Fetal Intervention - Significance, Techniques, and Possible Risks

Introduction

Fetal surgery is a technique done on a fetus inside the uterus (in utero) to help improve the long-term outcome of kids with particular birth abnormalities. Fetal surgery performed by a team of experts is focused on repairing and improving the abnormalities before birth because these defects frequently get worse as a fetus develops.

Which Birth Defects Can Be Treated With Fetal Intervention?

Over the past few decades, prenatal abnormality detection has made remarkable progress. As a result, only a few disorders need treatment before birth, although many may be correctly detected before birth using genetic and imaging techniques. In addition, numerous birth problems can be treated in utero by comprehensive medical facilities with fetal surgery knowledge and experience, including:

• Amniotic Band Syndrome - The condition, often referred to as constriction ring syndrome occurs when the amniotic sac's fibrous bands tangle with the growing fetus. The bands may, in rare instances, encircle the fetus' skull or umbilical cord.

• Bronchopulmonary Sequestration of the Lung - A rare birth abnormality occurs when an abnormal mass of non-functioning lung tissue develops during prenatal development. It can develop inside (interlobar) or outside of the lungs (extra lobar); however, it is not directly related to the airways.

• Congenital Cystic Adenomatoid Malformation (CCAM) Of the Lung - This is a benign lung lesion that first manifests as a tumor or cyst in the chest before birth. It is composed of defective lung tissue that does not work correctly but keeps expanding.

• Congenital Diaphragmatic Hernia (CDH) - A hole in the diaphragm, the delicate muscular sheet that separates the chest from the abdomen, results in CDH. The colon, stomach, or even the liver may travel into the chest cavity when this opening develops during a fetus's growth in the womb.

• Congenital High Airway Obstruction Syndrome (CHAOS) - It is a condition in which the fetus's trachea (windpipe) or larynx (voice box) is blocked. Numerous conditions, such as narrowing the airway (stenosis), a membrane resembling a web, or even a missing section of the trachea (atresia), can cause this obstruction.

• Fetal Anemia - Low levels of healthy red blood cells in a developing fetus.

• Lower Urinary Tract Obstruction (LUTO) - Blockage of the urinary tract in a developing fetus.

• Mediastinal Teratoma - A tumor derived from germ cells.

• Neck Mass - An abnormal growth in the neck of the fetus.

• Sacrococcygeal Teratoma (SCT) - A congenital tumor that originates from the baby's coccyx, also known as the tailbone.

• Spina Bifida (Myelomeningocele) - A congenital disability where the spinal cord of a developing newborn fails to mature normally.

• Twin Anemia-Polycythemia Sequence (TAPS) - Unbalanced blood counts between the twins while they are still in the womb.

• Twin Reversed Arterial Perfusion (TRAP) Sequence - Rarely, twins that share a placenta develop TRAP. One twin develops normally, but the other does so abnormally, usually without a heart that can be seen (acardiac).

• Twin-Twin Transfusion Syndrome (TTTS) - The condition occurs when only one placenta and two amniotic cavities and preferential blood flow to one of the twins. The receiving twin is the twin who receives the most blood. The donor twin is the other. This disorder can cause both twins to pass away before birth if it is not treated.

What Are the Techniques of Fetal Intervention?

The different techniques of fetal intervention are as follows.

1. Percutaneous Procedure - Refers to a method in which a small trocar (metal tube) or needle-like tool is guided into the womb using ultrasound.

• Fetal Shunt Placement - This treatment is used to drain the fetal bladder and collect a sample of fetal urine for testing when the fetus has serious renal or urinary abnormalities. Additionally, excess fluid from the fetal chest can be drained using stents. In certain instances of bladder outlet obstruction, pleural effusions, or cystic chest tumors, a shunt (a thin, flexible tube) is inserted into the fetal bladder or chest. To allow fluid to flow into the amniotic cavity, a specially made double pig-tail catheter is placed with one end outside the fetus and the other inside the fetal chest or bladder. Local anesthesia or maternal epidural anesthesia and IV sedation are frequently used to perform the surgery.

