松田るか
biomedicool
Haemorrhoids
Haemorrhoids, aka piles, are vascular structures in the anal canal, which act as cushions to help with stool control. At least 50% of people will experience problems with haemorrhoids in their life.
- Exist in everyone from birth - become a disease when swollen or inflamed
- Internal haemorrhoids - painless, bright red rectal bleeding when defecating.
- External haemorrhoids - often result in pain and swelling in the area of the anus, darker bleeding. Symptoms usually improve and heal.
Causes
Because of their rich vascular supply, highly sensitive location, and tendency to engorge and prolapse, haemorrhoidal venous cushions are common causes of anal pathology.
Exact cause unknown, a number of factors which increase pressure in the abdomen are believed to be involved - eg pregnancy, constipation, diarrhoea and strain. Lack of exercise, nutritional factors (low-fibre diets), obesity, prolonged sitting, and ageing have also been implicated .
- Often, no specific treatment is needed other than:
- increasing fibre intake, drinking fluids to maintain hydration, NSAIDs to help with pain, and rest.
- A number of minor procedures may be performed, while surgery is reserved for those who fail to improve.
Pathophysiology
Haemorrhoid cushions only become pathological when they experience abnormal changes. There are three main cushions present in the normal anal canal, in left lateral, right anterior, and right posterior positions.
- Composed of blood vessels lacking muscle tissue called sinusoids, connective tissue, and smooth muscle - making up the haemorrhoidal plexus
- Haemorrhoid symptoms result when these vascular structures slide downwards or when venous pressure is excessively increased.
- External haemorrhoids develop from ectoderm and are covered by squamous epithelium,
- Internal haemorrhoids are derived from embryonic endoderm and lined with the columnar epithelium of anal mucosa.
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Internal haemorrhoids cannot cause cutaneous pain, because they are above the dentate line and are not innervated by cutaneous nerves
- Bleeding will therefore be painless, but may cause itching and irritation