A chlorhexidine conundrum after an epidural delivery: The difficulty of differentiating between chlorhexidine burns and hypersensitivity reactions.

Chlorhexidine is a commonly used disinfectant throughout Australian hospitals. It is responsible for a number of iatrogenic complications. We describe a case of 27-yearold female who sustained a severe, blistering reaction at the site of chlorhexidine application, associated with significant pain. This reaction was initially managed with wet dressings and topical corticosteroids, but there was no improvement in pain or rash. Management was then changed to silver-coated polyethylene mesh dressings, with resolution of pain and rash after four days. No debridement was required, and area healed without scarring. Chlorhexidine is associated with a number of hypersensitivity reactions, ranging from anaphylaxis to irritant and allergic contact dermatitis. However, physical or chemical burns remain an underrecognised complication of chlorhexidine use. Intra-operatively, there is a risk of physical burn secondary to pooled chlorhexidine catching alight after cautery is applied, and this has been described in ten cases in the literature. Chemical burns from exposure to chlorhexidine can occur in neonatal patients, and in adult patients where a tourniquet has been used. It can be difficult to differentiate between chlorhexidine hypersentivity and burns clinically. When evaluating these patients, a differential diagnosis of burns should be considered, particularly if patients are not responsive to first line therapies. Surgeons and anaesthetists should consider the risk of burns when in theatres, and prevent any pooling of chlorhexidine - particularly when cautery is being used. Using chlorhexidine without alcohol, and allowing at least three minutes for the solution to dry can further reduce the risk of surgical fires.

Dear Editors,

Chlorhexidine is commonly used as an antiseptic agent in the hospital setting (Evans et al., 2017, Opstrup et al., 2019), but its use is not without complications. Chlorhexidine has been associated with a number of hypersensitivity reactions, ranging from irritant contact dermatitis to anaphylaxis (Opstrup et al., 2016, Opstrup et al., 2019). These reactions are most common in the perioperative setting (Evans et al., 2017, Opstrup et al., 2019). There is also a risk of both physical and chemical burns associated with its use in the perioperative setting (Sivathasan et al., 2010, Vo and Bengezi, 2014). Physical burns can occur with the use of chlorhexidine mixed with alcohol, which can catch fire when cautery is applied (Vo and Bengezi, 2014). Chemical burns from chlorhexidine have been reported in pediatric populations and with the use of tourniquets (Sivathasan et al., 2010). Clinically, irritant contact dermatitis and superficial burns can be difficult to differentiate in the first instance.

A 28-year-old woman presented in early labor and, after failure to progress, was transferred to the operating room for an emergency Caesarean section. Her medical history was significant for contact allergy to acrylic adhesives. In preparation for an epidural, the patient’s back was cleaned with 2% chlorhexidine/70% alcohol, and the solution was left to dry for 2 minutes. The abdominal surgical incision site was prepped with 2% chlorhexidine/70% alcohol, and the abdomen was wiped clean with normal saline after the procedure. No immediate complications were observed.

The patient developed pruritus, associated with a burning sensation, on her lower back the morning after the procedure. The next day, she developed a well-demarcated area of erythema with vesiculobullous lesions, corresponding to the site of chlorhexidine application. The rash was associated with significant pain that required parenteral opiates.

The patient was initially treated with topical corticosteroids (mometasone ointment 0.1% twice daily) for a presumed diagnosis of irritant contact dermatitis to chlorhexidine. Given the risk of secondary infection, the affected area was also dressed twice daily sterile paraffin gauze with absorbent pad dressing and crepe bandage and topical silver sulfadiazine. The patient showed mild improvement in symptoms, but the rash flared after 3 days of steroid application and was associated with a significant increase in pain. Bacterial and viral swabs were performed, and concurrent infection was excluded.

A differential diagnosis of chlorhexidine burn was considered, and an expert burns unit was consulted. Silver-coated polyethylene mesh dressings were recommended and applied. Four days after these were commenced, there was complete resolution of the vesicular lesions, improvement in the erythema, and significant improvement in associated pain and tenderness.

As the primary rash improved, the patient developed widespread erythematous macular lesions across her anterior abdomen, breasts, and upper back. Much of the affected area had not been exposed to chlorhexidine. The rash was consistent with a disseminated secondary eczema reaction due to either allergy to topical silver sulfadiazine or systematized allergic contact dermatitis. The lesions resolved with topical steroids and cessation of the agent.

This case highlights the difficulty of differentiating between chlorhexidine hypersensitivity reactions and superficial burns. The initial presentation suggested a hypersensitivity reaction, but severe pain requiring parenteral opiates and the relative unresponsiveness to steroid therapy made intraoperative superficial burns a more likely diagnosis. Patch testing would have assisted in the clarification of the potential diagnosis of allergic contact dermatitis; however, this was not performed because the patient declined. Immediate type testing, such as skin prick testing, can also be performed to differentiate between hypersensitivity and burns (Opstrup et al., 2019).

Chlorhexidine is associated with an increasing number of hypersensitivity reactions, ranging from anaphylaxis to irritant and allergic contact dermatitis (Opstrup et al., 2019). The exact incidence of chlorhexidine hypersensitivity is unknown, but the overall incidence in adults is estimated at approximately 1% (Opstrup et al., 2016). An Australian systematic review of the incidence of chlorhexidine-induced anaphylaxis found 27 cases of reported anaphylaxis to chlorhexidine between 2006 and 2016 (Evans et al., 2017). In addition, studies in the United Kingdom, Denmark, and Belgium reported an incidence of chlorhexidine allergy of 9%, 10%, and 9%, respectively, in patients with perioperative allergic reactions (Opstrup et al., 2019).

Despite this increasing awareness of chlorhexidine hypersensitivity, physical or chemical burns remain an underrecognized complication of chlorhexidine use. Intraoperatively, there is a risk of physical burns caused by pooled chlorhexidine catching fire after cautery is applied (Vo and Bengezi, 2014). Chemical burns from exposure to chlorhexidine have been reported in pediatric and neonatal patients and in adults on whom a tourniquet has been used (Sivathasan et al., 2010).

Chlorhexidine is extensively used in hospital settings, clinicians should be aware of the potential complications associated with its use. In cases where there is diagnostic uncertainty, we recommend that burns be considered as a potential differential diagnosis, particularly in patients who are nonresponsive to initial steroid therapy. The perioperative setting is at the highest risk of chlorhexidine complications (Evans et al., 2017, Opstrup et al., 2019); therefore, we recommend that surgeons and anesthetists consider the risk of burns when in the operating room and prevent pooling of chlorhexidine wherever possible. We also recommend the use of chlorhexidine without alcohol and allowing at least 3 minutes for the solution to dry to reduce the risk of surgical fires and chlorhexidine burns.