Accidental formaldehyde injection during prostate biopsy: a rare cause of rectal necrosis and perforation. Case report and review of the literature.

Introduction and importance: Accidental chemical injuries in medical settings are uncommon but can have devastating consequences. Formaldehyde (commonly in the form of formalin solution) is widely used as tissue fixative in clinics and laboratories. If inadvertently introduced into living tissue, formaldehyde causes rapid protein coagulation and tissue fixation, leading to cell death and necrosis. We present a rare case of rectal injury and perforation caused by accidental formaldehyde injection during a prostate biopsy.

Case presentation: A 70-year-old male underwent a transrectal prostate biopsy which was complicated by the accidental injection of formaldehyde 4% into the rectum. One week later, he presented to our clinic with persistent rectal pain and was found to have an extensive rectal wall necrosis with perforation. Prompt intervention was undertaken with broad-spectrum intravenous antibiotics, transanal surgical debridement of necrotic tissue, and endoscopic vacuum therapy (EVT) to manage the rectal defect. The patient's condition improved with each sequential sponge change over an 11-day period, leading to cavity closure and granulation. He was discharged in stable condition on postoperative day 14. Two months later the rectal wound had completely healed.

Clinical discussion: Accidental injection of formaldehyde into viable tissues is rare, but it can result in severe consequences. Early identification of the injury, followed by appropriate treatment (in our case, EVT), offered the best management approach and led to full recovery without the need for a diverting ostomy.

Conclusion: This case highlights a rare iatrogenic chemical injury with formaldehyde, its successful management with minimally invasive endoscopic vacuum therapy (EVT), and underscores the need for stringent precautions to prevent such hazardous incidents.