sealing it in an airtight bag is a practical, low-tech approach that works.
Storing Samples for Diagnostic Testing
Several companies now offer at-home diagnostic kits that use menstrual blood to screen for conditions like endometriosis or hormonal imbalances. These kits come with specific collection devices and preservative solutions designed to keep the sample stable during shipping.
General guidelines for diagnostic samples: after collection, store the transport tube between 2°C and 30°C for up to 14 days. If you can’t ship it within that window, freeze the sample at -10°C or colder, where it remains viable for up to 90 days. Always follow the specific instructions included with your kit, as preservative formulations vary between manufacturers.
Shipping Menstrual Blood Safely
If you need to mail a menstrual blood sample to a lab or banking facility, it’s classified as a Category B biological substance under shipping regulations. This requires triple packaging: a leak-proof primary container (the tube or vial holding the blood), a leak-proof secondary container (like a sealed plastic bag with absorbent material), and a sturdy outer box.
The outer package needs a UN 3373 diamond label with the words “Biological Substances, Category B,” plus the sender’s and receiver’s names, addresses, and phone numbers. Category B shipments don’t require hazardous materials declarations or special infectious substance labels, which makes the process simpler than shipping higher-risk materials. Most stem cell banking and diagnostic companies provide pre-labeled shipping materials in their kits, so you won’t need to source packaging yourself.
It’s recommended to place each tube in an individual sealable bag before packing. If you’re shipping in warm weather, include a cold pack to keep the sample closer to refrigerator temperature during transit, especially if the sample contains living cells you want to preserve.