The technique relies on indocyanine green, or ICG, a fluorescent tracer that has been approved for clinical use for decades. When injected into a vein, ICG binds to plasma proteins and stays within the bloodstream. Illuminated by near-infrared light, it emits a fluorescent signal that can be captured by a specialized camera system, allowing surgeons to watch blood perfusion unfold across the surface of an organ in real time. Because near-infrared light penetrates tissue more deeply than visible light and generates little background interference, the resulting images can reveal the boundary between tissue that is being fed by blood and tissue that has lost its supply.

In the study, published in BMC Pediatrics, a surgical team led by Li Tao, Xu Cao, and corresponding author Shu Dai applied this technology to ten children who underwent emergency surgery for testicular rupture between July 2023 and December 2025. During each operation, the surgeons injected ICG intravenously at a dose of 0.2 milligrams per kilogram of body weight and then used a near-infrared fluorescence imaging system to perform real-time angiography of the exposed testicle. The goal was to delineate, on the operating table and within minutes, the exact boundary between nonperfused tissue and tissue that was still receiving blood.

The results were strikingly consistent. In all ten patients, the fluorescence imaging clearly delineated the boundary between areas where fluorescence could be detected and areas where it could not. Those findings were incorporated into the surgeons’ overall intraoperative assessment and used to guide selective excision of tissue considered nonviable. Once the dead tissue had been removed, the team repaired the resulting defect using either sutures of the tunica albuginea, the tough fibrous capsule surrounding the testicle, or a patch of tunica vaginalis, the membrane that normally cushions the organ within the scrotum.

Follow-up examinations offered cautious encouragement. With a median follow-up of ten months, ranging from three to 32 months, all of the repaired testes showed regular morphology and homogeneous echogenicity on grayscale ultrasound, an indication that the tissue architecture had healed without the scarring or irregularity that often follows significant testicular injury. Color Doppler flow imaging, the standard ultrasound technique for visualizing blood flow, demonstrated normal blood flow signals in every case. No postoperative complications were documented in the available clinical records during the follow-up period.

The clinical stakes of this problem are considerable. Testicular rupture, in which blunt trauma tears the tunica albuginea and extrudes the delicate seminiferous tubules inside, is one of the most time-sensitive emergencies in pediatric urology. The viability of the gonad depends heavily on how quickly blood flow is restored and how accurately the surgeon judges which tissue can survive. Traditional assessment relies on visual inspection of color, texture, and bleeding at the cut edges, supplemented by preoperative ultrasound. These cues are notoriously subjective, and both errors carry lasting consequences: leaving devitalized tissue increases the risk of necrosis and atrophy, while over-resection removes germ cells that might otherwise have contributed to preserved fertility and hormone production.

ICG fluorescence imaging addresses that subjectivity directly by giving surgeons an objective, dynamic map of perfusion. The physics behind the technique is elegant. ICG absorbs light in the near-infrared range, around 800 nanometers, and re-emits it at slightly longer wavelengths. Because hemoglobin and water absorb relatively little light in this window, the fluorescence signal can be detected from tissue several millimeters to a centimeter beneath the surface, and the contrast between perfused and nonperfused regions appears within seconds of injection. In other surgical specialties, from colorectal anastomosis to reconstructive flap surgery, this real-time perfusion mapping has already changed intraoperative decision-making, and the Suzhou team’s work extends that logic to a delicate pediatric organ where every cubic millimeter of viable tissue matters.

The authors are careful to frame their findings as preliminary. This was a pilot feasibility study with only ten patients, conducted as a retrospective review of children who had already been treated under an approved new clinical technology application. The ethical approvals covered both the clinical use of ICG during testicular rupture surgery, granted in 2023, and the retrospective analysis of the resulting records, approved under number 2026CS087 before any data were abstracted. Because the study lacked a control group, it cannot yet demonstrate that ICG guidance improves long-term outcomes compared with conventional surgical judgment alone. The uniformly good results could reflect the imaging technique, careful patient selection, skilled surgery, or simply the natural history of promptly treated rupture. The authors explicitly state that their findings require validation in larger, controlled studies to determine the technique’s impact on long-term outcomes.

