What are the next steps and differential diagnoses for a 55-year-old male patient with one week of rectal bleeding?

Management of Rectal Bleeding in a 55-Year-Old Male

This patient requires colonoscopy within 2 weeks, as patients over 50 with unexplained rectal bleeding have a 6% risk of underlying bowel cancer, and this timeframe aligns with guideline recommendations for cancer screening in this age group. 1

Immediate Assessment and Risk Stratification

Initial Evaluation

• Perform a complete history and physical examination, including digital rectal examination (DRE), to assess for anorectal pathology and confirm the appearance of blood. 1
• Check vital signs and calculate the shock index (heart rate divided by systolic blood pressure) to identify active bleeding—a shock index >1 indicates hemodynamic instability. 1
• Order complete blood count (hemoglobin/hematocrit), coagulation studies (INR, platelets), and blood type/crossmatch if severe bleeding is suspected. 1

Oakland Score Risk Stratification

Calculate the Oakland score using age (2 points for ≥70 years, 1 point for 40-69 years), gender (1 point for male), previous lower GI bleeding admission, DRE findings, heart rate, systolic blood pressure, and hemoglobin level. 1

• Oakland score ≤8: Minor self-terminating bleed—patient can be discharged for urgent outpatient colonoscopy. 1
• Oakland score >8: Major bleed—requires hospital admission for inpatient colonoscopy on the next available list. 1

Diagnostic Algorithm

For Hemodynamically Stable Patients (Most Likely Scenario)

Given this patient's age (55 years) and one week of bleeding, arrange colonoscopy within 2 weeks regardless of Oakland score, as this meets criteria for urgent cancer screening. 1

• Colonoscopy is the preferred initial investigation with diagnostic yields of 42-90% and offers both diagnostic and therapeutic capabilities. 1
• Assessment of the anal canal and rectum should be performed using proctoscopy, rigid sigmoidoscopy, or flexible endoscopic examination to evaluate for anorectal conditions (which account for 16.7% of diagnoses). 1

For Hemodynamically Unstable Patients

If the patient has a shock index >1 after initial resuscitation or suspected active bleeding, perform CT angiography (CTA) first to rapidly localize the bleeding site, with sensitivity of 79-95% and specificity of 95-100%. 1, 2

Critical Diagnostic Caveat

Consider upper endoscopy to exclude an upper GI source, as 10-15% of patients presenting with severe hematochezia actually have an upper GI bleeding source. 1, 3

Differential Diagnoses by Likelihood

Most Common Causes in This Age Group (55 years)

Diverticulosis is the single most common cause of acute lower GI bleeding in patients aged 63-77 years (prevalence 20-41%), though this patient is slightly younger. 3

Hemorrhoids and anorectal conditions account for 16.7% of lower GI bleeding diagnoses and are frequently identified. 1

Colorectal cancer and polyps account for 6-27% of acute lower GI bleeding cases, with cancer risk of 2.4-11% in patients with rectal bleeding over age 40. 1, 3

Angiodysplasia accounts for 2-40% of cases (most studies show 3-15%), with incidence increasing with age. 3

Inflammatory bowel disease (ulcerative colitis, Crohn's disease) should be considered, particularly if associated with diarrhea, abdominal pain, or weight loss. 1, 4

Less Common but Important Differentials

Colonic polyps (neoplastic polyps were found in 32% of one colonoscopy series). 5

Diverticular disease (found in 16% of patients in one series, though often coexists with other pathology). 6

Proctitis (radiation-induced, ischemic, infectious, or associated with sexually transmitted diseases) requires interdisciplinary evaluation. 1, 7

Anorectal varices in patients with portal hypertension history (uncommon but can be life-threatening). 1

Solitary rectal ulcer syndrome is an occasional cause of bleeding. 1

Key Clinical Pearls

Symptoms Associated with Serious Disease

Three symptoms significantly correlate with serious pathology: blood mixed with stool (P<0.001), change in bowel habit (P<0.005), and abdominal pain (P<0.025). 6

Natural History

Approximately 80-85% of lower GI bleeding stops spontaneously, but 50% of patients with diverticular bleeding require blood transfusion. 3

Common Pitfall

Do not assume hemorrhoids are the sole cause of bleeding in patients over 40 years—serious pathology was detected in 44.4% of patients over 40 presenting with rectal bleeding in one study, including colorectal carcinoma in 8% and polyps in 25%. 6, 8