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Fetal surgery and anaesthetic implications



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Fetal surgery and anaesthetic
Griselda Cooper OBE FRCA FRCOG
Surgery to the fetus while it is still in utero is
used to treat an increasing number of lethal and
non-lethal conditions. The problems of preterm
labour and premature rupture of membranes
associated with open surgery have led to the
development of minimal access surgical tech-
niques. Although fetal surgery is a new and fast
moving frontier of medicine, it is not one that
all obstetric anaesthetists will encounter. The
first successful human fetal operation was per-
formed in 1983, but it is still only carried out
in a limited number of specialist tertiary
The broad challenges presented to the
anaesthetist are:
(i) those related to any anaesthetic in a preg-
nant woman;
(ii) techniques used to prevent preterm labour;
(iii) maintenance of maternal homeostasis in
the face of tocolytic techniques;
(iv) maintenance of fetal homeostasis;
(v) provision of fetal analgesia during
(vi) distance the mother may need to travel
from home.
It is expected that the indications for fetal
therapy will expand. The most frequently
occurring condition operated on relatively com-
monly in the UK is twin-to-twin transfusion
syndrome. Life-threatening conditions that have
had in utero intervention to lessen the severity
of pathology include congenital diaphragmatic
hernia, obstructive uropathy, and sacrococcy-
geal teratoma. There is also a prospective ran-
domized trial ongoing in the USA to determine
the role and efficacy of in utero surgery for
Fetal surgical interventions include the
(i) Minimally invasive ( percutaneous inser-
tion of shunts and in utero, intravascular
fetal transfusions); these are the most
commonly performed procedures.
(ii) Fetoscopic therapy.
(iii) Open procedure, involving a hysterotomy.
Intrauterine transfusions for rhesus disease and
fetal anaemia are performed by ultrasound-
directed fetal vessel puncture under local
anaesthesia. For other, more complex surgery,
the anaesthetist is part of a multidisciplinary
team which allows understanding of the patho-
genesis of the fetal conditions and how the
planned therapy may influence outcome. In this
article, it is assumed that the anaesthetist is
familiar with routine obstetric anaesthetic con-
siderations: those relevant to the fetal surgery
are highlighted.
Twintwin transfusion
Twin twin transfusion syndrome (TTTS) is a
serious complication of a twin pregnancy in
which there is only one placenta (monochorio-
nic twin gestation). It complicates 1020% of
monochorionic identical twin pregnancies.
is due to unequal blood flow across vascular
anastomoses between the two fetal circulations
with the larger twin being at risk of cardiac
overload and the smaller twin being relatively
hypoperfused. In addition to the severe haemo-
dynamic imbalance, there are discordant liquor
volumes, the ‘recipient’ twin having severe
polyhydramnios, and the ‘donor’ having severe
oligohydramnios adhering onto the uterine
wall. Both twins are therefore at risk of severe
haemodynamic compromise, death, and prema-
ture delivery. TTTS is diagnosed by ultrasound.
In addition to the fetal complications, parturi-
ents with severe TTTS may rarely develop
‘mirror syndrome’
which is characterized
by pulmonary oedema, anasarca (severe
generalized oedema), albuminuria, hyperten-
sion, and a reduction in haemoglobin concen-
tration due to haemodilution. The maternal
Key points
Fetal surgery is performed
in specialist centres and
requires multidisciplinary
In addition to obstetric
anaesthetic considerations,
the anaesthetist needs to be
conversant wit h tocolytic
Fetal analgesia is required
for some procedures.
The use of fetoscopic
procedures is increasing;
however, presently, only
laser ablation of placental
vessels is of proven efficacy.
Specialist Registrar
Department of Anaesthesia
Queen Elizabeth Hospital
Birmingham B15 2TH
Dame Hilda Lloyd Professor of Maternal
and Fetal Medicine
Birmingham Women’s Hospital
University of Birmingham
Metchley Park Road
Birmingham B15 2TG
Griselda Cooper OBE FRCA FRCOG
Consultant Anaesthetist
Department of Anaesthesia
Queen Elizabeth Hospital
Birmingham B15 2TH
Tel: þ44 121 627 2060
Fax: þ44 121 627 2062
(for correspondence)
Continuing Education in Anaesthesia, Critical Care & Pain | Volume 8 Number 2 2008
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manifestations generally reflect the severity of the fetal placental
Treatment options include amnioreduction (removing 1 4 litres
of amniotic fluid from around the recipient). This is often per-
formed before 26 weeks gestation and requires serial procedures
until delivery. Although this is a relatively inexpensive simple
technique that can be performed with limited experience and pro-
vides potential rescue for both fetuses, it does not affect the under-
lying pathology. There is little improvement in the fetal condition
in advanced disease and a randomized controlled trial has shown
that pregnancies treated using this method have a greater likelihood
of survivors with cerebral palsy.
