What in the World is an Anal Fissure?
It sounds pretty dramatic, doesn’t it? An "anal fissure." I can tell you from experience, patients come into my office a little panicked by the name alone. They’ve googled it, and now they’re here, convinced it's something terrible. So let’s start with a simple, reassuring truth: it's almost always a small tear in the lining of the anal canal. Think of it like a paper cut, but in a very, very sensitive place.
What makes it so painful? That’s where things get interesting. The anus is surrounded by a muscle—the sphincter—that is incredibly strong and tight. Every time you have a bowel movement, this tear is stretched open, causing a sharp, stinging pain. And because the muscle is so tense, it can prevent the tear from healing, leading to a vicious cycle of pain and spasm.
Now, here’s a medical mystery I’ve always found fascinating. While a tear could theoretically happen anywhere around the anal canal, fissures almost universally form in one of two places: the front or the back midline. If you think of a clock face, they are almost always at 12 o’clock or 6 o’clock. This isn’t a coincidence. It's a clue that has taken us years to fully understand.
For a long time, the prevailing theory was that the muscle itself was just too tight, causing the tear and preventing blood flow from reaching the area to heal it. This idea made perfect sense, especially since the treatments we’ve used for years—ointments like diltiazem, nifedipine, or nitroglycerin—all work by relaxing that very same muscle. Patients would come back, and lo and behold, their fissures were better. We thought we had it all figured out. We were treating the muscle tone, and the healing was a byproduct.
But what about the "why?" Why those two specific locations?
That's where the newer, more compelling theory comes in. It turns out that those two spots—the front and back midline—are what we call "watershed areas." Think of them like the peaks of a mountain ridge where the water divides. In the context of the anus, it means they are areas with the most limited blood supply. They have the worst blood flow of the entire anal canal.
So, perhaps those classic medications weren't just relaxing the sphincter muscle. We now believe they were also relaxing the tiny, smooth muscles in the capillaries and blood vessels, especially in those watershed areas. By increasing the blood flow to the tear, these medications were giving the body what it needed most to heal the wound—oxygen and nutrients. The muscle relaxation was a part of the puzzle, but the real key might be getting that blood supply to the injury. It’s a shift in perspective, moving from a problem of "too tight a muscle" to one of "too little blood flow."
This new understanding also sheds light on some other, more natural remedies. I've had incredible success with Manuka honey for chronic fissures. It’s a powerful natural healer, known for its antibacterial and anti-inflammatory properties, but also for promoting wound healing. When applied topically, it seems to do exactly what we now think those prescription ointments do—it helps get the environment right for the body to do its job and heal the tear. It's a testament to the idea that sometimes, the simplest solutions are the most effective.
If you think you might have a fissure, don’t suffer in silence. They are treatable, and with the right approach, you can break the cycle of pain and get back to feeling like yourself.