The Utilization of Magnets in Laparoscopic Uterine Prolapse Repairs

Alicia R. Chen, Daphne T. Simo, Megan K. Taylor, Marty Harvill, Ph.D., Mojgan Parizi-Robinson, Ph.D.

Uterine prolapse is characterized by the herniation of the uterus into or externally from the vagina, resulting from weakening ligamentous and fascia support (Dangal, 2005). Currently, the most effective treatment option for women experiencing uterine prolapse is through the laparoscopic fissure of the uterus and subsequent vaginal removal, referred to as a laparoscopic vaginal hysterectomy (Maher, 2001; Reich et al., 1989). The common issues in its practice, including potential infections at multiple port sites, coupled with limited field-of-view and depth perception, has led to the consideration of alternative and alleviated methodologies. Previous studies supporting the introduction of magnets in conjunction with other laparoscopic methods suggest possible alleviation of surgical healing time and invasiveness and therefore have prompted an investigation of using magnets to resolve issues concerning laparoscopic hysterectomies.

Abstract

Contrived to resemble a true uterine prolapse, the study design considerations included a laparoscopic box simulation that was constructed to combine the basic FLS tasks of cutting patterns and peg transfer (Ritter & Scott, 2007). Trials consisted of a controlled trial modeling the current standard of care with comparison to a magnetic-enhanced trial. A numerical score system was developed to account for speed and errors encountered by participants. Participants were composed of 22 undergraduate students enrolled in a beginner’s laparoscopic course. Analysis of score values via a paired t-test illustrated a significant difference (p = 0.0008) between techniques, indicating that the use of magnets caused a decrease in the overall efficiency of the procedure. This comparative analysis of traditional laparoscopy and the integration of magnets serves to provide preliminary insight on novel applications in laparoscopic procedures and additional information surrounding patient outcomes following prolapse repairs.

Introduction

Female pelvic floor dysfunction can manifest itself in a multitude of conditions, with general increases in prevalence following advancement in age, menopausal status, obesity, vaginal childbirth, connective tissue disorders, and chronic straining (Milsom & Gyhagen, 2014; Smith et al., 2014). Previous studies suggest the global prevalence of pelvic organ prolapse is estimated to be around 60% and between 2-20% for all parous women and premenopausal women, respectively (Dangal, 2005; Smith et al., 2014). These dysfunctions are often encountered in the form of uterine prolapse, commonly described as the descent of the uterus toward or through the opening of the vaginal canal following a defect in the connective tissues and pelvic musculature upholding the uterus (Uterine prolapse, 2019). According to a study conducted by the Department of Urogynecology at the University of Queensland, the preferred surgical treatment for uterine prolapse is a vaginal hysterectomy (Maher et al., 2001). In most cases, a laparoscopic approach is utilized to conduct the hysterectomy procedure.

The general philosophy behind the laparoscopic technique was first demonstrated by Dr. Hans Christian Jacobaeus in 1901 and later reintroduced in the late 1980s by Dr. Hans Troidl (Kelley, 2008). The invention of laparoscopy has arguably transformed the field of surgery, with its proven ability to improve overall postoperative complications, such as decreased recovery time and preservation of the natural state of the human body with minimally invasive incisions (Best & Cadeddu, 2010; Park et al., 2007). Each incision made in previously standard operative procedures has generally been proven to ultimately lengthen the recovery time for the patient and suggests the rise of comorbid complications later in life, in comparison to laparoscopic methods.

Differing from the historical lateral hysterectomies, a laparoscopic hysterectomy is a surgical procedure involving the use of minimally invasive instruments to effectively ligate the ovarian arteries and veins to then prepare the removal of the uterus vaginally (Lange et al., 2019). This procedure is initiated with a small incision site, or port, that is made in the navel region of the abdomen where a laparoscope (a thin fiber-optic tool characterized by its high-intensity light and high-resolution camera) is inserted into the abdominal wall for internal visualization of the pelvic region for surgical viewing (Shiel Jr, 2018). Two subsequent incisions are made in the lower

abdominal region, where metal tubes referred to as trocars are inserted as a passageway and mode of mobility for the laparoscope and laparoscopic tools. The uterus is eventually detached from its supporting connective tissues and ligaments and removed via the vaginal canal. Postoperative outcomes following this particular procedure include faster recovery time, enhanced cosmesis of the preoperative state of the body, and decreased risk of complications such as significant blood loss, post-operative pain, and scarring (Laparoscopy Laproscopic Hysterectemy, 2005).