Recently, laser ablation of placental vessels has emerged as a
potential treatment for severe TTTS. It involves fetoscopic laser
photocoagulation of unidirectional arteriovenous vessels on the
surface of the twin placenta and attenuation of the haemodynamic
consequences of this pathophysiology. This technique prolongs
pregnancy compared with amnioreduction.
A recent systematic
review indicated that fetoscopic laser ablation was associated with
improved outcomes for fetal survival of one or both twins and
a reduced risk of long-term neurodevelopmental morbidity in sur-
vivors, see Figure 1.
Real-time ultrasound allows location of the placenta, umbilical
cord, and amniotic membranes. Technically, an anterior placental
site may be more surgically demanding. However, modification of
surgical instruments, positioning of the patient, and the creation of
an adequate ‘operating window’ using amnioinfusion all aid ade-
quate visualization of the chorionic plate and inter-twin membrane.
Risks of the procedure include: amniorrhexis ( pre-labour ruptured
amniotic membranes) 5%; subchorionic bleed (, 1%); preterm
delivery; neuromorbidity; and double or single fetal death.
Follow-up is required as there is a 5% recurrence rate.
In many centres, maternal spinal, epidural, or combined
spinal/epidural anaesthesia is used. Alternatively, local infiltration
of the skin and subcutaneous tissues with lidocaine 1% (down
to the myometrium) and maternal sedation is used. In
addition to maternal sedation, pharmacotherapy also causes fetal
immobilization. In a randomized controlled trial, Missant and
demonstrated that remifentanil was a safer option
than diazepam.
Fig. 1 A systematic review of the RCT and two comparative controlled trials assessing the efficacy of fetoscopic laser ablation in the treatment of severe
Fetal surger y and anaesthetic implications
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number 2 2008
Congenital diaphragmatic hernia
The incidence of congenital diaphragmatic hernia is 1:2400 live
It causes pulmonary hypoplasia by compression of lung
tissue from the herniated organs and arguably abnormal develop-
ment of the pulmonary vasculature. Until recently, the possibilities
available to expectant parents of a fetus diagnosed with congenital
diaphragmatic hernia were termination of pregnancy or continu-
ation of the pregnancy until term with postnatal surgical correction.
A series of case cohort studies using modern fetoscopic procedures
have indicated that potentially severe congenital diaphragmatic
hernia with a high predicted risk of fatal pulmonary hypoplasia
may have improved overall survival with in utero therapy.
Recent studies have focused on in utero triage’ of the fetus
emphasizing the exclusion of co-existent structural and chromoso-
mal anomalies which carry a corresponding poor prognosis. In
addition, poor lung development can be prospectively identified by
ultrasound; liver in the fetal chest; and a lung head ratio of ,1
are relatively sensitive and specific for identifying fetuses develop-
ing pulmonary hypoplasia. Such triage has allowed the possibility
of fetal therapeutic intervention. Animal studies have indicated that
transient tracheal occlusion may prevent or lessen the structural
and physiological effects of pulmonary hypoplasia.
To date, two
studies have utilized lung head ratio to establish the prospective
high risk of pulmonary hypoplasia within groups of fetuses and
compared outcome after treatment by fetoscopic tracheal occlusion
with conservative management.
In such fetoscopic procedures, combined spinal anaesthesia or
local anaesthesia is required and immobilization of the fetus is
Ex utero intrapartum treatment procedure
The ex utero intrapartum treatment (EXIT) procedure is now used
to establish a patent airway in the management of fetuses with
potential airway obstruction.
It allows the continuing placental
perfusion of the partially exteriorized fetus until a formal airway
has been established. Some common indications include:
(i) mass obstructing the upper airway, e.g. cystic hygroma,
thyroid goitre;
(ii) congenital high airway obstruction syndrome (CHAOS). This
spectrum of anomalies includes laryngeal web, atresia, or
cyst, and tracheal atresia or stenosis. It is characterized by
enlarged lungs, dilated distal airways, everted diaphragm,
ascites, and ultimately non-immune hydrops fetalis;
(iii) thoracic abnormalities, e.g. hydrothorax, tumours.
The EXIT procedure allows intubation, tracheostomy, or even
resection of the lesion while the infant is still on placental support.
Management requires obstetricians, anaesthetists, otolaryngolo-
gists, and paediatric surgeons. EXIT procedures are performed
during caesarean section before clamping of the umbilical cord.
When performing a hysterotomy, only the fetal head and shoulders
are delivered to preserve umbilical blood flow and to prevent eva-
porative heat and fluid loss. This allows time to secure the neonatal
airway. Continued uteroplacental circulation has been maintained
for up to 1 h without fetal compromise.
A potential complication
is antepartum haemorrhage at the time in which the fetal airway is
being secured due to the need for uterine relaxation.
General anaesthesia is indicated. The mother is prepared for the
eventuality of major haemorrhage with monitoring instituted
before surgery, i.e. two large bore i.v. cannulae, arterial line,
central venous line, and availability of cross-matched blood.
