**3.1 Clinical history**

Patients with pruritus ani are often seen by a specialist after other treatments have failed, creating a challenge to establish a precise diagnosis. Clinical information, including presenting and associated symptoms, disease progression, co-morbidities, allergies, and medications, is warranted. Specifics about diet, sexual conduct, bowel habits, hygiene products and behaviors, and prior use of local agents should be part of the initial clinical encounter. History of atopia, anorectal disorders or surgeries, sexually transmitted


#### **Table 2.**

*The Washington hospital staging criteria.*

diseases, among others, can aid in narrowing the differential diagnoses. During the initial interview, we focus on any potential triggers associated with the beginning of symptoms, instead of recent treatments that may have changed the course of the disease.

#### **3.2 Physical examination**

Inspection of the perianal area, perineum, and genitalia should be the first step of the physical examination. The examiner should look for erythema, blisters, ulcerations, maceration of the skin, residual fecal material, drainage, scratch marks, etc. If creams or ointments have been applied, they must be gently cleansed to expose the area for proper evaluation. In the early stages of the disease, no obvious abnormalities are found on the initial evaluation. A digital anorectal exam followed by a circumferential anoscopy should be performed to rule out anal canal conditions, however, any painful maneuvers should be avoided and, in most cases, these procedures are deferred until some of the pain and discomfort have subsided.

The Washington criteria, developed at the Washington Hospital Center, are commonly used to classify the severity of the pruritus ani based on clinical findings (**Table 2**) [8, 14]. In patients with Stage I disease, erythematous inflamed skin may be the only finding. In Stage II, there is lichenified perianal skin because of excessive itching and scratching or rubbing of the skin, resulting in thick leathery appearing skin. In addition to these changes, Stage III patients exhibit the presence of coarse ridges and ulceration of the affected skin. These staging criteria should be documented during clinic encounters, as it is useful for follow-up and evaluation of the response to treatment.

*Microbiology testing* should be performed based on the index of suspicion and clinical findings. To avoid misleading results, appropriate sample collection and specimens' manipulation is essential. For example, when feasible, drainage, or secretions should be aspirated with a syringe and placed in a sterile container, viral cultures should be kept on ice for transportation, etc. In patients with diarrhea, bacterial stool cultures, as well as ova and parasites testing, must be included.

When considered appropriate, a more extensive endoscopic examination can be performed, including examination under anesthesia, flexible sigmoidoscopy, and colonoscopy with tissue sampling for biopsies and cultures. With non-healing skin lesions that persist despite appropriate treatment, a biopsy to rule out malignancy is indicated.
