Teaching ultrasound-guided invasive procedures in fetal medicine: learning curves with and without an electronic guidance system

DEGUM Recommendations on Diagnostic Puncture in Prenatal Medicine

Diagnostic puncture (amniocentesis, chorionic villus sampling, and fetal blood sampling) is an essential part of prenatal diagnostics and the only established and sufficiently scientifically evaluated possibility of diagnosing genetic diseases from pregnancy-specific cells. The number of diagnostic punctures in Germany, as in other countries, has fallen significantly. This is largely due to the introduction of first-trimester screening with further detailed ultrasound examination of the fetus and the analysis of cf-DNA (cell-free DNA) from maternal blood (noninvasive prenatal test - NIPT). On the other hand, knowledge about the incidence and appearance of genetic diseases has increased. The development of modern molecular genetic techniques (microarray and exome analysis) makes a differentiated investigation of these diseases increasingly possible. The requirements for education and counseling regarding these complex correlations have thus increased. The studies performed in recent years make it clear that diagnostic puncture performed in expert centers is associated with a low risk of complications. In particular, the procedure-related miscarriage risk hardly differs from the background risk for spontaneous abortion. In 2013, the Section of Gynecology and Obstetrics of the German Society for Ultrasound in Medicine (DEGUM) published recommendations on diagnostic puncture in prenatal medicine 1. The developments described above and new findings in recent years make it necessary to revise and reformulate these recommendations. The aim of this review is to compile important and current facts regarding prenatal medical puncture (including technique, complications, genetic examinations). It is intended to provide basic, comprehensive, and up-to-date information on diagnostic puncture in prenatal medicine. It replaces the publication from 2013 1.

Biplane mode for more precise intrauterine procedures

The evolution of ultrasound and the introduction of 3- and 4-dimensional ultrasound techniques led to a shift in the perception and usage of ultrasound in fetal medicine. The biplane mode might help in multiple fetal procedures, including but not limited to basic intrauterine thoracocentesis, thoracoamniotic shunting, amnioreduction, amnioinfusion, cordocentesis, intraumbilical infusion, and umbilical cord coagulation, with a possible reduction in the complication rate. Despite its theoretical usefulness, more studies are required to assess the clinical importance of this technique.

Second-Trimester Uterine Model for Teaching Ultrasound-Guided Obstetric Procedures

The declining number of ultrasound-guided obstetric procedures in clinical practice mandates a shift toward simulation-based teaching. Current uterine simulation aids are animal tissue-sourced or expensive, and improvement is needed. We describe a low-cost reusable uterine model with "fetus," cord and skin, constructed from synthetic gel and silicone rubber. Ultrasound appearance and tactile feedback approximate clinical use, and all parts of the model are portable, durable, and shelf-stable. Those made of ballistics gel can be recycled numerous times without noticeable effect. This appears to be ideal for proctored learning and independent practice within an ultrasound procedural curriculum.

Development and Assessment of a Novel Task Trainer and Targeting Tasks for Ultrasound-guided Invasive Procedures

RATIONALE AND OBJECTIVES

The American Institute of Ultrasound in Medicine (AIUM) recommends that all providers performing ultrasound-guided invasive procedures be competent in a core set of guidance skills common to all ultrasound-guided procedures, including in-plane and out-of-plane needle guidance and needle imaging optimization techniques such as probe translation, rotation, and heel-toe standoff. To allow for the practice and assessment of these core skills, we have created a novel task trainer and set of targeting tasks, and sought to obtain validity evidence in the content and response process domains for this training and assessment system according to the Standards for Educational and Psychological Testing.

MATERIALS AND METHODS

We have constructed an ultrasound-guided invasive procedure training system and five targeting tasks that focused on the needle guidance skills outlined by the AIUM. All tasks were performed by obstetrics and gynecology or maternal-fetal medicine physicians with and without experience in ultrasound-guided invasive procedures during a series of simulation workshops. All participants completed a survey regarding the trainer's and the tasks' usefulness in the training of inexperienced physicians.

RESULTS

The physicians who completed the tasks had favorable views of task trainer and curriculum. The targeting curriculum was felt to allow practice of all of the core guidance skills outlined by the AIUM. The average response provided for all of the tasks was 4.0 or greater, with half of the items having an average response of 4.5 or higher.

CONCLUSIONS

We have constructed a task trainer that incorporates all of the core skills outlined by the AIUM. All five tasks received very favorable reviews from both experienced and inexperienced providers. Taken together, our findings suggest they have strong content and response process validity evidence.

