Introduction
Colorectal cancer (CRC)- diagnosis and treatment
Endoscopic tattooing
Inks or dyes for colon tattoos
Advantages and disadvantages of colon tattoos
References
Further reading
Endoscopic tattooing is an important medical technique that is used to mark colorectal lesions for surgery or follow-up. This technique is important because it minimizes the challenges faced by surgeons in locating polypectomy sites or small lesions, laparoscopically. Hence, colon tattoos help reduce operating time and ensure that the correct colon segment is resected.
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Colorectal cancer (CRC)- diagnosis and treatment
Colorectal cancer (CRC) is one of the common types of cancer that infects 52.7 people per 100,000 of the population in the United States. CRC is mostly diagnosed in people who are older than 50 years, and, hence, this age group must be regularly screened for the disease. Endoscopy (colonoscopy and sigmoidoscopy), fecal occult blood test, double contrast enema, and stool DNA test are common tools and methods used for the diagnosis of CRC.
Researchers stated that family history is one of the most important risk factors for this type of cancer. Other risk factors associated with the incidence of CRC are an individual’s history of chronic inflammatory bowel disease (IBD), adenoma, and sessile serrated polyps. Although most patients’ colorectal lesions can be removed endoscopically, some patients require subsequent surgical resection. This is due to positive resected margins or a high risk of lymph node metastases.
Surgeons often face difficulties in locating a previous polypectomy site or small lesions while using the laparoscopic method. Hence, without precise preoperative localization, there is a high risk of incorrect removal of a segment of the intestine. To address this difficulty, many methods have been designed for preoperative localization; for example, the double-contrast barium enema technique is used to locate large tumors. However, this method is not highly effective for detecting small lesions. Endoscopic tattooing is a less invasive approach for preoperative localization.
Endoscopic tattooing
In 1958, Sauntry and Knudtson first introduced the concept of tattooing a colonic polyp using methylene blue dye. However, only in 1975, Ponsky and King proposed that this technique could be used for intraoperative localization of colonic lesions. Implementation of this technique significantly enhanced the success rate of tumor resection. Scientists have claimed this technique to be safe and effective for intraoperative tumor localization.
Colon tattoos are used to mark lesions that are useful for later endoscopic resection, subsequent surgical resection, and easy endoscopic follow-up of the resection site. Typically, tattooing is appropriate for lesions in all colon locations, except in the cecum. This is because the cecum by itself is a consistent landmark for both endoscopic and surgical follow-up. Several clinicians have stated that colon tattoos are extremely useful for CRC treatment.
Endoscopic tattooing involves infecting the entire volume of tattoo ink into the submucosal space. When carbon black is injected, it produces a physical black stain that can be easily visualized endoscopically. It is extremely important to inject the dye into the submucosa, and this is done via two methods.
The first method involves the initial insertion of 0.5- to 1.0-mL submucosal bleb of saline. Subsequently, a sterile needle is inserted into the saline bleb, and the tattoo ink is injected. The second method involves direct injection of the tattoo ink into the submucosa. Skilled endoscopists can easily perform this technique.
Typically, for surgical marking, four tattoos are placed opposite to each other but close enough to be nearly touching. These tattoos are placed around the circumference of the wall. However, for endoscopic follow-up, only one tattoo is created on the side of the colon wall.
Inks or dyes for colon tattoos
Ink is the most important aspect of a colon tattoo, which helps identify and, thereby, remove colonic tumors and polyps. To date, the US Food and Drug Administration (FDA) has approved a carbon ink formulation called Spot for endoscopic tattoos. Recently, another new formulation called Spot Ex has been reported to be significantly darker than the previous formulation. Researchers stated that dyes such as methylene blue, indocyanine green, and indigo carmine do not leave a permanent tattoo on the colon.
Although carbon dye, a form of India Ink, is an effective tattoo ink, it contains several immunostimulant substances. Studies have shown that injection of India ink causes many adverse effects, including inflammatory pseudotumor, formation of sterile abscess, and focal peritonitis.
Recently, scientists have formulated a next-generation ink for tattooing colon. This ink is based on metal-derived nanoparticles. Two of the key advantages of the new ink are superior biocompatibility to existing inks and the property of not triggering inflammation. This ink creates a dark-colored tattoo, which can be easily visualized under the visible light of a colonoscopy. More studies and clinical trials are required to validate this ink before it can be used on humans.
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Advantages and disadvantages of colon tattoos
As stated above, colon tattooing has substantially reduced operating time and surgical cost. Additionally, colon tattoos provide a precise location for colon resection. Thereby, this technique has enhanced the success rate of colon surgeries.
Although complications associated with colon tattooing are rare, in some cases, such as using India ink, immunologic complications occur. Ineffective tattooing occurs when a tattoo is difficult to locate by surgeons during laparoscopy or laparotomy. Additionally, muscle injury or submucosal fibrosis occurs when the tattoo spreads under the lesion. In some cases, biopsies from the tattoo sites exhibited mild chronic inflammation as well.
References
- Medina-Prado, L. et al. (2021) When and How To Use Endoscopic Tattooing in the Colon: An International Delphi Agreement. Clinical Gastroenterology and Hepatology, 19 (5), pp. 1038-1050. https://doi.org/10.1016/j.cgh.2021.01.024
- Rex, D.K. (2018) The Appropriate Use and Techniques of Tattooing in the Colon. Gastroenterology and Hepatology (N Y), 14(5), pp. 314-317.
- Costa, R.N. (2020) Tattooing will benefit patients with colorectal cancer. Clinical Medicine Journal. DOI: https://doi.org/10.7861/clinmed.20-2-s77
- Letarte, F. et al. (2017) Tattooing or not? A review of current practice and outcomes for laparoscopic colonic resection following endoscopy at a tertiary care centre. Canadian Journal of Surguery, 60(6), pp. 394–398.
- Yang, M. et al. (2017) Endoscopic tattoo: the importance and need for standardised guidelines and protocol. Journal of the Royal Society of Medicine. 110(7), pp. 287–291
- Trakarnsanga, A. and Akaraviputh, T. (2011) Endoscopic tattooing of colorectal lesions: Is it a risk-free procedure? World Journal of Gastrointestinal Endoscopy, 3(12), pp. 256-60. doi: 10.4253/wjge.v3.i12.256.
Further Reading