Colorectal cancer

Background

Anatomy of the anus and rectum.

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Colorectal cancer on gross pathology.

• Colorectal cancer is extremely common

Clinical Features

• Asymptomatic, frequently grow slowly for long period of time before symptomatic
• Lower GI bleeding (occult or visible BRBPR/hematochezia
• Fatigue, generalized weakness due to anemia
• Change in bowel habits, constipation, tenesmus in rectal cancer
• Obstruction if mass large enough (left colon > right)
  • Abdominal pain
    • Focal pain or Peritonitis if perforation
• Signs/symptoms of metastatic disease (e.g. hepatomegaly, ascites, lymphadenopathy) may be initial presentation

Differential Diagnosis

Undifferentiated lower gastrointestinal bleeding

• Upper GI Bleeding
• Diverticular disease
  • Diverticulosis
  • Diverticulitis
• Vascular ectasia / angiodysplasia
• Inflammatory bowel disease
• Infectious colitis
• Mesenteric Ischemia / ischemic colitis
• Meckel's diverticulum
• Colorectal cancer / polyps
• Hemorrhoids
  • Internal hemorrhoid
  • External hemorrhoid
• Aortoenteric fistula
  • Nearly 100% mortality if untreated
  • Consider in patients with gastrointestinal bleeding and known abdominal aortic aneurysms or aortic grafts
• Rectal foreign body
• Rectal ulcer (HIV, Syphilis, STI)
• Anal fissure

LLQ Pain

• Diverticulitis
• Kidney stone
• UTI
• Pyelonephritis
• Ectopic pregnancy
• Infectious colitis
• Inflammatory bowel disease (Crohn's Disease, Ulcerative Colitis)
• Inguinal hernia
• Mesenteric ischemia
• Epiploic appendagitis
• Mittelschmerz
• Ovarian cyst
• Ovarian torsion
• PID
• Psoas abscess
• Testicular torsion
• Appendicitis
• Abdominal aortic aneurysm
• Herpes zoster
• Endometriosis
• Colon cancer
• Irritable bowel syndrome
• Small bowel obstruction

Anorectal Disorders

• Anal fissure
• Anal fistula
• Anal malignancy
• Anal tags
• Anorectal abscess
• Coccydynia
• Colorectal malignancy
• Condyloma acuminata
• Constipation
• Crohn's disease
• Cryptitis
• GC/Chlamydia
• Fecal impaction
• Hemorrhoids
  • Internal hemorrhoid
  • External hemorrhoid
• Levator ani syndrome
• Pedunculated polyp
• Pilonidal cyst
• Proctalgia fugax
• Proctitis
• Pruritus ani
  • Enterobius (pinworms)
• Rectal foreign body
• Rectal prolapse
• Syphilitic fissure

Non-GI Look-a-Likes

• Prostatitis

Evaluation

• CBC, LFTs, coags if bleeding or signs of hepatic involvement
• CT abdomen- not definitive but may catch large mass or other alternative diagnoses
• Definitive diagnosis not likely to be made in ED, but suggestion of malignancy may be made on imaging if large mass seen
  • Colonoscopy with biopsy
  • Serum CEA
  • Surgical pathology

Management

• Transfuse pRBCs prn for anemia
• Consult surgery for obstruction or perforation
  • May also help coordinate outpatient diagnostic workup

Disposition

• Discharge if clinically stable

See Also

• Anorectal disorders

External Links

• https://www.merckmanuals.com/professional/gastrointestinal-disorders/tumors-of-the-gastrointestinal-tract/colorectal-cancer