[Training of residents in amniocentesis: Effectiveness of a craft simulator]

OBJECTIVE

This prospective study aims to assess a low fidelity simulation device for learning amniocentesis to gynecology-obstetrics residents.

METHODS

From 2013 to 2016, gynecology-obstetrics residents of all levels, from the maternity of Nancy hospital, which have already performed amniocentesis or not, participated in amniocentesis training on an artisanal simulator. Residents were evaluated on the amniocentesis simulator according to seven quality criteria. Three scores were assigned: the first (S1) at the beginning of the first training session, the second (S2) at the end of the first session after individualized personal training and the third (S3) two months after the first simulation.

RESULTS

A total of 40 residents were included. The scores obtained by the residents were 3.2±1.8 points for S1 versus 6.2±0.9 points for S2 (P<0.001). Two months after, the residents' performances remained significantly improved compared to the initial assessment with a score (S3) of 5.8±1.3 points at S3 (P<0.001).

CONCLUSION

Amniocentesis craft simulator is effective for performance improvement and allows a persistence of acquired skills two months after the training. At the time of "never the first time on the patient", it should be part of the curriculum of gynecology-obstetrics residents in order to guarantee patients quality care and optimum safety.

Simulator training in fetoscopic laser surgery for twin-twin transfusion syndrome: a pilot randomized controlled trial

OBJECTIVE

To evaluate the effect of a newly developed training curriculum on the performance of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS) using an advanced high-fidelity simulator model.

METHODS

Ten novices were randomized to receive verbal instructions and either skills training using the simulator (study group; n = 5) or no training (control group; n = 5). Both groups were evaluated with a pre-training and post-training test on the simulator. Performance was assessed by two independent observers and comprised a 52-item checklist for surgical performance (SP) score, measurement of procedure time and number of anastomoses missed. Eleven experts set the benchmark level of performance. Face validity and educational value of the simulator were assessed using a questionnaire.

RESULTS

Both groups showed an improvement in SP score at the post-training test compared with the pre-training test. The simulator-trained group significantly outperformed the control group, with a median SP score of 28 (54%) in the pre-test and 46 (88%) in the post-test vs 25 (48%) and 36 (69%), respectively (P = 0.008). Procedure time decreased by 11 min (from 44 to 33 min) in the study group vs 1 min (from 39 to 38 min) in the control group (P = 0.69). There was no significant difference in the number of missed anastomoses at the post-training test between the two groups (1 vs 0). Subsequent feedback provided by the participants indicated that training on the simulator was perceived as a useful educational activity.

CONCLUSIONS

Proficiency-based simulator training improves performance, indicated by SP score, for fetoscopic laser therapy. Despite the small sample size of this study, practice on a simulator is recommended before trainees carry out laser therapy for TTTS in pregnant women.

Noninvasive Prenatal Screening for Genetic Diseases Using Massively Parallel Sequencing of Maternal Plasma DNA

The identification of cell-free fetal DNA (cffDNA) in maternal plasma in 1997 heralded the most significant change in obstetric care for decades, with the advent of safer screening and diagnosis based on analysis of maternal blood. Here, we describe how the technological advances offered by next-generation sequencing have allowed for the development of a highly sensitive screening test for aneuploidies as well as definitive prenatal molecular diagnosis for some monogenic disorders.

Overview of the impact of noninvasive prenatal testing on diagnostic procedures

Noninvasive prenatal testing (NIPT) has had a profound influence in the field of prenatal diagnosis since the 1997 discovery of cell-free fetal DNA in maternal blood. Research has progressed rapidly, with clinical data supporting laboratory studies showing that NIPT is highly sensitive and specific for fetal aneuploidy, resulting in marked uptake in the high-risk patient population. The superior accuracy of NIPT compared with conventional screening methods has led to significant decreases in the number of invasive diagnostic procedures, in addition to a concomitant decrease in the number of procedure-related fetal losses. Yet, NIPT has been described as a 'disruptive innovation' due to the considerable changes the technology has commanded on current prenatal screening and diagnostic practices. This review summarizes both institutional and global experience with NIPT uptake, its effect on reducing diagnostic invasive procedures, and the unique challenges that reduced procedural volume may have on physician and trainee proficiency, cytogenetic laboratories, and neonatal outcome.

[Transabdominal chorionic villus sampling using biopsy forceps or needle: pregnancy outcomes by technique used]

OBJECTIVES

To compare pregnancy outcomes after transabdominal chorionic villus sampling using biopsy forceps or needle.

