Pruritus ani is the irritation of the skin at the exit of the

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

, known as the

anus In mammals, invertebrates and most fish, the anus (: anuses or ani; from Latin, 'ring' or 'circle') is the external body orifice at the ''exit'' end of the digestive tract (bowel), i.e. the opposite end from the mouth. Its function is to facil ...

, causing the desire to scratch. The intensity of anal

itch An itch (also known as pruritus) is a sensation that causes a strong desire or reflex to scratch. Itches have resisted many attempts to be classified as any one type of sensory experience. Itches have many similarities to pain, and while both ...

ing increases from moisture, pressure, and rubbing caused by clothing and sitting. At worst, anal itching causes intolerable discomfort that often is accompanied by burning and soreness. It is estimated that up to 5% of the population of the United States experiences this type of discomfort daily.

Causes

If a specific cause for pruritus ani is found it is classified as "secondary pruritus ani". If a specific cause is ''not'' found it is classified as "idiopathic pruritus ani". The irritation can be caused by intestinal parasites, anal

perspiration Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and Apocrine sweat gland, apocrine glands. The eccrine sweat glands are distribu ...

, frequent liquid stools,

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

, residual stool deposits, or the escape of small amounts of stool as a result of

incontinence Incontinence or Incontinent may refer to: * Urinary incontinence, the most commonly occurring type of incontinence, the involuntary excretion of urine *Fecal incontinence Fecal incontinence (FI), or in some forms, encopresis, is a lack of con ...

flatulence Flatulence is the expulsion of gas from the Gastrointestinal tract, intestines via the anus, commonly referred to as farting. "Flatus" is the medical word for gas generated in the stomach or bowels. A proportion of intestinal gas may be swal ...

. Another cause is

yeast infection Candidiasis is a fungal infection due to any species of the genus '' Candida'' (a yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the ...

candidiasis Candidiasis is a fungal infection due to any species of the genus '' Candida'' (a yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the ...

. Some diseases increase the possibility of yeast infections, such as

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

HIV The human immunodeficiency viruses (HIV) are two species of '' Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the im ...

infection. Treatment with

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

s can bring about a disturbance of the natural balance of intestinal flora, and lead to perianal thrush, a

affecting the anus.

Psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small localized patches to complete b ...

also can be present in the anal area and cause irritation. Abnormal passageways (

fistula In anatomy, a fistula (: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") is an abnormal connection (i.e. tube) joining two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other h ...

s) from the small intestine or colon to the skin surrounding the anus can form as a result of disease (such as

Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the ...

), acting as channels which may allow leakage of irritating fluids to the anal area. Other problems that can contribute to anal itching include pinworms,

hemorrhoid Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''h ...

s, tears of the anal skin near the mucocutaneous junction ( fissures), and

skin tag A skin tag, or acrochordon (: acrochorda), is a small benign tumor that forms primarily in areas where the Human skin, skin forms creases (or rubs together), such as the neck, armpit and groin. They may also occur on the face, usually on the ey ...

s (abnormal local growth of anal skin). Aside from diseases relative to the condition, a common view suggests that the initial cause of the itch may have passed, and that the illness is in fact prolonged by what is known as an itch-scratch-itch cycle. It states that scratching the itch encourages the release of inflammatory chemicals, which worsen redness, intensifies itchiness and increases the area covered by dry skin, thereby causing a

snowball effect A snowball effect is a process that starts from an initial state of small significance and builds upon itself (an exacerbating feedback), becoming larger (graver, more serious), and also perhaps potentially more dangerous or disastrous (a vicio ...

. Some authorities describe “psychogenic pruritus” or "functional itch disorder", where psychological factors may contribute to awareness of itching. Ingestion of pinworm eggs leads to

enterobiasis Pinworm infection (threadworm infection in the UK), also known as enterobiasis, is a human parasitic disease caused by the pinworm (parasite), pinworm, ''Enterobius vermicularis''. The most common symptom is pruritus ani, or itching in the Human ...

, indicative of severe itching around the anus from migration of gravid females from the bowel. Severe cases of enterobiasis result in

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...

and

eczema Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...

Diagnosis

Diagnosis is usually done with a careful examination of the anus and the patient's history. If the presentation or physical findings are atypical, ie change in bowel habits or personal/family history of colorectal cancer/adenomas, a colonoscopy should be proposed. In case of long-lasting symptoms, above all in patients over 50 years of age, a colonoscopy is useful to rule out a colonic polyp or tumor, that can show pruritus ani as first symptom.

Treatment

The goal of treatment is asymptomatic, intact, dry, clean perianal skin with reversal of morphological changes. For pruritus ani of unknown cause (idiopathic pruritus ani) treatment typically begins with measures to reduce irritation and trauma to the perianal area.

Stool softener Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

s can help prevent constipation. If this is not effective topical

steroids A steroid is an organic compound with four fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter mem ...

or injected

methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. As a medication, it is mainly used to treat methemoglobinemia. It has previously been used for treating cyanide poisoning and urinary trac ...

may be tried. Another treatment option that has been met with success in small-scale trials is the application of a very mild (0.006%) topical capsaicin cream. This strength cream is not typically commercially available and therefore must be diluted by a pharmacist or end-user. If the itchiness is secondary to another condition such as infection or psoriasis these are typically treated. A successful treatment option for chronic idiopathic pruritus ani has been documented using a clean, dry and apply (if necessary) method. The person is instructed to follow this procedure every time the urge to scratch occurs. The treatment makes the assumption that there is an unidentified bacteria in the feces that causes irritation and itching when the feces makes contact with the anal and perianal skin during defecation, flatulation or anal leakage (particularly during sleep). For otherwise idiopathic, intractable cases, a double-blind trial with 44 patients found that

capsaicin Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) (, rarely ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a potent Irritation, irritant for Mammal, mammals, including humans, and produces ...

may be an effective treatment. By applying topical capsaicin mixed with paraffin wax (both available over the counter) with a concentration of 0.006% to the perianal area every 1-2 days, approximately three quarters of patients reported total (or near-total) relief of symptoms.

References

External links

* {{Diseases of the skin and subcutaneous tissue Pruritic skin conditions

Causes

Diagnosis

Treatment

See also

References

External links