Recently, other modern surgical interventions have incorporated the use of magnets in vivo to facilitate fewer incisions made in the body cavity (Rice, 2018). With the potential expansion in the use of magnets within surgical procedures, surgeons would be able to take advantage of the magnetic forces and attach a magnet internally for surgical use (Best & Cadeddu, 2010). In theory, after the trocars are inserted in the abdomen, the magnet would be introduced internally through a detachable magnetic forceps grasper and attached to the target organ. The magnetic detachable grasper will be temporarily attached to the organ and an external magnet would be introduced, allowing a magnetic force to be created, with only the abdomen in between the two magnets. It is postulated that the force between the two magnets would be strong enough to allow manipulation of the organ, but not forceful enough to puncture the skin or any underlying membrane layers. Once the magnets are connected, the surgeon would be able to use the external magnet to move the organ to its desired location without having to create another incision.

This study was tasked with the introduction of magnets in laparoscopic procedures to deduce if the number of incisions made in the procedure could be decreased by at least one incision site. In reference to Image 1, a diagram depicting incisions for a laparoscopic hysterectomy, it is hypothesized that incision number three, normally used for an additional forceps, could be eliminated in favor of an alternative magnetic manipulation. It is also postulated that the introduction of magnets would allow enhanced visualization of the intraabdominal region and would provide additional, enhanced mobility for other inserted instruments to precisely access organs and avoid inadvertent punctures to surrounding organs during the procedure. Placing importance on minimizing the invasiveness of laparoscopic surgery with the use of magnets could serve to maintain the integrity of the preoperative state of the body via the decreased amount of incisions capable of producing scarring and coincidentally increase overall patient satisfaction following surgery.

Materials and Methods Preparation of Mock Laparoscopic Box:

The simulation was fashioned from a plastic box (STERILITE, 2018) with a camera, mimicking a body cavity and laparoscopic instruments, similar in design to previously established simulations of the Fundamentals of Laparoscopic Surgery (FLS) curriculum, provided in collaboration with the American College of Surgeons (Ritter & Scott, 2007). To constitute a similar environment to the abdomen in vitro, a balloon filled with superabsorbent water polymer beads was

UTERUS

VAGINAL CANAL

Image 1. An image depicting incision sites in a traditional laparoscopic hysterectomy used to treat a prolapsed uterus. LAVH (Laparoscopic-assisted vaginal hysterectomy)

wrapped in gauze to represent a membranous-like uterus. The balloon was suspended in the laparoscopic box by multiple rubber bands that were attached to each corner of the box to simulate similar resistance and support provided by the ligaments surrounding the uterus in vivo. A piece of Styrofoam was sculpted into a pelvic-like shape with an anatomically designated area for the balloon, or uterus, to fit into. Ambipolar N52 Neodymium Disc magnets were attached under the gauze surrounding the balloon to resemble the internal attachment of the magnet to the uterus. An external magnet structure was created by attaching two magnets, of the same grade, between four sticks of bamboo to allow the participants to move the magnets outside the box. Ambipolar N52 magnets are a type of rare-earth, permanent magnet composed from an alloy of the elements neodymium, iron, and boron. The magnets were chosen due to their strength and ability to hold and support the weight of the balloon, roughly half a pound.