A rapid sequence induction with left uterine displacement (redu-
cing aorto-caval compression) is carried out with the adminis-
tration of high concentrations of volatile anaesthetic agent
(e.g. isoflurane 2 3%) to maintain uterine relaxation. Other
tocolytics (Table 1) may be needed if there is inadequate uterine
relaxation. Vasopressor agents are required for the consequent
maternal hypotension in order to maintain uterine blood flow and
maternal well-being. Fetal anaesthesia is obtained via placental
transfer of volatile agents, but occasionally muscular paralysis may
be necessary to ensure fetal immobility.
Once the fetal airway has
been secured, the uterus is made to contract with an infusion of
Close monitoring of uterine contraction, cardiovascular par-
ameters, and any haemorrhage is essential after the operation.
Thus, mother and baby will both require high dependency care. In
the absence of contraindications (e.g. coagulopathy), epidural
analgesia can be considered for the mother.
Table 1 Tocolytic agents
Agent Advantages Caution
b-adrenergic agents, e.g.
terbutaline, ritodrine
Maternal tachycardia,
hypotension, myocardial
ischaemia, decreased glucose
tolerance, pulmonary oedema
Magnesium sulphate In high concentration fetal
side-effects include decreased
heart rate variability, reduced
muscular activity at birth
Halogenated volatile
agents, e.g. isoflurane
Used to provide
Prolonged use can cause fetal
Glyceryl trinitrate Rapid onset of
drugs, e.g.
Limited to short-term use for
48 h, and before gestational
age of 32 weeks, due to risk of
premature closure of ductus
arteriosus in the fetus,
decreased renal function
resulting in oligohydramnios,
increased risks of necrotising
enterocolitis and
intraventricular haemorrhage
Calcium antagonists Maternal hypotension
Fetal surger y and anaesthetic implications
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number 2 2008 73
Obstructive uropathy
Obstructive uropathy occurs in one in 1000 live births.
urinary tract obstruction is associated with less morbidity and mor-
tality than lower obstruction which is usually caused by posterior
urethral valves.
The obstruction increases bladder pressure, resulting in changes
in bladder structure and function, vesicoureteric reflux, hydroureter,
hydronephrosis, and a risk of chronic renal failure later in life.
The resulting oligohydramnios and pulmonary hypoplasia increases
neonatal mortality. Fetal surgery aims to prevent this from
Open surgery (nephrostomy) carries a high mortality, a risk of
amniorrhexis and preterm labour, and a third of those treated still
require transplantation at a later stage. It requires maternal hyster-
otomy and has largely been abandoned. Fetal vesicoamniotic
shunting is the placement of a catheter, using a percutaneous
needle under continuous ultrasound guidance, into the fetal
bladder. The distal end of the catheter traverses the fetal anterior
abdominal wall and drains into the amniotic cavity. This procedure
is usually performed under local anaesthesia with lidocaine.
The diagnosis of myelomeningocele is possible in early pregnancy.
It causes progressive neurological impairment and carries a poor
prognosis. Prenatal diagnosis and treatment may allow prevention
of the neurological deficit and preserve spinal cord cryoarchitecture.
Tocolysis is essential during fetal surgery and after operation as
fetal interventions are associated with preterm labour. Impaired
uterine blood flow or partial placental separation can occur due to
uterine manipulation or incisions, hence jeopardizing umbilical
placental blood flow. Even minor interventions (e.g. needle
insertion for intrauterine transfusion) can result in strong uterine
contractions, and hence may cause unintentional puncture of other
structures. Tocolysis is also important after operation as preterm
uterine contractions can still occur. Table 1 gives examples of the
tocolytic agents which can be used and the main points about
their use. The choice of agent is determined by maternal side-
Drugs acting on the uterus have been reviewed
Fetal stress
There is considerable evidence that the fetus may experience pain.
Not only is there a moral obligation to provide fetal anaesthesia
and analgesia, but it has also been shown that pain and stress may
affect fetal survival and neurodevelopment.
Factors suggesting
that the fetus experiences pain include the following.
(i) Neural development. Peripheral nerve receptors develop
between 7 and 20 weeks gestation, and afferent C fibres begin
development at 8 weeks and are complete by 30 weeks ges-
tation. Spinothalamic fibres (responsible for transmission of
pain) develop between 16 and 20 weeks gestation, and thala-
mocortical fibres between 17 and 24 weeks gestation.
(ii) Behavioural responses. Movement of the fetus in response to
external stimuli occurs as early as 8 weeks gestation, and
there is reaction to sound from 20 weeks gestation. Response
to painful stimuli occurs from 22 weeks gestation.
(iii) Fetal stress response. Fetal stress in response to painful
stimuli is shown by increased cortisol and b-endorphin con-
centrations, and vigorous movements and breathing efforts.
