A surgical procedure performed during space flight would occur in a un
ique microgravity environment. Several experiments performed during we
ightlessness in parabolic flight were reviewed to ascertain the behavi
or of surgical bleeding in microgravity. Simulations of bleeding using
dyed fluid and citrated bovine blood, as well as actual arterial and
venous bleeding in rabbits, were examined. The high surface tension pr
operty of blood promotes the formation of large fluid domes, which hav
e a tendency to adhere to the wound. The use of sponges and suction wi
ll be adequate to prevent cabin atmosphere contamination with all blee
ding, with the exception of temporary arterial droplet streams. The co
ntrol of the bleeding with standard surgical techniques should not be
difficult.