MATERIALS AND METHODS

Retrospective bicentric study including all women who had a transabdominal chorionic villus sampling between 2005 and 2009 (172 using biopsy forceps and 160 using needle). The primary endpoint was the rate of fetal loss, after excluding medical abortion due to the result of the biopsy. The secondary endpoint was the rate of premature rupture of the membrane. All cases were reviewed to try to determine the responsibility of the biopsy.

RESULTS

The pregnancy outcomes were not different between the two groups: 4 (4.4%) fetal losses in the biopsy forceps group and 6 (7.4%) in the needle group (P=0.52). Only one case (1.2%) of fetal loss can be attributed to the biopsy, using a needle, and none (0%) following a forceps biospy (P=0.29). The rate of premature rupture of the membrane was comparable in the two groups.

CONCLUSION

The pregnancy outcomes following chorionic villus sampling using a biopsy forceps or a needle seem comparable.

A transcervical chorionic villus sampling model for teaching

We sought to create a transcervical chorionic villus sampling model for teaching that would mimic a lifelike model. A model was created using silicone resembling the maternal interface. A cervix with an endocervical canal able to accommodate a catheter and a vagina was also created. Tap water was used as the amniotic fluid. Chorionic villus sampling was accomplished using this model with the actual ultrasound machines and environment as in the real model. This simulator allowed placental placement in different locations to increase the difficulty level as well as angulations and catheter handling. Given the low cost (less than $200), this model could be used indefinitely in a relaxed and controlled environment.

The use of simulation in maternal-fetal medicine procedure training

Many fields of medicine now routinely employ simulation while educating all levels of medical trainees. Unfortunately, OB-GYN has been slow to incorporate these beneficial adjuncts to traditional medical education, but thankfully the use of simulation is now increasing. Maternal-Fetal medicine procedures such as amniocentesis, in-utero stent placement, chorionic villus sampling, percutaneous umbilical blood sampling, and cervical cerclage placements are an area where simulation has great potential benefit. Here we describe the currently available simulation models for these procedures and outline specific training curricula designed to aid trainees in obtaining procedural competency in each. Although initial experiences with these training models and the curricula centered around them have been positive, in many cases their use remains limited. Our hope is that this manuscript will encourage others to incorporate simulation into their training programs as we believe it will enhance medical training and improve patient safety.

A cervical cerclage task trainer for maternal-fetal medicine fellows and obstetrics/gynecology residents

INTRODUCTION

Performance of cervical cerclage is a difficult procedure for learners with limited operative experience. We present a task trainer for cervical cerclage, which can facilitate learner training in a preclinical environment.

METHODS

A simulated vagina is first fashioned out of polyvinyl chloride pipe material to allow an appropriately shaped pelvic structure. To simulate collapsible vaginal sidewalls, a foam covered with latex sheets is used to line the inside of the task trainer. A "cervix" is made by cutting cylinders approximately 2 in in diameter and 4 in in length in frozen cow muscle. After thawing, the cervical models are fastened to a semirigid foam disk with suture, which is used to secure the cervix inside the polyvinyl chloride pipe at the top of the simulated vagina. The full cervical cerclage task trainer is then secured in a holder to stabilize it in place. Placement of a cervical cerclage can then be practiced with standard vaginal cerclage instruments.

RESULTS

Cervical cerclage can be practiced in a nonclinical environment using this model. Several aspects of the procedure can be modified including the amount of vaginal tissue, length and caliber of the vagina, and pubic arch angle. This model allows beginning learners sequential training of increasing difficulty. Faculty and trainees alike found the trainer to be useful and felt that it helped in the acquisition of the surgical skills needed for cerclage placement in a clinical setting.

CONCLUSIONS

This low-cost task trainer can provide Maternal-fetal Medicine fellows and obstetric/gynecology residents the opportunity to practice cervical cerclage placement in a nonclinical environment. It may help physicians to obtain or maintain proficiency despite the relative low frequency of the procedure in modern obstetric practice.

Clinical trial of multiplanar real-time 4- versus 2-dimensional sonographic guidance for transcervical chorionic villus sampling

OBJECTIVES

Real-time 4-dimensional (4D) sonography can visualize the location of a chorionic villus sampling (CVS) catheter simultaneously in 3 dimensions. We determined the utility of 4D versus 2-dimensional (2D) sonographic guidance for transcervical CVS.