There is no correlation between maternal and fetal norepi-
nephrine levels, suggesting a lack of placental transfer of nor-
epinephrine. This independent stress response in the fetus
occurs from 18 weeks gestation.
There may be long-term
implications of not providing adequate fetal analgesia such as
hyperalgesia, and possibly increased morbidity and mortality.
Fetal analgesia
As with any procedure, the provision of analgesia depends on the
likely severity of pain associated with the intervention. However,
analgesia is recommended for:
(i) endoscopic, intrauterine surgery on placenta, cord, and
(ii) late termination of pregnancy;
(iii) direct surgical trauma to the fetus.
For open surgery, where a general anaesthetic technique (with or
without an epidural) is used, the fetus obtains anaesthesia via the
placenta, although direct administration from i.m. injections can
also be used.
For fetoscopic fetal surgery, maternal anaesthesia is most
usually by local anaesthetic infiltration or a regional block. A com-
bined spinal/epidural minimizes haemodynamic changes.
These techniques can be supplemented with sedation or remi-
fentanil. Local or regional techniques are sometimes difficult
because of maternal anxiety; in addition, they may not adequately
immobilize the fetus. A mobile fetus can displace the endoscope
resulting in bleeding, fetal trauma, or compromised umbilical cir-
culation resulting in fetal death. The short-acting opioid remifenta-
nil is easy to titrate and crosses the placenta readily immobilizing
the fetus. Using a continuous infusion rate of remifentanil 0.1 mg
, fetal immobilization and maternal sedation are
Mild respiratory acidosis occurs but maternal apnoea
can be avoided and good operating conditions obtained. This tech-
nique is recommended for TTTS.
Fetal anaesthesia, homeostasis, and immobility can be provided
by direct fetal injections (i.m. or into the umbilical cord) with the
use of opioids, atropine, and neuromuscular blocking agents. Fetal
Fetal surger y and anaesthetic implications
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number 2 2008
i.m. opioids reduces the stress response.
Suitable anaesthetic tech-
niques for fetoscopic surgery on membranes, cord, and the pla-
centa are as discussed above.
The complications of minimal access fetal surgery are summarized
in Table 2.
Social factors
As minimal access fetal surgery is only carried out in specialist
centres, patients frequently have to travel long distances.
Organization needs to include social support for the families where
necessary. This is an important factor when considering discharge
from hospital. Good communication between the tertiary centre
and referring hospital is vital.
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Please see multiple choice questions 25 28
Table 2 Complications of minimal access fetal surgery
Complication How it can be minimized
Bleeding Avoid placenta on entering uterus
Preterm labour Use of tocolytics. Many theories used to describe why
this occurs (e.g. rapid changes in uterine volume,
infection, hormonal changes, fetomaternal stress,
and membrane rupture)
Chorioamniotic membrane
Surgical technique
Premature rupture of
Most common problem associated with fetal surgery.
Research is ongoing into sealing ruptured
membranes with collagen plugs
Fetal surger y and anaesthetic implications
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number 2 2008 75
... Recent researches indicated that infants not only experience pain, if inadequately or not anaesthetised, but pain and stress may also affect foetal survivor and neurodevelopment [22,23]. Based on preclinicial studies, there is stepwise, but significant, development of peripheral nerve receptors, afferent C fibres, and spinothalamic and thalamocortical fibres during 7-20, 8-30, 16-20 and 17-24 WoG, while the response to external stimuli, sound, and painful stimuli develop as early as 8, 20, and 22 WoG, respectively. ...
... This independent stress response in the foetus begins from 18 WoG, and in neonates, can be 3-5 times more than those in adults. These may be long-term implications of not providing adequate foetal analgesia such as hyperalgesia, and possibly increased morbidity and mortality [19,22]. ...
... From a medically ethical point of view amidst biological aspects, surgery in an innocent infant (who cannot tell whether it has pain or not) without anaesthesia is unethical and should be avoided [17,22]. Anyhow, general anaesthesia is always not the answer. ...
Full-text available
Tongue-tie (ankyloglossia) is a relatively common congenital anomaly characterised by an abnormally short lingual frenulum, causing limitation of tongue mobility. There have been immense controversies regarding diagnosis, clinical significance and management of such condition hitherto. Although most tongue-tie babies are asymptomatic without feeding difficulties, operative corrections may be necessary in some cases to improve their breastfeeding. Using a meta-narrative reviewing study design, the aim of this concise review was to demonstrate the current evidences for surgical indications, optimal type and timing, and functional improvement from tongue-tie surgery. We reviewed and discussed the included evidences based on five topics: (1) basic sciences, (2) clinical equipoise, (3) anaesthesia during childhood, (4) evidence-based practice and surgical meta-analyses, and (5) appropriate patient assessment in routine paediatric practice.
