What Are Hemorrhoids? Types, Causes, and Clinical Insight
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Key Facts
- Hemorrhoids are normal vascular cushions that help with continence but become problematic when swollen or prolapsed.
- Internal hemorrhoids are graded I–IV based on how much they protrude from the anus.
- External hemorrhoids can be especially painful due to their location below the dentate line.
- Increased pressure from constipation, straining, or pregnancy can trigger hemorrhoidal disease.
- Treatment ranges from lifestyle changes and medications to office-based procedures and surgery.
Hemorrhoids (also called piles) are one of those health issues no one likes to talk about—but they’re super common and affect millions of people worldwide. Hemorrhoids are swollen veins or blood vessels in the lower rectum and anus, and this swelling can cause discomfort, itching and even bleeding.
In fact, hemorrhoids are swollen veins like varicose veins in the legs, both caused by increased pressure in the blood vessels. While they’re often lumped into one category, hemorrhoids come in different types and stages, each with its own set of symptoms and treatment options.
Understanding what hemorrhoids are and why they happen can help reduce the stigma and encourage early care.
Table of Contents
- Anatomy and Physiology of Swollen Blood Vessels in Hemorrhoids
- Types and Classification
- Pathophysiology
- Clinical Significance and Rectal Bleeding
- Closing Thoughts
- References
Anatomy and Physiology of Swollen Blood Vessels in Hemorrhoids
Let’s start with the basics: hemorrhoids aren’t abnormal in and of themselves. They’re actually part of your normal anatomy. These vascular cushions are located just inside the anal canal and help maintain continence—essentially they help seal the anal opening along with the sphincter muscles. These cushions are made up of hemorrhoidal tissue which is present in everyone. This is different from other things like anal fistulas and anal fissures.
Each hemorrhoidal cushion contains:
- A dense network of arterioles and venules, including direct arteriolar-venular connections [7].
- Connective tissue that supports and anchors these blood vessels in place [2].
Trouble starts when these structures become engorged, lose their supportive tissue and slide down. This engorgement causes swollen blood vessels and that’s when we call them “hemorrhoidal disease” [1].
Types and Classification
Not all hemorrhoids are the same. They’re classified based on their location relative to the dentate (or pectinate) line—a key anatomical landmark in the anal canal. The symptoms of hemorrhoids vary depending on the type, internal and external hemorrhoids have different hemorrhoid symptoms like pain, bleeding, swelling, irritation and prolapse [3]. Recognizing these symptoms is important for diagnosis and treatment.
Internal Hemorrhoids
These are above the dentate line and are covered by rectal mucosa which has no pain receptors. That’s why internal hemorrhoids can go unnoticed—until they start bleeding or prolapsing. A common sign is the presence of bright red blood on toilet paper or in the toilet bowl. Rectal bleeding can be a symptom of hemorrhoids but should always be evaluated by a healthcare provider to rule out more serious conditions like colorectal cancer or anal fissures as these can also cause similar symptoms [4].
They’re classified into four grades:
- Grade I: No prolapse, just prominent vessels
- Grade II: Prolapse upon straining but retracts on its own
- Grade III: Prolapse that requires manual reduction
- Grade IV: Irreducible prolapse, often painful and thrombosed [1]
External Hemorrhoids
These develop below the dentate line, under the skin (anoderm) that’s rich in sensory nerves. That means they’re more likely to cause pain, itching and swelling. If a blood clot forms inside an external hemorrhoid (a condition called thrombosis), the pain can be intense [6]. A thrombosed external hemorrhoid typically presents as a firm, bluish or purple lump under the overlying skin, and is often associated with severe pain. The overlying skin may become stretched or irritated, and after the thrombosed hemorrhoid resolves, skin tags can develop as soft, painless protrusions [5].
Pathophysiology
So, what causes hemorrhoids to go from helpful cushions to problematic bulges?
It comes down to a few key mechanisms:
- Dilatation of vascular channels: Blood flow increases, causing the vessels to swell.
- Degeneration of connective tissue: The structures meant to support the vascular cushions weaken over time or due to strain [8].
- Sliding and congestion: As the cushions slide downward, blood pools in the vessels, causing even more pressure and stretching [10].
Think of it like this: if you over-inflate a water balloon, it stretches and weakens. Add gravity and pressure from below (like from straining), and it starts to bulge or even rupture.
Contributing factors include:
- Chronic constipation or straining during a bowel movement, which leads to increased pressure and too much pressure in the anal veins* Prolonged sitting on the toilet. This is different than other diseases like small bowel obstruction and irritable bowel syndrome.
