10.01 Simple laceration
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agk's Library of Common Simple Emergencies

Presentation
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There may be a history of being slashed by a 
knife, glass shard or other sharp object that 
results in a clean, straight wound. Impact with 
a hard object at an angle to the skin may tear 
up a flap of skin. Crush injury from a direct 
blow may produce an irregular or stellate 
laceration with a variable degree of devital- 
ized tissue, abrasion and visible contamin- 
ation. Wounds may involve vascular areas of the 
face and scalp where the risk of infection is 
low, or extremities where infection becomes a 
greater risk, along with the possibility of 
tendon and nerve damage. The elderly and 
patients on chronic steroid therapy may present 
with "wet tissue paper" skin tears following 
relatively minor trauma.

What to do:
-----------

- Establish the approximate time of injury. 
    After four hours, wounds should be scrubbed 
    to remove the protein coagulum. There is no 
    significant time-related difference in 
    infection rates for wounds closed within 18 
    hours.
- Determine the exact mechanism of injury, 
    which should alert you to the possibility 
    of an underlying fracture, retained foreign 
    body, wound contamination or tenden or 
    nerve injury.
- Investigate for any underlying factors that 
    may increase the risk of wound infection, 
    like diabetes, malnutrition, morbid 
    obesity, or patients taking chronic immuno- 
    supressive doses of corticosteroids, as 
    well as chemotherapy, AIDS, alcoholism and 
    renal failure.
- Ask about [tetanus] immunization status and 
    provide prophylaxis where indicated.