  • Procedure - A small skin incision is made on the mother's abdomen during shunt installation. Under ultrasound guidance, a special trocar is introduced through the stomach and into the uterus. An extremely small shunt (drainage tube) is then deployed after the device has been placed via the trocar and into the fetus. The mother may be discharged and closely monitored as an outpatient if the health of the mother and fetus has been confirmed.

• Radio Frequency Ablation (RFA) - RFA directs an electrode in the shape of a needle to the affected area using ultrasound and an energy source. The energy from the tip will block the area's blood supply. It can also be utilized for some fetal tumors and is frequently used to secure the blood flow to the a cardiac twin in the TRAP sequence.

  • Procedure - The method of choice for an RFA operation is a local anesthetic. An ultrasound-guided particular needle electrode is inserted into the uterus and directed to the afflicted fetal region once anesthesia has been obtained. The needle transmits energy until the area is left without blood flow. Recovery resembles shunt placement in specific ways.

• Cordocentesis (Intrauterine Transfusion) - A needle is inserted through the mother's belly and her uterus to reach the baby's umbilical cord during a cordocentesis. Maternal-fetal medicine specialists can take a blood sample from the baby, give a blood transfusion, or administer specialized medication because they have direct access to the infant.

• Fetoscopic Surgery - Fetoscopic surgery is a method that employs a tiny camera or scope to look within the womb of a pregnant woman and execute treatments. The twin-twin transfusion condition is the most common reason for fetoscopic surgery. Additionally, it can treat fetal endoscopic tracheal obstruction (FETO), amniotic band syndrome, and TRAP.

• Fetoscopic Laser Surgery - Finding the ideal location for the fetoscope insertion is the first step of the procedure, which is an ultrasound examination. The fetoscope is introduced into the uterus after making a small skin incision with continuous ultrasound guidance. Once inside the uterus, a laser fiber is placed into the fetoscope, where the TTTS-causing placental arteries are coagulated while being seen clearly. According to our research, the optimum result following laser surgery is achieved when the placental surface between the connecting vessels is coagulated (also known as the Solomon procedure or equatorial dechorionizing). The extra fluid is drained through the fetoscope after the procedure.

• Fetoscopic Endoluminal tracheal Occlusion (FETENDO) - This procedure is used in conditions like CDH and impaired lung development. Finding the ideal location to place the fetoscope begins with an ultrasound examination. Under continuous ultrasound supervision, the fetoscope is placed into the uterus following the creation of a small skin incision at that location. The fetus' mouth is then accessed through the fetoscope. Once within the mouth, the fetoscope is guided into the trachea using essential landmarks. A tiny balloon is inserted into a functioning channel of the fetoscope, filled with sterile saline, and then deployed once the device is in the trachea. Any extra amniotic fluid is evacuated through the fetoscope at the end of the surgery.

• Fetoscopic Spina Bifida Repair - It is an experimental therapy that uses a less invasive method to close the spina bifida. The benefit of the surgery is that it can fix fetal spinal deformity with minor alterations to uterine integrity. Unlike conventional open spina bifida surgery, vaginal delivery is possible after fetoscopic correction.

• Fetal Image-Guided Surgery or Intervention (FIGS-IT) - Guided by FIGS-IT entails fetal manipulation without uterine incision or intrauterine endoscopic view. The sonogram's cross-sectional real-time view is used exclusively during surgery. The procedure is similar to FETENDO in that it can be carried out through the mother's skin or, in rare cases, through a small incision in her abdomen. It may frequently call for local or regional anesthetic, such as a spinal or epidural. Being the least intrusive of the fetal access procedures, FIGS reduces complications for the mother in terms of preterm labor, discomfort, or hospitalization.

2. Open Fetal Surgery - To assure the safety of both the mother and the fetus, open fetal surgery is conducted during the second trimester of pregnancy. In the middle of a pregnancy, it has been used to intervene and remove life-threatening malignancies. It has primarily been utilized in the past ten years to treat a myelomeningocele defect in a small number of candidates while they are still in utero.