... Opioids can be provided to the foetus either via intramuscular injection or via umbilical cord [132,133]. Some investigators recommend administering 20 µg/kg intramuscular fentanyl to the foetus prior to the procedure [134,135], while others recommend giving the mother a continuous infusion rate of 0.1 µg/kg/min remifentanil to achieve foetal immobilization and maternal sedation, although they do not exclude the direct administration of analgesics to the foetus. Intra-amniotic administration of opioids to the foetus has been proposed: researchers have shown that higher plasma concentrations are obtained in foetal lamb than in sheep, suggesting that this pathway could be usable for humans [136]. ...
Full-text available
Objectives: Foetal surgery is a relatively new branch of medicine; the health providers involved are currently wondering what kind of anaesthesia should be provided to the foetuses. In the last few years, new advances have been reported on foetal sensoriality and capability for feeling pain; meanwhile alerts have been issued on the risks of prolonged anaesthesia in the early infancy. Aim of this paper is reviewing the main data on foetal pain, to be aware of which is the time in pregnancy when it is likely to be felt. The secondary aim is to point out which are the anaesthetics and analgesics appropriate for prenatal surgery. Mechanism: A review of the literature published in the last 20 years in the field of fetal sensoriality and fetal sergery has been carried out; the most pertinent papers have been retrieved, and their conclusions are here summarized and analysed. Findings in brief: Pain can be felt by the human fetus in the second half of pregnancy: data of physiological and behavioural studies show it with increasing evidence, as long as the gestational age increases. With regard to the best anaesthesia in this case, it seems that the mere anaesthetics given to the mother, though apparently sufficient during laparoscopic surgery, are not sufficient to anesthetize the foetus during open surgery; here some references are given for the best and safest foetal direct analgesic treatment. Conclusions: Surgeons should approach carefully fetal surgery, according with the latest findings in this field.
... Anesthetic challenges include care of a pregnant patient, modifying fetal stress responses during the procedure, provision of fetal anesthesia or analgesia, and maintenance of maternal and fetal homeostasis. [4] The ideal timing for the intervention is during the second trimester for which maternal safety and good fetal outcomes have been documented. [5] However, fetal intervention alone may not be adequate in all cases and delivery must be planned at a center equipped for perinatal cardiac care and the need for palliative surgery, valve replacement, and long-term follow-up. ...
... Some researchers recommend that 20 μg/kg of intramuscular fentanyl be administered to the fetus before the procedure, 94 while others recommend that a continuous infusion rate of remifentanil 0.1 μg kg −1 min −1 be administered to the mother to obtain the fetal immobilization and maternal sedation, although they do not exclude the direct administration of analgesics to the fetus. 101 Some researchers have used intra-amniotic opioids for fetal analgesia on lamb fetuses, 102,103 and have shown that higher plasma concentrations of opioids have been obtained in the fetal lamb than in their mother sheep, suggesting that this pathway could be used for humans. Van de Velde and De Buck 95 as well as Pelizzo 104 have provided useful schemes for the administration of analgesics to the mother and fetus during surgery. ...
Some doubts on the necessity and safety of providing analgesia to the fetus during prenatal surgery were raised 10 years ago. They were related to four matters: fetal sleep due to neuroinhibitors in fetal blood, the immaturity of the cerebral cortex, safety, and the need for fetal direct analgesia. These objections now seem obsolete. This review shows that neuroinhibitors give fetuses at most some transient sedation, but not a complete analgesia, that the cerebral cortex is not indispensable to feel pain, when subcortical structures for pain perception are present, and that maternal anesthesia seems not sufficient to anesthetize the fetus. Current drugs used for maternal analgesia pass through the placenta only partially so that they cannot guarantee a sufficient analgesia to the fetus. Extraction indices, that is, how much each analgesic drug crosses the placenta, are provided here. We here report safety guidelines for fetal direct analgesia. In conclusion, the human fetus can feel pain when it undergoes surgical interventions and direct analgesia must be provided to it. Fetal pain is evident in the second half of pregnancy. Progress in the physiology of fetal pain, which is reviewed in this report, supports the notion that the fetus reacts to painful interventions during fetal surgery. Evidence here reported shows that it is an error to believe that the fetus is in a continuous and unchanging state of sedation and analgesia. Data are given that disclose that drugs used for maternal analgesia cross the placenta only partially, so that they cannot guarantee a sufficient analgesia to the fetus. Safety guidelines are given for fetal direct analgesia.
... [14] Thus, D and X does not constitute infanticide or neonaticide; killing the fetus is not an essential element of D and X, as the procedure is often employed in cases of miscarriage. [17] The majority of surgical abortion procedures available during each trimester incorporates fetal dismemberment, specifically: manual vacuum aspiration, suction and curettage, dilation and curettage and D and E. [14,[62][63][64][65] The remaining procedures -IOL, hysterectomy and hysterotomy -usually employ feticidal solutions that generally asphyxiate and incinerate the fetus to effect fetal demise. [14,66,67] Evidently, D and X is significantly less destructive, and perhaps more humane than most feticidal abortion procedures available. ...
