Cognitive models for mentally visualizing a sharp instrument in a blind procedure

Abstract

Purpose

Our objective was to understand the cognitive strategies used by surgeons to mentally visualize navigation of a surgical instrument through blind space.

Methods

We conducted semi-structured interviews with 15 expert and novice surgeons following simulated retropubic trocar passage on 3D-printed models of pelvises segmented from preop MRIs. Midurethral sling surgery involves blind passage of a trocar among the urethra, bladder, iliac vessels, and bowel while relying primarily on haptic feedback from the suprapubic bone (SPB) for guidance. Our conceptual foundation was based on Lahav’s study on blind people's mental mapping of spaces using haptic cues. Participants detailed how they mentally pictured the trocar’s location relative to vital anatomy. We coded all responses and used constant comparative analysis to generate themes, confirmed with member checking.

Results

Expert and novice participants utilized multiple cognitive strategies combined with haptic feedback to accomplish safe trocar passage. Some used a step-by-step route strategy, visualizing sequential 2D axial images of anatomy adjacent to the SPB. Others used a map strategy, forming global 3D pictures. Although these mental pictures vanished when they were “lost,” a safe zone could be reestablished by touching the SPB. Experts were more likely to relate their body position to the trocar path and rely on minor variations in resistance. Novices were more inclined toward backtracking of the trocar.

Conclusions

Our findings may be extended to any blind surgical procedure. Teaching visualization strategies and incorporating tactile feedback can be used intraoperatively to help learners navigate their instrument safely around vital organs.

Introduction

Significant challenges exist in learning to perform a blind surgical procedure. Novice surgeons rely on direct visualization of their instrument as they manipulate it; in the absence of visual feedback, they must rely on haptic feedback, their understanding of the anatomy, and instruction from the surgical attending. This challenge is magnified when the anatomy contains vital structures that cannot be seen yet can be easily punctured or injured. Blind procedures are arguably even more challenging to attending surgeons, who must estimate, without feeling, the location of the instrument relative to the susceptible anatomy while simultaneously guiding the novice trainee through the procedure. Such uncertainty threatens both adequate surgical training and patient safety.

In this study, we explore how both teaching and learning surgeons mentally visualize navigation of a surgical instrument through blind space. We chose the passage of a trocar through the retropubic space during the midurethral sling surgery, a procedure for stress urinary incontinence that is performed approximately 200,000 times per year in the United States [1]. This procedure is performed by passing a sharp steel trocar from the vagina, within a periurethral tunnel, through the retropubic space, exiting through the suprapubic skin. While moving through this space, the trocar must pass vital structures, such as the bladder, iliac vessels, and bowels, which the surgeon cannot see. There is no intraoperative radiologic method (such as fluoroscopy) to aid in this procedure. Injuries to these structures are well-documented [2], and bladder injury in particular is associated with surgeon inexperience [3]. Novices are understandably anxious about performing this procedure due to the loss of visual feedback in addition to the potential for injuring the patient [4].

Conceptual foundation

Our conceptual foundation was inspired by research conducted by Lahav et al., who studied the technique used by blind people as they explore a new room [5, 6]. Blind people face great cognitive challenges as they mentally map new spaces and must rely on touch, haptic feedback, and hearing in order to safely navigate. The skill of navigating an unfamiliar space while blind has similarities with passing a sharp surgical instrument without being able to visualize it as both depend on a combination of haptic feedback and forming a cognitive picture, or 3D mental map of the space.

Lahav found that blind people use specific cognitive strategies to mentally map and visualize a space. Lahav studied two of these strategies: the route strategy in which an individual maps a space in a linear, sequential fashion; and the map strategy which involves mapping a 3D space from multiple perspectives to get a holistic view of the space in its entirety. In route strategy, the blind person moves from the door to the chair, to the couch, and to the lamp, sequentially touching each object and mapping the location of each object in relation to the previous one. Their mental 3D visualization includes a sequential ordering of how to get from one object to the next. By contrast, in map strategy, the blind person moves around multiple locations in the room, touching multiple objects many times, forming a 3D map of the space that can be both visualized and navigated from different perspectives.

Although blind individuals use the route strategy more often, the map strategy was more efficient. Additionally, many blind people demonstrated a hybrid of both route and map strategies, often alternating between the two. We hypothesized that surgeons would use similar cognitive strategies during a blind procedure, and that both novice and expert surgeons would use a combination of route and map strategies when navigating the retropubic space.

