Sea urchins are free-living echinoderms with egg-shaped, globular or flattened bodies. They are covered by tightly arranged spines and/or triple-jawed pedicellariae, which are seizing and envenoming organs. The spines can be brittle, hollow, sharp and venom-bearing or blunt and non venom-bearing (such as with Hawaiian pencil urchins). Most persons are envenomed when they step upon or brush against an urchin.
The clinical aspects are characterized by intense local tissue pain, which may radiate deeply into muscle. There may be redness and swelling, or perhaps punctate purple discoloration. The latter may represent dye leached from the surface of a spine, rather than indicate a retained spine. If a spine resides near a joint, particularly in the hand, there may be inflammation, which can cause swelling of a finger or the entire hand. When multiple spines enter a victim, there may be nausea, vomiting, numbness and tingling, nerve dysfunction causing weakness or paralysis, fainting, low blood pressure, or difficulty breathing.
Therapy for a sea urchin puncture(s) is as follows:
Extract any easily grasped spine fragments. Do not crush spines within the soft tissues.
If any pedecellariae (seizing organs) are still attached, remove these with a sharp edge and something like shaving cream.
For pain relief at any time during the process, immerse the wound(s) into non-scalding hot (113 degrees Fahrenheit or 45 degrees Centigrade) water to tolerance for 30 to 90 minutes. If pain recurs, repeat the hot water immersion.
A doctor may need to use a local anesthetic for pain control.
A doctor may need to obtain an x-ray, computed tomography (CT), magnetic resonance imaging (MRI) or ultrasound exam to locate the spine(s).
If a spine is situated near or within a joint and is causing severe symptoms (e.g., inflammation, infection), it may need to be removed.
A deep puncture wound of immune suppression of the victim is a possible indication of administration of a prophylactic antibiotic (such as ciprofloxacin, doxycycline, or trimethoprin-sulfamethoxazole). These treatment suggestions are similar to those that are recommended for puncture wounds from the spines of crown-of-thorns starfish.