• Procedure - General anesthesia will be administered to the mother to calm her uterus and maintain blood flow to the placenta throughout the procedure. To stop bleeding, the uterus is opened with a specialized stapling tool. Future pregnancies must be delivered via cesarean section because a traditional uterine incision was made. The placenta delivers anesthetic to the infant, while an injection administers further anesthesia. Fetal echocardiography is used during the surgery to monitor the fetus continuously. A unique procedure closes the uterus after the fetus has undergone surgery. A cesarean section will be necessary during delivery.

3. Ex Utero Intrapartum Treatment (EXIT) - A skilled multidisciplinary team is necessary for the EXIT Procedure, a highly modified Cesarean delivery. The objective is to partially deliver the baby while maintaining placental support so that surgery can be done before the baby is fully born. In contrast to a typical C-section, which would stop the blood flow and separate the placenta from the uterus, an EXIT surgery permits ongoing oxygenation between mother and child. This keeps the baby's blood, nutrients, and oxygen flowing, so the surgical team can open the airway and administer all required treatments.

• Procedure - The mother will be given a general anesthetic to relax her uterus and maintain blood flow to the placenta during the operation. The uterus is opened with a unique stapling device to prevent bleeding, but the incision is similar to a standard C-section that allows for possible future vaginal deliveries. The baby receives anesthesia via the placenta, and a shot delivers additional anesthesia. An EXIT process is usually used for the following two reasons:

• EXIT To Airway: The doctor will try to open the baby's airway by inserting a breathing tube into the trachea. The surgeon will perform a tracheostomy to open an airway if a breathing tube can't be inserted.
• EXIT To Surgery: A similar treatment is used for babies whose chest masses would make it difficult for them to breathe after delivery. An anesthetic injection would be administered, and a breathing tube would be firmly in place. After that, the infant would have surgery to remove the lump while still attached to the placenta.
• The umbilical cord is cut, and the baby is delivered when the surgery is finished. The placenta is removed, the uterus and abdominal wall are closed, and the mother is given medicine to make the uterus contract.

4. The EXIT-ECMO Procedure - This treatment is only performed on a small number of kids who, due to an underlying condition, have a very high chance of developing lung or heart failure at birth. Extracorporeal membrane oxygenation (ECMO), a heart-lung bypass machine, is used to aid in a comfortable transition from the womb.

• Procedure - The airway is secured, and ventilation is tried during the EXIT-ECMO process. While the newborn is still receiving placental support, ECMO cannulation (the insertion of tubes into the carotid artery and jugular vein) is carried out if the infant's oxygen exchange is inadequate. The baby is delivered once the infant is stabilized on ECMO.

What Are the Risks of Fetal Intervention?

The various risks of prenatal surgery are

• Membrane separation between the uterus and the amniotic sac's surrounding tissues could lead to early delivery or interrupt the blood supply to a fetus, like the legs or arms, birth during surgery.

• Cesarean section delivery due to uterine scarring.

• Significant risks to the mother include potentially lethal drug interactions from the drugs needed to stop early labor, excessive blood loss, uterine incision rupture, uterine infection, mental stress, infertility, and death.

• Babies born at or after 30 weeks of gestation are more likely to experience cerebral palsy, brain hemorrhages, and blindness.

• Prenatal surgery for spina bifida could result in additional nerve and spinal cord damage; intrauterine infection, causing early delivery; brain damage; body part deformation; and death.

Conclusion

The ethical propriety of performing intrauterine fetal surgery, which carries significant risks for the mother and the fetus, is still debatable. Furthermore, premature delivery complications and accompanying high costs are additional issues with the technique. Therefore, the choice to undergo intrauterine fetal surgery is crucial and must be made after thorough consideration. The most critical element is a precise prenatal diagnosis. Therefore, future efforts should concentrate on advancing the methods used for accurate prenatal diagnosis. However, when used in carefully considered situations, intrauterine fetal surgery can reduce mortality related to delivery problems and cure physical deformities early on, increasing the future quality of life.