The esophagus, aorta, and inferior vena cava pass between the thoracic and abdominal cavities through three openings in the diaphragm. These hiatuses are located in the portion of the diaphragm derived from the esophageal mesentery. Hiatal hernias occur through a physiologic defect (esophageal hiatus) in the diaphragm. Conversely, congenital diaphragmatic hernias occur through a pathologic defect in the diaphragm secondary to defective formation and/or incomplete fusion of the pleuroperitoneal membrane6.
A congenital paraesophageal hiatal hernia must be differentiated from the more common congenital diaphragmatic hernia. Congenital diaphragmatic hernias are most typically located posteriorlaterally on the left side (Bochdalek). These lesions are frequently associated with a mediastinal shift, cardiac axis deviation, polyhydramnios, and other fetal anomalies7-9. The ultrasonic findings present in this case were similar to those in the previously reported case of prenatally diagnosed hiatal hernia4. It is interesting to note that the hernia was not present on her 19 week ultrasound.
At the time of initial diagnosis in the early third trimester, the fetal stomach and duodenum appeared slightly dilated. In addition, a portion of stomach was retained in the fetal abdomen. The intrathoracic mass, located in the midline and anterior to the vertebral body, communicated directly with the fetal stomach. The mediastinum and cardiac axis were normal. No other fetal anomalies were present. The amniotic fluid volume was normal. Serial ultrasound evaluations in the third trimester revealed progressive herniation of the fetal stomach into the fetal chest. At the time of surgical exploration in the neonatal period, the entire stomach was located above the diaphragm.
Other causes of intrathoracic cystic masses include pulmonary sequestration, bronchogenic cyst, neuroenteric cyst, pericardial cyst, cystic adenomatoid malformation, and cystic teratoma10. In all of these cases, the stomach bubble is normally positioned in the fetal abdomen and is of normal size. With the exception of a cystic teratoma or bronchogenic cysts, these other cystic thoracic lesions are located in the lung parenchyma or the periphery of the chest. A paraesophageal hiatal hernia may be differentiated from these other conditions by the mediastinal location of the cystic mass and the continuity of the mass with a slightly dilated fetal stomach.
Initial ultrasound evaluation of a fetus suspected of having congenital hiatal hernia should include a detailed anatomic survey for other anomalies and assessment of amniotic fluid volume. Consultation with a pediatric surgeon is advisable. Serial ultrasounds are recommended to assess for increasing herniation and polyhydramnios. Planned delivery in an institution with experienced neonatalogists and available pediatric surgeons is preferred.
As demonstrated in our case, large herniations may be associated with neonatal respiratory distress due to extrinsic lung and cardiac compression2. With large herniation occurring early in gestation (before 24 weeks), the potential for pulmonary hypoplasia exists. Ventilatory support should be readily available. Air in the stomach, secondary to assisted ventilation, may further compromise neonatal respiration. A nasogastric tube should be placed to decompress the stomach if necessary. After nasogastric tube placement, a chest X-ray can be performed to assist in delineating the location of the stomach. A definitive diagnosis of paraesophageal hernia can be made on an upper gastrointestinal tract series performed by placing contrast down the nasogastric tube. After stabilization, infants with documented paraesophageal hernias should undergo prompt surgical correction to avoid complications related to regurgitation, incarceration, gastric volvulus, bowel obstruction and/or perforation11-13. Fixation of the stomach to reconstitute some of its normal attachments may prevent recurrent volvulus and possible gastroesophageal reflux.
1. Ellis FH. Diaphragmatic hiatal hernias. Postgrad Med 1990:88 (1);113-124.
2. Al-Arfaj L, Khwaja MS, Upadhyaya P. Massive hiatal hernia in children. Eur J Sur 1991:157;465-468.
3. Senocak ME, Buyukpamukcu N, Hicsonmez A. Massive paraesophageal hiatus hernia containing colon and stomach with organo-axial volvulus in a child. Turkish J Ped1990;32:53-68.
4. Bahado-Singh RO, Romero R, Vecchio M, Hobbins JC. Prenatal diagnosis of congenital hiatal hernia. J Ultrasound Med 1992:11;297-300.
5. Ellis FH, Croziga RE, Shea JA. Paraesophageal Hiatus Hernia. Arch Surg 1986; 121: 416-420.
6. Body Cavities, Primitive Mesenteries, and Diaphragm. In: Keith L Moore. The developing human: clinically oriented embryology. 3rd Edition. Philadelphia. WB Saunders Company, 1982: 167-178.
6. Benacerraf BR, Adzick NS. Fetal diaphragmatic hernia: ultrasound diagnosis and clinical outcome in 19 cases. Am J Obstet Gynecol 1987:156;573-576.
7. Thorpe-Beeston JG, Gosden CM, Nicolaides KH. Prenatal diagnosis of congenital diaphragmatic hernia: associated malformations and chromosomal defects. Fetal Ther1989:4;21-28.
8. Crawford DC, Wright VM, Drake DP, Allan LD. Fetal diaphragmatic hernia: the value of fetal echocardiography in the prediction of postnatal outcome. Bri J Obstet Gynaecol1989:96;705-710.
9. Hilpert PL, Pretorius DH. The thorax. In: Nyberg DA, Mahony BS, Pretorius DH (eds). Diagnostic ultrasound of fetal anomalies. Chicago. Year Bood Medical Puclishers, Inc., 1990; 262-290.
10. Landreneau RH, Johnson JA, Marshall JB, Hazelrigg SR, Boley TM, Curtis JJ. Clinical spectrum of paraesophageal herniation. Diges Dis Sci 1992:32(4);537-544.
11. Hill LD. Incarcerated paraesophageal hernia: a surgical emergency. Am J Sur 1973:126;286-291.
12. Ozdemir IA, Burke WA, Ikins PM. Paraesophageal hernia: a life threatening disease. Ann Thorac Surg 1973; 16(6):547-554.