INVITATION ARTICLES -  Current Trends in Intra Uterine Fetal Surgey by Dr.Sameer Dikshit

Current Trends in Intra

Uterine Fetal Surgery

Dr.Sameer Dikshit

MD, DGO, FCPS, FICOG

 

Introduction

Since a long time, mankind has appreciated that our external environment has an effect on the fetus. Ayurveda has suggested certain restrictions on the mother for a healthy and intelligent progeny. However, since the ancient man had no means of visualizing the fetus and hence no means of visualizing abnormal fetus, the interventions were only of preventive nature. It is only after the advent of USG that the fetus and fetal abnormalities could be seen before birth. This stimulated medical science to devise ways to correct these defects.

History

Dr. Sir A.W. Liley is considered father of intra uterine surgery. He carried out first intra uterine transfusion for the Rh incompatibility in 1965. Dr. Harrison did the first surgery for fetal ladder neck obstruction. He devised a Uterine Stapler which sealed the uterine vessels and the amnion. This invention allowed intra uterine surgery to be performed on a regular basis. Dr. Nicolaides has a huge experience in Fetoscopic laser ablation in Twin to Twin transfusion syndrome. Intra Uterine fetal surgical procedures are indicated in those conditions which interfere with normal development of the fetus and which when corrected will allow the normal or near normal development of the fetus.

These procedures are obviously contraindicated in cases which are incompatible with postnatal existence or in cases which have severe affliction or in cases with chromosomal/ genetic syndromes or in cases associated with other malformations.

Types of Intra Uterine Surgery

The various types of Intra Uterine Surgery are as follows:-

1) FIGS

2) FETENDO

3) Open Fetal Surgery

4) EXIT

1) FIGS or Fetal image guided surgery

This is the most basic type of Fetal Surgery, where the procedure is guided by ultrasound image. The fetus is visualized on ultrasound monitor. The needle is advanced under vision and the procedure is performed. The procedures performed are both diagnostic and therapeutic.

Diagnostic
1. Amniocentesis
2. Chorion Villus Sampling
3. Fetal Blood Sampling
4. Fetal skin biopsy

Therapeutic
1. Fetal reduction
2. RFA (Radio Frequency Ablation) of cord in TRAP
3. Placement of Bladder/ Hydrothorax shunts
4. Balloon dilatation in Aortic Stenosis

2) Fetendo or Fetal Endoscopic Procedure

Here, the fetus is observed under ultrasound vision, a small fetoscope is introduced into the amniotic cavity. The fetus is observed on both ultrasound monitor and the fetoscope monitor. This procedure is called Fetendo because the hand-eye coordination is similar to that involved in the children's game NINTENDO.

The procedures performed using this are:-

1. Laser Ablation in TTS
2. Balloon occlusion of Trachea in cases of CDH
3. Cord ligation in acardiac twin
4. Division of Amniotic bands

3) Open Intra Uterine Fetal Surgery

This is usually done in mid trimester. The mother is anaesthetized and sonography is performed to map the surface anatomy of the fetus and localize the placenta. Mother is usually given deep general anesthesia. This is essential to prevent intra operative uterine contractions and also to allow manipulation of the fetus. An appropriate hysterotomy incision is performed. The uterine stapler is used to seal the vessels and the amnion. Before surrey top up fetal anesthesia is administered. This consists of intramuscular injection of Inj Vecuronium and Inj Fentanyl. The affected fetal part is exteriorized and operated upon. The amniotic fluid which drains out is replaced by warm Ringer Lactate solution. The fetus is monitored using a miniature pulse oxymeter, intra operative fetal echocardiography and fetal hemoglobin estimation. The fetus is transfused with O-ve blood to replace for the lost blood. At the time of closure the mother is administered inj Magnesium Sulphate along with Indomethacin rectal suppository for prevention of preterm labour.

The indications are:-

1. Excision of CCAM
2. Repair of meningomyelocoele
3. Excision of Sacrococcygeal Teratoma

4) EXIT -Ex Utero Intra Partum Treatment Procedure

This is performed for those cases where the baby is likely to have a compromised airway post delivery. Here the procedure is started as a routine LSCS, performed with the intention of delivering the baby. However, it is performed under general anesthesia. The uterine incision is taken, the baby is delivered. However, the cord is not clamped allowing the baby to get oxygen from the mother. A laryngoscope is introduced and intubation is attempted. In case the intubation is unsuccessful, tracheotomy is performed and the tube is passed. Either ways, the airway is secured. The cord is then cut and the baby is separated from the mother and delivered. As the airway is secured, the baby can now be placed on a ventilator and the definitive surgery can be performed at a later date.

