Prepping a patient's skin before surgery is something your staff does dozens of times a day, often without putting much thought into it. But there's a lot of science behind proper prepping. Knowing the best prep for each situation improves your facility's infection prevention and helps avoid complications. Here's a quiz to test your prepping knowledge.

1. The correct method for applying a chlorhexidine-alcohol prep solution is _____ .
a. concentric circles
b. back and forth
c. both

Answer: b. Regardless of whether you're using chlorhexidine or povidone-iodine, friction is essential to good prepping. Adding friction makes sure that the prep solution gets into the crevices, grooves, hair follicles and sebaceous glands. For chlorhexidine, use a back-and-forth method for 30 seconds, starting from the surgical site and moving outward. For moist sites, such as the inguinal fold or the axilla, apply the prep for 2 minutes, as recommended by the manufacturer. For povidone-iodine, which covers the skin more easily, use the traditional concentric circles, beginning at the incision site.

As the sponge or applicator is used it shouldn't come in contact with areas that have already been prepped. If you need to go back and apply more prep to an already prepped area, use a new sponge or applicator.

2. Which surgical skin prep is recommended in the Joint Commission's National Patient Safety Goals for 2011-2012, AORN's Recommended Practices for Pre-operative Patient Skin Antisepsis and the CDC's Guideline for Prevention of Surgical Site Infection?
a. chlorhexidine
b. povidone-iodine
c. alcohol
d. none of the above

Answer: d. While there's much talk of the efficacy of chlorhexidine over povidone-iodine, the Joint Commission, the Association of periOperative Registered Nurses and the Centers for Disease Control and Prevention have yet to call for using chlorhexidine as a first-choice prep.

The Joint Commission calls for hospitals to "administer antimicrobial agents for prophylaxis for a particular procedure or disease according to methods cited in scientific literature or endorsed by professional organizations."

AORN, in its recommendations, says that the choice should be left to the facility and its infection control professionals. "Pre-operative skin antiseptic agents that have been FDA-approved or cleared and approved by the healthcare organization's infection control personnel should be used for all preoperative skin preparation," says AORN.

The CDC recommends chlorhexidine as a skin prep for catheters in its Guideline for the Prevention of Intravascular Catheter-Related Bloodstream Infections, but not for surgical prepping. The surgical site infection prevention guidelines were published in 1999, before a handful of recent studies that show that chlorhexidine is more effective than povidone-iodine in certain situations. "No studies have adequately assessed the comparative effects of these pre-operative skin antiseptics on SSI risk in well-controlled, operation-specific studies," says the CDC guideline.

3. It's important to make sure that chlorhexidine dries before making an incision because _____ .
a. the prep will burn subdermal layers of tissue
b. the prep has a high alcohol content and is flammable
c. the prep needs at least 2 minutes to become active
d. none of the above

Answer: b. A solution of chlorhexidine and 70% isopropyl alcohol creates a one-two punch microbial kill. Alcohol is fast-acting and kills a wide variety of microbes. It's more effective against gram-negative bacteria, Mycobacterium tuberculosis and fungi than chlorhexidine, according to the CDC. But alcohol evaporates quickly, making its effectiveness short-term. So adding chlorhexidine, which has a longer residual kill, extends the effectiveness of the skin prep.

The drawback, however, is that alcohol is highly flammable and can cause fires. The combination of a wet alcohol-based skin prep, drapes, oxygen and heat sources such as cautery devices creates a serious fire risk. Each year 550 to 650 fires break out in operating rooms across the United States, according to the ECRI Institute. Alcohol-based preps should be allowed to dry thoroughly before beginning any procedure. A chlorhexidine-alcohol prep needs at least 30 seconds to dry on most areas of the body. After application on moist areas, such as the inguinal fold or the axilla, allow at least 1 minute to dry. In situations when the patient will be draped after prepping, do not drape the patient for at least 3 minutes to make sure that the prep is completely dry. Allow more time if the prep is in the patient's hair. Wet hair is flammable.

Also, make sure that you don't let the prep pool underneath the patient, pneumatic cuffs or electrodes or in the belly button. This can cause irritation or burns as well as increase the risk of fire.

