Hemorrhoids are vascular structures in the anal canal that help with fecal continence. When these cushions of blood vessels and tissue become enlarged or displaced, they cause symptoms like bleeding, discomfort, and prolapse. Understanding the visual characteristics of internal hemorrhoids is difficult because they are not typically seen without a medical examination. Their appearance changes dramatically depending on their severity and whether they have moved outside their normal position.
Where Internal Hemorrhoids Form
Internal hemorrhoids originate in the lower rectum, specifically above the dentate line. This line marks the transition between the specialized tissue lining the rectum and the sensitive skin of the anal canal. The tissue covering the hemorrhoid plexus is columnar epithelium, similar to the rectal lining. This location lacks pain-sensing nerves, which explains why non-prolapsed internal hemorrhoids often cause painless bleeding instead of sharp pain. The internal hemorrhoidal cushions are typically located in three main positions: the left lateral, right anterior, and right posterior aspects of the anal canal.
Describing the Internal Appearance
When examined internally, a hemorrhoid appears as a swollen, cushion-like structure composed of engorged blood vessels. They are covered by the moist, smooth rectal mucosa. Because they are filled with blood, their color is often deep red or purplish. The surface is generally smooth and moist, contrasting with the skin outside the anal opening. They are not visible during an external examination unless they have enlarged and moved downward. Their appearance is primarily that of a bulging, deep-colored tissue mass inside the anal canal.
The Four Grades of Prolapse
The most important visual classification system for internal hemorrhoids is the degree of prolapse, which is categorized into four grades. This classification describes how far the hemorrhoid protrudes from the anal canal and whether it returns to its normal position. The visual presentation changes significantly from a completely unseen internal bulge to a permanently protruding mass.
- Grade I hemorrhoids remain inside the anal canal and do not protrude, making them completely invisible externally.
- Grade II hemorrhoids push out during straining but spontaneously retract back inside once the effort ceases. They may appear briefly as a soft, reddish-pink lump.
- Grade III hemorrhoids prolapse and do not return spontaneously, requiring manual reduction (gently pushing them back inside). They are visibly protruding, appearing as a swollen, reddish or purple bulge.
- Grade IV hemorrhoids are permanently prolapsed and cannot be manually pushed back inside. They are constantly visible outside the anal opening, often presenting as a large, swollen mass of tissue.
How They Differ from External Hemorrhoids
The primary distinction between internal and external hemorrhoids is their anatomical origin and the tissue covering them. Internal hemorrhoids originate above the dentate line and are covered by mucosa, which contributes to their deep red or purplish color when engorged. External hemorrhoids form below the dentate line and are covered by anoderm, which is specialized, sensitive skin. Visually, external hemorrhoids typically appear as a visible lump or swelling near the anal opening. When not thrombosed, they are usually skin-colored or slightly reddish. If an external hemorrhoid develops a blood clot, it becomes a thrombosed external hemorrhoid, characterized by a firm, tense lump that may appear blue or dark purple beneath the skin. This contrast in covering tissue and resulting color is the clearest visual difference between the two types.