The indications are:-

1. CHAOS (Congenital High Airway Obstruction Syndrome)
2. CCAM (Congenital cystadenomatoid malformation of the lung)
3. Removal of balloon implanted in larynx in cases of Congenital Diaphragmatic Hernia
4. Pulmonary Sequestration

Challenges in Intra Uterine Fetal Surgery

1) Maternal Risks

??? Tocolytic therapy can cause maternal pulmonary edema
??? Subsequent delivery is by LSCS
??? Intra operative blood loss
??? Amniotic Fluid Leak
??? Chorioamnionitis
??? Wound infection
??? Maternal mirror syndrome causing pulmonary edema in the mother
??? Deep anesthesia is required for intra operative manipulation ; this can depress
??? Maternal, fetal cardiovascular system and placental circulation.

2) Fetal Risks


??? Prematurity
??? Intra Uterine infection
??? Fetal vascular events like intestinal agenesis and renal atresia
??? Premature closure of Ductus Arteriosus
??? Fetal vascular insults due to hypoxia during anesthesia
??? Fetal organ system is immature
??? Fetal cardiac system is sensitive to heart rate change
??? Fetal has high vagal tone and responds to stress with precipitous bradycardia
??? Fetal circulating volume is low, hence is more at risk of hypovolemia
??? Deep maternal anesthesia puts fetus at risk
??? Fetus tends to lose heat more easily hence exposed fetal part places
??? Immature fetal coagulation system predisposes the fetus to intra operative bleeding

3) Ethical Issues

??? Not all procedures are performed regularly
??? Results are not always guaranteed
??? There are potential risks to mother and fetus
??? Should a procedure which is not guaranteed to provide favorable results (like sacrococcygeal teratoma) be performed on the insistence of the mother?
??? Should a procedure which is guaranteed to perform favorable results (like CCAM) be not performed on the refusal of the mother?
??? Research on Intra Uterine Fetal surgery is controversial as there are risks involved to both the mother and the fetus
??? Surgical animal models do not always replicate human conditions

4) Does the fetus feel pain?

Pain is a subjective phenomenon and hence there is no objective confirmation that the fetus feels pain. Some researchers have even questioned the assumption that the fetus feels pain. However, pain or noxious stimulus is also known to bring about certain physiological changes. These include release of fetal cortisol, fetal endorphins as well as initiation of brain sparing vascular changes. Fetal administration of anesthetics is known to suppress the release of fetal cortisol and fetal endorphins. Thus it can be induced that the fetus does feel pain and this sensation is suppressed at least to some extent by administration of anesthetics to the fetus. Fetal pain is also suspected to be the reason for preterm labour in some cases of intra uterine surgery.

5) Concept of Fetal Consciousness

The issue of intra uterine fetal surgery raises the question of fetal consciousness. This is important because the decision for surgery is taken on behalf of the fetus. Some researchers dismiss idea that there is fetal consciousness in utero. They say that it is only after birth that the fetus exists as an individual. However, some psychologists have proposed that the fetus has two kinds of "consciousness": one is the Self Consciousness, where the fetus is observed to respond to accidental needle prick at the time of amniocentesis and the other one is Transcendal Consciousness where the fetus is reported to be aware of its surrounding events.

Future possibilities

1) Deliver stem cells to the fetus in cases of certain inheritable condition. It is given through intra-amniotic or intra umbilical venous route. The advantage is that the fetus does not mount graft v/s host reaction. The conditions where it has been attempted are:

2) Intra uterine plastic surgery: The fetal tissues are known to heal without scarring. Hence repair of cleft lip and cleft palate has been attempted in animal experiment. In future, this may allow repair of these conditions in humans without any residual sign after birth. Thus fetal surgery is an exciting field where the possibilities are innumerable:

??? Hemoglobinopathies
??? Mucopolysaccharidoses
??? Mucolipidoses
??? Fanconi Anemia
??? Immunodeficiency syndromes
??? Diamond Blackfan Syndrome

 
     

 
         
     

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