Congenital Diaphragmatic Hernia

blog.hishamrana.com Congenital Diaphragmatic Hernia Introduction Congenital diaphragmatic hernia (CDH) is a developmental defect in the diaphragm that allows abdominal viscera to herniate into the chest. It occurs in 1 out of 2200 births. Affected neonates usually present in the first few hours of life with respiratory distress that may be mild or so severe as to be incompatible with life. With prenatal advances survival has improved but there still remains significant risk of death and complications. Approximately 30 percent of fetuses with CDH will be stillborn; up to 30 to 50 percent of those infants surviving to delivery will die before transfer to a neonatal center. Types Bochdalek Hernia is the most common type (95%). It occurs through old pleuroperitoneal canals (just lateral to either side of the spine). A neonate born with this form has either a left-sided (85%) due to “protection” from the liver or rightsided opening in the diaphragm posteriorly. Hernia may contain intestine, stomach, spleen, liver or omentum. These are considered more life threatening than any other type. If the defect is large, newborns usually present with severe respiratory distress, cyanosis, and scaphoid abdomen. Entire diaphragm is almost never absent. Some part of diaphragm is usually found at surgery, even if defect is very large. Hypoplasia of ipsilateral lung occurs from mass effect of bowel Most often these are isolated congenital abnormalities but they can have Figure 1: Bochdalek Hernia congenital heart disease, 13 ribs, and malrotation of GI tract is frequently present. Morgagni’s Hernia is far rarer (2% of cases). This occurs in the anterior midline through the sternocostal hiatus of the diaphragm known as an anteromedial parasternal defect (Space of Larrey). Maldevelopment of septum transversum. Right > left (heart protects). 90% of cases occurring on the right side. Usually not large and usually unilateral. Associated with pericardial defects and omental fat in the pericardial space. In central hernia of the diaphragm, herniation occurs through a central tendon defect, mainly into the pericardial cavity and left hemithorax. The Figure 2: Morgagni's Hernia pericardial effusion seen may be the result of pericardial irritation. Diagnosis CDH is usually diagnosed prenatally at 24 weeks using ultrasound. Left-sided CDH is characterized by the presence of a heterogeneous mass in the chest that usually results in mediastinal shift to the right. The fluid filled stomach may be identified in the chest cavity next to the heart and, therefore, absent in the abdomen. Fluid in the bowel and peristalsis of bowel in the chest helps to distinguish CDH from an intrathoracic mass. The liver may be also herniated.

blog.hishamrana.com Right-sided CDH is characterized by the presence of a homogeneous mass (liver) in the chest that often results in mediastinal shift to the left. Bowel may herniate as well. The left shift of the heart is a key finding since sonographically the liver is similar in appearance to fetal lung and bowel peristalsis may not be observed. Doppler ultrasound can be used to demonstrate the hepatic vessels. Gallbladder identification in the chest is also diagnostic of right sided CDH. Treatment Obstetrical management involves twice weekly non-stress testing. Ultrasounds are done at 28, 30, 32, and 34 to 35 weeks gestation to assess fetal growth and amniotic fluid volume. Polyhydramnios usually develops at 28 to 32 weeks (impaired fetal swallowing) while oligohydramnios may develop at 34 weeks (decreased urination and decreased lung secretion). Labor is usually induced at week 38 to 39 at a tertiary center with extracorporeal membrane oxygenation (ECMO) capability. Pediatric surgery and neonatology are put on standby. Inutero therapy involves patch closure of the diaphragmatic defect but this process failed in CDH with liver hernination due to kinking of the umbilical vien. Neonatal management via emergent surgical correction resulted in only 50% survival rate in the 1980s. The problem was the unaddressed pulmonary hypoplasia and and pulmonary hypertension. Therefore treatment switched to managing pulmonary pathology first then surgery followed at a later time. Aggressive medical management with decompression of the lung tissue, cardiovascular support with fluids and inotropes, and ventilatory support including high frequency via extracorporeal membrane oxygenation (ECMO) have shown improved survival rates. Surgery involves patching the defect. Complications include recurrent hernia, GER, FTT, and infection. Images

Figure 3: Chest X-Ray showing air-filled bowel loops in the left chest causing mass effect and mediastinal shift towards the right. The nasogastric tube terminates in the left thoracic stomach. The umbilical venous catheter takes an atypical course because the liver is partially herniated into the left chest.

Figure 4: (Left) High resolution fetal ultrasound demonstrates fetal stomach (ST) herniated into the left chest and fetal liver (FL) below the level of the diaphragm. (Right) Ultrasound demonstrates poor prognosis herniation of fetal liver (FL) into the left chest.

References 1. 2. 3. 4.

Gross, R. Congenital hernia of the diaphragm. Am J Dis Child 1946; 71:579. Congenital diaphragmatic hernia: survival treated with very delayed surgery, spontaneous respiration, and no chest tube. Uptodate “Congenital diaphragmatic hernia in the neonate” & “Congenital diaphragmatic hernia: Prenatal diagnosis and management”. Including images. Wikipedia “Congential Diaphragmatic Hernia”