A precise definition of hemorrhoids does not exist, but they can be described as masses or clumps ("cushions") of tissue within the anal canal that contain blood vessels and the surrounding, supporting tissue made up of muscle and elastic fibers.
The anal canal is the last four centimeters through which stool passes as it goes from the rectum to the outside world. The anus is the opening of the anal canal to the outside world.
Although most people think hemorrhoids are abnormal, they are present in everyone. It is only when the hemorrhoidal cushions enlarge that hemorrhoids can cause problems and be considered abnormal or a disease.
There are two types of nerves in the anal canal, visceral nerves (above the dentate line) and somatic nerves (below the dentate line). The somatic (skin) nerves are like the nerves of the skin and are capable of sensing pain.
The visceral nerves are like the nerves of the intestines and do not sense pain, only pressure. Therefore, internal hemorrhoids, which are above the dentate line, usually are painless.
As the anal cushion of an internal hemorrhoid continues to enlarge, it bulges into the anal canal. It may even pull down a portion of the lining of the rectum above, lose its normal anchoring, and protrude from the anus. This condition is referred to as aprolapsing internal hemorrhoid.
In the anal canal, the hemorrhoid is exposed to the trauma of passing stool, particularly hard stools associated with constipation. The trauma can cause bleeding and sometimes pain when stool passes. The rectal lining that has been pulled down secretes mucus and moistens the anus and the surrounding skin.
Stool also can leak onto the anal skin. The presence of stool and constant moisture can lead to anal itchiness (pruritus ani), though itchiness is not a common symptom of hemorrhoids. The prolapsing hemorrhoid usually returns into the anal canal or rectum on its own or can be pushed back inside with a finger, but it prolapses again with the next bowel movement.
Less commonly, the hemorrhoid protrudes from the anus and cannot be pushed back inside, a condition referred to as incarceration of the hemorrhoid. Incarcerated hemorrhoids can have their supply of blood shut off by the squeezing pressure of the anal sphincter, and the blood vessels and cushions can die, a condition referred to as gangrene. Gangrene requires medical treatment.
For convenience in describing the severity of internal hemorrhoids, many physicians use a grading system:
First-degree hemorrhoids: Hemorrhoids that bleed but do not prolapse.
Second-degree hemorrhoids: Hemorrhoids that prolapse and retract on their own (with or without bleeding).
Third-degree hemorrhoids: Hemorrhoids that prolapse but must be pushed back in by a finger.
Fourth-degree hemorrhoids: Hemorrhoids that prolapse and cannot be pushed back in.
Fourth-degree hemorrhoids also include hemorrhoids that are thrombosed (containing blood clots) or that pull much of the lining of the rectum through the anus.
In general, the symptoms of external hemorrhoids are different than the symptoms of internal hemorrhoids.
External hemorrhoids can be felt as bulges at the anus, but they usually cause few of the symptoms that are typical of internal hemorrhoids. This is perhaps, because they are low in the anal canal and have little effect on the function of the anus, particularly the anal sphincter. External hemorrhoids can cause problems, however, when blood clots inside them.
This is referred to as thrombosis. Thrombosis of an external hemorrhoid causes an anal lump that is very painful (because the area is supplied by somatic nerves) and often requires medical attention. The thrombosed hemorrhoid may heal with scarring and leave a tag of skin protruding from the anus. Occasionally, the tag is large, which can make anal hygiene (cleaning) difficult or irritate the anus.
It is not known why hemorrhoids enlarge. There are several theories about the cause, including inadequate intake of fiber, prolonged sitting on the toilet, and chronic straining to have a bowel movement (constipation). None of these theories has strong experimental support.
Pregnancy is a clear cause of enlarged hemorrhoids though, again, the reason is not clear. Tumors in the pelvis also cause enlargement of hemorrhoids by pressing on veins draining upwards from the anal canal.
One theory proposes that it is the shearing (pulling) force of stool, particularly hard stool, passing through the anal canal that drags the hemorrhoidal cushions downward. Another theory suggests that with age or an aggravating condition, the supporting tissue that is responsible for anchoring the hemorrhoids to the underlying muscle of the anal canal deteriorates. With time, the hemorrhoidal tissue loses its mooring and slides down into the anal canal.
One physiological fact that is known about enlarged hemorrhoids that may be relevant to understanding why they form is that the pressure is elevated in the anal sphincter, the muscle that surrounds the anal canal and the hemorrhoids.
The anal sphincter is the muscle that allows us to control our bowel movements. It is not known, however, if this elevated pressure precedes the development of enlarged hemorrhoids or is the result of the hemorrhoids.
Perhaps during bowel movements, increased force is required to force stool through the tighter sphincter. The increased shearing force applied to the hemorrhoids by the passing stool may drag the hemorrhoids downward and enlarge them.
It is believed generally that constipation and straining to have bowel movements promote hemorrhoids and that hard stools can traumatize existing hemorrhoids. It is recommended, therefore, that individuals with hemorrhoids soften their stools by increasing the fiber in their diets. Fiber is found in numerous foodstuffs including fresh and dried fruits, vegetables, grains, and cereals.
Generally 20-30 grams per day of fiber are recommended whereas the average American diet contains less than 15 grams of fiber. Supplemental fiber (psyllium, methylcellulose, or calcium polycarbophil) also may be used to increase the intake of fiber. Stool softeners and increased drinking of liquids also may be recommended. Nevertheless, there is no strong, scientific support for the benefits of fiber, liquids, or stool softeners.