4. Which prep is best suited for ophthalmic surgery?
a. chlorhexidine
b. povidone-iodine
c. alcohol
d. none of the above

Answer: b. Povidone-iodine is the standard prep for eye surgery because it does not irritate mucous membranes. The CDC rates povidone-iodine as excellent against gram-positive bacteria and good against gram-negative bacteria, viruses, tuberculosis and fungi. Prepping the eye and the skin around the eye with povidone-iodine has been shown to reduce the risk of endophthalmitis. Because it can be used on mucous membranes, povidone-iodine is also suited for prepping areas around the mouth and genitals. Although there's no alcohol in povidone-iodine solution, the prep should be allowed to dry so that the drape will stick to the patient's face.

5. If an ophthalmic patient reports that he's allergic to iodine, which is a suitable alternative?
a. parachlorometaxylenol (PCMX)
b. chlorhexdine
c. alcohol
d. baby shampoo

Answer: a. When patients say they are allergic to iodine or feel burning when a povidone-iodine prep is applied around the eye, you should use an alterative. Parachlorometaxylenol (PCMX) does not irritate mucous membranes, has a good kill rate against gram-positive bacteria and fair efficacy against gram-negative bacteria, tuberculosis, fungi and viruses, according to the CDC. Alcohol and chlorhexdine can cause corneal damage. Other products, such as baby shampoo or wipes marketed to remove eye makeup do remove some skin flora, but they do not create a sterile environment. (For more information on this topic, see "Eye Preps: When You Can't Use Povidone-Iodine" in Outpatient Surgery Magazine, March 2007).

6. In studies in the New England Journal of Medicine in January 2010, which prep was associated with a reduction in surgical site infections?
a. chlorhexidine
b. povidone-iodine
c. iodine povacrylex and alcohol
d. bone

Answer: a. A year ago, researchers reported in the January 7, 2010, issue of the New England Journal of Medicine that patients who received a chlorhexidine-alcohol prep had 40% fewer surgical site infections than those who received a povidone-iodine prep. The study included 849 participants and was paid for by a manufacturer that sells both chlorhexidine and povidone-iodine preps. This study was important because it was among the first large studies to look at surgical site infections when comparing skin preps.

Previous studies measured the bacteria killed by each prep. For example, researchers at Northwestern University in Chicago compared the bacterial kill of chlorhexidine, povidone-iodine and iodine povacrylex and alcohol on shoulder surgery patients. In results published in the August 2009 issue of the Journal of Bone and Joint Surgery, the rate of positive cultures was 31% for patients prepped with povidone-iodine, compared with 19% in the iodine povacrylex and alcohol group, and 7% in the chlorhexidine group.

7. Which prepping agent has the longest residual activity?
a. chloroxylenol
b. alcohol
c. chlorhexidine
d. povidone-iodine

Answer: c. According to the CDC, chlorhexidine has the longest residual activity (11 hours), followed by povidone-iodine (2 hours) and then alcohol, which has no residual activity once it has evaporated. With chlorhexidine and iodine solutions, the prep should not be washed off afterward so that the patient can benefit from the residual activity for as long as possible.

8. Which prepping agent has the quickest activation?
a. chloroxylenol
b. alcohol
c. chlorhexidine
d. povidone-iodine

Answer: b. Alcohol is the quickest antimicrobial, killing a wide range of bacteria, fungi, viruses and tuberculosis on contact by denaturing the proteins in the organisms. But alcohol's effectiveness is limited to the time when it's wet. Once it evaporates, its killing power disappears.

9. Is chlorhexidine suited for use on open wounds?
a. yes
b. no

Answer: b. Chlorhexidine is not suited for application on open wounds because it can cause irritation. According to AORN's Recommended Practices for Preoperative Patient Skin Antisepsis, open wounds, such as orthopedic injuries with exposed bone, should be washed with pulse lavage, which can greatly reduce wound contamination. Likewise, you shouldn't use chlorhexidine around the eyes or mouth because it can cause irreversible damage, or during lumbar puncture procedures because it is toxic to nerves. The solution is also associated with damage to the middle ear.