Study objective

The objective of this study was to explore the cognitive strategies used by surgeons to mentally visualize navigation of a midurethral sling trocar through the blind retropubic space. Understanding how surgeons visualize these spaces, especially the relationship between their instrument and the anatomy within these spaces, is necessary in developing a tailored approach to surgical education on performing blind procedures. Key to this exploration is uncovering the mental visualization strategies of both novice and expert surgeons.

Methods

We used Constructivist Grounded Theory (CGT) [7, 8] to study the cognitive strategies surgeons used to mentally visualize navigation of the trocar through blind space. CGT was chosen for multiple reasons. First, CGT provides a rigorous method for inductively generating knowledge by allowing participants to share their lived experience through semi-structured interviews. Second, CGT is particularly suited for understanding complex phenomena, such as a surgeon’s mental representation of a construct, which cannot be measured by other means. Third, CGT allows for an evolution of the researchers’ critical stance during the research process by systematically integrating it into the data analysis, thus enriching the data. Our critical stance was informed by our conceptual foundation [6].

Setting and participants

CGT data collection was associated with a larger study examining surgeon kinematics during simulated passage of a retropubic trocar on a simulation model with high biofidelity [9]. We interviewed the 15 participants in that study: 7 expert surgeons from Urogynecology practices in Kansas City and having performed at least 100 retropubic midurethral sling procedures; and 8 novice surgeons, Obstetrics and Gynecology residents, each of whom had never performed a midurethral sling procedure. Demographics are in Table 1: the majority of our participants were female, representative of Obstetrics and Gynecology providers nationally.

Table 1.

Demographics of Participants

Participant Number	Expert (E) or Novice (N)	Gender (M or F)	Years of experience (E) or training (N)
1	E	M	6–20
2	E	F	0–5
3	E	F	0–5
4	E	M	6–20
5	E	F	6–20
6	E	F	6–20
7	E	F	0–5
8	N	F	PGY 1
9	N	F	PGY 1
10	N	F	PGY 1
11	N	F	PGY 1
12	N	M	PGY 2
13	N	F	PGY 2
14	N	F	PGY 1
15	N	F	PGY 2

Research team

Our research team consisted of a medical student researcher (FM) who had assisted on MUS surgeries in both the OR and on cadavers testing biofidelity [9], a pelvic reconstructive surgeon with more than 20 years of surgical experience (GS), two biomechanical engineers (GK, AS), a PhD student who had developed the simulation model (Arif), and a research assistant (AB).

Simulation model, trocar, and experiment

In the larger study, pelvic MRIs were obtained from three women with stress urinary incontinence prior to undergoing surgical correction; all MRI scans were segmented using 3D slicer (slicer.org). We have previously reported on the development of the midurethral sling simulation model from these MRIs [9]. Briefly, we printed 3D models with an enclosure surrounding the suprapubic bones and the superior and inferior pubic rami. The model was filled with ballistic gel (Clear Ballistics, Inc., Greenville, SC) to mimic the haptics of passing the trocar through soft tissue and painted with a pigmented layer of silicone compound (Dragon Skin^™ 138, Smooth-On, Inc., Macungie, PA) to ensure opaqueness. A rigid body equipped with reflective markers was fit to a Gynecare TVT trocar model #810041B, with mesh tape removed, connected to a Gynecare TVT 125 Introducer model #810,051. (Ethicon, Inc., Somerville, NJ, USA).

Participants performed 15 bilateral trials (30 total), passing the trocar retropubically from the vagina, lateral to the urethra and bladder, medial to the iliac blood vessels, and caudal to the peritoneum. (Fig. 1) The 3D-printed bones provided haptic feedback. No haptic feedback was associated with the bladder, bowel and blood vessels, other than the ballistic gel, consistent with performing this procedure on a patient [10]. Reflective motion capture markers were placed on the model, the trocar rigid body, and the surgeons. Marker positions were tracked with 12 OptiTrack Flex 13 cameras controlled by Motive motion capture software (NaturalPoint, Inc., Corvallis, OR, USA) at a frame rate of 120 Hz. The motion capture system enabled us to track surgeon kinematics, along with the trocar tip location relative to the bones and all organs. During 12 of the trials, participants vocalized 4 locations: when the trocar first contacted the SPB (“bone”), when it reached the most cephalad portion of the posterior SPB (“turn”), when it reached the most anterior portion of the SPB (“top”), and when it exited the rectus fascia (“pop”) [11].

