Fetal Goiter - An Overview

What Is Goiter?

Goiter is a condition affecting the thyroid glands. A network of multiple glands releasing or secreting hormones from them is called an endocrine system. The thyroid is a butterfly-shaped gland that is a part of the body's endocrine system. It is located on the neck and produces and secretes hormones like thyroxine (T4), triiodothyronine (T3), reverses triiodothyronine (RT3), and calcitonin. A condition in which the thyroid gland gets more prominent in size is called goiter. The enlargement may be uniform or as multiple nodules or lumps called thyroid nodules. Many factors are responsible for causing goiter, some of which are: thyroiditis (inflammation of the thyroid glands), thyroid cancer, iodine deficiency, Hashimoto's disease (an autoimmune inflammation of the thyroid gland), Graves’ disease (an autoimmune condition where seld-cells attack the thyroid gland), pregnancy and more.

What Is Fetal Goiter?

A rare condition in which the thyroid glands of the fetus get enlarged in utero is termed fetal goiter. Hypothyroidism (an underactive thyroid gland) or hyperthyroidism can lead to this condition. It may also develop in the case of a normal thyroid gland (euthyroidism). Fetal goiter may cause risk to the fetus and may be life-threatening. When the thyroid gland enlarges, it puts pressure on the trachea (a U- shaped tube connecting the larynx or the voice box to the lungs) and esophagus (food pipe through which food passes from the throat to the stomach) of the fetus. This may cause breathing issues in the baby and pregnancy-related complications in the mother. It is also called congenital goiter since the baby will have a goiter at birth.

What Causes Fetal Goiter?

The following are the causes of fetal goiter:

• Graves’ Disease: Graves’ disease or Basedow’s disease is an autoimmune condition leading to an overactive thyroid gland, leading to increased production of thyroid hormones, or hyperthyroidism. The antibodies responsible for Graves’ disease will cross the pregnant mother's placenta and reach the fetus. This leads to thyroid conditions, like fetal goiter, in the fetus.

• Hashimoto’s Disease: Hashimoto’s disease or thyroiditis is also called chronic lymphocytic thyroiditis. It is an autoimmune condition in which the thyroid cells get attacked by their own cells. The factors responsible for the disease can cross the placenta and may lead to thyroid conditions in the fetus.

• Medications: Certain medications, including those consumed for thyroid problems taken during pregnancy, may cross the placental barrier and lead to congenital goiter.

• Iodine: Excessive intake of iodine or extreme iodine deficiency in the mother can lead to fetal goiter.

What Are the Symptoms of Fetal Goiter?

The following are the symptoms of fetal goiter:

• The enlarged goiter may pressure the trachea, causing breathing difficulties in the fetus. The obstructed or blocked airway may be a life-threatening condition. This can indirectly cause brain injuries in the fetus.

• Fetal goiter may also cause heart failure due to inadequate blood supply to support the growth and development of the heart.

• When the enlarged thyroid gland puts pressure on the esophagus, the fetus may be unable to swallow the amniotic fluid, leading to polyhydramnios. Polyhydramnios is when the uterus contains too much amniotic fluid. In mild to moderate cases, it will not cause many complications. The healthcare provider will carry out monitoring and checkups at regular intervals. But once it worsens, it can be dangerous, leading to premature delivery, umbilical cord prolapse (dropping of the umbilical cord from the normal position), postpartum hemorrhage (severe bleeding after delivery), and placental abruption. There are chances of a breech baby (baby’s feet or buttocks coming out of the vagina first) or stillbirth (death of the fetus within the uterus) in case of severe polyhydramnios.

• The cartilage of the fetal trachea may become weak, leading to tracheomalacia. It is due to the pressure exerted on the trachea by the enlarged thyroid gland, leading to improper growth and maturation.

• Fetal goiter may affect the development of the fetal lung. The underdeveloped lungs may be small, and the condition is called pulmonary hypoplasia.

• Fetal goiter may lead to edema or swelling in different parts of the fetal body, causing a condition called hydrops fetalis. It is a life-threatening condition.

• The head of the fetus may get too much extended in case of fetal goiter leading to an obstruction in the pathway of baby delivery. This may lead to prolonged labor time and associated complications.

How to Diagnose Fetal Goiter?

An ultrasound scanning can diagnose fetal goiter. During pregnancy, the mother will be subjected to routine ultrasound scanning, which may b helpful in diagnosing fetal goiter. An ultrasound may show an increased neck mass in case of goiter. Once it gets diagnosed, the scanning should be followed by fetal thyroid function tests. This helps determine the factors responsible for the condition and aids treatment planning.

In addition following advanced types of diagnostic steps may also be advised by the doctors:

• High-Resolution Fetal Ultrasound: It is a noninvasive imaging technique that uses high-frequency sound waves.

• Fetal Echo Test: Fetal echo test or fetal echocardiogram is a painless ultrasound diagnostic method that generates pictures of the fetal heart using sound waves. This helps diagnose the cardiac conditions associated with fetal goiter.

• Ultrafast Fetal MRI (Magnetic Resonance Imaging): Detailed fetal anatomy can be obtained with the help of ultrafast fetal MRI.

• Amniocentesis: Amniotic fluid will be taken to test the cells for diagnosing congenital conditions of the fetus.

• Fetal Blood Sampling: Fetal blood sampling will be done by collecting blood from the umbilical cord.

How to Treat Fetal Goiter?

Treating or managing fetal goiter may be done in different stages:

• In the case of polyhydramnios during pregnancy, medications will be provided to decrease the amount of amniotic fluid, or the excess fluid will be drained.

• Treatment will be done for the fetus to improve growth and development and to reduce labor complications.

• The doctor may recommend ex-utero intrapartum treatment or EXIT procedure for delivery. This treatment ensures adequate fetal breathing during labor.

• After delivery, the baby should be provided with the necessary treatments for goiter. Hormone replacement therapy will be beneficial in case of hypothyroidism. Surgeries can remove large goiter masses, and medications can manage hyperthyroidism.

Conclusion

Fetal goiter is the enlargement of the fetal thyroid gland due to many causes. It may lead to poor growth and development of structures associated with the thyroid gland and even be life-threatening for the fetus. Complex delivery can cause more complications to the health of the mother. The management and treatment of the condition can be started from the fetal period itself. The baby, after delivery, should also require treatments for thyroid hormone fluctuations.