How do I differentiate between benign and serious causes of fresh rectal bleeding in adults?

To differentiate between benign and serious causes of fresh rectal bleeding in adults, consider the patient's age, associated symptoms, and examination findings.

• Age and risk factors: Rectal bleeding in adults aged 50 and over, or those under 50 with unexplained abdominal pain or weight loss, warrants further investigation for colorectal cancer using quantitative faecal immunochemical testing (FIT) ¹.
• Associated symptoms: Serious causes are more likely if rectal bleeding is accompanied by unexplained weight loss, abdominal pain, or a palpable mass ¹.
• Physical examination: Findings such as a rectal mass or anal mass/ulceration should prompt urgent referral via a suspected cancer pathway ¹.
• Unexplained rectal bleeding without other symptoms in younger adults may be benign but still requires assessment to exclude serious pathology ¹.

In summary, fresh rectal bleeding with alarm features (age ≥50, weight loss, abdominal pain, palpable masses) suggests serious causes like colorectal cancer and requires urgent investigation and referral. Absence of these features may indicate benign causes but still needs appropriate evaluation ¹.