Emergency surgical obstetrics simulation training: an ex vivo low-cost model using bovine uterus and porcine bladder for haemostatic uterine brace suture techniques

Abstract

Postpartum haemorrhage remains a leading cause of maternal mortality and morbidity. While conventional obstetrics training curricula describe at length the management of postpartum haemorrhage, obstetrics trainees rarely have exposure to surgical management of postpartum haemorrhage in emergency situations due to reduced hours of training. Procedures such as the transverse or longitudinal haemostatic uterine brace sutures are recognised to be safe, simple and allow for the preservation of the uterus. Training during emergency situations is rarely practical or ideal. We describe a simple model that simulates the atonic postnatal uterus and allows trainees to practise the safe placement of the brace sutures. We use a bovine uterus model with attached broad ligament, bladder and ureters for the transverse haemostatic suture. For the longitudinal brace suture, we use a porcine bladder to simulate the uterus, with the ureters and bladder mesentery simulating the tubes and broad ligaments. The placement of the sutures can be practised with the uterus/bladder closed, or open akin to a caesarean section. Tissue dissection and feedback is almost similar to in vivo conditions. The sutures are inserted and driven using the material and correct placement used during real surgery. Our wet lab training model allows the acquisition, maintenance and enhancement of the required technical skills in a controlled environment, using inexpensive, reproducible and widely available specimens. The model has proved successful in both high and low-resource healthcare settings.

Key messages.

What is already known on this subject

• While obstetric haemorrhage remains a leading cause of maternal mortality and morbidity worldwide and in the UK, haemostatic uterine brace sutures are safe and allow for the preservation of the uterus.

• Training during emergency situations is rarely practical, and obstetricians rarely practice the relevant surgical techniques electively.

• To maximise opportunity and reduce patient harm, there is a drive towards simulation with animal models to aid surgical training.

What this study adds

• We describe a wet lab-facilitated course using simple ex vivo animal models that simulate the postnatal uterus and allow the safe practice haemostatic brace sutures.

• There was a significant improvement in the candidates’ mean confidence score for the surgical management of obstetric haemorrhage and for the insertion of haemostatic brace sutures.

• The model has proved successful in both high and low-resource healthcare settings.

Introduction

Following the implementation of the European Working Time Directive law in the UK in 1998 and its application to Obstetrics and Gynaecology Junior Doctors in 2009, trainees have had less exposure to surgical training time. To maximise opportunity and reduce patient harm, there is a drive towards simulation with animal models to aid surgical training. Such models act to mimic human tissue, replicating real-life experience to ensure the clinician is well practised in the skill prior to performing it on a patient.^{1 2}

Obstetric haemorrhage remains a leading cause of maternal mortality and morbidity worldwide and in the UK.^{3 4} The 2014–2019 UK Confidential Enquiries into Maternal Deaths (MBRRACE-UK: Mothers and Babies Reducing Risk through Audits and Confidential Enquiries across the UK) focused on basic skills training and prompt recognition of obstetric haemorrhage.⁴ In addition, the incidence of morbidly adherent placentae (accreta) is rising due to increasing caesarean section rates. The quoted rate ranges from 3% for the first caesarean section and increases incrementally up to 61% at the time of the fourth caesarean section. Postpartum haemorrhage (PPH) secondary to abnormal placentation is the most common indication for postpartum hysterectomy (40%–60%).⁵

Haemostatic uterine brace sutures are safe and allow for the preservation of the uterus. The longitudinal brace suture (‘B-Lynch’) is most useful for controlling atonic PPH. The transverse brace suture aids control of lower segment bleeding in placenta praevia with or without accreta.^{6 7} The 2014 Scottish Confidential Audit of Severe Maternal Morbidity concluded that where haemostatic brace suturing was used for the management of severe PPH, hysterectomy was averted in 76% of women.⁸ The Royal College of Obstetricians and Gynaecologists (RCOG) echoes this advice, recommending haemostatic brace suturing as ‘an effective measure in controlling severe PPH and in reducing the need for hysterectomy’.⁹

Training during emergency situations is rarely practical and while conventional obstetrics training curricula describe at length the management of postpartum haemorrhage, obstetricians rarely practise the relevant surgical techniques electively.⁴ The haemostatic brace suture techniques are often taught and acquired through didactic, lecture-based teaching sessions, which enhance a trainee’s understanding of the theory behind the procedures. However, such methods do not teach the practical, manual dexterity skills to perform the required techniques under pressure in emergency obstetric situations.

In order to teach the technical and non-technical skills required for haemostatic uterine suture techniques, we developed a wet lab-facilitated course using simple ex vivo animal models that simulate the postnatal uterus and allow the safe practice haemostatic brace sutures.

