Contents: Medical Education: Procedures and Instruments
Breech extraction of a second twin is a useful skill for any health care provider planning on undertaking vaginal delivery of twins. It often requires proper tactile identification of the presenting fetal part through a tense amniotic sac. Delay in delivery can lead to regression of cervical dilatation, with increased risk of cesarean delivery or head entrapment, and attempt at delivery of a misidentified fetal part can cause fetal injury.
Simulation of a breech extraction can be used to enhance education of obstetric care providers of all training levels and may help lower cesarean delivery rates. Two simulation models have been reported for health care provider education in breech delivery,1,2 although neither addresses the tactile sensation of fetal part identification of a floating fetus and grasping of the presenting part through a smooth, tense but fragile, convex, and slippery amniotic sac. Recent literature prioritizes health care provider simulation in vaginal breech extraction as essential for skill acquisition and maintenance for continued offering of this important delivery route to patients.3
We sought to develop a simulation device that realistically, reliably, affordably, and reproducibly simulated one of the most difficult and most critical portions of the breech extraction of a second twin, which is the prompt and proper identification, grasping, and delivery of the fetal foot or feet.
To begin, a hole is cut in the bottom of a whey protein container (Appendix 1, available online at http://links.lww.com/AOG/B89) with care to ensure that no sharp edges protrude, because these could puncture the balloon when stretched by vacuum application. The diameter of the hole should not exceed the diameter of the vacuum hose. The fetal doll should be evaluated for appropriate head size, because it must fit through the opening of the whey protein container, as well as feet size,4 because these should realistically simulate a fetus for which extraction is contemplated (Appendix 2, available online at http://links.lww.com/AOG/B89).
Next, the mouth of the balloon is stretched (Appendix 3A, available online at http://links.lww.com/AOG/B89) over the upper opening of the whey protein container; only large balloons work, because the mouth needs to be stretched over the large opening of the whey protein container (Appendix 3B, available online at http://links.lww.com/AOG/B89). The doll should be readily accessible for swift insertion. An assistant is required to hold the vacuum cleaner hose up to the cut hole and turn the vacuum suction on; this will suck the balloon downward, nearly filling the whey protein container (Appendix 4, available online at http://links.lww.com/AOG/B89) and stretching the opening of the balloon wide enough to put the fetal doll inside (Fig. 1). The vacuum is turned off when the doll is completely or almost completely inside (Fig. 2). The balloon will then collapse around the doll (Fig. 3). The “doll-in-balloon” complex should then be carefully removed through the top opening of the whey protein container (Fig. 4).
Next, the balloon is filled with water (Fig. 5A). This simulates a fetus inside the amniotic sac, and gestational-age specific volumes may be used if desired.5 If a soft-bodied doll is used, before tying a knot in the balloon (Fig. 5B), an attempt to squeeze the air bubbles out of the cloth should be made to prevent the later development of large air bubbles, which can develop as the cloth body takes on more water.
When choosing the sac for the simulated uterus, the use of a neoprene bag allows flexible “molding” of the uterus. Commercially available zippered neoprene lunch sacs (Appendix 5, available online at http://links.lww.com/AOG/B89) require no assembly and allow visual monitoring of the progress of trainees; an 8- to 10-cm hole should be cut from the undersurface of the neoprene bag to simulate the fully dilated cervix. If a lunch sac with straps is available, it can be worn around the waist by a standardized patient and positioned between the legs, or the straps can be used to affix the simulated uterus to a model trainer. Another approach is to sew together two neoprene wine bottle “koozies” for more realistic visualization, but these are harder to hold during the extraction simulation (Appendix 6, available online at http://links.lww.com/AOG/B89). Regardless of which neoprene bag is chosen, a linear cut can be made in the bag to simulate a hysterotomy at cesarean delivery, thereby allowing for the model to be used for teaching beyond vaginal breech extraction (to teach breech delivery through hysterotomy at cesarean delivery). Additionally, one could use neoprene or other materials to construct a simulated vagina, although this does add a level of complexity to the model and increases the likelihood of the sac rupturing during simulation (Appendix 7, available online at http://links.lww.com/AOG/B89).
Once the neoprene bag is chosen or assembled and modified by cutting a hole, which simulates the fully dilated cervix, the doll-in-balloon complex is inserted into the neoprene bag (Fig. 6). Simulation education then can commence.
The simulation can begin, after orientation to the model, by asking the resident or trainee to close her eyes; alternatively, she may be blindfolded. This removes visual cues and simulates a breech extraction in the absence of ultrasound-provided visual feedback. The trainee then should be instructed to reach up into the neoprene uterus through either the hole that was cut (as the fully dilated cervix) or up into the vagina add-on and verbally describe what she is feeling, just like in a breech extraction. If the zippered lunch bag model is used, the instructor can watch from above.
Use of this model allows the instructor to demonstrate expectations of the trainee in an actual breech extraction; without her own hands inside the patient's vagina or uterus, the instructor cannot determine what the trainee is feeling or grasping, and simulation of this part of the delivery can help the instructor assess the trainee's skills and also demonstrate the verbal cues that they expect to receive as the trainee performs critical steps.
Rupture of the sac was unpredictable and seemed to vary by batch of balloons. Some balloons ruptured after more than 20 simulated deliveries; others ruptured on the first attempt. Purchasing a larger supply of latex balloons can help control for this unpredictability, although rupture with subsequent large egress of fluid can be disconcerting to the trainee.
This model is an easily and inexpensively constructed educational device, modeled after a craft video,6 for use in simulation of a breech extraction of a second twin and has extended applicability in delivery of a breech fetus by cesarean. The model is inexpensive to maintain and can supplant existing simulator models. Although several devices are available for use in breech delivery training, our model would seem to more realistically simulate a fetus floating in an amniotic cavity and challenges the learner from a tactile standpoint on delivery of the fetal foot or feet.
1. Deering S, Brown J, Hodor J, Satin AJ. Simulation training and resident performance of singleton vaginal breech delivery. Obstet Gynecol 2006;107:86–9.
2. Easter SR, Gardner R, Barrett J, Robinson JN, Carusi D. Simulation to improve trainee knowledge and comfort about twin vaginal birth. Obstet Gynecol 2016;128(suppl 1):34–9S.
3. Easter SR, Taouk L, Schulkin J, Robinson JN. Twin vaginal delivery: innovate or abdicate. Am J Obstet Gynecol 2017;216:484–8.e4.
4. Wyk LV, Smith J. Postnatal foot length to determine gestational age: a pilot study. J Trop Pediatr 2016;62:144–51.
5. Brace RA, Wolf EJ. Normal amniotic fluid volume changes throughout pregnancy. Am J Obstet Gynecol 1989;161:382–8.
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