Participants:

The participants were composed of 22 pre-medical freshmen enrolled in BIO 1V90, the Laparoscopic 1 and 2 courses at Baylor University (Waco, TX). The students were taught beginner level laparoscopic skills over five months and were tested for proficiency in skills such as pegboard exercises, cutting a paper circle, and tying a loop suture. After achieving appropriate proficiency, the participants acquired a sufficient level of skill necessary for the completion of the simulation.

Data Collection:

The simulation was designed to have the participants pull the balloon (uterus) above the carved Styrofoam (pelvis), cut the specific rubber bands (ligaments) suspending it, and releasing the balloon safely into the designated area of the Styrofoam

Image 2. An opened sample laparoscopic box depicting the pelvic region in which a laparoscopic uterine prolapse repair is to occur.

(a general setup of the task is exhibited in Image 2). For proper insertion and use of laparoscopic tools in the simulation, each box included portholes, stabilized with trocars, indicative of incision sites that would be made in the abdomen for the procedure (exhibited in Image 1). For the controlled test, the participants used both ports for the insertion and use of laparoscopic instrumentation, a forceps and a pair of scissors, as traditionally utilized in laparoscopic hysterectomy procedures. For the variable simulation, the participants were only allowed to use one port for the insertion of the scissor-modified forceps; in place of the grasping forceps, a magnetic-like joystick was placed outside of the box to maneuver the balloon, already enhanced with an inner magnet, to the desired position for the simulation.

The scoring range was designed similar to the FLS scoring metrics the participants used in previous proficiency training and tests (Ritter & Scott, 2007). A normalization score of 300 was used as a base starting number to account for and properly analyze the proficiency of each participant regarding the task given. The successful completion of the task was timed and subtracted as a measurement of efficiency and precision; procedural error points were accounted for by subtraction using the following scale shown in Table 1:

Description of Error

Missing the Styrofoam target Cutting the bands in the wrong spot Puncturing the balloon or ripping the gauze

Points Accounted For

-10 -20 -5

These error points were assigned based on the severity of the error that they would account for in actual laparoscopic surgery. For instance, puncturing the balloon or ripping the gauze was worth the most points due to the postoperative repercussions of puncturing the uterus or ripping its tissue.

A “score” range, totaled out of 300 points, was formulated as follows:

a base number of 300 minus the time (seconds) the trial took minus each error encountered in the trial

Similar to the FLS scoring system (Ritter & Scott, 2007), a high score indicated superior rating, with factored-in considerations of both the efficiency and error component to the overall scoring.

A total of five trials were run for both the control and variable experiments. The trials were collected back-to-back with an expectation that the score would improve as time proceeded. The control trials were collected first followed by the variable trials to account for the interference of the false appearance of better scores in the variable trials due to experience with the exercise. The two varying tests were collected one week apart, with the participants not allowed to practice laparoscopic skills in between. All twenty-two students performed a total of ten trials, five of each test, providing a total of 110 trials for each test.

Results

For the best, unbiased statistical analysis, the “scored” data values for each trial of both the control and treatment experiments were averaged for each participant. The “average score” observation for both experiments was then paired together by participant and ran in RStudio Version 1.2.5033 as a paired student t-test 1 . A significant t-statistic value = 3.924 2 and a reported p-value = 0.0008 3 (Figure 1, Table 2) were recorded. With assumptions of the model holding 4 (Figure 2, Table 3), the hypothesis was rejected that there was no difference between the two laparoscopic techniques. To determine which method was faster, summary statistics (Table 4) were compared between

1 “A paired t-test is used to compare two population means where you have two samples in which observations in one sample can be paired with observations in the other sample. Examples of where this might occur are before and after observations” (Shier, 2004); contrary to a z-test, this test is more robust for assumption of normality of populations. 2 The t-statistic is used in conjunction with a Gaussian curve to formulate a p-value for confirmation/rejection of the null hypothesis 3 “The null hypothesis postulates the absence of an effect, such as no difference between two groups, or the absence of a relationship between a factor and an outcome. The smaller the p-value, the greater the statistical incompatibility of the data with the null hypothesis, if the underlying assumptions used to calculate the p-value hold” (Wasserstain & Lazar, 2016). 4 Assumptions such as independence and normality between the residuals used for calculation of the t-test (Paired samples t-test in R, n.d)

-50 0 100 50 Control-Magnet Dierence between Means

Figure 1. 2-dimensional graph showcasing the distribution of the frequency (binwidth=5) of each difference in mean score values of the control experiment in comparison to the treatment experiment. The central tendency is roughly observed around 23, with 95% of differences lying under the normal distribution between 10 and 36; this is in accordance with the difference and CI intervals calculated through the paired means statistical analysis.

