Intrapartum ultrasound during rotational forceps delivery: a novel tool for safety, quality control, and teaching.

BACKGROUND: Operative vaginal delivery and, in particular, rotational forceps delivery require extensive training, specific skills, and dexterity. Performed correctly, it can reduce the need for difficult late second-stage cesarean delivery and its associated complications. When rotation to occiput anterior position is achieved, pelvic trauma and anal sphincter injury commonly associated with direct delivery from occiput posterior positions may be avoided. OBJECTIVE: We report the original and novel use of real-time intrapartum ultrasound simultaneously during Kielland's rotational forceps delivery to monitor correct execution and increase maternal safety. STUDY DESIGN: This is a prospective observational study performed at the Charité University Hospital in Berlin between 2013 and 2018. Simultaneous, real-time, intrapartum suprapubic ultrasound during Kielland's rotational forceps deliveries were performed in a series of laboring women with normal fetuses and arrest of labor in the late second stage and with a fetal head malposition, requiring operative vaginal delivery. In addition to vaginal palpation for head station, rotation, and asynclitism, intrapartum ultrasound was also used to objectively determine head station, head direction, and midline angle. The operator was not blinded to the ultrasound findings. The delivering obstetrician examined the woman and performed the delivery. An assistant, trained in intrapartum ultrasound, placed a curved-array transducer transversely in the midline just above the pubic bone to display the forceps blades being applied and the rotation of the fetal head in occiput anterior position. RESULTS: In all 32 laboring women included in the study, the blades were applied correctly and the fetal heads successfully rotated to an occiput anterior position with direct ultrasound confirmation, and vaginal delivery was achieved. There were no cases of difficult application, repeat application, slippage of the blades, or rotation of the fetal head in the wrong direction. Maternal outcomes showed no vaginal tears, cervical tears, or postpartum hemorrhage >500 mL. There was 1 case of third-degree perineal tear (3a). Neonatal outcomes included mild hyperbilirubinemia (n=1), small cephalohematoma conservatively managed (n=1), and early-onset group B streptococcus sepsis secondary to maternal colonization (n=1). There were no neonatal deaths. CONCLUSIONS: Ultrasound guidance during Kielland's rotational forceps delivery is an original and novel approach. We describe the use of intrapartum ultrasound in assessing fetal head station and position and also to simultaneously and objectively monitor performance of rotational forceps delivery. Intrapartum ultrasound enhances operator confidence and, possibly, patient safety. It is a valuable adjunct to obstetrical training and can improve learning efficiency. Real-time ultrasound guidance of fetal head rotation to occiput anterior position with Kielland's forceps may also protect the perineum and reduce anal sphincter injury. This novel approach can lead to a renaissance in the safe use of Kielland's forceps.

Evaluation of Suzor forceps training by studying obstetric anal sphincter injuries: a retrospective study.

BACKGROUND: Instrumental deliveries are an unavoidable part of obstetric practice. Dedicated training is needed for each instrument. To identify when a trainee resident can be entrusted with instrumental deliveries by Suzor forceps by studying obstetric anal sphincter injuries. METHODS: A French retrospective observational study of obstetric anal sphincter injuries due to Suzor forceps deliveries performed by trainee residents was conducted from November 2008 to November 2016 at Limoges University Hospital. Perineal lesion risk factors were studied. Sequential use of a vacuum extractor and then forceps was also analyzed. RESULTS: Twenty-one residents performed 1530 instrumental deliveries, which included 1164 (76.1%) using forceps and 89 (5.8%) with sequential use of a vacuum extractor and then forceps. Third and fourth degree perineal tears were diagnosed in 82 patients (6.5%). Residents caused fewer obstetric anal sphincter injuries after 23.82 (+/- 0.8) deliveries by forceps (p = 0.0041), or after 2.36 (+/- 0.7) semesters of obstetrical experience (p = 0.0007). No obese patient (body mass index> 30) presented obstetric anal sphincter injuries (p = 0.0013). There were significantly fewer obstetric anal sphincter injuries after performance of episiotomy (p <  0.0001), and more lesions in the case of the occipito-sacral position (p = 0.028). Analysis of sequential instrumentation did not find any additional associated risk. CONCLUSION: Training in the use of Suzor forceps requires extended mentoring in order to reduce obstetric anal sphincter injuries. A stable level of competence was found after the execution of at least 24 forceps deliveries or after 3 semesters (18 months) of obstetrical experience.

