Please confirm that you would like to log out of Medscape. If you log out, you will be required to enter your username and password the next time you visit. They are among the most common causes of anal pathology, and subsequently are blamed for virtually any anorectal complaint by patients and medical professionals alike. Hemorrhoidal venous cushions are normal structures of the anorectum and are universally present unless a previous intervention has taken place. Because of their rich vascular supply, highly sensitive location, and tendency to engorge and prolapse, hemorrhoidal venous cushions are common causes of anal pathology. Symptoms can range from mildly bothersome, such as pruritus, to quite concerning, such as rectal bleeding. Although hemorrhoids are a common condition diagnosed in clinical practice, many patients are too embarrassed to ever seek treatment. Consequently, the true prevalence of pathologic hemorrhoids is not known. Historical note Hemorrhoidal symptoms have historically been treated with dietary modifications, incantations, voodoo, quackery, and application of a hot poker. Molten lead has also been described as a treatment.
The adverse effects of these treatments have a direct relationship to whether patients relay persistent or recurrent complaints to the clinician or return for further treatment. For patient education information, see Hemorrhoids, Anal Abscess, Rectal Pain, and Rectal Bleeding. Hemorrhoids are present in utero and persist through normal adult life. Evidence indicates that hemorrhoidal bleeding is arterial and not venous. External hemorrhoids develop from ectoderm and are covered by squamous epithelium, whereas internal hemorrhoids are derived from embryonic endoderm and lined with the columnar epithelium of anal mucosa. Similarly, external hemorrhoids are innervated by cutaneous nerves that supply the perianal area.
These nerves include the pudendal nerve and the sacral plexus. Internal hemorrhoids are not supplied by somatic sensory nerves and therefore cannot cause pain. Hemorrhoidal venous cushions are a normal part of the human anorectum and arise from subepithelial connective tissue within the anal canal. Minor tufts can be found between the major cushions. Present in utero, these cushions surround and support distal anastomoses between the superior rectal arteries and the superior, middle, and inferior rectal veins. They also contain a subepithelial smooth muscle layer, contributing to the bulk of the cushions.
Venous drainage of hemorrhoidal tissue mirrors embryologic origin. Internal hemorrhoids drain through the superior rectal vein into the portal system. External hemorrhoids drain through the inferior rectal vein into the inferior vena cava. Rich anastomoses exist between these 2 and the middle rectal vein, connecting the portal and systemic circulations. Mixed hemorrhoids are confluent internal and external hemorrhoids. Hemorrhoids are present in healthy individuals. In fact, hemorrhoidal columns exist in utero. When these vascular cushions produce symptoms, they are referred to as hemorrhoids. Hemorrhoids generally cause symptoms when they become enlarged, inflamed, thrombosed, or prolapsed.
Most symptoms arise from enlarged internal hemorrhoids. Abnormal swelling of the anal cushions causes dilatation and engorgement of the arteriovenous plexuses. This leads to stretching of the suspensory muscles and eventual prolapse of rectal tissue through the anal canal. The engorged anal mucosa is easily traumatized, leading to rectal bleeding that is typically bright red due to high blood oxygen content within the arteriovenous anastomoses. Although many patients and clinicians believe that hemorrhoids are caused by chronic constipation, prolonged sitting, and vigorous straining, little evidence to support a causative link exists. Some of these potential etiologies are briefly discussed below. Decreased venous return Most authors agree that low-fiber diets cause small-caliber stools, which result in straining during defecation. This increased pressure causes engorgement of the hemorrhoids, possibly by interfering with venous return. Pregnancy and abnormally high tension of the internal sphincter muscle can also cause hemorrhoidal problems, presumably by means of the same mechanism, which is thought to be decreased venous return.
Straining and constipation Straining and constipation have long been thought of as culprits in the formation of hemorrhoids. This may or may not be true. Patients who report hemorrhoids have a canal resting tone that is higher than normal. Of interest, the resting tone is lower after hemorrhoidectomy than it is before the procedure. Pregnancy Pregnancy clearly predisposes women to symptoms from hemorrhoids, although the etiology is unknown. Notably, most patients revert to their previously asymptomatic state after delivery. The relationship between pregnancy and hemorrhoids lends credence to hormonal changes or direct pressure as the culprit. Portal hypertension and anorectal varices Portal hypertension has often been mentioned in conjunction with hemorrhoids. However, hemorrhoidal symptoms do not occur more frequently in patients with portal hypertension than in those without it, and massive bleeding from hemorrhoids in these patients is unusual.
Bleeding is very often complicated by coagulopathy. If bleeding is found, direct suture ligation of the offending column is suggested. Anorectal varices are common in patients with portal hypertension. Varices occur in the midrectum, at connections between the portal system and the middle and inferior rectal veins. Varices occur more frequently in patients who are noncirrhotic, and they rarely bleed. Treatment is usually directed at the underlying portal hypertension.
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