Antegrade Methylene Blue Mapping for Identification of Causative Pores in Pilonidal Sinus Disease
This study demonstrates that Etiology-oriented Antegrade Mapping Sinusectomy (EAMS), a technique utilizing antegrade methylene blue injection to identify causative pores, offers a simple and tissue-sparing surgical approach for pilonidal sinus disease that may reduce recurrence by enabling targeted excision of diseased tissue.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Pilonidal sinus disease is a common and often painful condition that affects the skin at the very top of the buttock crease. It typically strikes young adults and involves a small hole in the skin that allows hair to penetrate inward. Once inside, the hair acts as a foreign object, triggering a chronic reaction that leads to infection, the formation of a tunnel under the skin, and eventually a painful abscess that may drain fluid or pus. For decades, surgeons have debated the best way to fix this problem. Many traditional approaches focus on cutting out a large area of tissue to ensure nothing is left behind, or on using complex flaps of skin to close the wound. While these methods work, they often involve significant recovery time and can leave large scars. The core challenge has always been knowing exactly where the disease starts and how far the hidden tunnels extend, because missing even a tiny piece of the problem can lead to the condition returning.
A new approach described by researchers Keying Song and David R. Song shifts the focus from how much tissue to remove to exactly where the disease begins. They propose that not all holes on the skin's surface are the same. Some are the true starting points where hair enters the body, while others are merely exit wounds where infection has burst through the skin later on. To distinguish between these two types of openings, the team developed a technique called Etiology-oriented Antegrade Mapping Sinusectomy, or EAMS. This method treats the surgery like a careful exploration of a hidden cave system. Instead of guessing where the tunnels go, the surgeons use a simple, safe blue dye to trace the path from the suspected starting point all the way to the exit.
The researchers tested this idea by reviewing the records of twenty patients who underwent twenty-one procedures at a single clinic between 2010 and 2025. The process began with the patient under anesthesia, allowing the surgeons to carefully shave and clean the area without the patient feeling pain or tensing up. Under bright light and with magnifying lenses, they examined the skin for any tiny pits or dimples that might be hidden entry points. Once a candidate pore was found, they gently inserted a tiny tube and slowly injected a small amount of methylene blue dye. If the dye traveled through a tunnel and came out of a different hole on the skin, it confirmed that the first hole was indeed the true source of the problem and that the two openings were connected. This step was crucial because it allowed the surgeons to see the full path of the disease before they made a single cut.
With the blue dye clearly marking the infected tissue, the surgeons could then plan a precise incision. They removed only the stained tissue and the specific pores involved, sparing the healthy skin around it. In most cases, the wounds were closed with simple stitches rather than complex skin flaps, and patients were able to return to their normal activities quickly. The results were promising. Out of the twenty-one procedures performed, only one patient experienced a return of the disease. When that patient came back, it turned out the surgeons had missed a second, very subtle starting pore that was located lower down than the first one they had found. Because this hidden pore was not removed, the disease persisted. However, when the patient underwent the same mapping procedure again, the surgeons identified the missed pore, treated it, and the problem was resolved permanently.
One particularly telling case involved a surgeon who had previously had the condition treated but saw it return. During his initial surgery, the team had focused on a visible crusty spot higher up on the skin. However, after the new mapping technique was applied, they discovered a tiny, almost invisible pit lower down that was the actual source. When blue dye was injected into this lower pit, it traveled upward and emerged from the higher, crusty spot, proving that the lower pit was the true origin. This confirmed that the visible drainage spot was just a secondary exit, not the cause. By targeting the lower pit, the team was able to cure the condition without needing to remove a large amount of tissue.
The study suggests that the key to preventing recurrence in pilonidal sinus disease may not be removing more tissue, but rather finding the correct starting point with greater accuracy. The researchers found that missing a causative pore, even a small or hidden one, is a likely reason for the disease to come back. Their method offers a way to visualize the hidden connections between skin pores and the tunnels beneath them, ensuring that the surgery addresses the root cause rather than just the symptoms. While the study was conducted on a small group of patients and needs further testing in larger groups, the findings point toward a simpler, more targeted way to treat this stubborn condition. By using a low-cost dye to map the disease from the inside out, surgeons can perform smaller, more precise operations that spare healthy tissue and help patients heal faster.
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