Bochdalek hernia

A Bochdalek hernia is one of two forms of a congenital diaphragmatic hernia, the other form being Morgagni hernia. A Bochdalek hernia is a congenital abnormality in which an opening exists in the infant’s diaphragm, allowing normally intra-abdominal organs (particularly the stomach and intestines) to protrude into the thoracic cavity. In the majority of patients, the affected lung will be deformed,^[1] and the resulting lung compression can be life-threatening. Bochdalek hernias occur more commonly on the posterior left side (85%, versus right side 15%).

Causes

Most likely, Bochdalek hernias are formed throughout the growth process and organ construction during fetal development. During fetal development, the diaphragm is formed between the seventh and tenth week. Also, during this time, the esophagus, stomach, and intestines are formed. Therefore, a Bochdalek hernia forms either from malformation of the diaphragm, or the intestines become locked into the chest cavity during the construction of the diaphragm. Although these are some factors that contribute to a Bochdalek hernia, it does not take all variables into account. Bochdalek hernias, along with Morgagni hernias, are both multifactor conditions, meaning that there are many reasons and multiple variables that contribute to the malformations. For example, in each case there could be genetic and or environmental condition(s) that can add to the probability of this birth defect.^[2]

Epidemiology

Bochdalek hernias make up about 0.17% to 6% of all diaphragmatic hernia cases and about one in every 2200 to 12,500 births every year.^[3] Babies who are born with a Bochdalek hernia are more than likely to have another birth defect caused by the hernia. About twenty percent of those children born with a Bochdalek hernia, also have a congenital heart defect. In addition, infants born with this condition may also have other abnormalities. “Between five and sixteen [percent of infants] have a chromosomal abnormality.”^[2] In most cases, left-sided hernias or Bochdalek hernias have a ratio of 3:2 of males to females. In other words, Bochdalek hernias are more common in men.

Morbidity and mortality

Bochdalek hernia can be a life-threatening condition. Approximately 85.3% of newborns born with a Bochdalek hernia are immediately high risk.^[4] Infants born with a Bochdalek hernia have a “high mortality rate due to respiratory insufficiency.”^[5] Between 25-60% of infants die from a Bochdalek hernia.^[6] The lungs, diaphragm, and digestive system are all forming at the same time, so when a Bochdalek hernia permits the abdominal organs to invade the chest cavity rather than remain under the diaphragm in the correct position, it puts the infant in critical condition. These "foreign bodies” in the chest cavity compress the lungs, impairing their proper development and causing pulmonary hypoplasia.^[2] Since the lungs of infants suffering from a Bochdalek hernia have fewer alveoli than normal lungs, Bochdalek hernias are life-threatening conditions due to respiratory distress.^[2] Also, if the invasion of the intestine or stomach punctures the lung, then the lungs cannot fill completely with air. The baby will not be healthy or stable with this condition because he or she cannot take in enough air and oxygen to keep the body operating properly. Like the lungs, the intestines may also have trouble developing correctly. If the intestines are trapped within the lungs, then the lungs and intestines may not be receiving the amount of blood they need to stay healthy and function properly.

Symptoms

In normal Bochdalek hernia cases, the symptoms are often observable simultaneously with the baby’s birth. A few of the symptoms of a Bochdalek Hernia include difficulty breathing, fast respiration and increased heart rate. Also, if the baby appears to have cyanosis (blue-tinted skin) this can also be a sign.^[3] Another way to differentiate a healthy baby from a baby with Bochdalek Hernia, is to look at the chest immediately after birth. If the baby has a Bochdalek Hernia it may appear that one side of the chest cavity is larger than the other and or the abdomen seems to be concave (caved in).^[2]

Diagnosis

One way to determine if a baby does in fact have a Bochdalek hernia, would be to have a pediatrician perform a physical on the infant. A chest x-ray can also be done to examine the abnormalities of not only the lungs but also the diaphragm and the intestine. In addition to these, a doctor can also take a blood test, drawing arterial blood to check and determine how well the baby is breathing and his or her ability to breathe. A chromosomal test (done by testing the blood) can also be performed to determine whether or not the problem was genetic. The doctors can also take an ultrasound of the heart (echocardiogram) to evaluate the health of the heart.

Treatment

In order to treat a Bochdalek hernia, the baby’s physician must take into account multiple factors. First, the diagnosis will vary depending on whether the Bochdalek hernia was found during fetal development or after birth. “The key to survival lies in prompt diagnosis and treatment.” ^[6] Second, the baby’s overall health and medical history will be evaluated. Third, the doctor will look at the seriousness of the condition. Fourth, the baby will need to be evaluated at the level of medication, procedure and therapy he or she can handle, and finally, the doctor will take into consideration the opinion and preference of the parents. After these things are all taken into consideration and evaluated, the doctor will determine how to treat the baby. There are three different treatments available. The first treatment includes the baby’s admission into the NICU (Neonatal Intensive Care Unit).^[2] In most Bochdalek Hernia cases, babies who are admitted in the NICU, are placed on a mechanical ventilator to help breathing. Another treatment involves putting the infants on a temporary heart/lung bypass machine, called an ECMO.^[2] This normally pertains to children who have severe problems. ECMO performs the tasks the regularly functioning hearts and lungs do. ECMO allows oxygen to be regulated into the blood and then pumps the blood throughout the entire body. Normally, this machine is used to stabilize the baby’s condition. The third option in treatment is surgery.^[7]

After the baby is stable and his or her state has improved, the diaphragm can be fixed and the misplaced organs can be relocated to their correct position.^[2] Although these are various treatments for Bochdalek Hernias, it does not guarantee the baby will survive.^[2] Since the baby must go through some or all of the previous treatments, the baby’s hospital stay is usually longer than that of a “normal” newborn. The average infants born with a Bochdalek Hernia stay in the hospital between 23.1 and 26.8 days.^[6]

Mnemonic

A useful way to remember the localization of this hernia vs. Morgagni is "Bochdalek is back and to the left" (re the postero-lateral localization).

References