Differential Diagnosis for Constipation, Anal Pain, and Fever with Leukocytosis
Single Most Likely Diagnosis
- Anal Fissure with Secondary Infection: This condition often starts with constipation and passing hard stools, leading to anal pain. If the fissure becomes infected, it can cause fever and leukocytosis, making it a likely diagnosis given the progression of symptoms.
Other Likely Diagnoses
- Hemorrhoids with Thrombosis and Infection: Hemorrhoids can cause anal pain and constipation. If a hemorrhoid becomes thrombosed and then infected, it could lead to fever and an elevated white blood cell count.
- Perianal Abscess: An abscess in the perianal region can cause severe anal pain, constipation (due to pain), and if it becomes infected, fever and leukocytosis can occur.
- Proctitis: Inflammation of the rectum can cause constipation, anal pain, and if severe, fever and leukocytosis, especially if caused by an infectious agent.
Do Not Miss Diagnoses
- Appendicitis: Although the primary symptom of appendicitis is abdominal pain, in some cases, especially if the appendix is located near the rectum (retrocecal appendicitis), it can cause constipation, anal pain, and fever. Missing this diagnosis can lead to severe consequences, including perforation and peritonitis.
- Diverticulitis: Inflammation of a diverticulum in the colon can cause severe pain, changes in bowel habits, fever, and leukocytosis. It's crucial not to miss this diagnosis due to the risk of complications like abscess formation or perforation.
- Inflammatory Bowel Disease (IBD) Flare: Conditions like Crohn's disease or ulcerative colitis can cause constipation, anal pain, fever, and leukocytosis during a flare. Missing an IBD flare can lead to significant morbidity.
Rare Diagnoses
- Anorectal Malignancy: Although rare, tumors in the anorectal region can cause constipation, anal pain, and systemic symptoms like fever if they become infected or metastasize.
- Tuberculosis of the Rectum: A rare condition that can cause chronic constipation, anal pain, and systemic symptoms including fever and weight loss.
- Actinomycosis: A rare bacterial infection that can cause a variety of symptoms including constipation, anal pain, and fever, often associated with a history of trauma or recent surgery.