Hypothyroidism may be an elusive clinical entity because of the variety of end-organ effects and wide range of disease severity. It is potentially serious in young women because of the lower fertility rate than euthyroid women and neuroendocrine and ovarian dysfunction [5, 6]. Normal thyroid gland function is critical for pregnancy [ 7]. Hypothyroidism affects women, either before, during, or directly after pregnancy, and Early diagnosis and treatment may optimize the condition of both the mother and fetus [8]. once the diagnosis was confirmed, treatment is straightforward, and the patient’s prognosis is excellent. However, some hypothyroidism cases were often clinically overlooked at the early stage of pregnancy, and accompanied by a variety of pregnancy complications. Because of these complications, the patient need to be examined, and thus hypothyroidism is easy to detect. Severe maternal untreated congenital hypothyroidism with term pregnancy is extremely rare. In our case, she was weigh only 28 Kg and was 112 cm in height at term. She had no any laboratory tests and treatments before admission in our hospital. The neonates have no obvious features of hypothyroidism at birth. We speculated that there may be a transfer of thyroxine(T4) from mother to fetus at birth. To determine, neonate need to detect the thyroid hormone in the serum of the baby in the first few days of life. We also recommend screening for the baby, but his father firmly refused. Then we didn’t know whether the neonate’s condition progressively deteriorates in the following weeks after discharged. But early screening, diagnosis and treatment of thyroid hormone deficiency was crucial for high-risk baby whose mother suffered from severe hypothyroidism. Therefore, we suggest that when possible, primary thyrotropin or thyroxine (T4) testing, the mainstay of newborn screening, should be performed between 2 and 5 days of life.
The clinical manifestation of hypothyroidism refers to not only neuroedocrine and reproductive system, but also cardiovascular system, neuromuscular function, and hematological system. In cardiovascular system, severe untreated hypothyroidism can lead to bradycardia, increased systemic vascular resistance, and decreased cardiac output [9], obstructive sleep apnea[10], Both systolic and diastolic myocardial functions are impaired [11], which occasionally causes congestive heart failure. In neuroendocrine system, a familiar set of symptoms and signs have been associated with depression, psychosis, seizures, and even coma. A basic question about the pregnancy woman who subsequently have severe hypothyroidism is what is the optimal anesthetic management strategy. No prospective randomized studies have conducted to compare the safety or efficacy among various anesthetic techniques in pregnant or nonpregnant hypothyroid patients. Considering the minimization of the anesthesia side effect for our patient with severe maternal thyroid deficiency, we thought epidural anesthesia may be the optimal method. After carefully checking the history, physical examination and the laboratory test to verify the normal coagulation, epidural anesthesia was performed in this case.
The main cause of epidural anesthesia performed are as follows. The first is to avoid the use of sedatives, analgesics, and neuromuscular blockers. Epidural anesthesia may avoid respiratory depression and muscle weakness due to general anesthetics, opioids, and neuromuscular blockers. During normal cesarean section, 2% lidocaine was often used for epidural anesthesia. Patients with severe hypothyroidism are very sensitive to anesthetic drugs and may have poor tolerance of surgery. So, in this case, 1.5% lidocaine was used, and satisfactory anesthetic effect without any side effects was observed. Second, epidural anesthesia is accomplished with a decreased risk of the effects of sedatives and analgesics transferred from mother on the newborn.
Anesthesia may cause the incidence of heart failure elevated in hypothyroid patient. The main reasons are as follows. The capacity of circulation is not sufficient. The sympathetic nerve is blocked, which decreases the resistance of vascular and the blood pressure. However, this effect could be partially inversed by a classic agent, ketamine, which has unique central sympathomimetic, vagolytic and analgesic properties [12]. ketamine certainly was not a first-line anesthetic, but an excellent complementary drug because of its wide margin of safety in relation to vital functions. When ketamine was used, ventilatory depression was scant, and there was a slight increase in the duty cycle confirmed by Eikermann’s [13]. It was also confirmed that ketamine can be used in spontaneous ventilation and that the airway remains unobstructed. Although obstructive sleep apnea was common in hypothyroid patient [14], in this case, the patient had no symptoms to indicate airway obstruction. In addition to the effect on the cardiovascular and respiratory system, low dose ketamine could protect the patient against intraoperate nausea and vomiting during CS [15]. In our case, low doses ketamine (1mg/kg) was used to complement in sedation and analgesia, and became a reasonable candidate for epidural anesthesia in the patient with severe hypothyroidism. It was important that ketamine intravenous should not be given at more than 1mg/kg in this severely high-risk patient.
In conclusion, we report the rare case of a parturient with severe maternal thyroid deficiency during CS at term. In high-risk patients, we recommend strongly that epidural anesthesia in combination with low dose ketamine may be an optimal and safe technique. we also suggest that when possible, primary thyrotropin or thyroxine (T4) testing, the mainstay of newborn screening, should be performed between 2 and 5 days of life for the newborn.