Detail Correction for Gross Classification of Esophageal Atresia Based on 434 Cases in China
Esophageal atresia (EA) is one of the most common congenital abnormalities of the esophagus, often accompanied by tracheoesophageal fistula (TEF) in 70% to 90% of cases. Since Vogt first recognized and classified the types of anomalies in 1929, several classification systems have been proposed, including those by Ladd, Gross, Swenson, and Kluth. Among these, the Gross classification, introduced in 1953, remains one of the most widely accepted and utilized systems. Despite its widespread use, recent advancements in surgical and imaging techniques have revealed certain inconsistencies and “defects” in the illustrations of the Gross classification. This study aims to address these discrepancies by reviewing 434 consecutive cases of EA/TEF in China and proposing necessary modifications to the Gross classification.
The study protocol was approved by the Medical Ethics Committee of Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, in accordance with the Declaration of Helsinki. The requirement for patient informed consent was waived due to the retrospective nature of the study. Data extraction was performed using a predesigned form, which included general patient information, imaging results, and operative reports. Two experienced radiologists independently measured the diameter of the proximal esophageal pouch at its widest point on esophagograms, with the intra-class correlation coefficient (ICC) used to evaluate the consistency of their measurements. Data were analyzed using SPSS version 22.0, with continuous variables presented as mean and standard deviation or median (Q1, Q3) and categorical variables as counts and percentages.
A total of 434 patients with EA/TEF underwent surgical intervention at Beijing Children’s Hospital and The Affiliated Children’s Hospital of Nanchang University between January 2007 and January 2020. The demographic and clinical characteristics of these patients are detailed in Supplementary Table 1. The diameters of the proximal esophageal pouch were measured in five cases for each type of esophagogram, with the parameters measured by the two radiologists showing good consistency (ICC = 0.89).
Based on the esophagograms and intraoperative findings, the following modifications were made to the illustrations of the Gross classification:
Corrigendum A: Gross Type A
Patients with Gross type A typically present with a notably distended proximal blind-ending pouch. The underdeveloped esophageal remnant at the distal end leads to a stomach that is significantly smaller (approximately 5 mL) compared to the normal neonatal gastric volume of 20 to 30 mL. The gap length between the two esophageal pouches ranges from 5 to 8 vertebrae.
Corrigendum B: Gross Type B
The proximal blind-ending pouch in type B appears less dilated than in type A. The fistula is found to be ascendingly connected to the posterior tracheal wall, rather than horizontally. The gap length between the blind pouches measures roughly the same as in type A, and the stomach remains small (approximately 5 mL).
Corrigendum C: Gross Type C
Similar to type A, the upper esophageal pouch in type C is hypertrophied and dilated. An inflated stomach and a shortened gap length (approximately two vertebrae) can be observed. The diameter of the proximal esophageal pouch (usually 1.5–2.0 cm) differs significantly from that of the distal tracheal esophageal fistula (often 0.5 cm).
Corrigendum D: Gross Type D
Children with type D EA/TEF are identified with a narrow upper pouch with a blind end and a gas-filled stomach. Similar to type B, the fistula ascends from the anterior esophageal wall to the posterior of the trachea.
Corrigendum E: Gross Type E
Congenital pure TEFs (type E) are usually located at the first thoracic vertebral level (level of the superior thoracic aperture).
Corrigendum F: Gross Type F
The site of stricture favors the lower third of the esophagus.
The study closely observed the esophagograms of 434 consecutive cases of congenital EA/TEF, comparing them with the classic illustrations of the Gross classification. Several inconsistencies were identified, which have also been noted by other scholars. The proposed modifications aim to provide a more accurate depiction of the anatomical patterns of EA/TEF.
The hypertrophied proximal pouch in Gross type A cases arises from the fetus’s effort to swallow amniotic fluid and the blind end’s failure to drain the fluid downward. In contrast, the underdeveloped esophageal end in type B allows a small amount of amniotic fluid to drain to the airway through the TEF, decompressing the upper esophageal pouch and making it appear less hypertrophied. The blind distal esophageal end in type B prevents the passage of fluid or air, resulting in a gasless and atrophied stomach. In type C cases, the upper esophageal pouch is hypertrophied and dilated due to the buildup of amniotic fluid, while air flowing through the distal TEF leads to gastric distention. Type D cases are characterized by both a decompressed (narrow) upper pouch and an aerated stomach, as both proximal and distal fistulas allow the free movement of air or fluid.
The dilation of the proximal esophageal pouch provides valuable diagnostic insight. In type A and C patients, the proximal pouch appears dilated with accumulated ingested fluid, whereas in type B and D patients, it remains narrow. Subsequent investigations, such as esophageal endoscopy, bronchoscopy, or three-dimensional computed tomography, are recommended to detect the fistulous tract. The proximal esophageal end should be handled with extreme care, especially when it is not dilated, to prevent complications such as choking, cyanosis, respiratory distress, or chronic pneumonitis caused by aspiration.
The timing of esophageal anastomosis plays a crucial role in surgical outcomes, particularly in long-gap EA cases (types A and B). The application of extra-thoracic esophageal elongation can reduce anastomotic tension and improve prognosis. The gap between the proximal and distal pouches, marked with vertebrae in the revised illustration, serves as an important reference for bedside decision-making.
The proximal fistulas in types B and D branch from the lateral esophagus and reach upward to the trachea posteriorly, contradicting the horizontally joined fistula depicted in the original illustration. Secondary ligation of the proximal fistula, in the absence of severe pulmonary infection, promises lower risks of complications associated with anastomosis and is suggested for patients with smaller proximal fistulas. The esophageal elongation technique can be safely applied in patients with long-gap EA/TEF, as proximal fistulas connect laterally rather than perforate directly into the trachea. A nasogastric tube should be placed above the level of the proximal fistula to prevent pneumonia.
An accurate depiction of the gap length reveals why gastrotomy is preferred over primary anastomosis in type A and B patients. The distal esophageal remnant barely extends beyond the hiatus of the diaphragm, making the gap between the pouches too wide for one-stage reconstruction. The site of the opening during the gastrostomy procedure should be carefully decided, ideally made just below the inferior edge of the rib at the midline in type A and B cases.
In conclusion, this study provides a detailed correction to the Gross classification of EA/TEF based on the review of 434 consecutive cases in China. The proposed modifications aim to rectify the deviations from actual findings and serve as a valuable reference for pediatric surgeons, particularly in underserved areas. A correctly illustrated, state-of-the-art reference is essential for both clinical practice and academic endeavors in the field of pediatric surgery.
doi.org/10.1097/CM9.0000000000001673
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