Fetal surgery refers to the surgical treatment of the developing baby in the womb to rectify congenital defects. Surgery of the fetus is performed to fix the prenatally diagnosed anomalies. However fetal surgery is a complicated procedure and comes with lot of risks to both mother and the baby. Yet, doctors recommend fetal surgery, if the risks associated with continuing the pregnancy, without surgical intervention, outweighs the risks that come with fetal surgery. Certain abnormalities, if left to progress in the womb, may turn fatal and infant may die soon after the birth. However fetal intervention is initiated only after taking the safety of the mother into consideration. The common risks that are associated with fetal surgery are premature delivery, infection of the uterus, leaking of amniotic fluid through the membrane, potential infertility and the risk of anesthesia.
There are various techniques followed to diagnose fetal anomalies. The diagnostic method can be non invasive such as ultrasound, fetal echocardiography, MRI, Radiography, Measuring MSAFP (maternal serum alpha-fetoprotein) and Measuring maternal serum beta-human chorionic gonadotropin (HCG) or invasive procedure such as amniocentesis, Chorionic villus sampling and Percutaneous umbilical blood sampling (PUBS) are used to detect the birth defects.
Types of Fetal Surgery
Depending on the incision level, fetal surgery is classified into three types.
Open Fetal Surgery
Open fetal surgery is almost similar to cesarean section and involves a total opening of the uterus. In this type of surgery, a long incision is made in the mother's abdomen and then on the uterus to reach the fetes. Once the surgical correction is performed on the fetus to treat the birth defect, the uterus and abdominal is closed back leaving the fetus intact. Open fetal surgery is performed under general anesthesia. Surgery is performed using special instruments containing staples to prevent bleeding from uterus. During the operation, warm saline water is infused to maintain the position of placenta and umbilical cord and surgeon will keep a vigil on the pulse and heart rate of the baby with the help of the oximeter. After the surgery, the mother is hospitalized for close to a week to facilitate close monitoring. One should remember that, with open fetal surgery, mother will forgo the option of vaginal delivery for the present and future deliveries. She can deliver the baby only through C-section. She may be given some medication to avoid pre term labor. Open fetal surgery is followed for the conditions like chest mass, neck mass, spinbifida, myelomeningocele and Sacrococcygeal teratoma (SCT) (a tumor at the base of the child's tail bone).
There is one more variation to the open fetal surgery called the EXIT (Ex Utero Intrapartum Treatment) Procedure. EXIT surgery is performed at the end of the full term and just before the delivery. In this method the baby is partially delivered by bringing out only a part of the fetes from uterus and keeping rest of the fetes attached to placenta and umbilical cord to allow blood circulation. Once the defect is rectified, the baby is delivered fully. Exit procedure is essentially followed to correct the airway blockage in the baby.
Fetoscopic surgery is minimally invasive and unlike open fetal surgery, fetes remains inside the uterus while operating. Surgeon uses special instruments such as laser and makes a small incision with the help of the fetoscope to correct the birth defects. Fetoscopic surgery has shown high success rate in conditions such as Twin-Twin Transfusion Syndrome (TTTS), Twin Reversed Arterial Perfusion (TRAP), Amniotic band syndrome, and Tracheal occlusion for CDH. Fetoscopic surgery does not pose a risk of pre term labor and also eliminates most of the risks associated with open fetal surgery. This is essentially why fetoscopic surgery is the preferred choice, yet one should note that few complicated birth defects can be corrected only through open fetal surgery.
Fetal image guided surgery
Fetal image guided surgery is the least invasive of all wherein surgery is performed with the guidance of images of fetus produced on the external screen by ultrasound. Very thin instruments are inserted through a small opening in the abdomen and the correction is made without any endoscopic view and the whole procedure is guided by the sonogram images.
Various congenital conditions treated through fetal intervention
Congenital diaphragmatic hernia (CDH): Congenital diaphragmatic hernia (CDH) refers to the opening in the diaphragm through which the contents of the abdomen enter the chest cavity leaving no space for the lungs to develop properly. This is a serious condition and may lead to respiratory failure after birth. This condition, depending upon its severity, is treated through fetal intervention.
