What causes nocturnal pruritus ani (anal itching at night)?

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Differential Diagnosis for Chronic Anal Itching at Night

  • Single most likely diagnosis
    • Anal fissure: This is a common cause of anal itching, especially at night, due to the increased pressure on the anal sphincter when lying down. The pain and discomfort from an anal fissure can lead to itching and scratching.
  • Other Likely diagnoses
    • Hemorrhoids: Internal or external hemorrhoids can cause anal itching, particularly at night, due to increased venous pressure when lying down.
    • Pruritus ani: A condition characterized by chronic itching around the anus, often without a clear cause, but can be exacerbated by factors like diet, hygiene, or allergies.
    • Pinworms (Enterobius vermicularis): A parasitic infection that can cause intense anal itching, especially at night, as the worms migrate out of the anus to lay eggs.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Anal cancer: Although rare, anal cancer can cause chronic anal itching, and it is crucial to rule out this diagnosis to ensure timely treatment.
    • Inflammatory bowel disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause anal itching, among other symptoms, and require prompt diagnosis and treatment to prevent complications.
  • Rare diagnoses
    • Lichen sclerosus: A rare skin condition that can cause anal itching, pain, and skin changes.
    • Psoriasis: A chronic skin condition that can affect the anal area, leading to itching and inflammation.
    • Dermatitis: Contact dermatitis or atopic dermatitis can cause anal itching, especially if the individual has a history of skin allergies or sensitivities.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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