Training and teaching fetoscopic laser therapy: assessment of a
high fidelity simulator based curriculum
1
Department of Obstetrics, Division of Fetal Medicine,
2
Department of Pediatrics, Division of
Neonatology, Leiden University Medical Center, The Netherlands.
SHP Peeters1, J Akkermans1, E Lopriore2, JM Middeldorp1, FJ Klumper1, D Oepkes1
1. Department of Obstetrics, Division of Fetal Medicine
2. Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, The
Netherlands.
Background
Multiple gestations comprise around 1% of all pregnancies; however 10% of the overall perinatal
mortality occurs in multiple pregnancies. One specific group of multiple gestations, monochorionic
twin pregnancies, is associated with a particularly high risk of morbidity and mortality. This is the result
of an unbalanced exchange of blood due to vascular anastomoses on a shared placenta that
connects the circulations, causing the twin-to-twin transfusions syndrome (TTTS).
Fig 1. Monochorionic twin pregnancy in separate amniotic
Fig 2. Monochorionic placenta injected with
sacs sharing one placenta
colored dye, showing vascular connections.
TTTS carries a high risk of adverse perinatal outcome due to miscarriage, intrauterine death and
premature birth. The transfusion causes the donor twin to have decreased blood volume and
decreased urinary output, leading to a lower than normal level of amniotic fluid (oligohydramnios). The
blood volume of the recipient twin is increased, which can strain the fetal heart and eventually lead to
heart failure, and also higher than normal urinary output, which can lead to excess amniotic fluid
(polyhydramnios). If not treated, mortality rates in TTTS may be as high as 80 to 100%.1-3
Recipient twin
Donor twin
Amniotic fluid ↑
Amniotic Fluid ↓
Bladder full
Bladder empty
Fig. 3. Recipient and donor twin, developing TTTS
Fetoscopic laser coagulation, a technique used to separate the fetal circulations by coagulating the
connecting vessels with a laser beam, is considered the treatment of choice. 1;4
Therefore a fetal surgeon enters the uterus by
introducing the fetoscope into the amniotic cavity
of the recipient twin, finds the vascular equator
(place where the vascular anastomoses meet) and
tries to laser them one by one, finishing with a line
to connect the laser spots, to prevent small
connections in between to be missed. Missed
(residual) anastomoses are the most common
cause of complications, fetal morbidity and
mortality.
Fig 4. Overview of fetoscopic laser surgery
Fig 5. Fetoscopic laser coagulation.
The incidence of monochorionic twinning is 1 in every 400 pregnancies. TTTS complicates 10-15% of
monochorionic twin pregnancies. With an annual birth rate of 188.000, between 47 and 67 cases of
TTTS are expected in the Netherlands per year.5 Without treatment, this disease would lead to
perinatal death of 80-140 fetuses/neonates annually, a significant proportion of the overall perinatal
mortality of 1153 (2007). Survival rates after laser coagulation for TTTS currently approach 75%.
Further improvement is still urgently needed. TTTS is one of the most challenging clinical problems
concerning multiple gestations. Optimization of fetal therapy in twin pregnancies may contribute to a
major decrease in perinatal mortality. Since these gestations include two fetuses, by one intervention,
two lives can be saved.
Since 2000, monochorionic twin pregnancies complicated by TTTS have been treated with fetoscopic
laser coagulation of placental anastomoses in the Leiden University Medical Center (LUMC), which is
a tertiary medical center in the Netherlands and serves as the national referral center for fetal therapy.
Annually up to 70 patients are treated with laser surgery.
Challenges
Recent published series of laser surgery for TTTS in expert centers still show a relatively high
percentage of single or double fetal loss, premature rupture of membranes and preterm birth. 6;7 With
the acceptance of laser surgery as the best treatment, an increasing number of centers offering this
procedure are expected. There is some concern that a more widespread use of this technique may, at
least temporarily, may lead to less favourable outcome due to learning curve effects. Since TTTS is
relatively rare, and the surgical procedure is quite complex, concentration of care in specialized
Maternal Fetal Medicine (MFM) centers has been advocated.
As for any other procedure it seems logical to offer appropriate training and supervise early practice.