Spina bifida: Spina bifida refers to a condition wherein spinal column of the baby does not close properly around the spinal cord and the nerves start to protrude through the opening. Spina bifida can range from mild to severe form, and the severe cases lead to serious neurological problems after the birth. Only the severe form of spina bifida like Meningocele and Myelomeningocele call for fetal intervention through open fetal surgery.
Neck masses: Neck masses are the tumors of the neck that may obstruct the airway and esophagus of the child and also increase the level of amniotic fluid surrounding the baby. Typically, tumors of any kind are treated after birth. In rare cases they grow very large and may even cause heart failure. In such cases fetal intervention becomes necessary to remove the tumors.
Lung lesions: Lung lesions refer to the abnormal growth of lung tissue and these lesions can be cystic (fluid filled) or solid. There are various types of lung lesions and treatment depends upon their size and location. During pregnancy, continuous monitoring is necessary to keep vigil on the size of the lesion. Most often lung lesions shrink and make way for normal development. Lesions of smaller and moderate size are best treated after delivery. But if the size of the lung tumor is abnormally huge and poses a risk of hydrops (excess accumulation of fluid in the fetus) fetal intervention is initiated. Cystic lesions are normally removed through needle aspiration under the constant guidance of ultrasound images, but solid lesions require more elaborate procedure such as EXIT.
Congenital heart diseases: Not all congenital heart defects call for fetal intervention. Sometimes the septum (wall separating the right and left side of the heart) of the heart develops a hole while in the womb. However septum defects are typically treated after the birth of the child and rarely require fetal surgery. But if the heart develops severe obstructive cardiac disorders such as aortic stenosis, pulmonary stenosis and coarctation of the aorta,a fetal image-guided procedure may be necessary to open or enlarge the narrowed valve. This procedure involves placing a balloon catheter by inserting it through the uterus and into the fetal’s heart.
Amniotic Band Syndrome: This is a condition where fetus is entrapped in fibrous amniotic bands in the womb, restricting blood flow to the affected portion of the fetes. It normally affects legs, arms, toes and fingers. In utero surgery may be performed to rectify the condition if there is risk of amputation of the limb after the birth.
Twin-to-twin transfusion syndrome (TTTS): TTTS is a condition that occurs in identical twins wherein unbalanced exchange of blood takes place between the twins. One receives higher amount of blood whereas the other receives less amount. The fetus with less blood supply may become anemic and the one with excess blood supply may suffer heart failure due to excess fluid. Fetal surgery through laser fetal intervention is the preferred option to correct the condition. This procedure involves inserting a laser along with small telescope into the uterus and separating the blood vessels on the placenta that are connected to both twins.
Congenital high airway obstruction syndrome (CHAOS): Congenital high airway obstruction syndrome (CHAOS) refers to the blocking of fetal airway resulting in enlarged lungs, windpipe and bronchial tube. A complete or near to complete blockage may lead to a heart failure. Though congenital high airway obstruction syndrome (CHAOS) is treated after birth, in severe cases where fetes is at high risk such as hydrops, fetal surgery is performed.
Leber Congenital Amaurosis
Leber Congenital Amaurosis or LCA is an inherited retinal degenerative disease that causes severe loss of vision in infants. Retina is located at the back of the eye. It contains photoreceptors called rods and cones, through which retina captures light. It converts the light into chemical signals that go to the brain via the optic nerve to interpret it as an image. In case of Leber Congenital Amaurosis, rods and cones do not develop properly and thereby retina ceases to function effectively causing visual impairment. Though LCA can cause complete blindness, most often, infants are born with residual vision.
LCA is a genetic condition that is transmitted by autosomal recessive pattern in which both the parents carry a defective gene to result in LCA. Infants with LCA usually develop other eye related problems such as roving eye movements known as nystagmus, extreme farsightedness hyperopia, deep-set eyes, and sensitivity to bright light. Leber Congenital Amaurosis is a rare disease and only 3 in every 1,00,000 newborns are said to be affected by this condition.