Table 3: A Shapiro Wilkes’ Test for Normality 8 , indicating a wellmodeled distribution of the paired difference in scores for the modeling of time efficiency and errors within the uterine prolapse repair simulation (n=22).

Group

Control

MagneticManipulation

Variable of Analysis

Score

Score

Population Count

n=22

n=22

Mean

264.104

241.147

Standard Deviation

20.494

30.548

Table 4. Descriptive statistics depicting the mean and standard deviation of the control and treatment values, using data from the developed score system.

Mean of Dierence t-statistic Degrees of Freedom

P-value 95% Condence Interval9

μ=22.956

t=3.924 21

0.0007791* [10.79015, 35.12318]

Table 2: A table representing the t-test results of using each participants’ score values. A t-test conducts a measure of a significant difference between the mean values of the control and treatment experimental data.

Plot of Quantile Distributions

Experimentation Grouping

Control Magnet Variable

Figure 2. A one-dimensional box plot distribution of each treatment population score values (with n=22 for each treatment). The boxes are indicative of the interquartile ranges (of 25 and 75% respectively), and the median (50%) by the black lines within the boxes. The tails extending outwards from the box indicate accepted maximum and minimum values of the model. 6 Stars indicate outlier values of each population. 7

the mean score values of each treatment. It was determined that mean of differences observed between the recorded “scores” of each population 5 was μ=22.956, with the control experiment exhibiting a mean (average score) of μ=264.104 and the variable experiment had a mean of μ= 241.147. It was concluded that the more effective laparoscopic measure, within this design study, was the control method— for both efficiency and error reduction.

Discussion

This study was conducted to heighten understanding of the incorporation of magnets in abdominal and pelvic laparoscopic procedures. With the underlying conjecture that the introduction of magnets to laparoscopic surgery could provide an alternative method for hysterectomies to treat prolapsed uteri, it was presumed that this procedure would allow for better outcomes for women who suffer from uterine prolapse. The incorporation of magnets would provide better postoperative outcomes through the efficiency in both surgery and recovery time through the minimization of incision sites and possible negative outcomes due to surgical cutting and puncturing errors.

The results yielded through this design study were opposite of the hypothesized outcome of the introduction of magnets

5 Assuming difference calculated by control(avg)- magnetic (variable, avg) 6 See, (Statistics, n.d.) 7 After careful review of each outlier (according to the methods prescribed by Joshua Patrick, PhD Baylor University (Patrick, 2019)), no outliers were deemed necessary for removal from the results. 8 See, (Paired samples t-test in r, n.d) 9 We can be 95% sure that the true mean decrease lies somewhere between these; for more on CI, see (Paired samples t-test in r, n.d)

to an abdominal laparoscopic surgical procedure. Incorporating magnets led to a negative outcome in the completion of a uterine prolapse repair. Specifically, the reported p-value (p = 0.0008) from the paired student t-test indicated there was a significant difference in the scores between use and no use of magnets. The simulation’s control treatment, modeled off of the current standard of care in laparoscopic hysterectomies, yielded a higher mean average score, at 264.104; conversely, integrating magnets produced a mean average score of 241.147.

After careful consideration and analysis of the experimental method used, methods of simulation, and materials available, many confounders surrounding the study design were proposed to possibly counteract the results obtained in this experiment and are outlined below:

Selection of Participant Population:

The test subjects utilized in this experiment may have not been accurate representatives of the target population, as they were amateur college freshman students with minimal knowledge and training in the laparoscopic procedure within the areas of instrument manipulation and depth perception, in comparison to actual surgeons with an FLS training certification. The students, therefore, may have adversely been inadequate in their performance of a simulation procedure.