METHODS

Chorionic villus sampling was performed on 40 patients at 10 to 13 weeks' gestation (20 in each study group). Primary outcomes were as follows: (1) time in seconds needed to complete the procedure; (2) procedure failure, defined as the inability to obtain an adequate sample by a single catheter insertion or a necessity to switch to the alternative imaging modality; and (3) acquisition of a sample of chorionic villi sufficient for cytogenetic analysis. Wilcoxon rank sum and Fisher exact tests were used for categorical and continuous variables, respectively. Figure 1. A, Two-dimensional guidance of the transcervical chorionic villus sampling procedure. Arrows indicate the chorionic villus sampling catheter. B, Multiplanar 3-dimensional guidance of the procedure.

RESULTS

The procedure time was significantly longer in the 4D group than the 2D group (161.4 versus 80.4 seconds, respectively; P = .001). The success rate at first introduction of the catheter was higher for 2D guidance (90%) than 4D guidance (70%) but was not statistically significant with the study group sizes. Adequate sample sizes were obtained in all patients. The main limiting factor in 4D guidance was a low frame rate.

CONCLUSIONS

Our findings show the feasibility of 4D guidance for transcervical CVS, although at the expense of a prolonged procedure time when compared to 2D sonographic guidance. The value of 4D guidance for less experienced operators remains to be determined.

Quality control for intravascular intrauterine transfusion using cumulative sum (CUSUM) analysis for the monitoring of individual performance

INTRODUCTION

Intravascular intrauterine transfusion (IUT) is an effective and relatively safe method for the treatment of fetal anemia. Although implemented in centers all over the world in the 1980s, the length and strength of the learning curve for this procedure has never been studied. Cumulative sum (CUSUM) analysis has been increasingly used as a graphical and statistical tool for quality control and learning curve assessment in clinical medicine. We aimed to test the feasibility of CUSUM analysis for quality control in fetal therapy by using this method to monitor individual performance of IUT in the learning phase and over the long term.

METHODS

IUTs performed in the Dutch referral center for fetal therapy from 1987 to 2009 were retrospectively classified as successful or failed. Failed was defined as no net transfusion or the occurrence of life-threatening procedure-related complications. The CUSUM statistical method was used to estimate individual learning curves and to monitor long-term performance. Four operators who each performed at least 200 procedures were included.

RESULTS

Individual CUSUM graphs were easily assessed. Both operators pioneering IUT in the late 1980s had long learning phases. The 2 operators learning IUT in later years in an experienced team performed acceptably from the start and reached a level of competence after 34 and 49 procedures.

DISCUSSION

CUSUM analysis is a feasible method for quality control in fetal therapy. In an experienced setting, individual competence may be reached after 30 to 50 IUTs. Our data suggest that operators need at least 10 procedures per year to keep a level of competence.

Amniocentesis: technique and education

PURPOSE OF REVIEW

To review available data on the technique and education of amniocentesis.

RECENT FINDINGS

Literature shows many tools facilitating training for amniocentesis. These models can be either bought or hand made. Initial teaching should ideally be part of a specific curriculum. Reports of fetal loss due to amniocentesis differ greatly among authors, varying from 0.13 to 2.2%.

SUMMARY

Developing an adapted curriculum for amniocentesis training is important and emphasizes the usefulness of a standardize technique. Available data on the risks of amniocentesis should help counseling women/couples.

In-utero stenting: development of a low-cost high-fidelity task trainer

OBJECTIVE

To develop an in-utero stent placement training model.

METHODS

The in-utero stent task trainer was constructed using a formalin-preserved gravid pig uterus. Altering the size of the uterine segment, changing the fluid level in the uterus and addition of a large Ziploc freezer bag variably filled with differing amounts of ultrasound gel can vary the procedural skill required.

RESULTS

Thoracoamniotic and vesicoamniotic shunts can be simulated using this life-like model. The cost of eight to 10 learning stations is approximately US $ 60. Fetal position, maternal size and amniotic fluid status can be altered rapidly to increase the complexity of the procedure.

CONCLUSIONS

This low-cost and realistic task trainer can provide the opportunity to practice in-utero shunt procedures in a non-clinical environment. This model should enhance learning and reinforce acquired skills.

Evaluation of ultrasound-guided radial artery cannulation in children

OBJECTIVE

To compare ultrasound (US)-guided radial artery cannulation with the traditional palpation technique.

DESIGN

: Prospective randomized study.

SETTING

Operating room in a tertiary care pediatric center.

PATIENTS

One hundred fifty-two children under 18 yrs of age requiring radial artery cannulation.

INTERVENTIONS

Patients were randomized to either 1) palpation or 2) US guidance technique for radial artery cannulation.

