The digestive system is made up of the gut (extending from the mouth to the anus) and other accessory organs such as pancreas, liver, gallbladder, etc. The lowermost part of the gut consists of the rectum (where feces are stored) and the anal canal that terminates with the anus. The blood vessels that supply this part of the gut lie within its wall (as in other parts of the gut) and covered by the lining of the wall of the gut known as mucosa.
The abnormal dilatation (swelling) and tortuosity of these vessels within the wall of the rectum and anal canal is what is known as hemorrhoids. The blood vessels are normally present and along with the surrounding connective tissues and muscles form what is known as hemorrhoidal cushions. However, the term hemorrhoid is used to describe a disease condition when these cushions become swollen, tortuous, protrudes outward or bleed.
It is one of the common diseases affecting the rectum and the anus in humans. Most people often use the word “pile” to refer to hemorrhoid; however, others may use the word to refer to other problems of the anus and rectum apart from hemorrhoids such as anal fissure, anal itching, etc. It is therefore, wise not to assume that everybody that complains of “pile” has hemorrhoid.
In the general population, about 4.4% of have the symptoms of hemorrhoid. In the United States, about 10million people are estimated to be suffering from hemorrhoids out of which only one-third seek treatment in the hospital. Both males and females are thought to be affected equally but males tend to go to the hospital for treatment more than females. As one increase in age, the chance of developing hemorrhoid also increases and those within the age of 45 to 65 years have the highest prevalence.
What are the causes of hemorrhoids?
The particular cause of the swelling and dilatation of these blood vessels is not known. However, there are possible causes and risk factors that may predispose an individual to developing hemorrhoid.
One of the presumed causes of hemorrhoid is obstruction to the flow of blood within the hemorrhoidal veins (obstruction of venous return). Causes of this include;
Chronic constipation: consumption of refined foods, low fiber diets and inadequate water intake may result to constipation. This will make defecation difficult and painful and necessitate straining. Straining will exert pressure on the hemorrhoidal cushions with obstruction of the blood flow.
Pregnancy: the enlarged womb during pregnancy may compress the big vein in the abdomen (inferior vena cava) and obstruct the free return of blood from the lower part of the body. This will also affect the veins in the hemorrhoidal cushions as majority of the blood coming from the lower part of the body gets to the heart through the inferior vena cava. This is also the explanation behind the development of varicose (abnormal, swollen, elongated tortuous veins) in the legs of pregnant women.
The opponents of pregnancy as a probable cause of hemorrhoid claimed that most pregnant women with symptoms of hemorrhoid often developed it when the age of pregnancy was still small and the womb was not big enough to cause compression. However, the fact that these symptoms resolve after pregnancy is a pointer to the role of pregnancy in causing hemorrhoid. Another implicated cause during pregnancy is the effects of the pregnancy hormones on the wall of these blood vessels resulting in weakening and prolapse.
Prolonged sitting on the toilet has also been linked to the development of hemorrhoid. It leads to impairment in the flow of blood within the veins around the anal region.
Portal hypertension: the veins in the rectal and anal wall drain indirectly into the inferior venal cava via the portal vein system which passes through the liver. Thus, a disease condition in the liver that results in blockage of this vein may lead to increase in pressure within the vein, high enough to cause a backflow leading to swelling and prolapse of the hemorrhoidal cushions. Nevertheless, a portal hypertension can cause varicose veins in the wall of the rectum apart from those in the hemorrhoidal cushions.
Other risk factors that have been linked to the development of hemorrhoid include:
- History of symptomatic hemorrhoid in a family member
- Liver disease
- Previous surgery in the rectum
- Anal intercourse
- Inflammatory bowel disease, such as Crohn disease and ulcerative colitis.
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