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Clinical Features | Radiological Evaluation | Discussion

Clinical Features:

A four-year-old girl, a known case of acyanotic congenital heart disease presented with history of recurrent respiratory tract infections in the past and failure to thrive.
The first episode was at the age of two months and subsequently she has been having two to three episodes each year for which she had been hospitalized twice in
the past. Each episode was treated with antibiotics and other supportive and symptomatic therapy. At present she was febrile with pulse of 106 beats/min and right
sided crepitations. Clinical evaluation of her abdomen was normal.

Radiological evaluation:

Frontal and right lateral radiographs of the chest were obtained. (Fig 1A, 1B)

Fig. 1A	Fig. 1B

There is cardiomegaly with raised right dome of diaphragm and a suspicious right posterior mediastinal shadow. There is "too much" of the heart on the right side of
the spine. There is also a right concave scoliosis with a suspicious retrocardic shadow seen on the frontal view. This is better appreciated on the lateral film. A CT
scan of the chest was suggested to rule out an associated pulmonary abnormality such as a sequestration.

Plain and contrast of the chest and abdomen were performed. These are seen on images 2A-2D

Fig. 2A	Fig. 2B
Fig. 2C	Fig. 2D

These show herniation of the right kidney into the right hemithorax along with the right liver. The renal pedicles with the renal hilum were seen coursing inferiorly. Also, the medial aspect of the right hemidiaphragm was not well visualised. The left hemithorax, major vascular structures were normal. The mediastinum, bony thorax, spleen and
left kidney were normal. An film of the abdomen obtained at the conclusion of the CT study shoes the high position of the right kidney. No ureteral or bladder abnormalities
is seen.

Fig. 3

For academic purposes, an ultrasound with colour doppler study of the abdomen was done which showed a part of the posterior segment of the liver along with the right kidney to be in the right hemithorax along with a pulled up right hepatic vein. The right kidney with right renal artery and vein were seen posterior to the inferior vena cava.
The herniated portion was posteromedial to the diaphragm.(Fig4A-4D)

Fig. 4A	Fig. 4B
Fig. 4C	Fig. 4D

Thus a diagnosis of right-sided congenital diaphragmatic hernia with a "hyper ascended kidney" in a known case of acyanotic congenital heart disease was made.

DISCUSSION:

Embryology:

The diaphragm develops from the caudal pair of ridges of the pericardioperitoneal canals, which form the pleuroperitoneal membrane. As the lung buds grow superiorly
and the liver and peritoneal spaces expand, these membranes become more prominent and attach themselves to the abdominal wall along the dorsal and lateral margins.
The anterior half of the diaphragm is formed by the septum transversum, which arises as a condensation of the mesoderm around three to four weeks of gestation. From
six to 12 weeks, myoblasts from the abdominal wall migrate into the peripheral aspects of these membranes and contribute to the growth of the diaphragm. The myoblasts also grow into the dorsal esophageal mesentery forming the diaphragmatic crura. The diaphragm is formed by four separate elements - the septum transversum, the pleuroperitoneal membrane, the dorsal mesentery of the esophagus and the body wall. Also the diaphragm shifts markedly in position. Initially the diaphragm lies at
the level of the third to fifth cervical somites. It receives innervation from these levels. Later there is rapid growth in the dorsal part of the embryo, which causes apparent descent of the diaphragm. Thus the diaphragm lies at the thoracolumbar level but receives innervation from the C3-C5 level in the form of the phrenic nerve.

Congenital diaphragmatic may be of the following types:

1) Retrosternal: Morgagni hernia
2) Posterolateral: Bochdalek hernia
3) Posterior hernia- this is due to failure of development of the posterior part of the diaphragm. One or both crura may be absent. The aorta and esophagus lie in the
gap but there is no hernial sac.
4) Central hernia- it is a rare left sided defect, which is supposed to be due to rupture of the fetal membranous diaphragm in the region of the left dome.

Morgagni hernia:

It occurs through the space between the xiphoid and costal origins of the diaphragm (foramen of Morgagni or space of Larrey). It is more common on the right side and
usually lies between the pericardium and the pleura. It accounts for about 2-4% of all diaphragmatic hernias. The herniated viscera include colon, omentum, and liver. Respiratory and gastrointestinal complaints are rare and the child may be asymptomatic. Only 50% are detected by the age of 5 years on chest films done for a
nonrelated purpose.

The differential diagnoses of air containing Morgagni hernia include pneumonia, atelectasis, pneumatocele, abscess, and cystic adenomatoid malformation. If the liver herniates through, then the solid appearance may simulate a pericardial mass, diaphragmatic tumour or an anterior mediastinal mass.

Morgagni hernias are corrected even if asymptomatic because there is potential for incarceration and strangulation.

Bochdalek hernia:

It is by far the commonest in type (1 per 3000 live births). It occurs through the pleuorperitoneal hiatus (foramen of Bochdalek) situated at the periphery of the diaphragm
in the region of the attachments of the 10th and 11th ribs. It is more common on the left side. This occurs probably due to the fact that the pleruoperitoneal canal closes earlier on the right; about 3% children have bilateral diaphragmatic hernia. Reports based on CT sans of adults suggest a prevalence of 6%. This is largely due to the fact
that CT readily recognizes asymptomatic small hernias not visualized on plain radiographs.

Neonates generally present with severe respiratory distress and have a scaphoid abdomen. Also associated are midline defects like cleft lip, cleft palate, spina bifida and omphalocele and cardiac defects like VSD and tetralogy of Fallot. Irrespective of the side of the hernia there is bilateral pulmonary hypoplasia present which is critical to
the outcome of the infant.

Radiological features:

a) Antenatal USG: mediastinal shift from the midline, presence of mass in the thorax (unaerated gut, liver), fetal ascites, fetal pleural effusion and polyhydramnios.

b) Neonatal imaging: left sided bowel loops filled with air with mediastinal shift to the right, right sided liver appears more solid with pleural effusion. Can be confirmed by injecting air into the nasogastric tube to distend stomach and bowel loops. Abdominal USG to confirm the location of other viscera (spleen, kidneys) is needed.

The treatment is by surgical correction of the defect. Mortality rates very between 20-80%. Improvement in terms of development of the hypoplastic lung in long term postoperative survivors is remarkable. Thus early detection of the defect ideally inutero is critical to successful outcome of the infant.