Lymphatic · Splen
Spleen
Your blood's quality control department, and a specialist at killing encapsulated bacteria.
- Mass
- ~150 g
- Blood filtered
- ~5% of cardiac output
- Platelets stored
- Up to a third of your total
- Survivable without
- Yes, with lifelong vaccination and care
What it does
Filter aged red cells, recycle iron, hold a reserve of platelets and white cells, and mount immune responses against blood-borne organisms.
The marvel
It reads every red blood cell that passes through. Cells too stiff or too old to squeeze through the splenic cords get pulled out and recycled, iron and all. It is also a frontline defender against bacteria with polysaccharide capsules, which is why people without a spleen need specific vaccines for life.
How to serve it well
If yours was removed, take it seriously
Asplenia means lifelong risk of overwhelming infection. Vaccination against pneumococcus, meningococcus, and Hib, plus a plan for fevers, is not optional.
Respect mononucleosis advice
Glandular fever enlarges the spleen and makes rupture possible. The advice to avoid contact sport for weeks is about that, not about tiredness.
Wear a seatbelt properly
The spleen is the most commonly injured organ in blunt abdominal trauma. A correctly positioned lap belt matters.
Book an appointment
- Fullness or discomfort in the upper left abdomen
- Feeling full quickly when eating
- Frequent infections, or easy bruising
Emergency, go now
- Severe left upper abdominal pain after trauma, with dizziness or pallor
- Any fever above 38°C if you have no spleen: this is a medical emergency
What you may have been told
“The spleen is a vestigial organ you do not need.”
You can survive without it, which is not the same as not needing it. People without a spleen carry a lifelong elevated risk of rapidly fatal sepsis from specific bacteria.
Where this comes from
- UK Health Security Agency · Asplenia and vaccination
- NHS · Spleen problems and splenectomy
- Centers for Disease Control and Prevention · Vaccines for asplenic patients
LUMEN is education, not medical advice, and it cannot know anything about you. It does not diagnose. If something here matches what you are experiencing, take it to a clinician who can examine you.