Fig. 1.

Experimental setup. Participant passes the midurethral sling retropubic trocar blindly through the pelvic simulation platform, made non-transparent with thermoballistic gel and black silicone. Motion capture markers on the model and on the rigid body are used to track surgeon kinematics for a different study

Conceptual foundation and development of semi-structured interview

FM and GS generated the semi-structured interview (see supplementary material for final interview guide) utilizing our conceptual foundation of the cognitive route and map strategies used by blind people [6]. Questions were designed to elicit what our participants were picturing in their head at the time of the simulated surgery. We specifically asked what they were seeing in their mind when conducting the blind component of the procedure, i.e., when they could not visually confirm the trocar tip position. We asked the same questions to novice and expert participants, and consistent with CGT, modified the questions as new data emerged.

Data collection and analysis

Individual semi-structured interviews were conducted virtually or in person by GS and FM immediately after completion of the simulated 30 passes. Interviews averaged 14 min (range 7–21 min). Each interview was audio recorded, transcribed, and de-identified. Data was analyzed using constant comparative coding: FM and GS individually coded the transcripts, compared their analyses, and disagreements were discussed and resolved. Themes were noted and analysis was again revised with the assistance of AB. We developed a central model to provide a visual representation of the participants’ cognitive strategies, highlighting what they were mentally visualizing during blind trocar passage. We did not assess data saturation, and instead used the interviews from all 15 participants.

Reflexivity

Throughout this study, the team paid attention to principles of reflexivity with frequent pauses to reflect on the evolution of the semi-structured interview and how it impacted both data collection and analysis. Consistent with CGT, we frequently checked our biases and historical perspectives, challenging our views on analysis of the data [7]. Each participant provided consent for participation. We performed member checking by sending the central model and the results to all 15 participants. This study was approved by our institution’s IRB as minimal risk/expedited.

Results

We found that both expert and novice participants utilized multiple cognitive strategies, forming a mental picture of the space, combined with haptic feedback to accomplish safe passage of the trocar. These mental images were crucial in maintaining knowledge of where the trocar tip was in blind space, in relation to the surrounding organs. Maintaining these mental images, plus the haptic feeling of the bone, elicited a sense of surgical safety, whereas loss of both signaled danger and anxiety.

Conceptual model of mentally visualizing a sharp instrument in a blind procedure

We demonstrate the mental images in Fig. 2. The Cartoon in the center of the image demonstrates midsagittal view of the pathway of the trocar during its blind retropubic passage as it navigates between Suprapubic bone and bladder. On the left, Route Strategy can be visualized in the 4 axial MRI images in which the blue dot represents the location of the trocar. The four images, from bottom to top of the figure, represent the 2D mental images described by our participants as they haptically encounter the four separate landmarks on the suprapubic bone (“bone,” “turn,” “top,” “pop”). On the right, Map Strategy can be visualized by the two 3D images in which all structures are imagined in relation to each other and the moving trocar within a 3D space. These 3D images can be rotated within the participant’s mental image to give a global impression of the location of the trocar relative to the surrounding organs. Although they cannot see the bone, these 2D and 3D mental images supplement the haptic feedback to help surgeons understand where the trocar tip is within blind space.

Fig. 2.

Conceptual Model of Mentally Visualizing a Sharp Instrument in a Blind Procedure. This cartoon demonstrates our central findings, namely the mental images, supplemented by haptic feedback, associated with blind retropubic trocar passage during the midurethral sling procedure. The cartoon in the center of the image demonstrates the retropubic pathway of the trocar between the suprapubic bone and bladder. On the left, 4 axial MRI images represent Route Strategy (blue dot is the location of the trocar). The four images represent the 2D mental images described by our participants as they haptically encounter the four separate landmarks on the suprapubic bone. On the right, two 3D images represent Map Strategy. All structures are imagined in relation to each other and to the trocar and can be mentally rotated to produce a global impression of the instrument and all organs

Haptic feedback

Haptic feedback from the SPB elucidated a mental picture of the bone for many subjects. Touching the bone allowed them to “see” it: “I'm visualizing what I think I'm feeling.” (E2) Maintaining contact with the trocar against the SPB was key to producing this mental image. In this way the SPB was the central landmark of the procedure, despite the varied surface anatomy and contour of the SPB among the 3 models, and was also central in ensuring a safe passage between entry and exit points.