The use of a hybrid mannequin for the modern high-fidelity simulation in the labor ward: the Italian experience of the Ecografia Gestione Emergenze Ostetriche (EGEO) group.

Regular training in the management of intrapartum emergencies has been demonstrated to yield measurable benefits in terms of maternal and perinatal outcomes. Thanks to technologic advances, computerized, full-body mannequins have been created and made available for high-fidelity simulation in obstetrics. The technical skills subjected to training are conventionally represented by classical manual maneuvers, which are recommended in the case of instrumental vaginal delivery, shoulder dystocia, or postpartum hemorrhage. During the past few years, manual skills in the labor ward have been increasingly supported by the use of ultrasound, and this has substantially altered the practical management of intrapartum emergencies in real life. Based on this, a new generation of mannequins suitable for both clinical maneuvers and ultrasound examination seems to be the most appropriate tool for the modern high-fidelity simulation in the management of intrapartum complications. The use of these new hybrid clinical ultrasound mannequins may usher in a new era in high-fidelity obstetric simulation and can hopefully optimize the competencies and technical skills of labor ward professionals in the management of obstetric emergencies. It is from this background that at the beginning of 2018, the Ecografia Gestione Emergenze Ostetriche group was founded in Italy. This group has aggregated a multiprofessional labor ward team including obstetricians, midwives, and anesthesiologists under the common philosophy that ultrasound provides an essential added value in the management of obstetric emergencies. Thanks to the use of these mannequins, the multiprofessional Italian Ecografia Gestione Emergenze Ostetriche group has started to run practical workshops to promote the culture of extraordinary synergy of ultrasound and clinical skills as the best approach to handle intrapartum complications.

Advanced technology in obstetric education: a high-fidelity simulator for operative vaginal delivery.

A high-fidelity simulator is described here, specifically designed for vacuum extraction and forceps delivery training. The main purpose behind its development is to remedy the current limited opportunity for training in operative vaginal delivery (OVD), making it easier for young obstetricians to become proficient in this important area of obstetrics. Its introduction into teaching hospitals and academic departments may also help older obstetricians maintain their own competence during periods of inactivity, ensuring patient safety.

Global perspectives on operative vaginal deliveries.

Operative vaginal delivery (OVD) refers to the use of an instrument (forceps or vacuum device) to assist with the delivery of the fetus from the vagina. This can help improve maternal and fetal outcomes and has to be weighed up against the risks and benefits of performing second-stage cesarean deliveries. OVD forms an integral part of basic emergency obstetric care and a skilled birth attendant's duties. Outlet forceps and vacuum extraction should be used to shorten the second stage of labor and to improve maternal and fetal outcomes associated with delayed second stage. Despite the known benefit of OVD, available data on the use of OVDs in low- and middle-income countries show very low rates, mostly due to the lack of skilled healthcare workers and equipment shortages. Increased use of OVD can safely reduce the number of second-stage cesarean deliveries with its associated morbidity and mortality. We recommend implementing training programs to increase the number of skilled healthcare workers and strengthening health systems to provide birthing facilities with the equipment required to perform OVD.

Video-Based Teaching in Patient and Instrument Selection for Operative Vaginal Deliveries.

OBJECTIVE: Worldwide, the rate of operative vaginal deliveries has decreased, and as a result trainees are lacking exposure and training. The aim of this study was to determine whether a video-based masterclass can improve trainees' confidence, comfort, and knowledge in performing second stage labour assessments and selecting appropriate patients and instruments for operative vaginal deliveries. METHODS: Current University of Toronto obstetrics and gynaecology residents were invited to participate. The intervention included two videos on second stage assessment: (1) selecting the appropriate patient and (2) selecting the appropriate instrument for an operative vaginal delivery. Trainees' comfort and confidence were assessed pre- and post-intervention. A focus group was conducted that assessed trainees' knowledge acquisition. Descriptive thematic analysis was performed, and common themes were extracted. RESULTS: On average, residents have performed more vacuum deliveries than forceps deliveries as primary operators (26.4 vs. 7.9). Following the video intervention, there was a statistically significant improvement (P ≤ 0.05) in trainees' comfort in the following areas: (1) understanding the maternal pelvis, (2) choosing instruments, (3) choosing forceps, (4) deciding the location of delivery, (5) identifying favourable clinical factors, and (6) identifying poor prognostic clinical factors. There was no difference in trainees' self-confidence. Major themes from focus group data included new knowledge gained on second stage assessment techniques, new approaches to existing knowledge, and the multiple challenges and barriers that exist to learning. CONCLUSION: Video-based education on second stage labour assessment and operative vaginal delivery improves trainees' comfort and serves as a valuable complementary tool to clinical learning.

