How bone marrow donation works
Blood-forming stem cells are collected in two ways: peripheral blood stem cell (PBSC) donation and surgical marrow harvest. The official registry and medical team coordinate the method, timing, and donor care.
Enrollment and donor-cost policies vary by registry • Both methods explained
The two donation methods, side by side
Most people picture a large needle in the hip. For the large majority of donors today, that is not what happens. The default method is PBSC, where stem cells are collected from your bloodstream while you stay awake. The surgical harvest still exists, but it is the exception. NMDP reports that about 90% of donations use PBSC and about 10% use surgical marrow harvest. Both PBSC and marrow harvest are established collection methods, but recipient risks and outcomes differ by age, diagnosis, and clinical context. The transplant team selects the method for the patient. See the NMDP marrow-donation guidance. Here is how the two compare before we walk through each one in detail.
| PBSC (Peripheral Blood Stem Cell) | Marrow Harvest (Surgical) | |
|---|---|---|
| Share of donations (NMDP) | About 90% | About 10% |
| Method | Blood drawn from one arm; stem cells separated by machine | Needles into the pelvic bone under anesthesia |
| Procedure time | 4–8 hours, in one day | 1–2 hours, in one day |
| Return to activities | Usually 1–7 days | Usually 2–7 days |
| Median full recovery (NMDP) | 7 days | 20 days |
| Anesthesia | None | General |
| Scar | None | None |
| Comparable feeling | A long blood donation plus Filgrastim aches | Hard-workout soreness |
PBSC (Peripheral Blood Stem Cell)
- Share of donations (NMDP)
- About 90%
- Method
- Blood drawn from one arm; stem cells separated by machine
- Procedure time
- 4–8 hours, in one day
- Return to activities
- Usually 1–7 days
- Median full recovery (NMDP)
- 7 days
- Anesthesia
- None
- Scar
- None
- Comparable feeling
- A long blood donation plus Filgrastim aches
Marrow Harvest (Surgical)
- Share of donations (NMDP)
- About 10%
- Method
- Needles into the pelvic bone under anesthesia
- Procedure time
- 1–2 hours, in one day
- Return to activities
- Usually 2–7 days
- Median full recovery (NMDP)
- 20 days
- Anesthesia
- General
- Scar
- None
- Comparable feeling
- Hard-workout soreness
Enrollment and donor-cost policies vary by registry • Both methods explained
PBSC donation: the day-by-day timeline
PBSC is the method most donors give through. It runs on a short, predictable schedule: a few days of Filgrastim injections to move stem cells from your marrow into your bloodstream, then one day of collection at an outpatient center, then a short recovery. Nothing in this method involves surgery or anesthesia — the entire collection is done through IV lines while you stay awake. Here is what each stage looks like, day by day.
Days 1–5 (before donation)
- The donor center coordinates daily filgrastim doses; where and how they are administered varies by registry and donor-center plan. See the NMDP PBSC donation timeline.
- Common side effects are mild bone aching (often described as “like the flu”), headache, and fatigue.
- Those effects usually start 24 to 48 hours into the injection cycle.
- Most donors carry on with normal life — work, light exercise, and family time.
Day 5 (or Day 6) — donation day
- You arrive at the collection center, typically a specialized blood bank or hospital outpatient unit.
- An IV is placed in one arm, and blood is drawn through it.
- The blood passes through an apheresis machine that separates out the stem cells — the cells the patient needs — from the rest of the blood.
- The remaining blood, including red cells and plasma, is returned to you through a second IV in your other arm.
- Total collection time is 4 to 8 hours, sometimes split across two days.
- You stay awake. Most donors read, watch a screen, work on a laptop, or sleep.
- Some donors feel tingling in the lips or fingers from the anticoagulant used in the machine; staff manage it with calcium supplementation.
Day 6–7 (after donation)
- NMDP reports that most PBSC donors return to work, school, and regular activities within one to seven days.
- NMDP reports a median time to full PBSC recovery of seven days.
- Some report mild fatigue that lingers for 3 to 5 days.
- Your stem cells regenerate fully within about 4 to 6 weeks.