“Well, I really just see the bone. I mean, I think about. I'm going to the bone and I'm pulling up and then once I get to a place that I think I can get behind the bone … and then pulling back against the bone … What I am visualizing is what I am able to actually feel, … which is the bone.”

(E5)

Curved path is a straight line

Participants visualized the curved path around the SPB as a “straight line” or tunnel because the visual clues of entry and exit points on the model did not guarantee success. Haptic feedback from the SPB served as a landmark for staying on that safe path. The curved path was like “a big, long line just like rulers.” (E1) The line was created from the surgeon’s hand through the exit point to the patient’s unilateral shoulder, keeping the trocar “in the correct diagonal” (N1).

“Periurethral tunnels was a big guide you know also looking at the pubic bone right … So, I was always trying to point the trocar toward the bone, making sure you know it's pointing upwards.”

(N3)

Route strategy

Some surgeons used a step-by-step route strategy, advancing the trocar from one known point, such as the posterior aspect of the SPB, to another known location, such as the cephalad aspect of the SPB, before moving forward. Route strategy mirrors the surgeon’s knowledge of the steps of the surgery, and they move in order through each step. For our participants, whether expert or novice, each step gave confidence that the trocar was advancing safely. Some described their visualization similar to sequential 2D axial images of anatomy adjacent to the SPB: “exactly like scrolling through a CT is how I think about it.” (N1) They described this as “seeing the steps linearly on a three-dimensional model.” (E2).

A route strategy mostly incorporated visualizing the SPB: “I'm very aware of staying behind the bone so you don't catch the bladder as you go around it. What I am visualizing is what I am able to actually feel, that I want to feel, which is the bone.” (E5) Others incorporated nearby structures into their 2D visualizations:

“Once I get that trocar in I stop and think where am I where should I be, what should I be passing now, ok, we should be close to the dome of the bladder, ok, I should be close to the top of the skin, that kind of thing”

(E7)

Map strategy

Some participants used a map strategy, visualizing global 3D pictures of surrounding organs. This involved picturing the bladder, bowel, and blood vessels as they related to the SPB, and the trocar’s position within that 3D space. This strategy helped to define a safe zone “I can see that it's moving past those structures in that space. So, I've got a safe space as a triangle right in there behind the pubic bone and I want to see that as I move my hand” (E1) The mental 3D image was like “looking at the structure as a whole, trying to do the steps from there” (N3).

“This is to the left of where I want to go, that's behind where I want to go, and this is in front of where I want to go. So, I'm trying to just go through that space that's in between those different objects”

(E1)

Expert surgeon participants described their maps with robust details, for example the curvature of the suprapubic bone in relation to the location of the bladder. Some visualized only portions of the pelvis:

“I'm thinking about the shape of the pelvis … I'm visualizing the bony pelvis, basically, not the vasculature, not the bowel, not the bladder, because that should be far away if you're in the right space you shouldn't have to worry about that.”

(E4)

Combined strategies

Some participants combined the route and map strategies, combining a visualization of different 2D images (i.e.: Axial plus coronal) to generate 3D images in their head. “A 2D progression … sagittal” (N1). One described this as “conceptually take that 2D picture and imagine it in a 3D way” (N4) and described using a similar mental strategy when dissecting cadavers, practicing 3D online simulations, and looking at their own body to mentally convert a 2D image to 3D.

Losing the mental image

Often these mental pictures vanished when they were “lost,” most commonly when losing contact with the SPB. Without a mental representation as an anchoring point, they were “just blindly moving the trocar.” (N2) Losing the mental image was associated with anxiety about injuring surrounding vital structures, even during a simulation. To regain the image and quell the anxiety, they would adjust the trocar to reestablish contact with the SPB, “pull (the trocar) back to double check myself” (E2) “push forward a little bit” (E7) which would help to reestablish the mental picture.

“When I did not hit the bone. That's what I was like, I don't know where I am. I would like back out and try to like wiggle the trocar around to try to get to the bone again”

(N5)

Expert vs novice mental images

Experts possessed a more nuanced and detailed conceptualization of the 3D space, including the 3D shape of the SPB and the surrounding organs. One reported “just feeling the angle, is it wide, is it narrow? And then where is the top of the pubic bone, how thick it is, how wide it is.” (E4) Regarding surrounding organs: “it’s the thickness of the tissue below the urethra and making sure that you're not splitting that tissue” (E3) This detailed visual representation of the bone was associated with a more nuanced haptic descriptions: “there's a very slick feeling when the trocar’s behind the bone” (E5) or “feel it scraping” (E4).