A Simulator for Breech Extraction of the Second Twin.

BACKGROUND: Breech extraction of a second twin is a skill useful for any health care provider planning on undertaking vaginal delivery of twins. However, training opportunities in this skill may be limited. METHOD: Using readily available supplies, a reusable model neoprene uterus can be constructed, as can a balloon model to simulate a fetus in the amniotic cavity. EXPERIENCE: The model allowed demonstration of skills expected of trainees and is easy to construct. A simulated vagina addition increased extraction difficulty and increased the probability of balloon (amniotic sac) rupture during simulation. A hysterotomy addition enhanced model applicability for use at simulated cesarean delivery of the breech fetus. CONCLUSION: This educational device for simulation of breech extraction realistically simulates a fetus suspended in an amniotic cavity and challenges learners to use tactile cues for prompt and proper identification, grasping, and delivery of the fetal foot or feet.

Simulation Training for Forceps-Assisted Vaginal Delivery and Rates of Maternal Perineal Trauma.

OBJECTIVE: To evaluate the association of a forceps simulation training curriculum for obstetrics residents on rates of severe perineal lacerations after forceps deliveries. METHODS: This was a retrospective cohort study. We created a novel simulation curriculum for forceps-assisted vaginal delivery based on the best practices of local experts, and trained all residents beginning in 2013. We then retrospectively reviewed all forceps deliveries performed in the 2.5 years after initiation of the training and the 7.5 years before the training program. We identified patients who experienced a severe perineal laceration (third- or fourth-degree) and examined the relationship of resident training status and perineal laceration. Known risk factors for lacerations were identified and a multilevel multivariable model was created including these factors as well as resident training. RESULTS: During the study period, we identified 6,058 forceps-assisted vaginal deliveries. We examined temporal trends in rates of forceps of severe perineal laceration. We identified a decrease in severe lacerations between 2005 and 2008, ending 5 years before the initiation of the training curriculum. These years were censored from the data, yielding a baseline observational period of 4,279 deliveries with no significant trend in laceration rate. Univariate analysis reveals a 22% reduction in severe perineal laceration (odds ratio [OR] 0.78; P=.005) among women delivered by residents who had completed forceps simulation training compared with women delivered by residents who had not. After adjusting for known maternal and delivery risk factors for perineal laceration, the magnitude of the reduction increased to 26% in the full data set model (OR 0.74; P=.002). CONCLUSION: A forceps simulation curriculum for obstetrics residents was associated with a significant reduction in severe perineal lacerations.

Obstetric Forceps: A Species on the Brink of Extinction.

Both resident training in the use of obstetric forceps and forceps deliveries are experiencing precipitous declines in the United States. Current minimum training requirements are insufficient to ensure competency in this skill. These trends bear striking similarities to observations regarding the decline and ultimate extinction of biologic species and portend the inevitable disappearance of this valuable skill from the obstetric armamentarium. Attempts by experienced teaching faculty to provide residents with experience in a few forceps deliveries are of little value and may do more harm than good. There would seem to be only two viable solutions to this dilemma: 1) abandon attempts to teach forceps and prepare residents for a real-world practice setting in which management of second-stage labor does not include the availability forceps delivery; or 2) prioritize the development of high-fidelity simulation models in which fetal head size and attitude and pelvic size and architecture can be continuously varied to allow residents to obtain sufficient experience to know both how and when to proceed with forceps delivery. We believe this latter approach is the sole alternative to inevitable extinction of this species.

Persistent occiput posterior.

Persistent occiput posterior (OP) is associated with increased rates of maternal and newborn morbidity. Its diagnosis by physical examination is challenging but is improved with bedside ultrasonography. Occiput posterior discovered in the active phase or early second stage of labor usually resolves spontaneously. When it does not, prophylactic manual rotation may decrease persistent OP and its associated complications. When delivery is indicated for arrest of descent in the setting of persistent OP, a pragmatic approach is suggested. Suspected fetal macrosomia, a biparietal diameter above the pelvic inlet or a maternal pelvis with android features should prompt cesarean delivery. Nonrotational operative vaginal delivery is appropriate when the maternal pelvis has a narrow anterior segment but ample room posteriorly, like with anthropoid features. When all other conditions are met and the fetal head arrests in an OP position in a patient with gynecoid pelvic features and ample room anteriorly, options include cesarean delivery, nonrotational operative vaginal delivery, and rotational procedures, either manual or with the use of rotational forceps. Recent literature suggests that maternal and fetal outcomes with rotational forceps are better than those reported in older series. Although not without significant challenges, a role remains for teaching and practicing selected rotational forceps operations in contemporary obstetrics.