Materials and methods

Animal tissue

All animal parts are supplied by Medical Meat Supplies (Oldham, UK) that provides various types of tissue to aid surgical simulation. The products are derived from healthy animals which are intended for human consumption and humanely slaughtered in abattoirs in accordance with the Animal Health Veterinary Laboratories Agency and European Economic Commission regulations that allow for providing animal tissue material for educational purposes.

Models

For the longitudinal (vertical) brace suture (mainly used for controlling bleeding from an atonic postpartum uterus in vivo), we use a porcine bladder (figure 1). The pig bladder has the tactile sensation and tissue resistance that simulate the atonic uterus, with the ureters and bladder mesentery simulating the tubes and broad ligaments.

Figure 1.

Porcine bladder with the ureters simulating the Fallopian tubes, and the bladder mesentery simulating the broad ligament.

We use a bovine uterus model (figure 2) with attached broad ligament, bladder and ureters for the transverse (horizontal) haemostatic suture. The bovine uterus has a single cervix which has three to five muscular cartilaginous transverse annular folds, and the uterus is suspended by the broad ligament. The uterine body is approximately 4–5 cm long, and has two horns each of 15–25 cm long, with an oviduct attached to each horn. The cattle uterus has similarities in size to the parturient uterus, and realistic tissue resistance/consistency like the myometrium of the lower uterine segment in an elective caesarean section. Hence, we used it for the transverse haemostatic suture training (mainly used for controlling bleeding from a lower segment abnormal placentation in vivo).

Figure 2.

Bovine uterus with attached broad ligament, bladder and ureters for the transverse haemostatic suture. The bovine uterus has a single cervix and a uterine body with two horns.

Techniques

We organise a 1-day course on emergency and complex operative obstetrics simulation at the Kirklands Medical Education and Training Centre. The centre is a purpose-built suite of conferencing and training facilities operated by NHS Lanarkshire and hosts educational and training events for the West of Scotland medical and surgical trainees.

The facilitator initially assists the trainee, providing guidance and feedback. Subsequently, trainees form surgical teams with the facilitator observing, giving advice where required allowing them to safely practise and develop non-technical skills of leadership, teamwork, delegation and situation awareness.

The candidates are taught and practise the insertion of the brace suture as originally described.^{10 11} The placement of the sutures can be practised with the uterus/bladder closed, or open in its lower part like a caesarean section incision.

Longitudinal brace suture

In summary, for the longitudinal brace suture, the porcine bladder is punctured 3 cm from the right lower edge of the simulated ‘uterine’ incision, 3 cm from the lateral border on the right with a blunt, 70 mm semicircular needle, mounted with a 90 cm, No 1 Monocryl (Ethicon). The suture is then threaded through the cavity emerging through the upper incision margin 3 cm above and 4 cm from the lateral border. The model’s fundus is compressed by passing the suture over approximately 3–4 cm from the right cornual border. The assistant assists with manual compression and the suture is pulled under tension. The length of the suture is passed back posteriorly through the same surface marking as per the right side. As with on the right, the suture passes posteriorly and vertically over the fundus to lie anteriorly, compressing the fundus on the left side. The needle is passed in the same fashion on the left side through the model cavity and out approximately 3 cm anteriorly and below the lower incision margin on the left side. The suture is pulled tight while the assistant exerts bimanual compression. The assistant keeps tension on the long ends of the suture until the surgeon closes the caesarean section incision. The surgeon ties a knot to ensure surgical tension after closure of the caesarean section incision (figure 3) (online supplementary video 1).

Figure 3.

Longitudinal haemostatic brace suture demonstrated on a porcine bladder model. (A) Incision simulating a caesarean section. (B) Insertion of the suture. (C) Insertion of suture complete. (D) Suture tied to achieve compression.

Transverse brace suture

Then practising the transverse brace suture on the cattle uterus, the candidates use a blunt, 70 mm semicircular needle mounted with a 90 cm, No 1 Monocryl suture (Ethicon). The uterus is punctured 3 cm above the upper margin of the incision posteriorly and behind the parauterine vascular bundle. The needle is retrieved through the cavity of the uterus and pulled inferiorly. The needle then perforates the posterior wall of the uterus 3 cm below the inferior margin of the ‘Caesarean’ incision and exits behind the vascular bundle of the same side of the uterus. It is then retrieved, passed through the avascular area of the broad ligament around the vascular pedicle and runs on the surface of the lower segment below the incision margin parallel to it and taking a 1 cm bite of tissue for stabilisation running to the opposite side. After encircling the opposite parauterine vasculature, the needle then perforates the posterior side of the uterus behind the opposite vascular bundle entering the uterine cavity. The suture exits 3 cm above the upper margin of the incision, posteriorly and behind the vascular bundle, then meets the suture from the other side, both having passed through the avascular area of the broad ligament, anterior to the uterus. At the end of the suture application and before tying the knots, the lower segment is compressed transversely while the suture is held taut. Then the lower segment incision is closed in the traditional way. The lower segment is compressed again, while both limbs of the suture are milked through with sufficient tension to maintain haemostasis. The assistant maintains the pressure on the long edges of the suture until the surgeon closes the caesarean section incision. The suture is then tied to ensure the tension is maintained (figure 4) (online supplementary video 2).