Procedure standards for the US donor program are published by the HRSA C.W. Bill Young Cell Transplantation Program. Recovery ranges come from the NMDP after-donation guidance. A peer-reviewed study of PBSC donors in Haematologica (Pulsipher et al., 2019) tracked donor symptoms during collection and recovery over the following year, and found that the most common effects — bone pain and fatigue — were usually short-lived, with most donors recovering within weeks.
Bone marrow harvest: when it’s chosen and what happens
The surgical harvest is the older method, and for most of the public it is still the mental image of “donating bone marrow.” In reality it is now the minority path, used in about one in ten donations, according to NMDP. Here is when it is chosen and exactly what the day involves.
When harvest is chosen (not PBSC)
- The transplant team selects harvest based on patient need — most often when the recipient is very young, very small, or has a condition where marrow stem cells are preferred over peripheral blood stem cells.
- NMDP reports that it accounts for about 10% of donations.
- The choice is made by the medical team, not by the donor.
The procedure day
- You arrive at the hospital in the morning.
- General anesthesia is administered, so you are unconscious for the procedure.
- The medical team makes several small needle punctures — not incisions — into the back of the pelvic bone, called the iliac crest.
- Liquid marrow is drawn out through the needles using syringes.
- The procedure itself takes about 1 to 2 hours.
- You wake up in recovery and typically go home the same day.
Recovery
- Expect soreness in the lower back and hip area, similar to a hard workout.
- Most donors return to work, school, and regular activities within 2 to 7 days.
- NMDP reports a median time to full recovery of about 20 days.
- Follow your donor team's guidance before resuming physical work or exercise.
- Your marrow regenerates fully within about 4 to 6 weeks.
- Soreness is managed with over-the-counter ibuprofen; some donors need a brief prescription.
The procedure and recovery described here match the patient-facing guidance published by the Cleveland Clinic, the Mayo Clinic, and Fred Hutchinson Cancer Center, the institution where modern bone marrow transplantation was pioneered.
The complete donor journey
The two procedures above sit inside a longer path that starts the day you register and ends with follow-up after you donate. Most people are on the registry for years before they are ever called, and many are never called at all. Here is the full sequence, end to end.
- Register. Register through your official registry. Enrollment method, timing, and cost rules vary.
- Wait. Most donors are on the registry for years before being called. Some are never called.
- Get the call. If you are a potential match for a patient, the registry contacts you. You confirm or decline.
- Confirmation testing. A blood sample for more detailed HLA testing to confirm the match.
- Final confirmation and health screening. A full medical workup. The transplant team makes the final go or no-go decision.
- Method selected. PBSC or harvest, chosen by the team based on what the patient needs.
- Donation. As described in the PBSC and harvest sections above.
- Recovery and follow-up. The registry follows up on your wellbeing for weeks to months after you donate.
Enrollment and donor-cost policies vary by registry • Both methods explained
What happens after you donate
Once your cells are collected, they are transported — often by a dedicated courier on the same day — to the hospital where the recipient is waiting. Timing matters, so the handoff is carefully coordinated around the patient’s treatment schedule.
By the time your cells arrive, the recipient has already been prepared with conditioning chemotherapy or radiation that clears out their existing marrow. Your cells are then infused into their bloodstream, much like a transfusion. Over the following days and weeks, the donated stem cells migrate to the recipient’s bone marrow and begin producing new, healthy blood cells — a process called engraftment. Until those new cells take hold, the recipient has very little immune defense and is cared for under close monitoring. The National Cancer Institute explains how the transplanted cells rebuild the blood and immune system after this kind of transplant.
The recipient’s own recovery takes months, but the goal is lasting: many people go on to long-term remission or cure. You can read one such outcome in Torsten and Jada’s story, where a stranger’s donation reached a child who needed it.
Frequently asked questions
What to do next
Now that the process is clear, here are the questions most people want answered before they register.
- Wondering about pain? Does bone marrow donation hurt?
- Planning for after donation? What recovery is like
- Wondering about eligibility? Can I donate bone marrow?
- Curious how matching works? What is HLA matching?
- Ready to register? How to find and join your registry
You now know what donation actually involves, day by day, for both methods. Registering begins with the official registry serving your country; enrollment method, timing, and cost rules vary. That registry handles eligibility, typing, and coordination if you are ever matched.
Enrollment and donor-cost policies vary by registry • Both methods explained