Qualitative analysis by interviews and video recordings to establish the components of a skilled rotational forceps delivery.

OBJECTIVE: To define the skills of a mid-cavity rotational forceps delivery to facilitate transfer of skills from expert obstetricians to trainee obstetricians. STUDY DESIGN: Qualitative interviews and video analysis carried out at maternity units of two university teaching hospitals (St. Michael's Hospital, Bristol, and Ninewells Hospital, Dundee). Ten obstetricians were identified as experts in conducting operative vaginal deliveries. Semi-structured interviews were carried out to identify key technical skills. The experts were also video recorded conducting mid-cavity rotational deliveries in a simulation setting. The interviews and video recordings were transcribed verbatim and analysed using thematic coding. The anonymised data were individually coded by the three researchers and then compared for consistency of interpretation. The experts reviewed the data for respondent validation. The themes that emerged following the coding were used to formulate a taxonomy of skills. RESULTS: Rotational forceps were preferred by eight experts and two experts preferred manual rotation followed by direct traction forceps. The final taxonomy included detailed technical skills for Kielland rotational forceps delivery and manual rotation followed by direct traction forceps delivery. CONCLUSION: This explicitly defined skills taxonomy could aid trainees' understanding of the technique of rotational forceps delivery. This is an important potential contributor to safely reducing the rate of second-stage caesarean section.

Prevention of the first cesarean delivery: the role of operative vaginal delivery.

While the cesarean delivery (CD) rates have increased worldwide, operative vaginal delivery (OVD) rates continue to decline, with the United States having some of the lower rates amongst developed countries. It is clear that the use of forceps or vacuum can safely assist in accomplishing a vaginal delivery and prevent a cesarean during the IInd stage of labor performed for a variety of maternal or fetal indications. In the absence of randomized trials between OVD's and immediate CD's for anticipated difficult births the question of the balance of risks between the two interventions remains unanswered. Properly performed OVD's are associated with lower maternal morbidity compared with cesarean, without an increase in significant neonatal morbidity. In order to reverse the current trends and for these skills to continue active training in OVD's is clearly needed during and after residency. The availability of clinicians with expertise in OVD's should aid in decreasing the rates of CD and the training of newer generations of practitioners. The professional endorsement of OVD's is also fundamental not only to frame the practice for physicians but to promote and improve the general acceptance of assisted deliveries and facilitate the societal discourse to reduce CD rates.

Does forceps training on a birth simulator allow obstetricians to improve forceps blade placement?

OBJECTIVE: The aim of this study was to evaluate whether forceps training on a birth simulator allows obstetricians to improve forceps blade placement. STUDY DESIGN: Analysis was based on 600 forceps blade placements performed by ten trainees on a simulator. The trajectories used by the trainees were assessed using reference spheres that reflected an optimal bimalar placement. Three definitions of success were used: small-sphere success, medium-sphere success and large-sphere success were respectively defined by the forceps blade tip being within 5, 10 or 15mm of the center of the sphere (the small-sphere being nested within the medium-sphere and the small and medium being nested within the large-sphere). Wilcoxon paired analysis was performed to compare the first (50 trajectories) and final (50 trajectories) sets of five forceps placements. Graphical representation and linear regression were used to visualize the learning process. RESULTS: 596 trajectories were available for analysis. During the last set of five forceps the success rate was respectively 28%, 72% and 86% for small-sphere, medium-sphere and large-sphere success with the right blade and 8%, 32% and 70% for the left blade. Wilcoxon analysis showed a highly significant improvement for all kinds of success in the right blade and for large-sphere success in the left blade. Linear regression slopes were significant. Using a projection, the theoretical numbers of placements needed to achieve a 100% success rate for small-sphere, medium-sphere and large-sphere were respectively 80, 45 and 35. CONCLUSION: These results strongly suggest that performing forceps blade placement on birth simulator allows obstetricians to improve their skills.

Instrumental delivery: clinical practice guidelines from the French College of Gynaecologists and Obstetricians.