Nevertheless, the safety profile observed in this small cohort is reassuring. ICG has a long track record of clinical use, with adverse reactions generally rare and mild, and no adverse events were observed in these ten children. The dose used, 0.2 milligrams per kilogram, is modest, and the imaging procedure adds only a few minutes to an emergency operation, a meaningful consideration when ischemia time is a critical determinant of organ survival. For pediatric urologists, the appeal of the technique lies precisely in this combination of speed, simplicity, and visual clarity: a single injection and a camera turn an invisible physiological variable, blood flow, into an immediately interpretable image on the operating room monitor.

The broader significance of the study extends beyond urology. It represents part of a growing movement in surgery toward fluorescence-guided decision-making, in which molecular tracers and optical imaging replace guesswork with measurable signals. If larger trials confirm the Suzhou results, ICG imaging could become a standard adjunct in pediatric scrotal trauma, helping surgeons preserve organs that would once have been lost. For the children in this study, the glowing green map on the operating room monitor appears to have done exactly what such technology promises: it showed the surgeons where life remained in damaged tissue, and it helped them keep it. Whether that promise holds across hundreds of patients will be the question that future controlled studies must answer, but the first step has now been taken, and it was taken in glowing green.

Subject of Research: Intraoperative indocyanine green fluorescence imaging to assess tissue perfusion during pediatric testicular rupture surgery

Article Title: Indocyanine green fluorescence imaging for intraoperative assessment of tissue perfusion in pediatric testicular rupture: a pilot feasibility study

Article References: Tao, L., Cao, X., Huang, M., Wang, T., Zhang, L., Xia, H., Fu, M., Zhou, Y., Zhang, T., Yan, X., & Dai, S. (2026). Indocyanine green fluorescence imaging for intraoperative assessment of tissue perfusion in pediatric testicular rupture: a pilot feasibility study. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07846-8

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07846-8

Keywords: indocyanine green, fluorescence imaging, testicular rupture, pediatric surgery, tissue perfusion, near-infrared imaging, intraoperative assessment, urology, pilot study, organ preservation, surgical imaging, BMC Pediatrics

The study’s foundation is the entrustable professional activity, or EPA, a framework that has rapidly reshaped how surgical residency programs think about assessment. Rather than rating abstract competencies such as professionalism or medical knowledge in isolation, EPAs describe the concrete tasks a surgeon must be able to perform—like performing an laparoscopic cholecystectomy or managing an acutely ill patient—and ask supervising attendings to rate the level of supervision a resident actually required. In 2024, a national pilot study published in Annals of Surgery demonstrated that general surgery programs across the United States could implement EPA-based assessment at scale, and subsequent work has validated EPAs in national samples of programs. But implementation is only half the battle. Once programs collect thousands of microassessments, they face a harder question: what do all those numbers actually mean?

That question matters because intraoperative assessments are confounded by factors that have nothing to do with the resident’s ability. A resident who performs a straightforward hernia repair for the tenth time may earn a high entrustment rating, while the same resident struggling through a complex, first-time pancreatic resection may look far weaker than they truly are. The attending doing the rating adds another layer of variability: some raters are systematically generous, others harsh, and some vary widely from case to case. A simple average of ratings therefore blends together trainee skill, procedural difficulty, repetition, and rater temperament into a single number that is difficult to interpret. The research team set out to disentangle these threads using a statistical approach known as multilevel modeling, a technique with deep roots in educational measurement and generalizability theory.

The dataset behind the study is substantial. The researchers analyzed 949 intraoperative EPA microassessments collected during the 2024–2025 academic year at a large academic general surgery residency program. The assessments spanned 57 residents across all five postgraduate training years, rated by 72 different attending surgeons, and covered 14 distinct intraoperative EPA categories. This volume and diversity of data is exactly what makes the modeling approach feasible: with enough ratings per resident, per procedure type, and per rater, the model can statistically separate the components of each score. The study used de-identified assessment data and was reviewed by the local Institutional Review Board, which determined it to be exempt from full ethical review.

The core of the algorithm is a multilevel model with random intercepts for residents, for EPA categories, and for attending raters, combined with a fixed effect for procedural repetition. In practical terms, the model treats each individual entrustment rating as the sum of several influences: the resident’s underlying ability, the inherent difficulty of the procedure being performed, the stringency of the particular attending, and the learning that comes simply from having done the operation before. By estimating each of these components simultaneously, the model produces a composite entrustability score for every resident that is adjusted for the circumstances under which their ratings were earned. Procedural repetition emerged as a meaningful factor, with a positive association to entrustability (a coefficient of 0.028, statistically significant at p < 0.001)—confirming quantitatively what every surgeon knows intuitively: doing an operation more times makes you better at it.

