Address correspondence to William Cusick, MD University of Connecticut Health Center, Division of Maternal-Fetal Medicine, 263 Farmington Avenue, Farmington, CT 06030-2950. Ph: 203-679-3267; Fax: 203-679-1271, * St Francis Hospital and Medical Center, 114 Woodland Street, Hartford, CT 06105-1200.

Synonyms: Paraesophageal, diaphragmatic esophageal hiatal hernia.

Definition: Herniation of the abdominal contents into the thorax through the esophageal hiatus. Three types of hiatal hernias exist: sliding (accounting for 90% of cases), paraesophageal, and mixed. The esophagogastric junction migrates cephalad through the hiatus with a sliding hiatal hernia and is in a normal intra-abdominal position with a paraesophageal hernia.

Prevalence: The prevalence in newborns is unknown but assumed to be rare. It is found in 0.8 - 2.9% of patients undergoing upper gastrointestinal studies. M1:F1.

Etiology: Unknown, but some cases with short esophagus may have an autosomal dominant inheritance.

Pathogenesis: A congenital or acquired enlargement of the esophageal hiatus allows for progressive herniation of the abdominal contents into the thoracic cavity. The herniation may be facilitated by the negative pressure generated in the thoracic cavity during normal respiration.

Associated anomalies: Gastric volvulus.

Differential diagnosis: Congenital diaphragmatic hernia, bronchogenic cyst, neurenteric cyst, pericardial cyst, pulmonary sequestration, cystic adenomatoid malformation, and cystic teratoma.

Prognosis: Excellent with early diagnosis and surgical correction.

Recurrence risk: Not increased.

Management: Prompt neonatal evaluation followed by early surgical correction in confirmed cases of paraesophageal hiatal hernias.

MESH: Hernia, hiatal

Introduction

The diaphragm separates the thoracic and abdominal cavities. Three openings exist in the diaphragm, allowing for passage of the esophagus, aorta, and inferior vena cava between the thoracic and abdominal cavities. Hiatal hernia results when an enlarged esophageal hiatus allows for the cephalad migration of the distal esophagus and/or stomach into the thoracic cavity. Hiatal hernias are most frequently diagnosed in adults and are classified into three types: sliding, paraesophageal, and mixed1. Reports of paraesophageal hiatal hernias in neonates and children exist2,3. Bahado-Singh et al. reported a case of hiatal hernia diagnosed by ultrasound in the third trimester4.

We describe a case of congenital paraesophageal hiatal hernia diagnosed by ultrasound in the third trimester following a normal second trimester ultrasound evaluation. We also present the salient diagnostic features and the evolution of the ultrasonic findings in the third trimester.

Case report

A 23-year-old G3P2002 woman was referred to the antepartum diagnostic unit at our institution at 19 weeks gestation for ultrasound evaluation. The patient"s medical and obstetrical course had previously been uncomplicated. Fetal biometry was consistent with dates. A detailed ultrasound evaluation of fetal structural anatomy, including four-chamber cardiac view, was normal (fig. 1).

Figure 1: Axial section (19 weeks gestation) through the chest at the level of the four-chamber heart. No intrathoracic mass is present. Sp: spine

At 35-weeks gestation, the patient returned for evaluation of fetal growth. Fetal biometry was consistent with a 35-week gestation. The fetal stomach and proximal duodenum appeared slightly dilated. A portion of the fetal stomach located in the midline, anterior to the vertebral body and posterior to the right atrium, appeared to be extending cephalad above the level of the diaphragm (fig. 2). The amniotic fluid volume was normal, and the remainder of the fetal anatomic survey, including fetal echocardiogram, was normal. The differential diagnosis included either an evolving congenital diaphragmatic hernia or a fetal hiatal hernia. The patient was counseled regarding these findings and offered genetic studies. Amniocentesis was performed which showed a normal 46XY fetal karyotype.