- Test distal sensory and motor function. Test 
    tendon function against resistance. If 
    function is intact but there is pain, 
    suspect a partial tendon laceration. Tendon 
    and nerve lacerations deserve specialty 
    consultation.
- Consider imaging studies if there might be a 
    radio-opaque retained foreign body.
- Consider anxiolytic conscious sedation for 
    children, like oral, nasal or rectal 
    midazolam (Versed). Follow your hospital 
    protocol.
- Children may also benefit from a topical 
    anesthetic agent, especially for scalp and 
    facial lacerations. Lidocaine 4% plus 
    epinephrine 1:1000 plus tetracaine 0.55 
    (LET) is safe, effective and inexpensive. 
    Put 3mL on a 2x2" gauze square and press 
    firmly into the wound for 15 minutes either 
    with tape or the parent's gloved hand. 
    After removing the gauze, test the effect- 
    iveness of the anesthesia by touching with 
    a sterile needle. If any sensitivity 
    remains, infiltrated the area with buffered 
    lidocaine as described below.
- Buffer plain lidocaine solution by adding 1mL 
    of sodium bicarbonate solution to 9-10mL 
    and allow it to approximate body temp- 
    erature in your pocket. Bupivacaine 
    (Marcaine) is slightly slower in onset but 
    has a much longer duraction of action and 
    may be useful for crush injuries and 
    fractures where pain is expected to be 
    prolonged beyond closure of the laceration. 
    Epinephrine added to lidocaine is generally 
    not recommended for its short-lived help 
    with hemostasis and duration of anesthesia, 
    and its use should generally be discouraged 
    because of its increased pain on injection 
    and its slower healing and increased 
    infection rate. Bicarbonate inactivates 
    epinephrine.
- Inject slowly, subdermally, beginning inside 
    the cut margin of the wound, avoiding 
    piercing intact skin, working from the area 
    already anesthetized, using a 27 or 30 
    gauge needle on a 5 or 10mL syringe.
- Use regional blocks to avoid distorting 
    tissue or where there is no loose areolar 
    tissue to infiltrate, such as the finger 
    tip.
- Clean the wound after anesthesia is complete. 
    Superficial lacerations with little or no 
    visible contamination may be cleaned by 
    gentle scrubbing with a gauze sponge soaked 
    in normal saline or a 1% solution of 
    povidone-iodine (dilute the stock 10% 
    betadine tenfold with 0.9% NaCl). Deeper 
    contaminated lacerations may require 
    pressure irrigation with a syringe and 
    splash shield like Zero-Wet using the same 
    1% povidone-iodine solution or plain saline 
    if the patient is allergic to iodine. All 
    visible debris and devitalized tissue must 
    be removed, either by scraping with the 
    edge of a scalpel blade or excision with 
    scalpel or scissors. Cosmetic consider- 
    ations will influence the degree to which 
    you debride facial lacerations, but 
    excision of contaminated, macerated wound 
    edges will often produce a neater scar.
- Hair generally does not need to be removed. 
    When necessary, shorten hair with scissors 
    rather than shaving with a razor.
- Simple lacerations seldom require special 
    techniques for hemostasis. Direct pressure 
    for ten minutes, correct wound closure, and 
    a compression dressing should almost always 
    stop the bleeding.
- Examine the wound free of blood with good 
    lighting. Examine any deep structures like 
    tendons by direct visualization through 
    their full range of motion, looking for 
    partial lacerations. If the wound has been 
    heavily contaminated with debris, crushed, 
    macerated, neglected for a day, exposed to 
    pus, feces, saliva or vaginal discharge, 
    consider excising the entire wound and 
    closing the fresh surgical incision, if 
    practical. Otherwise, provide for open 
    management by packing with sterile fine- 
    mesh gauze covered with multiple layers of 
    coarse absorptive gauze. Unless the patient 
    develops a fever, leave the dressing 
    undisturbed for 4 days. If there are no 
    signs of infection, the granulating wound 
    edges may then be approximated as a delayed 
    primary closure.
- Close the wound primarily only if it is clean 
    and uninfected. Minimize the amount of 
    suture material inside. The less used, the 
    less chance of infection. Wound closure 
    tapes offers the least risk of infection, 
    and are most successfully used on simple 
    superficial lacerations with minimal 
    tension. They are the closure of choice for 
    "Wet tissue paper" skin tears. Prior to 
    application, degrease the skin with 
    alcohol, being careful not to get any into 
    the wound. An adhesive agent such as 
    tincture of benzoin may then be thinly 
    applied to the skin surrounding the 
    laceration (again, avoiding the open 
    wound). Push the wound edges together and 
    apply the stripe to maintain approximation.
- Most scalp lacerations and many trunk and 
    proximal extremity lacerations that are 
    straight without edges that curl under 
    (invert) can be most easily repaired using 
    skin staples. Push edges together and 
    staple so edges evert slightly. Hair does 
    not interfere with this technique and does 
    not cause a problem if caught under a 
    staple.
- For deep or irregular lacerations or on face, 
    hands or feet and skin over joints, use a 
    monofilament non-absorbable suture like 
    nylon or polypropylene either 4-0, 5-0, or 
    6-0, the smallest diameter with sufficient 
    strength. A good strategy to realign skin 
    and minize sutures is to begin by 
    approximating the midpoint of the wound and 
    then bisect the remaining gaps. Simple 
    interrupted stitches should be about 1cm 
    apart and 1cm deep and 1cm back from from 
    the wound edge, although these dimensions 
    may be reduced for cosmetic closure on the 
    face. Angle the needle going and in and 
    coming out so it grasps more subcutaneous 
    tissue than skin, and the wound edges 
    should evert so the dermis meets and the 
    scar is minimized. Tie each stitch with 
    only enough tension to approximate the 
    edges. A continuous running suture is a 
    more rapid technique of closing a straight 
    laceration. When there is wound edge 
    inversion, the length of the wound edge can 
    be completely excised or vertical mattress 
    sutures can be placed between simple 
    interrupted stitches. Unless deep fascial 
    planes are disrupted, avoid buried sutures 
    because they increase the risk of 
    infection.
- After closing the wound, apply antibiotic 
    ointment and a sterile dressing which will 
    protect the wound and provide absorption, 
    compression and immobilization. Scalp and 
    facial wounds may be covered only with 
    ointment is hemostasis is not required. 
    Splint lacerations over joints. Facial 
    wounds should be cleaned twice a day with 
    half strength hydrogen peroxide on a cotton 
    tipped applicator to prevent crusting 
    between wound edges followed by re- 
    application of antibiotic ointment.
- Schedule a wound check at two days if the 
    patient is likely to develop any problems 
    with infection, dressing changes, or 
    continued wound care. Instruct patients to 
    return at any time for bleeding, loss of 
    function or signs of infection: increasing 
    pain, pus, fever, swelling, redness, heat. 
    After 48 hours, most sutured wounds can be 
    re-dressed with a simple bandage that can 
    be easily removed and replaced by the 
    patient allowing a shower each day.
- Wound closure strips can be left in place 
    until they fall off on their own. 
    Additional tape can be applied if the 
    original closure falls off prematurely.
- Remove facial sutures in four to five days to 
    reduce visible stitch marks. The epidermis 
    should have resealed by this time, but the 
    dermis has not developed much tensile 
    strength, so reinforce the wound edges with 
    wound closure strips for a few more days.
- Most scalp, chin, trunk and limb stitches 
    should be removed in a week. Sutures may be 
    left in 10-14 days where there is tension 
    across wound edges as on the shin and over 
    the extensor surfaces of large joints. 
    Sutures are easily and painlessly cut with 
    the tip of a scalpel. Cut alternate loops 
    of running sutures.