Routine use of a partograph is associated with a reduction in the use of forceps, but is not associated with a reduction in the use of vacuum extraction (Level A). Early artificial rupture of the membranes, associated with oxytocin perfusion, does not reduce the number of operative vaginal deliveries (Level A), but does increase the rate of fetal heart rate abnormalities (Level B). Early correction of lack of progress in dilatation by oxytocin perfusion can reduce the number of operative vaginal deliveries (Level B). The use of low-concentration epidural infusions of bupivacaine potentiated by morphinomimetics reduces the number of operative interventions compared with larger doses (Level A). Placement of an epidural before 3-cm dilatation does not increase the number of operative vaginal deliveries (Level A). Posterior positions of the fetus result in more operative vaginal deliveries (Level B). Manual rotation of the fetus from a posterior position to an anterior position may reduce the number of operative deliveries (Level C). Walking during labour is not associated with a reduction in the number of operative vaginal deliveries (Level A). Continuous support of the parturient by a midwife or partner/family member during labour reduces the number of operative vaginal deliveries (Level A). Under epidural analgesia, delayed pushing (2h after full dilatation) reduces the number of difficult operative vaginal deliveries (Level A). Ultrasound is recommended if there is any clinical doubt about the presentation of the fetus (Level B). The available scientific data are insufficient to contra-indicate attempted midoperative delivery (professional consensus). The duration of the operative intervention is slightly shorter with forceps than with a vacuum extractor (Level C). Nonetheless, the urgency of operative delivery is not a reason to choose one instrument over another (professional consensus). The cup-shaped vacuum extractor seems to be the instrument of choice for operative deliveries of fetuses in a cephalic transverse position, and may also be preferred for fetuses in a posterior position (professional consensus). Vacuum extraction deliveries fail more often than forceps deliveries (Level B). Overall, immediate maternal complications are more common for forceps deliveries than vacuum extraction deliveries (Level B). Compared with forceps, operative vaginal delivery using a vacuum extractor appears to reduce the number of episiotomies (Level B), first- and second-degree perineal lesions, and damage to the anal sphincter (Level B). Among the long-term complications, the rate of urinary incontinence is similar following forceps, vacuum extraction and spontaneous vaginal deliveries (Level B). Anal incontinence is more common following forceps delivery (Level B). Persistent anal incontinence has a similar prevalence regardless of the mode of delivery (caesarean or vaginal, instrumental or non-instrumental), suggesting the involvement of other factors (Level B). Rates of immediate neonatal mortality and morbidity are similar for forceps and vacuum extraction deliveries (Level B). It appears that difficult instrumental delivery may lead to psychological sequelae that may result in a decision not to have more children (Level C). The rates of neonatal convulsions, intracranial haemorrhage and jaundice do not differ between forceps and vacuum extraction deliveries (Levels B and C). Rapid sequence induction with a Sellick manoeuvre (pressure to the cricoid cartilage) and tracheal intubation with a balloon catheter is recommended for any general anaesthesia (Level B). Training must ensure that obstetricians can identify indications and contra-indications, choose the appropriate instrument, use the instruments correctly, and know the principles of quality control applied to operative vaginal delivery. Nowadays, traditional training can be accompanied by simulations. Training should be individualized and extended for some students.

Simulation of an instrumental childbirth for the training of the forceps extraction: control algorithm and evaluation.

This paper presents the control algorithm implanted on the childbirth simulator BirthSIM in order to provide training to novice obstetricians. The forceps extraction is an obstetric manipulation learned by experience. However, nowadays the training is mainly provided during real childbirths. This kind of training could lead to dramatic consequences due to the lack of experience of some operators. This paper explains the approach that has been used to simulate the dynamic process of a childbirth on the BirthSIM simulator. We especially focus on one procedure that reproduces a difficult instrumental delivery. The recorded tractive force to extract the fetus corresponds to the literature results that confirm the realism of the simulator. The novice results emphasize the need of a childbirth simulator in order to gain initial experience without any risks.

[Learning use of spatulas: risks of perineal injuries and newborns morbidity]. / Risques néonataux et périnéaux liés à l'apprentissage des spatules.