- Pregnancy, which increases abdominal pressure
- Aging, which weakens supportive tissues
To prevent hemorrhoids, focus on prevention strategies such as adding fiber to your diet by consuming high fiber foods, whole grains, vegetables and whole grains, and fruits vegetables and whole. Using a fiber supplement or fiber supplements can also be beneficial. Make sure to drink adequate fluid to help soften stools and promote regular bowel movements [9]. Maintaining digestive health is important, as issues like digestive and kidney diseases or kidney diseases can impact overall well-being. These strategies can help prevent hemorrhoids.
Clinical Significance and Rectal Bleeding
Hemorrhoids are a common reason patients visit colon and rectal surgeons. While not life-threatening, they can significantly affect quality of life when symptoms become chronic or severe.
Diagnosis begins with a detailed medical history and physical exam, often including a digital rectal exam to check for blood and abnormalities. Additional procedures like anoscopy or colonoscopy may be used to rule out other causes and ensure accurate diagnosis, guiding appropriate hemorrhoids treatment.
Most hemorrhoid symptoms—such as pain, swelling, itching and bleeding—can be managed with conservative care. Common signs include blood on toilet paper or in the toilet bowl after bowel movements. Home treatments like warm baths, sitz baths and using damp toilet paper help reduce irritation and provide relief.
When symptoms persist or hemorrhoids are large, office treatments such as rubber band ligation, infrared coagulation or sclerotherapy may be recommended, often performed with numbing medicine for comfort.
For severe or persistent cases unresponsive to conservative or office-based treatments, surgical options like hemorrhoidectomy or stapled hemorrhoidopexy may be necessary. These procedures remove problematic hemorrhoid tissue and are reserved for more serious conditions.
Post-procedure, mild pain is common and manageable with home care. Health care providers play a vital role in diagnosis, treatment guidance and postoperative care. Lifestyle modifications, including high-fiber diets and improved toilet habits, remain essential for preventing hemorrhoid flare-ups and maintaining digestive health.
Closing Thoughts
Hemorrhoids are a part of our anatomy but when they become swollen, prolapsed or thrombosed they become a problem. They are classified into two types—internal and external—with varying degrees of severity. At the core of the issue are vascular changes and weakened support structures which is often made worse by straining, poor diet or sitting for too long.
Understanding the anatomy and mechanics of hemorrhoids helps not only in diagnosis but also in choosing the right treatment. And for many, simple lifestyle changes can go a long way in preventing hemorrhoidal disease from taking over their daily life.
References
[1] Mott, T., Latimer, K., & Edwards, C. (2018). Hemorrhoids: Diagnosis and Treatment Options. American family physician, 97(3), 172–179. https://pubmed.ncbi.nlm.nih.gov/29431977/
[2] Lohsiriwat V. (2012). Hemorrhoids: from basic pathophysiology to clinical management. World journal of gastroenterology, 18(17), 2009–2017. https://doi.org/10.3748/wjg.v18.i17.2009
[3] Reese, G. E., von Roon, A. C., & Tekkis, P. P. (2009). Haemorrhoids. BMJ clinical evidence, 2009, 0415. https://pubmed.ncbi.nlm.nih.gov/19445775/
[4] Sneider, E. B., & Maykel, J. A. (2010). Diagnosis and management of symptomatic hemorrhoids. The Surgical clinics of North America, 90(1), . https://doi.org/10.1016/j.suc.2009.10.005
[5] Halverson A. (2007). Hemorrhoids. Clinics in colon and rectal surgery, 20(2), 77–85. https://doi.org/10.1055/s-2007-977485
[6] Sanchez, C., & Chinn, B. T. (2011). Hemorrhoids. Clinics in colon and rectal surgery, 24(1), 5–13. https://doi.org/10.1055/s-0031-1272818
[7] Bernstein W. C. (1983). What are hemorrhoids and what is their relationship to the portal venous system?. Diseases of the colon and rectum, 26(12), 829–834. https://doi.org/10.1007/BF02554764
[8] Mounsey, A. L., Halladay, J., & Sadiq, T. S. (2011). Hemorrhoids. American family physician, 84(2), 204–210. https://pubmed.ncbi.nlm.nih.gov/21766771/
[9] Fox, A., Tietze, P. H., & Ramakrishnan, K. (2014). Anorectal conditions: hemorrhoids. FP essentials, 419, 11–19. https://pubmed.ncbi.nlm.nih.gov/24742083/
[10] Sardinha, T. C., & Corman, M. L. (2002). Hemorrhoids. The Surgical clinics of North America, 82(6), 1153–vi. https://doi.org/10.1016/s0039-6109(02)00082-8
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