Figure 4.

Transverse haemostatic brace suture demonstrated on a cattle uterus model. (A) The uterus is punctured posteriorly and behind the parauterine vascular bundle. (B) The needle is retrieved through the cavity of the uterus and pulled inferiorly. (C) The needle then perforates the posterior wall of the uterus below the inferior margin of the ‘Caesarean’ incision and exits behind the vascular bundle of the same side of the uterus. (D) Suture retrieved, passed through the avascular area of the broad ligament around the vascular pedicle and runs on the surface of the lower segment below the incision margin parallel to it and taking a bite of tissue for stabilisation running to the opposite side. (E) After encircling the opposite parauterine vasculature, the needle then perforates the posterior side of the uterus behind the opposite vascular bundle entering the uterine cavity. (F) The suture exits above the upper margin of the incision, posteriorly and behind the vascular bundle, then meets the suture from the other side, both having passed through the avascular area of the broad ligament, anterior to the uterus. The suture is then tied to ensure the tension is maintained.

Results

All facilitators (n=6) evaluated the ease of use of the models; their quality and effectiveness in delivering the training session; and their real-life fidelity and tissue feedback (online supplementary material 1). All candidates were aware of the new training course, and provided their consent for participation, and for completion of the feedback questionnaire (online supplementary materials 2 and 3). All candidates to date (n=32) completed a pre/postcourse questionnaire.

The questionnaires used a 5-point Likert scale to rate the candidates’ confidence (1—least confident to 5—most confident) in their ability to surgically manage a postpartum haemorrhage and insert haemostatic uterine brace sutures. The questionnaire was repeated 6 months after training course. The results were analysed using a two-sample t-test for comparison of means.

Following the training, there was a significant improvement in the candidates’ mean confidence score for the surgical management of obstetric haemorrhage (3.67 vs 4.67, p<0.001) and for the insertion of haemostatic brace sutures (3.33 vs 4.56, p<0.001) (online supplementary material 4).

Discussion

Postpartum haemorrhage is a major cause of maternal morbidity and mortality. Prompt recognition and management is vital; however, practising haemostatic brace sutures is rarely appropriate in emergency situations. The RCOG recognises the haemostatic brace suture as a key competency in the training curriculum and has created e-learning packages to teach trainees the theory behind the various techniques.

Tissue dissection, suture material, placement and feedback are similar to in vivo conditions. Animal models served to allow trainees to develop skills, including hand–eye coordination, manual dexterity, recognition of the varying degrees of tension applied to tissues and direction of surgical assistants. Surgical skills and confidence were developed in an ‘elective’ environment which transfers to acute obstetric situations.

A disadvantage to animal models is their inability to simulate bleeding which is of particular relevance to haemostatic brace suturing. Thus, animal models should be used as an adjunct rather than a substitute to standard surgical training.

Our wet lab training model allows the acquisition, maintenance and enhancement of the required technical skills in a controlled environment, using inexpensive, reproducible and widely available specimens. The wet lab training programme has been running and evolving since 2016 generating reproducible results and tangible outcomes. Feedback from candidates confirmed increased confidence with surgical procedures including haemostatic uterine sutures which was maintained in the workplace. Two trainees reported using the technique successfully in vivo within 6 months of the course.

To the best of our knowledge, this is the first paper to describe the use of animal models to simulate training in insertion of the haemostatic brace sutures. Other models have been previously described using fabric/cloth material^{12 13}; or refashioned, folded and sutured piece of flank steak meat.¹⁴ Using true anatomical organs provides better tissue feedback, suture drag and real-life fidelity to the model. The presence of a hollow organ cavity also allows for simulation of a caesarean section incision. The presence of adnexa, blood vessels or ureters and their mesentery also allows for better simulation of structures adjacent to the uterus in real life. There is minimal preparation required for our models with no extra suturing or fashioning required.

The model has proved successful in both high and low-resource healthcare settings. It is used in obstetrics emergency courses and training sessions in the West of Scotland Deanery, and has been introduced by the authors in low-resource healthcare settings (Alexandria University Maternity Hospital, Egypt).