MEASUREMENTS AND MAIN RESULTS

The primary end point of the study was the time taken for attempted cannulation by the first operator at the first site. Secondary end points included the number of attempts at arterial cannulation, the number of cannulae used, and the need for additional assistance from another anesthesiologist. Eighty and 72 children were randomized to the palpation and the US-guided groups, respectively. There were no statistically significant differences in age, gender, weight, and systolic blood pressure between the two study groups. The designated first operator (20 pediatric subspecialty trainees and eight consultant anesthesiologists) had previous experience in US-guided arterial cannulation in <10 cases, with 94% having experience in <5 cases. Although the radial artery was eventually cannulated in all patients, the designated operator was successful at the first site of cannulation in only 66% and 69% in the palpation and US groups, respectively. There were no statistically significant differences between the groups in time to successful cannulation, total number of attempts, number of successful cannulations during the first attempt, or in the number of cannulae used for catheterization.

CONCLUSIONS

US guidance did not facilitate faster cannulation of the radial artery in children in our study.

A needle tracking device for ultrasound guided percutaneous procedures

A novel tracking device is proposed for measuring the position and orientation of a needle with respect to an ultrasound probe. This device is intended to guide an operator during a percutaneous needle insertion so that the needle trajectory can be visually aligned with the target before insertion. The tracking device uses a pair of cameras to track the needle location so that a standard needle can be used without attaching a separate sensor to the needle. The main challenge is to calibrate the tracking system with sufficient accuracy. Calibration methods are described for each of the system parameters. A series of tests show that an overall error of 3.1 +/- 1.8 mm is achieved with two commercial cameras and an error of 6.5 +/- 5.7 mm is achieved with two inexpensive consumer cameras. An analysis of the source of errors reveals that the errors arise from all of the calibration steps. Overall system accuracy is therefore determined by both the quality of the cameras and the performance of calibration.

Training in chorionic villus sampling: limited experience for US fellows

OBJECTIVE

This study was undertaken to assess training availability, methods, and plans for future practice of invasive procedures for maternal fetal medicine (MFM) fellows.

STUDY DESIGN

A survey was sent to all MFM fellows registered with the American Board of Obstetrics and Gynecology in March of 2001.

RESULTS

Of 91 surveys, 55 (60.4%) were returned. All respondents were trained in second-trimester amniocentesis and planned on performing the procedure after fellowship. Of the 55 respondents, 53 (96.4%) were trained on continuing pregnancies. Despite 82% of training institutions performing chorionic villus sampling (CVS), only 24 of 45 (53%) fellows had availability for training. Of those 24, 14 (58%) initiated training on pregnancies that were undergoing termination. Median number of procedures performed by fellows (continuing pregnancies and before termination) was 3 (range 0-120), with 40 procedures (range 0-140) expected to be performed before completing fellowship. Twenty-eight fellows planned on performing CVS after training.

CONCLUSION

The number of centers training MFM fellows in CVS and the number of procedures performed in the United States is limited.

[Foetal sampling techniques]

This article describes the current techniques of foetal sampling. All of them are actually ultrasound guided, and therefore generally very safe. Nevertheless, an elaborate learning process remains indispensable, in addition to a particular attention to the quality of the physician-patient dialogue. The choice of a technique depends on the indication and on the term of the pregnancy. The most frequently used technique is amniocentesis which presents a low risk of foetal loss, estimated between 0.2 and 0.5 percent. The interest of chorionic villus sampling is the possibility to obtain results at an earlier stage of pregnancy, with a lower risk taking when compared to early amniocentesis. We prefer the transabdominal chorionic villus sampling to the transvaginal. Foetal blood sampling is still required in some cases, but the risk of complications is higher--around 1 percent.

Chorionic villus sampling and amniocentesis: what are the risks in current practice?

PURPOSE OF REVIEW

Public demand for genetic counselling and prenatal diagnosis has increased during the past decade. As invasive diagnostic methods, such as chorionic villus sampling and amniocentesis, still have an important role to play in evaluating the fetus, one of the most important questions to address during genetic counselling is the procedure-related risk of these techniques.

RECENT FINDINGS

The possible factors modifying the specific risk of the actual fetus are discussed, together with factors that have an impact on procedure-related fetal loss and other complications. Risk factors regarding twin pregnancies, first and second-trimester chorionic villus sampling, early and mid-trimester amniocentesis are discussed separately. New developments have recently occurred in the laboratory techniques used in prenatal diagnosis. Their impact on genetic counselling and the employment of invasive techniques are also addressed.

SUMMARY

During genetic counselling, an individually tailored risk assessment needs to be established before any invasive procedure. This should take into account all the factors modifying the specific risk for aneuploidy or other disorders of the fetus, as well as the actual procedure-related risks.