Design Study-Physical Setup and Associated Mechanical Errors:

To keep uniformity between test subjects, all boxes were constructed in the same manner; these boxes’ dimensions, however, were not similar in dimension to the human body, which is less rigid in form. This made the spacing and placement of the pelvis and prolapsed uterus quite difficult to manipulate, possibly leading to slower times.

Another source of design error was found in the physical design of the magnetic joystick itself. During the experiment, many of the subjects expressed issues in the use of the magnetic joystick for manipulation; in fact, these mechanical errors reduced the overall participation size, as some boxes had to be swapped out and trials discontinued or thrown out due to this error. This decision was decided upon to avoid the risk of confounding data values, due to the time and experience component that comes with having to learn and replicate a task over many trials, and thereby contradicting the unbiased measures set aside in the original study design. In addition, the laparoscopic forceps, scissors, and magnets were of a lower grade quality than those used in real surgery and may have also led to time and error complications in both treatments. For example, many test subjects had great difficulty cutting within the simulation furthering their complications with the task, leading to possible discrepancies with their performance in the experimental trial.

Optimization of Scoring Methodology:

Timing considerations were measured to be indicative of the efficiency of the surgeon completing the assigned task in surgery. In addition, error points were assigned based upon the severity of consequences for the type of error committed. While the overall scoring of this experiment was modeled in accordance with current FLS scoring guides (Ritter & Scott, 2007), it is recognized that this may have not been the most optimal way to collect data. The current scoring guide was one dimensional in its variable analyses content, as it only looked at the comparison in the overall score a participant received, with little to no consideration or weight of if the score was achieved primarily by efficiency or by lack of error terms. Since the purpose of this study was multifaceted, with an aim for a reduction of incisions site, overall efficiency, and reduction of procedural error, it could be proposed that a new scoring guide is devised for similar experiments in the future that allows for statistical consideration and analyses of each component separately to get a well-rounded conclusion for each component.

Conclusion

Studying the integration of magnets into laparoscopic procedures identifies and infers its potential use in hysterectomies for uterine prolapse repairs for women. Ultimately, it must be recognized that magnets in surgery are still highly experimental and thus require further investigation on their functionality and applicability for optimized study designs that allow for appropriate mimicking of similar laparoscopic procedures. This experiment functioned primarily as a preliminary study to indicate how magnets could be used in a laparoscopic procedure with regards to the anatomical region of the pelvis and associated dysfunction and disease. With regard to this study design, many errors were reported. Some errors, if present in both studies, were natural blockers of their own results and may, therefore, have minimized their weight as overall confounders to these results achieved. The errors unique to the variable test could be proposed as the biggest confounders leading to unexpected results, calling for optimization in the future. Although the reports of this study were found to satisfy all statistical assumptions, deeming them valid results, it is still an opinion that this particular experimental method would be tested on experienced, trained surgeons with proper surgicalgrade instruments. The prediction of the outcomes may not reproduce similar results reported in this study but rather results in favor of the magnetic manipulation technique.

Overall, this study still offers some possible insight into magnetic laparoscopy and is worth consideration. Even with the time increase reported in more than 75% of the participants, all were able to successfully complete the task only using one port. Regardless of the results achieved in this study, additional trials must be conducted on more accurate models such as a cadaver or true-to-size uterus model, along with FLS certified surgeons to simulate similar clinical environments before considering the adoption of magnets as an additional technology for use in laparoscopic settings.

Acknowledgements

We would like to thank Alexis Ford, Rianna Larios, Katie Dearth, Kyle Langston, Taylor Weber, Hank Chen, Madison Ambrose, and Earle Hall Living and Learning Center for their continuous help and support. We would also like to thank the BIO 1V90 student participants for their cooperation and willingness to participate in our study.

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