There are 14 types of genes that are associated with Leber Congenital Amaurosis and mutations in any of these genes hinder the development and effective function of the retina. However mutations in the genes naming CEP290, CRB1, GUCY2D, and RPE65 are the most common causes of the LCA.
Symptoms and diagnosis
Infants with LCA may have roving and sunken eyes, cone-shaped corneas termed as Keratoconus and also exhibit oculo-digital reflex in which they press or poke their eyes regularly. Most infants also have sluggish pupils and hyperopia. Rarely, infants with LCA may also have problems with central nervous system and hearing impairment. They may experience seizure disorders, motor impairments and developmental delays.
With LCA, initially, the eyes of the infant may look normal. The diagnosis process is generally initiated after few weeks of the birth, when the infant fails to respond to the visual stimuli. The LCA cannot be easily diagnosed based on the symptoms alone as many other eye diseases also present with similar warning signs. Electroretinography (ERG) test is usually advised to evaluate the retinal function and diagnose LCA. If ERG results confirm poor retinal function, genetic testing will be performed to confirm Leber Congenital Amaurosis.
Treatment of Leber Congenital Amaurosis
No effective treatment is currently available for Leber Congenital Amaurosis. Palliative and supportive care is normally provided to the patients based on symptoms. Those with slight remaining vision are given low-vision aids, including electronic, computer-based and optical aids.
Also known as a mole, nevi is a benign growth that could appear like hyperpigmentation of the skin, colored macules, plaques or papules. Nevi are mostly congenital. They are confined to a particular area of the skin. They are also commonly referred to as birthmarks or beauty marks. Benign nevi typically means that the specific pigmented skin portion has not shown any signs of abnormality that is typical of skin cancer.
How do nevi occur?
Development of nevi is influenced by age of the person, environmental factors like sun exposure, race and genetic factors. It can develop in any part of the body though it can be predominant in sun-exposed areas like arms, face or neck when compared to intermittently exposed areas like chest, back or legs. Though most nevi are benign, 25% of malignant melanoma arise from pre-existing nevi.
For males, nevi are concentrated on the face and neck while for females nevi are concentrated on thighs and upper arms. Dark skinned individuals have a low count of total body nevus when compared to light skinned individuals. However dark skinned individuals develop nevi on the palms and soles. Nevi count in males is higher than in females. Nevi count in children depends on the nevi count in their parents. Commonly acquired nevi follow the ABCDE rule:
Nevi can be classified into different types as listed below
Connective tissue nevus: This type is very rare to occur; they are fleshy deep nodules.
Epidermal nevus: They are present at birth (congenital), and appear on the upper torso of the body. They resemble the color of flesh and appear raised or like a wart.
Nevus sebaceous: A variant of epidermal nevus, it appears on the scalp. The affected scalp area becomes hairless and looks yellowish in color. Melanocytic nevus: Benign production of melanocytes i.e. the skin cells make the brown pigment melanin. Therefore most of the nevi are brown to black in color. They are the common type of nevi and are present in almost all adults. They could be congenital or may develop at a later stage in life. Different types under melanocytic nevus are:
Acquired melanocytic nevus: Acquired at a later stage in life; will not be present in birth or near birth period.
Congenital nevus: Present from birth or near birth.
Dysplastic nevus: Acquired type of melanocytic nevus and difficult to differentiate from melanoma. It could be an indicator for the risk of developing melanoma.
Nevi are grouped based on their location. The different categories are:
Compound: They are hyper pigmented macules located in the epidermis and dermis.
Junctional: They are hyper pigmented macules located in the epidermis.
Intradermal: They are brown/skin colored papules located in the dermis layer.
Diagnosis and treatment of nevi
Diagnosis of nevi is generally done through visual examination; a dermatoscope may also be used. While diagnosing nevi, the main concern lies in identifying a benign nevus from a dysplastic nevus and melanoma. If physical examination doesn't suffice, a skin biopsy may help in identification.
Treatment for benign nevi
In general, benign nevi need not be treated. However a few may want it to be treated for cosmetic reasons. You can opt for laser treatment with a qualified skin specialist.
Protecting skin with nevi
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Bibliography / Reference
Collection of Pages - Last revised Date: November 19, 2019