Since fetoscopic procedures are performed on an infrequent basis currently there is a need for
prolonged and expensive stay in distant fetal therapy centers to accumulate hands-on experience, as
surgical training programs commonly prescribe a certain length of time or a set number of procedures
performed to certify operators as competent. Even large fetal treatment centers have limited numbers
of cases, and animal models are lacking, therefore teaching and training this procedure is
challenging. The availability of a highly realistic simulator model provides excellent training
opportunities without jeopardizing patient safety.
A simulator based curriculum for fetoscopic surgery is set up for training and teaching novice fetal
surgeons. In this curriculum we use a high fidelity silicon simulator model (University of Toronto,
Canada), that was also used as a teaching and training facility for perinatal procedures in previous
studies.8
Fig. 6. Simulator model for fetoscopic surgery
Fig. 7. 2D image of placental vessel through
fetoscope in simulator model
The model has been modified with a monochorionic placenta and silicon fetuses. The silicone
interface at the top of the trainer mimics the abdominal wall. The simulator contains water and has
appropriate sonographic properties.
The simulator allows an operator to practice manual dexterity skills necessary to select the best site
for introduction of the instruments: including the fetoscope mounted with a camera and laser beam
through a cannula. The addition the stuck donor twin on the placenta and free recipient twin simulates
the reality based complex situation of floating fetal extremities and umbilical cord in the recipients’ sac
and the inability to oversee the complete vascular equator. Since each placenta is different the
procedure is never the same. Therefore it is important to generate different variations of the vascular
equator, but also simulate other different clinical situations such as: more advanced gestational age
(fetuses and placenta are bigger), unequal sharing of the placenta, contractions during surgery or
maternal agitation.
Assignment
During laser surgery several problems and complicating factors occur. Technical difficulties, such as
bleeding in amniotic cavity, stuck twin on vascular equator or anterior position of the placenta, are
often related to insufficient visibility for the operating surgeon. These conditions may prevent complete
coagulation of the vascular equator, which is crucial in the treatment for TTTS and have major
influence on perinatal outcome.
In this assignment we want to escalate our simulator model with a couple of features to provide a
more realistic training environment. We will focus on different types of technical challenges, examples
being severely decreased visibility, anterior location of the placenta, unequal sharing of the placenta,
inability to oversee the complete equator due to the donor twin that is stuck on the placenta.
By the end of the assignment a contribution can be made to an advanced realistic and feasible
training simulator that can be added to the training curriculum and be implemented in Maternal Fetal
Medicine Centers worldwide.
Contact Information
Suzanne Peeters, MD, PhD Candidate
Researcher Medical Delta Fetal Therapy
Leiden University Medical Center
Albinusdreef 2, 2300 RC
Leiden, The Netherlands
phone: +31 6 22644625
email: s.h.p.peeters@lumc.nl
site: www.deltafetus.nl
Dick Oepkes, MD, PhD
Professor in Obstetrics and Fetal Therapy
Department of Obstetrics, K-06-35
Leiden University Medical Center
P.O.Box 9600
2300 RC Leiden, The Netherlands
T: +31-71-5262896 F: +31-71-5266741
email: d.oepkes@lumc.nl
site: www.lumc.nl/verloskunde
Recommended literature
Twin-twin transfusion syndrome.
Society for Maternal-Fetal Medicine, Simpson LL.
Am J Obstet Gynecol. 2013 Jan;208(1):3-18. doi: 10.1016/j.ajog.2012.10.880. Epub 2012 Nov 27.
Erratum in: Am J Obstet Gynecol. 2013 May;208(5):392.
The vascular anastomoses in monochorionic twin pregnancies and their clinical
consequences.
Lewi L, Deprest J, Hecher K.
Am J Obstet Gynecol. 2013 Jan;208(1):19-30. doi: 10.1016/j.ajog.2012.09.025. Epub 2012 Sep 28.
Review.
Fetal and maternal complications after selective fetoscopic laser surgery for twin-to-twin
transfusion syndrome: a single-center experience.
Rustico MA, Lanna MM, Faiola S, Schena V, Dell'avanzo M, Mantegazza V, Parazzini C, Lista G,
Scelsa B, Consonni D, Ferrazzi E.
Fetal Diagn Ther. 2012;31(3):170-8. doi: 10.1159/000336227. Epub 2012 Mar 23.
Reference List
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