From the Guidelines
Internal hemorrhoids develop due to the abnormal swelling of the anal cushions, stretching of the suspensory muscles, and dilation of the submucosal arteriovenous plexus, resulting in the prolapse of upper anal and lower rectal tissue through the anal canal, as described in the american gastroenterological association technical review on the diagnosis and treatment of hemorrhoids 1. The pathophysiology of internal hemorrhoids is complex and involves both vascular and mechanical factors.
- The hemorrhoidal cushions, which are normal vascular structures in the anal canal, consist of connective tissue cushions surrounding the direct arteriovenous communications between the terminal branches of the superior rectal arteries and the superior, inferior, and middle rectal veins 1.
- The anal subepithelial smooth muscle arises from the conjoined longitudinal muscle layer, passes through the internal anal sphincter, and inserts into the subepithelial vascular space, suspending and contributing to the bulk of the hemorrhoidal cushions 1.
- The cushions contribute approximately 15%–20% of the resting anal pressure and serve as a conformable plug to ensure complete closure of the anal canal 1. The symptoms of internal hemorrhoids, such as bleeding, protrusion, itching, and pain, arise from the prolapse of the rectal mucosa, leading to deposition of mucus on the perianal skin and trauma to the tissue, resulting in bright red blood due to the arterial oxygen tension caused by arteriovenous communications within the anal cushions 1. Although the exact pathogenesis of enlarged, prolapsing cushions is unknown, factors such as inadequate fiber intake, prolonged sitting on the toilet, and chronic straining at stool have been proposed as potential contributors to the development of symptomatic hemorrhoids 1.
- Elevated anal resting pressure in patients with hemorrhoids compared to controls has been observed, with voluntary contraction pressure remaining unchanged 1.
- The elevated resting pressure may be caused by or due to enlarged hemorrhoids, but it becomes normal after hemorrhoidectomy 1.
From the Research
Pathophysiology of Internal Hemorrhoids
- Internal hemorrhoids are normal vascular structures underlying the distal rectal mucosa and anoderm, located above the dentate line 2
- They can produce bleeding and prolapse, and are typically characterized by painless rectal bleeding during defecation with or without prolapsing anal tissue 3
- The size, thrombosis, and location of internal hemorrhoids determine the extent of pain or discomfort 4
Symptoms and Grading
- Internal hemorrhoids are traditionally graded from I to IV based on the extent of prolapse 4
- Grade I: no prolapse
- Grade II: prolapse during straining, reducible
- Grade III: prolapse during straining, irreducible
- Grade IV: irreducible prolapse
- Symptoms may include anal bleeding, prolapse, and discomfort 5, 3, 4
Treatment Options
- Medical management, including stool softeners, topical over-the-counter preparations, and dietary modifications, is often the first line of treatment 5, 4
- Office-based treatments, such as rubber band ligation and injection sclerotherapy, may be used for grades I-III internal hemorrhoids 4, 6
- Surgical options, including excisional hemorrhoidectomy and stapled hemorrhoidopexy, may be necessary for higher-grade or recurrent hemorrhoids 5, 3, 4