CDH can happen to different degrees of severity and in different parts of the diaphragm, says Holly L. Hedrick, MD, a pediatric and fetal surgeon at Children’s Hospital of Philadelphia (CHOP), and an expert in treating CDH babies. According to CHOP, a healthy newborn’s lung can be the size of a baseball. Some babies with CDH have lungs as small as a penny. The two main issues that confront newborns with CDH are:
Pulmonary Hypoplasia When the lungs can’t develop fully, they don’t form the proper internal structure or enough alveoli, which facilitate breathing. If you think of the lungs’ insides as the branches of a tree, it’s like the tree has been pruned too much.Pulmonary Hypertension When the lungs are compressed during development, the blood vessels in them end up being thicker, less elastic, and less able to exchange gases as normal, explains Dr. Hedrick, which leads to pulmonary hypertension, or high blood pressure in the lungs.
CDH is rare, but not vanishingly so. About 1 in every 2,500 babies is born with it. While it may have a genetic component, most cases of CDH appear to be idiopathic, meaning there’s no identifiable cause. The DHREAMS study (Diaphragmatic Hernia Research & Exploration, Advancing Molecular Science), a data-gathering project across many research institutions, is currently investigating possible genetic causes of CDH. Researchers have pinpointed a gene called ROBO1 that plays a role in the development of both the heart and the diaphragm. They’ve concluded that a very small subset of CDH babies (less than 1 percent) have a genetic mutation that causes heart problems along with CDH. Many cases of CDH are discovered in a routine ultrasound during pregnancy. Most cases develop as early as 11 weeks, but they may not be detectable on an ultrasound, or the mother may not have an ultrasound until a routine anatomical scan around 20 to 24 weeks. Then there are some cases that are not caught until birth, when a newborn exhibits breathing difficulties. There are several types of CDH, according to the U.S. National Library of Medicine. They are:
Posterior Lateral Also called a Bochdalek hernia, this defect accounts for the vast majority of CDH. They can be left side (more common) or right side (less so).Anterior Also called a Morgnani hernia, this defect occurs in the front of the diaphragm. These are far less common than posterior lateral CDH.Other Types In extremely rare cases, a defect occurs in the center of the diaphragm, or there is only a thin membrane in place of a normal structure.
How Congenital Diaphragmatic Hernia Is Treated
Knowing a baby is going to be born with CDH gives parents and doctors an important advantage, in terms of planning the delivery and knowing what’s ahead. The only treatment for CDH is surgery, but before that can happen the baby needs to be stabilized and in good enough overall health to withstand it, says Hedrick. “We used to think of surgery as something that had to happen immediately, but now we talk in terms of stabilization first.” Here’s what typically happens: Immediately after birth, the baby is put on a ventilator to help him breathe, and another tube may be threaded down into the stomach to keep air from further expanding the intestines. Another intervention some babies need is called extracorporeal membrane oxygenation (ECMO), a treatment in which a pump circulates the baby’s blood through an artificial lung. “About a quarter of babies need ECMO as a bridge to get them stabilized, and if they need it, it’s usually in that first day,” says Hedrick. Once the baby is stabilized, he’s brought to the neonatal intensive care unit (NICU). After that, she says, “it’s a day-to-day wait in terms of seeing how the baby’s heart is functioning and how he’s responding to therapy,” before surgery can occur. Surgical repair of CDH involves an incision below the baby’s ribs. The surgeon brings the organs that have migrated into the chest back down into place, and then repairs the diaphragm. “About 70 percent of the time we use a Gore-Tex patch to replace the missing part of the diaphragm,” says Hedrick. Also in some cases, such as when the liver is up in the chest cavity and must be brought down, the abdomen is too “crowded” for the surgical wound to be closed right away, and another type of mesh or patch is kept over the area.
The Future for Babies With CDH: Prognosis and Complications
The good news is that the current survival rate for CDH babies is over 80 percent, says Hedrick, a significant increase from even a decade ago. Some factors that impact recovery include whether the baby also has other birth defects, and how severe the pulmonary hypoplasia is. Another important factor is whether the liver is among the organs that herniated. “The liver is a solid, nonyielding organ, so the lung has even more trouble growing against it,” explains Hedrick. Post-surgery, the goal is to slowly wean the infant off breathing support, and start normal feeding, something that must wait until the digestive system begins to work. Longer term issues that may affect a CDH baby include:
Reflux Gastroesophageal reflux disease (GERD) is common among CDH babies. The backing up of stomach contents into the esophagus can also trigger further breathing problems. Sometimes GERD can be treated with medication, and in severe cases the child may need an operation called fundoplication, in which the upper stomach is wrapped around the bottom of the esophagus to stop reflux.Developmental Delays The more severe the defect is, and the longer a baby is in the NICU, the more likely he or she may experience developmental delays. The important factor here, says Hedrick, is to intervene with therapy (physical, occupational, and feeding therapy) as soon as possible. “We try to be as aggressive as we can about initiating therapy as soon as a baby can medically withstand it, because we think it makes a difference.”
The (Near) Future: Fetal Surgery Congenital Diaphragmatic Hernia
The future of treatment for some babies with CDH is intervening before birth, via a procedure called fetoscopic endoluminal trachaeal occlusion (FETO). Usually done around 27 weeks gestation, it involves a surgeon passing instruments through the mother’s abdomen, into the uterus, and into the fetus’s mouth and down his or her airway. A tiny balloon (the size of a grain of rice) is placed in the trachea. Once inflated, this stops fluid that would normally flow out of the developing lungs from doing so, thus helping inflate the lungs, promoting development. A review published in 2017 in the European Journal of Pediatric Surgery found that FETO increased survival rates of babies born with CDH, but that more data and a large, multicenter clinical trials are warranted.
What to Do if Your Baby Has CDH
The most important thing you can do if you find out your unborn baby has CDH is to work with a hospital or medical center that has experience with its treatment, and has a NICU. Also, advises Hedrick, “find as much information as you can, and educate yourself. There’s a rich network of parents who have been through this and can help.” CDH International is a good place to start.