Figure 2: On this longitudinal section taken at 35 weeks gestation, the spine is up. The fetal stomach (S) is dilated and extends into the fetal chest posterior to the heart. S: stomach, RV: right ventricle, RA: right atrium

On repeat ultrasound evaluation at 37 weeks gestation, the fetal stomach remained dilated. The amount of the stomach present above the diaphragm had increased and was now visible in the midline, posterior to the heart at the level of the four-chamber view. There was no mediastinal or cardiac axis deviation noted (fig. 3,4). Over the next two weeks serial ultrasound evaluations showed progressive herniation of the dilated stomach into the fetal thorax. At no time was a mediastinal shift or cardiac axis deviation seen.

Figure 3: Transverse section through the fetal chest at 37 weeks gestation. Taken at the level of the four-chamber heart, the fetal stomach (S) can be seen anterior to the spine (SP) and posterior to the right atrium. No cardiac or mediastinal shift is present. S: stomach, Sp: spine

Figure 4: On this longitudinal section taken at 37 weeks gestation, the sternum is up. The fetal stomach (S) is seen in the chest, posterior to the right ventricle (RV). S: stomach, RV: right ventricle, D: diaphragm

Induction of labor was undertaken at 39 weeks 4 days. A male infant weighing 3175g with Apgars of 9 and 9 was delivered without complications. Following initial stabilization and transfer to the NICU, the infant became cyanotic and required emergency intubation and ventilatory assistance. A chest X-ray showed normal lung fields with a large air-density pouch demonstrated behind the cardiac silhouette and a small amount of bowel gas noted in the left upper quadrant of the abdomen (fig. 5). Further radiologic contrast studies confirmed the presence of a midline stomach within the chest cavity (fig. 6,7).

Figure 5: An anteroposterior chest film taken after nasogastric tube placement. A large air-density pouch is seen in the midline of the chest.

Figure 6: An anteroposterior chest film after placement of radiopaque dye. The intrathoracic mass is in continuity with the esophagus.

Figure 7: Lateral chest film showing contrast in the stomach, which is located superior to the diaphragm and posterior to the heart.

The infant underwent partial decompression of the stomach with a nasogastric tube and, after evaluation by the pediatric surgeon, was taken for an exploratory laparotomy. At time of surgery, the stomach was not visible within the abdominal cavity. Further exploration confirmed the presence of the entire stomach within the chest cavity. Herniation of the stomach had occurred in the midline through an enlarged esophageal hiatus. An associated axial mesenteric gastric volvulus was present. The gastric volvulus was reduced, followed by repair of the hiatal crura, a Thal gastropexy and G-tube placement. Following surgery, the infant"s postoperative course was uncomplicated. The infant came off ventilatory support on the third postoperative day. At time of discharge (9 days after surgery), the infant was tolerating oral feedings and progressing well.

Discussion

An enlarged diaphragmatic esophageal hiatus is common to both sliding and paraesophageal hiatal hernias. The intrathoracic location of the esophagogastric junction differentiates the more common sliding hiatal hernia from the paraesophageal type1. Although the etiology is uncertain, it appears that both congenital and acquired enlargement of the esophageal hiatus may contribute to the development of hiatal hernia. The majority of patients with hiatal hernia are asymptomatic, making it difficult to accurately estimate the incidence in the general population. Symptomatic patients with a sliding hiatal hernia frequently complain of persistent gastroesophageal reflux. Symptoms typically absent in patients with paraesophageal herniation. In patients with paraesophageal hiatal hernia, symptoms are due to mechanical obstruction secondary to gastric incarceration or volvulus1 (fig. 8).

Figure 8: Drawing depicting the relationship among the stomach, esophagogastric junction, and the esophageal hiatus. The anatomical relationship in the paraesophageal and sliding hiatal hernia can be compared to the normal (left).

Embryology

The diaphragm develops from four structures(fig. 9). The septum transversum forms the central tendon of the diaphragm. During the sixth week of fetal life, the partition between the thoracic and abdominal cavities is completed as the septum transversum fuses with the paired pleuroperitoneal membranes and the dorsal mesentery of the esophagus to form the primitive diaphragm. During the ninth to twelfth weeks, the formation of the diaphragm is completed as tissue from the body wall fuses peripherally with the primitive diaphragm6.

Figure 9: Drawing illustrating the development of the fetal diaphram and its four embryologic components.

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.

Differential diagnosis

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.

Management

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.

References

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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.