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StimSite is a non-sterile device intended to provide electrical stimulation to ureter smooth muscle tissue to help locate and identify ureters by testing ureter smooth muscle excitability.

StimSite is a non-sterile, non-patient contacting device that generates an electrical signal that elicits visible contractions of smooth muscle tissue. StimSite is a software-controlled signal box that is placed outside of the surgical field, and connects to standard, FDA cleared surgical instruments (sterile disposable, and reprocessed) that are designed to carry bipolar electrical signals through them such as laparoscopic Kleppingers, Maryland graspers and atraumatic graspers among others. StimSite is designed to provide the surgeon with the ability to generate a visible physiologic smooth muscle contraction response intraoperatively to identify and verify the ureter via characteristic muscle tissue movement. This device is intended for use as an adjunct to the standard of care visual assessment currently performed by surgeons to manually stimulate muscle tissue to identify ureters during surgical procedures.

StimSite is non-sterile, a piece of durable medical equipment that resides in the operating room. It is comprised of a Signal Box, a connected Footswitch with cable, and an Interconnect Cable. StimSite also utilizes a disposable Activation Card which tracks and manages device use, allowing a select number of procedures before it is exhausted and needs to be replaced. All materials of construction are common to use and comply with industry standards for use as durable medical equipment. Using the provided Interconnect Cable, surgeons have the option to connect to a currently marketed electrosurgical unit (ESU) or generator such as the Medtronic FT10, Conmed 2450, and the Megadyne Mega Power. StimSite is controlled by user selection buttons on the face of the device and a Footswitch is used to trigger a stimulation signal by the user. Through the selection buttons, StimSite can be placed in one of two modes: STIM (for stimulation) or ESU (for passthrough from the generator).

Here's an analysis of the provided text to extract information about the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly presented in a table format within the provided document. However, based on the non-clinical and clinical testing summaries, we can infer the performance aspects that were evaluated. The document focuses more on safety and functionality rather than specific quantitative performance metrics for identifying ureters.

2. Sample Size Used for the Test Set and Data Provenance

• Animal Study: The animal study used a female Yorkshire pig model. The specific number of pigs is not explicitly stated, but it mentions "a laparotomy was then performed on the other side of the animal," implying at least one animal, possibly more, to allow for the comparison of stimulated vs. non-stimulated tissue.
• Human Factors Testing:
  • Initial testing: 5 intended users.
  • Subsequent testing: 19 surgeons (14 general and 5 Ob/Gyn surgeons).
• Clinical Testing (Pilot): 11 total procedures were performed. The procedures were gynecological (robotic, handheld laparoscopic, and open abdominal).
• Data Provenance:
  • Animal Study: Retrospective (implicitly, as the study was completed and reported). The "Yorkshire pig model" suggests a controlled laboratory setting, likely within the US, but the country of origin is not explicitly stated.
  • Human Factors Testing: Retrospective. Conducted on animal models (porcine).
  • Clinical Testing: Retrospective (pilot data collected between September 2018 and December 2019). The location of these clinical procedures is not specified but is implicitly within the context of a US submission.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

• Animal Study (User Acceptance/Efficacy): 3 representative device users (2 Ob/Gyn surgeons and 1 General and Trauma Surgeon) conducted the simulated surgery. Their experience level is not specified beyond their specialty. The effectiveness was based on their ability to identify ureters and their feedback.
• Animal Study (Tissue Injury): Pathology was used. The report states "a StimSite stimulation was delivered to tissue...and in another the grasper was used to grasp tissue but no stimulation was provided. There was no evidence of thermal injury or trauma to any specimen." This implies a pathologist reviewed the tissue specimens, but the number and qualifications of the pathologist(s) are not mentioned.
• Human Factors Testing: Involves observation of surgeons (19 of them) performing tasks. The "ground truth" here is compliance with the task and identification of use errors, which was collected via direct observation by the study staff. The "experts" in this context are the surgeons themselves, evaluating the usability.
• Clinical Testing (Pilot): The clinical procedures were carried out by 2 Ob/Gyn surgeons (one performed 10 procedures, the other 1). The ground truth for safety, specificity, and efficacy in eliciting contraction was based on "surgeon feedback through the questionnaire" and implicitly derived from the surgeons' observations during the procedures. Their qualifications are "Ob/Gyns" but years of experience are not noted.

4. Adjudication Method for the Test Set

• Animal Study: No explicit adjudication method is described beyond the surgeons' consensus on identification and the pathological assessment for injury.
• Human Factors Testing: Adjudication was through direct observation by study staff and self-correction by users. No formal consensus or 2+1/3+1 method is mentioned for specific task outcomes.
• Clinical Testing (Pilot): The pilot study's findings are based on the operating surgeons' observations and questionnaire feedback. No external adjudication or multi-reader review is mentioned.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size of Human Readers Improve with AI vs without AI Assistance

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study comparing human readers with and without AI assistance was not done. The StimSite device is a surgical tool that aids in direct identification of smooth muscle contraction, not an AI-assisted diagnostic imaging tool interpreted by readers.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done

No, a standalone (algorithm only) performance study was not done. The StimSite is a hardware device that provides electrical stimulation with a software-controlled signal box. Its function is to elicit a physical response (muscle contraction) that a human surgeon observes and interprets. It is inherently a human-in-the-loop device.

7. The Type of Ground Truth Used

• Animal Study: User (surgeon) observation of ureter identification and pathological assessment of tissue for injury.
• Human Factors Testing: Direct observation of task performance by study staff and user feedback.
• Clinical Testing (Pilot): Surgeon observation of visible ureter muscular contraction and subjective surgeon feedback via questionnaires.

8. The Sample Size for the Training Set

The document does not mention a training set in the context of an algorithm or AI. The StimSite is an electrical stimulation device, not an AI-driven vision system that requires a training set for model development. The software mentioned is for controlling the signal box and processing data, not for making diagnostic or identification decisions based on image data. Therefore, a "training set" in the common AI sense is not applicable here.

9. How the Ground Truth for the Training Set Was Established

Since there is no mention of a training set or an AI algorithm that requires one, this question is not applicable.

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