Using contrast agents during surgery to improve imaging of endometriosis lesions is a promising approach, but requires additional research, a review study reports.
The research, “Intraoperative enhanced imaging for detection of endometriosis: A systematic review of the literature,” was published in the European Journal Obstretics &Gynecology and Reproductive Biology.
However, lesions in endometriosis can vary substantially and may be difficult to distinguish from healthy tissue. As for laparoscopy, prior data show that although negative diagnosis is highly accurate for excluding endometriosis, positive diagnosis has limited value when used alone.
These limitations led to the use of contrast agents, substances that increase the visibility of body structures, which may be used during surgery to ease pain and reduce endometriosis-associated infertility. Also, improving visualization during surgery may reduce disease recurrence by enabling a more complete destruction of lesions.
The agents include 5-ALA, methylene blue (MB), indigo carmine, indocyanine green, and bloody peritoneal fluid, which may result from bleeding during surgery, have been used to help outline areas of endometriosis.
Researchers reviewed the literature on the use of contrast agents for enhanced visualization of peritoneal endometriosis during laparoscopic surgery. They analyzed nine studies with a total of 171 endometriosis patients. Four studies evaluated 5-ALA, two MB, one indigo carmine, one indocyanine green, and another bloody peritoneal fluid.
Overall, the studies demonstrated the contrast agents’ potential to increase visibility of lesions. Results showed that the use of 5-ALA, the most widely studied agent and usually given orally, is feasible and may allow for better diagnosis of active endometriosis, with a sensitivity of up to 100 percent and specificity of 78 percent.
The results indicate that a 5-ALA dose of 10–30 mg/kg administered between 1.5 and 24 hours before surgery may be adequate.
Regarding the other agents, all given during surgery, MB showed ability to identify endometriosis in 85 percent of suspected lesions. As for indigo carmine, indocyanine green and bloody peritoneal fluid, the authors noted that additional studies are needed to better assess their effectiveness.
However, they commented that fluorescent imaging with indocyanine green, an approach that enables analysis of the density of blood vessels, is promising, as supported by a case report.
Seven complications were reported, all related to 5-ALA, an agent that may be cause irritation under light. These complications included facial erythema, a type of skin inflammation, edema (swelling), and blistering. However, five of these patients did not comply with the required precautions, the authors noted.
Among the review’s limitations, the scientists mentioned that two studies did not confirm diagnosis through histologic (tissue analysis), and that others had a low number of subjects, which precluded analysis of sensitivity or specificity.
“We hypothesize that fluorescence imaging is at present the most promising technique and advocate further investigation for improved detection of endometriosis,” the researchers wrote. However, they also considered that no technique of preference can be identified at this time.