Resection of large sacrococcygeal teratomas (SCTs) in premature neonates has the potential to be fatal and is associated with a high rate of perinatal mortality [
1]. SCTs are the most common congenital neoplasms, occurring in 1 of 40,000 infants, with a female predominance of 95% [
2]. Large SCTs are associated with significant perinatal morbidity and mortality (5-50%) [
3]. Treatment consists of surgical removal of the sacral mass, which has hypervascularity derived from the middle sacral artery [
1], and is usually performed immediately after birth [
4]. Therefore resection of these tumors is a high risk procedure, requiring careful anesthetic management [
5]. We describe here two premature neonates who experienced cardiac arrest during excision of a huge SCT.
Discussion
A large vascular SCT carries a high risk of prenatal complications, including high-output cardiac failure and fetal hydrops caused by arteriovenous shunting through the tumor. Therefore preterm neonates with large SCTs are at very high risk of death [
1]. Although the mortality rate for newborns with SCT is at most 5%, the mortality rate for fetal SCT exceeds 50%, and fetal SCT associated with non-immune hydrops is uniformly fatal [
3]. Predictors of poor outcome include diagnosis before 20 weeks gestation, delivery before 30 weeks, low birth weight, Apgar score less than 7, malignant histotypes, polyhydramnios, placentomegaly and development of hydrops [
2].
Treatment for SCTs consists of surgical removal of the sacral mass [
4]. Surgical resection should be performed immediately after birth as coagulopathy appears to worsen with time [
6]. The etiology of the coagulopathy associated with SCTs is unclear, but appears to be multifactorial, including prenatal diagnosis, polyhydroamniosis, large sized (> 10 cm) tumor, prematurity and hydrops fetalis [
7]. Surgical removal of a SCT is a high risk procedure and requires careful anesthetic management [
4].
During the operation, respiratory ventilation is difficult because of the tumor pressing onto the chest, and that may be worsen by prone position. Abraham et al. [
2] has been reported that the manual ventilation and lifting the tumor by surgeon can help with the ventilation. And it is very difficult to maintain body temperature because of the large surface area of the SCT compared to the patient. Hypothermia could worsen coagulopathy, and prolong the effect of the anesthetics [
2]. In order to maintain body temperature, thermoneutral incubator, force warming device, and intravenous fluid warmer should be used.
Most clinical reviews of SCT have reported that the cause of death is cardiac arrest due to electrolyte imbalances, especially hyperkalemia [
8]. Hyperkalemia, which may have been associated with manipulation of the tumor during resection, especially manipulating the tumor for intra-abdominal resection, and massive transfusion of pRBCs containing high levels of potassium [
4]. In addition, metabolic and respiratory acidosis, hypocalcemia, hypothermia and oliguria may worsen hyperkalemia [
9]. Hypoxemia and hypovolemia also contributed to cardiac arrest [
4].
Concerning case 1, as respiratory ventilation was expected to be difficult, the surgeon performed abdominal decompression immediately after induction. Hence, adequate ventilation was maintained during resection of sacral mass. However, during manipulation of intra-abdominal mass, respiratory ventilation was difficult because of the tumor pressing onto the chest. Therefore, we frequently had to ventilate manually and had the tumor lifted by surgeon, but acidosis had continued to get worse. In addition, severe hyperkalemia, which may have been released from necrotic foci on the tumor, had caused cardiac arrest. In particular, severe acidosis caused by difficult ventilation and massive transfusion of pRBCs containing high levels of potassium would have worsen hyperkalemia. While in case 2, circulatory collapse without hyperkalemia suddenly occurred, which is probably thought to be due to persistent bleeding.
However, even though both of our patients showed hemodynamic instability, the occurrence of massive hemorrhage was not recognized. Moreover, the amount of bleeding was not correlated with emergency laboratory results. Mortality secondary to blood loss, either into the tumor or during surgery, has also been reported in neonates with SCT. For example, post-surgical deaths due to bleeding were reported in 9 of 247 patients [
10] and in 4 of 41 neonates with SCT [
11]. Especially, the occurrence of intra-tumoral hemorrhage may mask bleeding, so frequent laboratory tests should be prepared for massive bleeding.
SCTs are now often prenatally diagnosed by ultrasound. Treatments in utero include cyst aspiration, open fetal surgery, radiofrequency ablation, and thermocoagulation, with variable success, but there have been no large case series [
12]. Preoperative radiologic embolization can effectively reduce blood loss during surgery and enable faster and safer resection of the tumor [
1]. Therefore, preoperative embolization should be considered essential in preventing complications.
Our findings indicate the importance of careful anesthetic management during resection of SCTs, since this operation takes high risk, especially in neonates. In particular, hyperkalemia, associated with tumor lysis syndrome and massive transfusion, can lead to cardiac arrest [
8]. A surgical manipulation of very advanced solid tumors can increase the probability of tumor lysis [
4]. Consequently, if there are multiple necrotic foci on the tumor, surgeon should carefully manipulate the tumor to minimize tumor lysis. In addition, during resection of SCTs, unrecognized intratumoral bleeding often occurs and requires massive transfusion. Therefore, we should be vigilant monitoring and frequent laboratory tests, especially potassium and hemoglobin, before and during surgery are necessary.
In conclusion, during resection of huge SCTs, which contain multiple necrotic foci, in neonates, anesthesiologist should be aware of possibility of difficult ventilation and hyperkalemia. Also, preoperative embolization should be performed for the prevention of complications.