Diarrhea is believed to aggravate the symptoms of hemorrhoids and it is recommended that diarrhea be controlled with fiber and anti-motility drugs.
Over-the-counter medications for hemorrhoids
Many over-the-counter products are sold for the treatment of hemorrhoids. These often contain the same drugs that are used for treating anal symptoms such as itching or discomfort. There are few studies showing that they do anything for hemorrhoids. They probably only reduce the symptoms of hemorrhoids. It is possible, however, that their effectiveness relates to their treatment of anal conditions other than hemorrhoids, for example, idiopathic anal itching, that often accompany hemorrhoids.
Products used for the treatment of hemorrhoids are available as ointments, creams, gels, suppositories, foams, and pads. Ointments, creams, and gels - when used around the anus - should be applied as a thin covering. When applied to the anal canal, these products should be inserted with a finger or a "pile pipe." Pile pipes are most efficient when they have holes on the sides as well as at the end. Pile pipes should be lubricated with ointment prior to insertion. Suppositories or foams do not have advantages over ointments, creams, and gels.
Most products contain more than one type of active ingredient. Almost all contain a protectant in addition to another ingredient. Only examples of brand-name products containing one ingredient in addition to the protectant are discussed below.
Local anesthetics: Local anesthetics temporarily relieve pain, burning, and itching by numbing the nerve endings. The use of these products should be limited to the perianal area and lower anal canal. Local anesthetics can cause allergic reactions with burning and itching; therefore, if burning and itching increase with the application of anesthetics, they should be discontinued.
Local anesthetics include:
- Benzocaine 5% to 20% (Americaine Hemorrhoidal, Lanacane Maximum Strength, Medicone).
- Benzyl alcohol 5% to 20%.
- Dibucaine 0.25% to 1.0% (Nupercainal).
- Dyclonine 0.5% to 1.0%.
- Lidocaine 2% to 5%.
- Pramoxine 1.0% (Fleet Pain-Relief, Procto Foam Non-steroid, Tronothane Hydrochloride).
- Tetracaine 0.5% to 5.0%.
Vasoconstrictors: Vasoconstrictors are chemicals that resemble epinephrine, a naturally occurring chemical. Applied to the anus, vasoconstrictors make the blood vessels become smaller, which may reduce swelling.
They also may reduce pain and itching due to their mild anesthetic effect. Vasoconstrictors applied to the perianal area - unlike vasoconstrictors that are taken orally or by injection - have a low likelihood of causing serious side effects, such as high blood pressure, nervousness,tremor, sleeplessness, and aggravation of diabetes or hyperthyroidism.
- Ephedrine sulfate 0.1% to 1.25%.
- Epinephrine 0.005% to 0.01%.
- Phenylephrine 0.25% (Medicone Suppository, Preparation H, Rectacaine).
Protectants: Protectants prevent irritation of the perianal area by forming a physical barrier on the skin that prevents contact of the irritated skin with aggravating liquid or stool from the rectum. This barrier reduces irritation, itching, pain, and burning.
There are many products that are themselves protectants or that contain a protectant in addition to other medications.
- Aluminum hydroxide gel
- Cocoa butter
- Mineral oil (Balneol)
- White petrolatum
- Zinc oxide or calamine (which contains zinc oxide) in concentrations of up to 25%
- Cod liver oil or shark liver oil if the amount of vitamin A is 10,000 USP units/day.
Astringents: Astringents cause coagulation (clumping) of proteins in the cells of the perianal skin or the lining of the anal canal. This action promotes dryness of the skin, which in turn helps relieve burning, itching, and pain.
- Calamine 5% to 25%.
- Zinc oxide 5% to 25% (Calmol 4, Nupercainal, Tronolane).
- Witch hazel 10% to 50% (Fleet Medicated, Tucks, Witch Hazel Hemorrhoidal Pads).
Antiseptics: Antiseptics inhibit the growth of bacteria and other organisms. However, it is unclear whether antiseptics are any more effective than soap and water.
Examples of antiseptics include:
- Boric acid.
- Benzalkonium chloride.
- Cetylpyridinium chloride.
- Benzethonium chloride.
Keratolytics: Keratolytics are chemicals that cause the outer layers of skin or other tissues to disintegrate. The rationale for their use is that the disintegration allows medications that are applied to the anus and perianal area to penetrate into the deeper tissues.
The two approved keratolytics used are:
- Aluminum chlorhydroxy allantoinate (alcloxa) 0.2% to 2.0%.
- Resorcinol 1% to 3%.
Analgesics: Analgesic products, like anesthetic products, relieve pain, itching, and burning by depressing receptors on pain nerves.
Examples of analgesics include:
- Menthol 0.1% to 1.0% (greater than 1.0% is not recommended).
- Camphor 0.1% to 3% (greater than 3% is not recommended).
- Juniper tar 1% to 5%.
Corticosteroids: Corticosteroids reduce inflammation and can relieve itching, but their chronic use can cause permanent damage to the skin.
They should not be used for more than short periods of a few days to two weeks. Only products with weak corticosteroid effects are available over-the-counter. Stronger corticosteroid products that are available by prescription should not be used for treating hemorrhoids.