CHAOS is a syndrome in which there is blockage of the upper airway of the fetus during pregnancy. The human airway has several components that start with the mouth, windpipe (trachea), and voice box (larynx). During development, portions of the amniotic fluid are produced and exhaled by the lungs. If there is a blockage of the airway at any level, fluid from the lungs can back up. Longstanding and severe cases of CHAOS can cause heart failure and can lead to fetal demise. Although most infants will make it to birth without problems, there is great concern that the infant will not be able to breathe at time of delivery. This will require special considerations and treatments, such as an EXIT (Ex Utero Intrapartum Treatment) procedure at birth.
What is Congenital High Airway Obstruction Syndrome (CHAOS)?
CHAOS is diagnosed by prenatal ultrasound that demonstrates obstruction of the airway and enlarged lungs. The diaphragm can be pushed down and the heart can be compressed. If the heart is severely compromised, there may be signs of fetal heart failure (hydrops) that can be detected by ultrasound. Once this condition has been detected, a targeted ultrasound will be performed to rule out the presence of associated anomalies. A specialized ultrasound of the fetal heart, called an echocardiogram, and an amniocentesis to look for chromosomal anomalies may also be performed.
Will fetal treatment be required?
In fetuses diagnosed with CHAOS, doctors will closely monitor the progress of your pregnancy. The need for fetal intervention depends on signs of heart failure (hydrops) and the gestational age at which this develops. If this occurs early in gestation, fetal surgery to relieve the obstruction may be an option but this a very rare occurrence and should be considered carefully after appropriate testing. If hydrops occurs later in gestation, your doctors may consider early delivery. An EXIT procedure will be planned for the delivery of your child.
What special considerations should be made for delivery?
Type of delivery - Typically, if there are concerns regarding the airway of an infant due to obstruction, a multi-disciplinary team will be organized for the delivery of your child. This will include specialists in maternal and pediatric anesthesia, pediatric surgery, and obstetrics. An EXIT procedure may be performed in an effort to ensure breathing capabilities of your baby at delivery. This is done at a planned cesarean delivery. This decision is best made between you and your entire team of doctors and specialists from the Center.
Place of delivery - Babies with CHAOS require a hospital with adult and pediatric specialists to care for mother and child. Because of the concerns with breathing at birth and the potential need for an EXIT procedure, this disease requires specialists that can care for the mother and child at delivery as well as after birth. If the cause of CHAOS requires surgery, the infant must be in a facility that has neonatal surgical and intensive care capabilities. Therefore, delivery should be in a facility with a neonatal intensive care unit and immediate access to pediatric surgeons, neonatologists (specialists in high-risk infants), and maternal-fetal specialists.
Time of delivery - There is no reason to intentionally induce early delivery unless there are concerns that your baby is developing heart failure (hydrops). As long as the fetus and mother are stable, the pregnancy should be allowed to proceed to term. If the baby's condition deteriorates, earlier delivery may be necessary.
What will happen at birth?
If the infant has been diagnosed with CHAOS, your doctors at the Center will have concerns about breathing difficulties for your baby at birth. An EXIT procedure may be necessary at the time of delivery. An EXIT procedure allows your doctors to examine the airway and provide a breathing tube (intubation) while the baby is still connected to the placenta by the umbilical cord and supported by mother. This allows the doctors to perform several procedures which may be needed for your baby's safety. If there is an obstruction of the airway, your baby may need to have the blockage surgically repaired at that time or go on heart-lung bypass (ECMO). The EXIT procedure is performed through a Cesarean incision.
The EXIT procedure is performed in the operating room with all of the special equipment necessary to ensure the safety of you and your baby. Afterwards, the mother will be admitted to the Women's Center and the baby to the Neonatal Intensive Care Unit at Children's Memorial Hermann Hospital to monitor for complications. The mother's recovery will be similar to those following a regular Cesarean delivery. A pediatric surgeon will evaluate the cause of CHAOS and discuss the next appropriate steps in therapy.
Contact the Texas Fetal Center to make an appointment with a high-risk pregnancy doctor.
Note: This information regarding your condition is meant to be a helpful, informative introduction. Because every newborn is different, this may not be applicable to all cases, especially if there are additional defects. Your team of experts at the Center will provide you with information specific to your pregnancy.