OBJECTIVES: To examine the acute neonatal and maternal perineal morbidity due to resident training on spatulas assisted deliveries. MATERIAL AND METHODS: We conducted a retrospective observational study of succesful spatulas-assisted deliveries at Nice University Hospital between January2003 and December2006. We performed univariate analysis and logistic regression to assess risk of severe perineal injuries, vaginal laceration and newborn hospitalization according to operator status, controlling for confounders. RESULTS: Among 1004 deliveries, 86.4% were performed by residents. No significant difference was found on incidence of severe perineal tears between the 872 extractions performed by residents and the 132 performed by an attending physician (6.9% versus 7.9% p=0.706; OR=0.86 IC95% [0.41-1.81]), but extraction performed by young residents were associated to more severe perineal tears than those performed by senior residents (8.0% versus 4.5% p=0.035; OR=2.10 IC95% [1.16-3.77]). There was no difference between groups concerning newborn morbidity and hospitalisation in special care units (6.4% versus 9.8% p=0.149; OR=1.49 IC95% [0.73-304]). CONCLUSION: According to our data, training of resident do not increase the incidence of severe perineal injuries, neonatal complications and hospitalisation linked to spatulas assisted delivery.

Operative vaginal delivery.

Operative vaginal delivery remains a valid option when problems arise in the second stage of labor. The most common indications are fetal compromise and failure to deliver spontaneously with maximum maternal effort. There is a clear trend to choose vacuum extraction over forceps to assist delivery, but the evidence supporting that trend is unconvincing. Recent literature confirms some advantages for forceps (eg, a lower failure rate) and some disadvantages for vacuum extraction (eg, increased neonatal injury), depending on the clinical circumstances. To preserve the option of forceps delivery, residency training programs must incorporate detailed instruction in forceps techniques and related skills into their curricula. Simulation training can enhance residents' understanding of mechanical principles and should logically precede clinical work.

Fear of failure: are we doing too many trials of instrumental delivery in theatre?

OBJECTIVES: Cesarean section has largely replaced the role of difficult midcavity instrumental deliveries. The aim of this study was to determine the trend in trials of instrumental delivery as well as the maternal and fetal factors associated with successful and failed trial of instrumental deliveries. SETTING: North Middlesex University Hospital, a teaching hospital in London. STUDY DESIGN: A retrospective review of trials of instrumental delivery in theatre involving singleton term pregnancies between 2000 and 2005. RESULTS: Of the 114 trials, 82 (40 forceps and 42 vacuum extraction) were successful. Women who had successful trials were similar in age (27.8+/-5.9 vs. 27.1+/-5.4 yrs), gestation (40.5+/-2.1 vs. 40.5+/-1.1 wks) and parity (0.4+/-1.2 vs. 0.3+/-1.6) when compared to those who were unsuccessful (p>0.05). The two groups also had similar birth weight (3.6+/-0.7 vs. 3.7+/-0.4 kg) and duration of second stage (164.9+/-12.0 vs. 162.8+/-16.0 min) (p>0.05). Babies born following failed trial of instrumental deliveries were more likely to be acidotic (p=0.014) but admission to Special Care Baby Unit was similar in both groups. Women who had failed trials of instrumental delivery were more likely to have post-partum hemorrhage (802.7+/-100.0 vs. 425.4+/-120.0 ml) and pyrexia (15.6% vs. 6.1%) (p<0.05). Trial of instrumental delivery was twice as likely to fail if occipito-posterior and three times more likely to succeed if the presenting part was visible (p<0.05). However, 25% of babies had presenting parts well below the ischial spines but still had instrumental deliveries in theatre and 80% of this subgroup were delivered by junior trainees. Although 71.9% of trials of instrumental delivery were successful, many were relatively uncomplicated and did not necessarily require delivery in theatre. CONCLUSION: Unsuccessful trials are associated with maternal rather than neonatal morbidity. The shortening of duration training as well as reduction of working hours in the United Kingdom has led to obstetric trainees being less experienced in conducting instrumental deliveries. Thus, many junior trainees may prefer to conduct relatively uncomplicated instrumental deliveries in theatre. Appropriate training and senior staff input would help reduce this.

Evaluation of obstetric gestures: an approach based on the curvature of quaternions.

This paper presents a method to evaluate a gesture carried out by a resident obstetrician by comparing it to a gesture carried out by an expert obstetrician. The studied gesture is the forceps blade placement. Resident paths were recorded on a childbirth simulator while placing forceps blades instrumented with six degrees of freedom sensors. The path is characterized by the positions and the orientations. In this paper we particularly focus on the orientations. Forceps orientations are expressed in the quaternion unit space and the curvature of quaternion path is compared by correlation to a reference defined by an expert. Residents have been trained on a simulator and their gestures are evaluated by comparing their orientation path curvatures to reference path curvatures. Quantitative results confirm the qualitative analysis, residents become more similar to the reference while training on simulator.