... Some researchers recommend administering 20 μg/kg of intramuscular fentanyl to the fetus prior to the procedure [45], while others recommend the administration to the mother of a continuous infusion rate of remifentanil 0.1 μg kg−1 min−1, to achieve fetal immobilization and maternal sedation, though they do not exclude directly administering analgesics to the fetus [46]. Some researchers utilized intra-amniotic opioids for fetal analgesia on lamb fetuses [47]: they showed that greater plasma concentrations were obtained in the fetal lamb as compared with the ewe, suggesting that this route might be utilizable for humans. ...
Fetal pain is difficult to assess, because the main feature needed to spot pain, is the subject's capability of declaring it. Nonetheless, much can be affirmed about this issue. In this review we first report the epochs of the development of human nociceptive pathways; then we review since when they are functioning. We also review the latest data about the new topic of analgesia and prenatal surgery and about the scarce effect on fetal pain sentience of the natural sedatives fetuses produce. It appears that pain is a neuroadaptive phenomenon that emerges in the middle of pregnancy, at about 20-22 weeks of gestation, and becomes more and more evident for bystanders and significant for the fetus, throughout the rest of the pregnancy.
With advances in ultrasound, birth defects are increasingly detected during pregnancy and may be amenable to surgical correction before delivery, to improve outcomes. This essential book discusses the different birth defects that can be treated during pregnancy and the important anesthetic considerations for the mother and fetus undergoing these procedures. Experts in the fields of anesthesiology, maternal fetal medicine, surgery, and pediatrics have come together to develop the content of this book. Enhanced throughout with full color images and illustrations, the book covers important topics such as spina bifida, twin-twin transfusion syndrome, sacrococcygeal teratoma, and lung masses, as well as fetal cardiac intervention, intrauterine transfusion, ex utero intrapartum treatment, and multidisciplinary approaches to fetal surgery. An invaluable guide for pediatric and obstetric anesthesiologists, anesthesiology, obstetrics, and surgical trainees, nurse anesthetists, and maternal-fetal medicine specialists.
Over the last three decades, advances in early diagnosis of fetal anomalies, imaging and surgical techniques have led to a huge expansion in fetal surgery. A small number of specialist centres perform fetal surgery, which involves high‐risk anaesthesia for the mother and fetus. The anaesthetist plays an integral role within the large multispecialty and multidisciplinary team, involved in planning and delivering care for complex surgical procedures. This article reviews three fetal surgical procedures, congenital diaphragmatic hernia, myelomeningocele repair and ex‐utero intrapartum treatment for airway obstruction. The underlying fetal pathology, surgical management, anaesthetic considerations and risks for both the mother and fetus are described for each. Fundamental to this is the understanding that clear communication and collaboration between all team members is vital to ensure successful outcomes of patients, the mother and the fetus.
Fetal surgery presents the anesthesiologist with a unique set of challenges depending on the surgical approach – be it during gestation or at the time of delivery. Anesthesia must be provided for the mother to eliminate pain and optimize muscle relaxation for uterine incision and fetal exposure. In addition, anesthesia is required for the fetus/partially born patient to account for pain and stress that accompany any invasive procedure. Consideration must be given to the physiological changes that occur to a woman during pregnancy and the specific issues that are presented by fetal development at various stages. The different approaches to anesthesia for these procedures are presented along with the possible complications.
Full-text available
Fetal surgery in utero is an alternative for treatable congenital malformations. Prognosis will improve with early correction. Once the surgical technique is planned, the anesthetist's knowledge of maternal and fetal physiology is crucial for the selection of the ideal anesthetic technique for each individual case, considering the type of surgical procedure and the expected degree of fetal stimulation. In this way, the optimal surgical field with maternal and fetal safety will be ensured. This article describes 1 case of twin-to-twin transfusion syndrome under spinal anesthesia and sedation, and a second case of hydrothorax drainage under sedation.
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Monochorionic twin pregnancies complicated by severe twin-to-twin transfusion syndrome at midgestation can be treated by either serial amnioreduction (removal of large volumes of amniotic fluid) or selective fetoscopic laser coagulation of the communicating vessels on the chorionic plate. We conducted a randomized trial to compare the efficacy and safety of these two treatments. Pregnant women with severe twin-to-twin transfusion syndrome before 26 weeks of gestation were randomly assigned to laser therapy or amnioreduction. We assessed perinatal survival of at least one twin (a prespecified primary outcome), survival of at least one twin at six months of age, and survival without neurologic complications at six months of age on the basis of the number of pregnancies or the number of fetuses or infants, as appropriate. The study was concluded early, after 72 women had been assigned to the laser group and 70 to the amnioreduction group, because a planned interim analysis demonstrated a significant benefit in the laser group. As compared with the amnioreduction group, the laser group had a higher likelihood of the survival of at least one twin to 28 days of age (76 percent vs. 56 percent; relative risk of the death of both fetuses, 0.63; 95 percent confidence interval, 0.25 to 0.93; P=0.009) and 6 months of age (P=0.002). Infants in the laser group also had a lower incidence of cystic periventricular leukomalacia (6 percent vs. 14 percent, P=0.02) and were more likely to be free of neurologic complications at six months of age (52 percent vs. 31 percent, P=0.003). Endoscopic laser coagulation of anastomoses is a more effective first-line treatment than serial amnioreduction for severe twin-to-twin transfusion syndrome diagnosed before 26 weeks of gestation.