The psychometric evaluation of the resulting scores is where the study becomes particularly compelling for measurement scientists and program directors alike. The composite scores were normally distributed, with a mean of 2.67 on the entrustment scale and a range spanning 1.29 to 3.77. Normality matters because many downstream statistical procedures and competency benchmarks assume a roughly bell-shaped distribution, and skewed or clumped score distributions can distort decisions about promotion or remediation. Perhaps most reassuringly, the modeled scores correlated at r = 0.98 with the raw average ratings, indicating that the algorithm refines rather than replaces the intuitive signal that attendings already provide. The model does not invent a new construct; it sharpens an existing one by stripping away measurement noise.

Validity evidence came from a classic known-groups analysis. If the scoring algorithm captures something real about surgical development, senior residents should score higher than junior residents—and they did, decisively. Senior residents earned a mean composite score of 3.32 compared with 2.33 for junior residents, a difference that was highly statistically significant (p < 0.001). This gradient across training levels supports the construct validity of the measure: the algorithm tracks the developmental trajectory that surgical educators expect to see as residents accumulate operative experience. The analysis also documented substantial variability in procedure difficulties and in attending rater stringency, confirming that the confounders the model adjusts for are not hypothetical—they are present and measurable in real program data.

For residency programs, the implications are practical. Competency-based, time-variable training has been proposed as a way to allow trainees to progress at their own pace, but regulatory structures and assessment systems have struggled to keep pace with that vision. A scoring algorithm that can synthesize local EPA data into defensible resident-level estimates gives program directors and clinical competency committees a tool for making promotion decisions that is more rigorous than eyeballing averages. It also provides earlier warning signals: a resident whose adjusted entrustability trajectory lags behind peers can be identified and supported before problems compound. The approach aligns with the Standards for Educational and Psychological Testing, the joint framework from the American Educational Research Association, American Psychological Association, and National Council on Measurement in Education that governs how validity evidence should be accumulated for educational measures.

The study also speaks to a broader movement in surgical education toward large-scale workplace assessment. Systems such as SIMPL, developed to implement operative performance assessments at scale, have shown that mobile microassessment tools can generate the volume of data needed for meaningful statistical modeling. What has often been missing is the analytical layer—methods that transform raw ratings into trustworthy summaries. The multilevel approach described in this study draws on hierarchical linear modeling traditions dating back to the foundational work of Bryk and Raudenbush, and on generalizability theory frameworks articulated by measurement specialists such as Bloch and Norman. By applying these established psychometric tools to the specific problem of intraoperative entrustment, the researchers bridge a gap between assessment collection and assessment interpretation.

Limitations remain, as the authors acknowledge through the structure of their analysis. The data come from a single large academic program in the New England region, and the underlying data are not publicly available due to institutional restrictions protecting learner confidentiality. Whether the algorithm’s parameters—particularly the estimates of procedure difficulty and rater stringency—generalize to other programs with different case mixes and faculty cultures will require multi-institutional replication. The strong correlation with raw means also suggests that for many purposes, simple averages may already capture most of the signal; the model’s advantage lies in edge cases, where unusual case mixes or idiosyncratic raters could otherwise distort a resident’s apparent performance. Still, as EPA-based assessment becomes embedded in surgical training nationwide, this study offers a template for turning the daily stream of supervisory judgments into scores that programs can trust—scores that measure the resident, not the moment.

Subject of Research: Development of a multilevel scoring algorithm for intraoperative resident entrustability using EPA assessment data

Article Title: Developing a scoring algorithm for intraoperative entrustability among general surgery residents using local EPA data

Article References: Chen, D., Mckinley, S., Thomas, J., Witt, E., Phitayakorn, R., Greer, J., Moses, J., & Smink, D. (2026). Developing a scoring algorithm for intraoperative entrustability among general surgery residents using local EPA data. Global Surgical Education – Journal of the Association for Surgical Education, 5(1), Article 153. https://doi.org/10.1007/s44186-026-00550-2

Image Credits: AI Generated

DOI: 10.1007/s44186-026-00550-2

Keywords: entrustable professional activities, surgical education, general surgery residency, multilevel modeling, entrustability, workplace-based assessment, psychometrics, competency-based medical education, intraoperative assessment, scoring algorithm, rater stringency, programmatic assessment