Is Bad Odor from a Wound VAC Normal?
A foul odor from a wound VAC is NOT normal and indicates either wound infection, inadequate debridement before VAC placement, or contamination of the wound—you must remove the VAC dressing immediately, inspect the wound for signs of infection, and ensure complete surgical debridement has been performed before reapplying negative pressure therapy. 1, 2
Understanding Why Odor Occurs with VAC Therapy
The presence of a bad smell suggests one of three problems:
Active wound infection: Purulent discharge, friable tissue, or foul odor are secondary signs of bacterial infection in wounds, particularly when classic inflammatory signs may be absent 3. The VAC system itself does not cause infection but will not eliminate existing infection without proper debridement 1, 2.
Incomplete initial debridement: NPWT should never be applied to infected wounds until complete surgical removal of all necrotic and infected tissue has been accomplished 1. If necrotic tissue remains under the VAC, bacterial proliferation will continue and produce malodorous compounds 1, 2.
Wound contamination during therapy: While VAC systems are designed to be watertight and contain secretions, contamination with stool and urine must be avoided when VAC dressings are applied to the vulva and perineum 3. Fecal contamination is a particular concern in perineal wounds.
Immediate Actions Required
When you detect foul odor from a VAC dressing:
Remove the VAC dressing immediately and perform a thorough wound inspection looking for purulence, spreading erythema, friable granulation tissue, or undermining of wound edges 3.
Obtain wound cultures if purulence or spreading cellulitis is present, as these are indications for microbiological sampling 3.
Perform or arrange for complete surgical debridement if any necrotic tissue, purulence, or infected tissue is identified—sharp debridement with scalpel, scissors, or tissue nippers remains the gold standard and is preferable to any topical agent 2.
Do not reapply NPWT until all infected and necrotic tissue has been completely removed and the wound bed shows healthy granulation tissue 1, 2.
Evidence on VAC and Bacterial Contamination
Research demonstrates that properly functioning VAC systems do not disperse bacteria into the environment—contamination of the VAC machine is considerably lower than environmental or wound contamination, and NPWT does not represent a risk factor for healthcare-associated infections 4. However, some studies have shown that VAC can paradoxically increase microorganisms in the wound if applied to inadequately debrided tissue 5.
Common Pitfalls to Avoid
Never use VAC as a substitute for proper surgical debridement—the therapy removes excess fluid and reduces bacterial load only after adequate debridement has been performed 1, 2.
Do not assume the odor will resolve with continued VAC therapy—foul odor indicates active bacterial proliferation that requires intervention 3.
Avoid applying VAC to wounds with residual necrotic tissue or uncontrolled infection, as this prevents the therapy from working effectively and allows infection to progress 1.