Experts were more likely to rely on “minute calculations in my head” (E2) in trocar path relative to surface angles and width of the SPB. This gave them precise control over surgical movements: “I am pulling up against the bone, and then I drop my hand, quickly, and I always tell the residents, that doesn’t mean fast” (E5) Experts often related their core body position to their conceptualization of the trocar path and the resistance encountered. They incorporated more visual clues when creating that conceptualization:

“I'm also looking at the handle. The handle is supposed to be horizontal. So, I know that if the handle is splayed too much this way or that way, it might be deviating into the vessels laterally or if the points come out to close together, then it might be in the bladder”

(E6)

The more detailed visualization plus the precise motions led to more fluid movements, based on muscle memory: “It becomes fluid and its programmed. You don't have those steps in your mind anymore. It's just a process, a quick thing.” (E3) This led to a fluid combination incorporating both motion and mental visualization:

“I can feel my hand, so based on where my hand is … I know the proximity of where my tip is, and the torque of where I need to be, but I feel like that's only from holding this.”

(E7)

Novices by contrast were more likely to be missing any conceptualization of the space: “I can’t really visualize it in space” (N6) and rely solely on haptic clues: “from there, it was just completely blind and then I angled down and then I was feeling for the anterior wall on the fascia for it to poke through the fascia, the top.” (N2) Novices were also more likely to employ backtracking of the trocar when not feeling the SPB.

In Table 2, we present a summary of the 2 strategies, examples from our data, and its application to surgical teaching of a blind procedure.

Table 2.

Route versus Map Strategy and Application to Surgical Teaching

Strategy	Definition [5, 6]	Examples from our Data	Teaching to a Novice
Route	Mapping a space and generating navigation paths by scanning a space in a linear, sequential fashion	“Before I even start to pass the trocar, I'm visualizing what I think their anatomy would look like if I did a CT scan on them and how … much soft tissue fat is there going to be between the pubic bone and the bladder. … As I'm doing it, I’m getting feedback in terms of okay my image that I had generated beforehand is accurate or no maybe it's not and I need to go deeper or be more superficial and that sort of thing.” (E2	Simulation training includes 2D images of the instrument’s location relative to surrounding anatomy Reviewing pre-operative imaging and discussing how the anatomy surrounding the trocar Preop mental exercises in which the novice mentally visualizes the instrument’s location at each important step Pausing during the surgery at each step to discuss what anatomy is in close proximity to the instrument
Map	Mapping a space and generating navigation paths from multiple perspectives to get a holistic view of the space in its entirety	“I see the urethra, so I know the bladder is right there, the uterus is there, the bowels there, the rectum is there, the vagina is there. … I picture myself going through the vagina. And trying to avoid the iliac and the cardinal ligaments.” (N5)	Simulation training includes taking apart an anatomic model and putting it back together again Preop mental exercises in which the novice mentally visualizes the holistic 3D space and the instrument’s path Discussing alterations in the path or the trocar in response to changes in the direction of angle of the handle Asking the novice to provide continuous verbal feedback about the location of their instrument relative to multiple anatomical structures

Member checking

We received feedback about the central model and the results from 3 (20%) of the 15 participants, who were supportive of the model and findings. Feedback included emphasizing the relationship between a steady body position and a trocar passage without deviations and suggestions that we study which strategy was more effective at avoiding injury.

Discussion

We found that surgeons use a combination of cognitive strategies to visualize the location of the retropubic trocar in a blind space. Similar to the blind persons in the Lahav study, our participants utilize varying hybrids of route and map strategies, augmented by haptic feedback, to form mental pictures of trocar, bone, and surrounding organs. The image was maintained through haptic feedback and lost without it. Expert surgeons imagined mental images with more details than novices; for example, the relationship between their body position, the trocar handle, and their mental image of the instrument tip.

In our previous work, surgeons described engaging in a cognitive process that we referred to as mental 3D visualization [12], the ability to form a conceptual picture of and manipulate surgical instruments through an anatomical space. These cognitive strategies require visual–spatial perception, or the ability to comprehend and remember the visual and spatial relations among objects within space [13]. The map strategy in particular involves high-level visual–spatial skills, including the ability to mentally rotate objects in three dimensions [14]. Localization of anatomic structures in a 3D space or model is more accurate and requires less mental workload than localizing them in a 2D view [15]. Superior visual–spatial perception is associated with both subjective and objective assessments of technical ability and the rate of skill acquisition, [16], and we suspect that learners with such skills will learn these procedures more quickly.

