Sutures are the stitches doctors, and especially surgeons, use to hold
skin, organs, blood vessels and all other tissues of the human body
together, after they have been severed in minor or major surgery.
Sutures are designed to help the healing of the body by closely
opposing the two sides of a wound to minimize scar formation or to
prevent leaking blood, like in vessels. They have to comply with
several requirements to be effective. They must be strong (so they do
not break), non-toxic and hypoallergenic (to avoid adverse reactions
in the body), and flexible (so they can be tied and knotted easily).
In addition, they must lack the so called "wick effect", which means
that sutures must not allow fluids to penetrate the body through them
from outside, what could easily cause infections.
Absorbable and non-absorbable sutures
Absorbable sutures are made of materials which are metabolized inside
the body after around three weeks, and then disappear. They are used
therefore in many of the inner tissues of the body. In most cases,
three weeks is sufficient for the wound to close firmly. The suture is
not needed any more, and the fact that it disappears is an advantage,
as there is no foreign material left inside the body.
Absorbable sutures were originally made of the intestines of sheep,
the so called catgut. The manufacturing process was similar to that of
natural musical strings for violins and guitars, and also of natural
strings for tennis raquets. Today, natural absorbable sutures are made
primarily of bovine intestine. However, the major part of the
absorbable sutures used are now made of synthetic fibers, like
Non-absorbable sutures are made of materials which are not metabolized
by the body, and are used therefore either on skin wound closure,
where the sutures can be removed after a few weeks, or in some inner
tissues in which absorbable sutures are not adequate. This is the
case, for example, in the heart and in blood vessels, whose rhythmic
movement requires a suture which stays longer than three weeks, to
give the wound enough time to close. Other organs, like the bladder,
contain fluids which make absorbable sutures disappear in only a few
days, too early for the wound to heal.
There are several materials used for non-absorbables sutures. The most
common is a natural fiber, the silk, which undergoes a special
manufacturing process to make it adequate for its use in surgery.
Other absorbable sutures are made of artificial fibers, like polyester
or nylon. Finally, there are also metal wires used in orthopedic
surgery because of their strength and in some other tissues because of
the metal's outstanding tolerance by the body.
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Traumatic and atraumatic sutures
Traumatic sutures are those which are supplied to the hospital plain,
i.e., the suture thread with nothing else. The needle required to use
the suture is a separate item. The suture must be thread as it is done
when sewing at home.
Atraumatic sutures include a needle on each thread. The advantages of
having the needle mounted on the suture are several. The doctor or the
nurse do not have to spend time threading the suture on the needle.
More important, yet, is the fact that needle and thread form a single,
even body. In case of the traumatic suture, the thread comes out of
the needle's hole on both sides. When passing through the tissues,
this type of suture rips to a certain extent the tissue.
With the atraumatic sutures this does not happen. They produce no trauma to the
tissue, hence the name "atraumatic". Because of these advantages, the
atraumatic sutures are today very widely used.
There are several shapes of atraumatic needles, like straight, half
curved, one-third curved, and others. The body of the needle is
avaible also in different makes, like circular, with edge on the outer
side, with edge on the inner side, and others.
Sizes of sutures
The sutures were originally manufactured ranging from #1 to #6. (To
give an idea about these numbers, a #4 suture would be more or less
the diameter of a tennis raquet string.) The manufacturing techniques,
derived at the beginning from the production of musical strings, did
not allow thinner diameters. As the procedures improved, #0 was added
to the suture diameters, and later, thinner and thinner threads were
manufactured, which were identified as #2/0 to #6/0. This last
diameter, thinner than a human hair, was used during the last decades
primarily for eye surgery. Now, there are even thinner sutures, down
to #10/0. Atraumatic needles are manufactured in most of the shapes
for all these sizes.