Cellulitis, abscess and necrotising soft-tissue infection: SAQ

This school-age child presents the classic constellation of necrotising fasciitis: a skin portal of entry, severe pain that is disproportionate to the visible erythema, systemic toxicity with tachycardia and a prolonged capillary refill, tense swelling, and the development of haemorrhagic bullae and dusky discolouration that signal skin ischaemia from thrombosed perforating vessels. This is a surgical emergency in which every hour of delay to debridement worsens survival, so resuscitation and surgical preparation must proceed in parallel. ^[2]

Question 1 (10 marks)

Outline your immediate assessment, investigations, and the role of the LRINEC score in this child. ^[2]

Begin with an airway, breathing, circulation assessment. This child is in compensated shock with a heart rate of 150 and a capillary refill of 4 seconds, so he needs immediate resuscitation and senior surgical review. Measure a full set of vital signs including blood pressure, oxygen saturation, and temperature, and weigh him for drug dosing. Confirm the disproportionate nature of the pain, the tense induration, and the haemorrhagic bullae, and mark the margin of the affected area with the time to track progression. ^[2]

Establish intravenous access and draw a full blood count, C-reactive protein, electrolytes, creatinine, creatine kinase, sodium, glucose, coagulation studies, blood cultures, and a blood gas with lactate. A high lactate, a markedly raised C-reactive protein, hyponatraemia, and a rising creatine kinase each support the diagnosis and quantify severity. ^[2]

The LRINEC score combines six laboratory values to estimate the probability of necrotising fasciitis, but it must never be used to exclude the diagnosis. A low score in a child with disproportionate pain, toxicity, and haemorrhagic bullae is still a surgical emergency, because the clinical picture remains the most sensitive test. Imaging with computed tomography may help define the extent of deep infection but must not delay surgery in a child with this convincing a clinical picture. ^[3]