Application to learning surgery

Our findings have meaning for novice surgeons learning to perform any blind procedure involving insertion of a sharp instrument. Examples include insertion of a Veress needle, external fixation of the sacroiliac joint, sagittal split mandibular osteotomy, and thoracic spine osteotomy. In these procedures, the novice must master not only the ability to determine the ideal orientation of the instrument, but also its pathway into soft tissues [17].

In the example of the Veress needle, the needle must be inserted through multiple layers of the abdomen and guided into the peritoneal cavity in close proximity to the bowel and bifurcation of the aorta and inferior vena cava. A surgeon with a predilection toward route strategy would augment the haptic feedback by envisioning every layer and organ along the pathway of the tip of the needle, whereas one preferring map strategy would form a global 3D picture of the abdominal wall, peritoneal cavity, and retroperitoneum. We encourage surgical learners to practice mental imagery using their preferred cognitive strategy to accelerate their learning curve [18]. This could be done either before or during the procedure and will improve with practice. Mental imagery can be augmented with 2D radiologic images (as in Route strategy) and animated 3D images (as in Map Strategy), and we suggest the development of such images, similar to what we developed in Fig. 2. Mental imagery has been associated with improvements in dexterity, visual–spatial skills, and operative flow [19], as well as other assessments of surgical performance [20].

Application to teaching surgery

Our findings also have relevance for teaching surgeons, who must guide their learner through blind procedures. Trainees are anxious about the possibility of placing the needle incorrectly [4], and attending surgeons are arguably more anxious because without their hands on the instrument, they do not receive haptic feedback and must rely on verbal feedback from the trainee. In cases where a resident injures the patient, the attending surgeon often does not recognize the injury until it is too late.

These cognitive strategies allow the attending surgeon to dialog with the resident while the needle is being passed. “What are you seeing in your mind when passing the instrument?” is a good question to ask both before, during, and after the procedure? For example, if the resident prefers route strategy, then the attending can ask them to pause and describe where the instrument is relative to nearby structures. This will reinforce their imagery, augment the trainee’s ability to verbalize how their mental image correlates to what they are feeling along the pathway, and help the attending to make corrections.

Application to surgical simulation

Simulation of a blind surgical procedure can take advantage of these concepts. Most current simulations rely on teaching an entry point, an ideal angle of insertion, and an exit point. Haptic feedback can be provided with the proper materials. We advocate for adding mental exercises, asking the learner to visualize the instrument in blind space. One such approach might include displaying images, similar to those in Fig. 2, while the learner simulates motion of the instrument. The teacher then asks the learner to pause, look at the image, and correlate their own mental picture to what they are haptically feeling.

Strengths and limitations

Our study is the first to examine mental strategies used by surgeons to navigate blind spaces. Strengths include the rigorous application of Constructivist Grounded Theory, the inclusion of both learning and teaching surgeons, the concurrence of the interview with practice on a high-fidelity pelvic simulation model, and the use of a conceptual foundation centered on blind persons navigating a new room. Furthermore, our expert participants were recruited from multiple health systems, increasing our generalizability. Limitations include the dearth of underrepresented races and ethnicities among our participants. Furthermore, the novices were from one residency program, although their lack of experience can be generalized to novices from other training programs. We only studied one procedure from one surgery; further studies might elucidate how our results generalize to other surgical procedures. Our interviews immediately followed a simulation. Interviewing participants after performing a live procedure might have provided additional information on these mental strategies. Finally, our study was not designed to compare expert versus novice cognitive strategies. It would be interesting to follow a novice surgeon longitudinally through their first 10–20 procedures to see how their cognitive strategy evolves.

Conclusion and future directions

In conclusion, both expert and novice surgeons use a combination of route and map strategies to supplement their haptic feedback and help them to mentally visualize their retropubic trocar in blind space. We would like to test teaching scripts, incorporating route versus map strategies, in simulation or the OR, and assess how that helps the resident learn to safely perform the procedure. Future study could also explore the relationship between a resident’s visual–spatial perception [21] and their ability to master blind procedures.

Data availability

Data is available upon reasonable request.