What not to do:
---------------

- Do not prescribe prophylactic antibiotics for 
    simple lacerations. They do not reduce 
    infection rates, and only select for 
    resistant organisms.
- Do not close a laceration if there is visible 
    contamination, debris, non-viable tissue or 
    signs of infection.
- Do not substitute antibiotics for wound 
    cleansing and debridement. Reserve 
    antimicrobials for infections and deep 
    innoculated puncture wounds which cannot be 
    cleaned.
- Do not substitute x rays for meticulous 
    direct wound examination when a foreign 
    body is suspected by history.
- Do not use undiluted skin cleansing solution 
    like 10% povidone-iodine or any skin-scrub 
    containing detergents or soap within an 
    open wound. It kills tissue and increases 
    the infection rate.
- Do not shave an eyebrow. The hair is a useful 
    marker for re-approximating the skin edges, 
    and can take months to years to grow back.
- Do not remove too much skin or underlying 
    tissue when debriding the face and scalp.
- Do not use buried absorbable sutures in a 
    wound with a high risk of infection.
- Do not insert drains in simple lacerations. 
    They are more likely to introduce infection 
    than prevent it.
- Do not use Neosporin ointment. Many patients 
    are allergic to the neomycin and develop 
    allergic contact dermatitis.

Discussion:
-----------

The most important goal of early wound care is 
preventing infection. Ointments probably 
facilitate healing and reduce infection by 
their occlusive rather than antibiotic 
properties. Extensive primary excision limits 
options for later scar revision, and sometimes 
it reasonable to close a contaminated facial 
laceration for cosmetic reasons, but this is 
the exception that proves the rule.

Although not yet available in the US outside of 
veterinary practice, butyl cyanoacrylate 
(Histoacryl blue) the less toxic version of 
SuperGlue, works well for minor pediatric 
lacerations. The technique is to hold edges 
together (the same as for tape or staples), 
drip one drop onto the gap every centimeter, 
and hold for ten seconds.

References:
-----------

- Cummings P, Del Beccaro MA: Antibiotics to 
    prevent infection of simple wounds: a meta- 
    analysis of randomized studies. *Am J Emerg 
    Med* 1995;13:396-400.
- Schilling CG, Bank DE, Borchert BA et al: 
    Tetracaine, epinephrine (adrenaline) and 
    cocaine (TAC) versus lidocaine, epinephrine 
    and tetracaine (LET) for anesthesia of 
    lacerations in children. *Ann Emerg Med* 
    1995;25:203-208.
- Mehta PH, Dun KA, Bradfield JF et al: 
    Contaminated wounds: infection rates with 
    subcutaneous sutures. *Ann Emerg Med* 
    1996;27:43-48.

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