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Twin to twin transfusion syndrome (TTTS) affects 10 to 15% of monochorionic twin pregnancies. Untreated, perinatal loss exceeds 80%, of which survivors have a great risk for long-term neurological disorders as psychomotor retardation or cerebral palsy. TTTS can be treated using foetoscopy and selective ablation of the twin-to-twin blood vessels under local or regional anaesthesia. However, local or regional anaesthesia does not always result in excellent maternal comfort, nor does it provide foetal immobilisation, necessary for optimal surgical conditions. Using a continuous infusion rate of remifentanil 0.1 microg/kg/min, perfect foetal immobilisation and excellent maternal sedation was achieved. Only mild respiratory acidosis was observed as a result of mild respiratory depression. In no mother apnoe occurred. All haemodynamic parameters, both foetal and maternal, remained stable during the procedure. Maternal sedation, respiratory depression and foetal immobilisation were quickly reversible following cessation of the remifentanil infusion.
Ballantyne syndrome was first described in association with severe hydrops fetalis caused by rhesus isoimmunization, and lately, in association with diverse etiologies of nonimmunological severe fetal hydrops. This report is a case of typical Ballantyne syndrome in association with lethal hydrops fetalis caused by Ebstein's anomaly. It is likely that any severe fetal hydrops with massive placental hydrops may produce Ballantyne syndrome. Hemodilution could be the main biological feature, differentiating Ballantyne syndrome from usual preeclamptic syndromes. Pathophysiological hypotheses are discussed.
Fetal and maternal plasma noradrenaline responses to invasive procedures were determined in pregnancies of 18 to 37 wk gestation. Fetal umbilical venous blood sampling was performed either from the placental cord insertion, which is not innervated, or the intrahepatic vein, which is innervated, and thus may be more stressful for the fetus. Samples from diagnostic procedures, as well as from transfusion procedures, were compared between the two sites. Fetal plasma levels were significantly elevated in blood samples obtained from the intrahepatic vein compared with those from the placental cord insertion during diagnostic procedures [p < 0.05, geometric means and 95% confidence intervals (CI) were 0.67 nmol/L (0.43-1.04) and 0.36 nmol/L (0.25-0.54), respectively]. Plasma levels in samples taken before transfusion from the intrahepatic vein were also significantly higher than those from the placental cord insertion. After transfusion, there was a significant rise in fetal plasma noradrenaline levels at both sites; however, after transfusion through the intrahepatic vein, the rise was substantially greater than after transfusion through the placental cord insertion (p < 0.05, change, mean deltaNA, and 95% CI were 0.67 (0.37-1.22), and 0.20 (0.12-0.33), respectively). The deltaNA was significantly associated with the duration of the stimulus (the time the needle remained in situ) (p = 0.05, adjusted R2 = 0.48) and with gestational age. Maternal levels rose substantially and equally after transfusions at either site (mean deltaNA and 95% CI, 6.46 nmol/L, 1.74 to 11.18 and 9.49 nmol/L, 6.24 to 12.75 for the intrahepatic vein and placental cord insertion groups, respectively). There was no significant correlation between baseline fetal and maternal levels (r = 0.08, n = 41) or between deltaNA pre- and posttransfusion maternal and fetal values in either group. These results indicate that the fetus is capable of mounting an independent noradrenaline stress response to a needle transgressing its trunk from 18 wk gestation. The effect was observable in samples taken at a mean of 5.6 min after needling. The lack of correlation between maternal and fetal levels suggests that virtually no noradrenaline crosses the placenta directly, and that the observed fetal responses are not due to direct transport from the mother.
Whether the fetus can experience pain remains controversial. During the last half of pregnancy, the neuroanatomic connections for nociception are in place, and the human fetus mounts sizable stress responses to physical insults. Analgesia has been recommended for intrauterine procedures or late termination, but without evidence that it works. The authors investigated whether fentanyl ablates the fetal stress response to needling using the model of delayed interval sampling during intrahepatic vein blood sampling and transfusion in alloimmunized fetuses undergoing intravascular transfusion between 20 and 35 weeks. Intravenous fentanyl (10 microg/kg estimated fetal weight x 1.25 placental correction) was given once at intrahepatic vein transfusion in 16 fetuses, and changes (posttransfusion - pretransfusion) in beta endorphin, cortisol, and middle cerebral artery pulsatility index were compared with intrahepatic vein transfusions without fentanyl and with control transfusions at the placental cord insertion. Fentanyl reduced the beta endorphin (mean difference in changes, -70.3 pg/ml; 95% confidence interval, -121 to -19.2; P = 0.02) and middle cerebral artery pulsatility index response (mean difference, 0.65; 95% confidence interval, 0.26-1.04; P = 0.03), but not the cortisol response (mean difference, -10.9 ng/ml, 95% confidence interval, -24.7 to 2.9; P = 0.11) in fetuses who had paired intrahepatic vein transfusions with and without fentanyl. Comparison with control fetuses transfused without fentanyl indicated that the beta endorphin and cerebral Doppler response to intrahepatic vein transfusion with fentanyl approached that of nonstressful placental cord transfusions. The authors conclude that intravenous fentanyl attenuates the fetal stress response to intrahepatic vein needling.
The development of fetal surgery has led to promising therapeutic options for a number of congenital malformations. However, preterm labor (PTL) and premature rupture of membranes continue to be ubiquitous risks for both mother and fetus. To reduce maternal morbidity and the risk of prematurity, minimal access surgical techniques were developed and are increasingly employed. Congenital diaphragmatic hernia (CDH), obstructive uropathy, twin-to-twin transfusion syndrome (TTTS), and sacrococcygeal teratoma have already been successfully treated using minimal access fetal surgical procedures. Other life-threatening diseases as well as severely disabling but not life-threatening conditions are potentially amenable to treatment. The wider application of minimal access fetal surgery depends on a continued improvement in technology and a better understanding of complications associated with fetal intervention.
Refined techniques and skills have enabled sophisticated prenatal diagnosis in utero and resulted in the newly evolving specialty of fetal surgery in a few centres worldwide. Most of the procedures performed today have been preceded by extensive experimental research in animals, whereas fetal anaesthesia is mainly based on clinical experience and a few studies performed in pregnant sheep. Major limitations of fetal surgery include the high frequency of preterm labour and delivery which may offset any fetal benefit of the surgical procedure. The development of more potent tocolytic drugs than the drugs currently available may thus be compared to the meaning of potent immunosuppressive agents in organ transplantation. Fetal mortality and maternal morbidity consequently lead to a more cautious way of treatment, as with the development of endoscopic fetal surgery. The invasive fetal surgery is still considered as being in a research stage in most cases. Therefore most procedures are performed as minimally invasive, avoiding substantial risks by accessing the uterus through minimal openings. Some new devices are under investigation for monitoring the myometrial electrical activity and mechanical contractility and the fetal electroencephalogram, the continuous monitoring of the fetal arterial oxygen saturation, PO2 and PCO2, and for monitoring fetal cerebral oxygenation, blood volume and blood flow by near infrared spectroscopy.
The ex utero intrapartum treatment (EXIT) procedure was developed originally for management of airway obstruction after fetal surgery, and indications have continued to expand for a variety of fetal anomalies. The authors review their single-institution experience with EXIT. Retrospective review of all patients who underwent an EXIT procedure from 1993 to 2003 (n = 52) was performed. Variables evaluated include indication for EXIT, gender, gestational age at EXIT, birth weight, maternal blood loss, operative complications, operative time, and survival rate. Technique, personnel, and anesthesic management were reviewed. Long-term follow-up was available for all patients. Fifty-one of 52 patients were born alive; currently, 27 of 52 patients (52%) are alive. All deaths have been in patients with congenital diaphragmatic hernia. Forty-five patients underwent EXIT for reversal of tracheal occlusion for congenital diaphragmatic hernia. Of these patients, 30 underwent tracheal clip removal. Two patients had repair of tracheal injury from clipping at EXIT. Fifteen patients underwent bronchoscopy and tracheal balloon removal. Five patients underwent EXIT procedure for neck masses. Tracheostomy was performed in 3 of these patients. One patient was intubated successfully, and 1 patient underwent resection of the neck mass while on placental support. Two patients underwent EXIT procedure and tracheostomy for congenital high-airway obstruction syndrome. Average gestational age at delivery was 31.95 +/- 2.55 weeks. Average birth weight was 1,895 +/- 653 g. Average maternal blood loss was 970 +/- 510 mL. Average operating time on placental support was 45 +/- 25 minutes with a maximum of 150 minutes. EXIT procedures can be performed with minimal maternal morbidity and with good outcomes. It is an excellent strategy for establishing an airway in a controlled manner, avoiding "crash" intubation or tracheostomy. Longer procedures on placental support allowing for definitive management of neck masses and airway obstruction have been realized. EXIT procedures have evolved from an adjunct to fetal surgery to a potentially life-saving procedure in fetuses with airway compromise at birth.
Drugs acting on the uterus
  • Eagland
Eagland K, Cooper GM. Drugs acting on the uterus. Bull Royal Coll Anaesth 2001, 10: 473-6