Prediction of Gap Length by Plain Radiograph of Chest with Nasogastric Tube in the Upper Esophagus in Patients with Esophageal Atresia and Distal Tracheoesophageal Fistula.

AIM: This study was aimed at prediction of the gap length between the two esophageal ends in cases of esophageal atresia and distal tracheoesophageal fistula (EA-TEF) by preoperative radiography with a nasogastric tube in the upper esophagus and its correlation with intraoperatively measured gap length.
MATERIALS AND METHODS: All consecutive cases of EA-TEF were prospectively included in this study. Plain radiographs were taken with an 8 Fr nasogastric tube inserted in the upper esophageal pouch till its arrest. The patients were grouped into T1-T2; T2-T3; T3-T4; and T4 groups depending on the thoracic vertebral level of arrest of the NG tube on the radiograph. Intraoperative gap between the two esophageal ends was measured with Vernier caliper, and the patients were grouped into A, B, and C groups based on gap length (gap length >2.1 cm; >1-≤2 cm; and ≤1 cm). The operative gap groups were compared with the radiography groups.
RESULTS: A total number of 118 cases were included over a period of 3 years. The arrest of nasogastric tube at T1-T2 and T2-T3 vertebral level corresponded to gap length Group A in 39/41 (95.12%) * patients. In gap length Group B, the arrest of tube at T2-T3 and T3-T4 vertebral level was seen in 44/44 (100%)* patients, in gap length Group C, the arrest of tube was noted at T3-T4 and T4 vertebral level in 31/33 (93.93%)* patients (*P < 0.001).
CONCLUSION: Prediction of gap length by vertebral level of arrest of the nasogastric tube in the upper pouch in a preoperative chest X-ray correlated well with intra operatively measured gap length in cases of EA-TEF. Copyright:

INTRODUCTION

Esophageal atresia (EA) comprises a group of congenital anomalies that have a defect of the esophageal continuity with or without a fistula to the trachea or bronchi.[1] The gap length between the two esophageal ends in cases of EA and tracheoesophageal fistula (EA-TEF) have been described as short, intermediate or long gap by many authors over the centuries.[2345] Gap between the esophageal pouches plays a major role in determining the ease and feasibility of a primary repair. It also helps in the preparedness and prognostication for the delayed or staged procedure in long gap cases. For the purpose of the assessment of this gap length, various investigations including computed tomography (CT) scan have been advised by many authors and performed at many centers worldwide.[6789] A diagnostic plain radiograph with a nasogastric tube in situ might provide reliable information regarding the gap length if interpreted carefully without involving additional risk and cost.

This study was aimed at assessment of the gap length between the two esophageal ends in cases of EA and distal TEF by preoperative radiography with a nasogastric tube in the upper esophageal pouch.

MATERIALS AND METHODS

This was a prospective observational cohort study conducted in a tertiary care children's hospital including all cases of Gross type C EA-TEF over a period of 3 years. Plain radiograph including chest and abdomen with nasogastric tube no 8 Fr in the upper esophagus were taken for all patients to confirm the diagnosis and to look for any apparent anomalies. The nasogastric tube was inserted into upper esophageal pouch till its arrest, and a plane radiograph was taken in supine position.

The thoracic vertebral level of the arrest of the most distal end of the nasogastric tube was noted. This corresponds to the lower end of the upper esophageal pouch. With the level of clavicle depicting the first thoracic vertebrae, a presumptive assessment was carried out about the lower limit of the upper pouch in relation to the thoracic vertebra.

The radiographic findings were grouped into four groups as T1–T2; T2–T3; T3–T4; and T4 depending on the thoracic vertebral level of arrest of the nasogastric tube. Group T1-T2 included all cases where nasogastric tube was at level T1 but above T2. Similarly, group T2-T3 included all cases where nasogastric tube was at level T2 but above T3 and henceforth. All these cases underwent right posterolateral thoracotomy and the gap length between the two esophageal pouches was measured intraoperatively in centimeters using a Vernier calliper before the fistula ligation and upper pouch mobilization [Figure 1].

Figure 1

Intraoperative measurement of gap length using Vernier caliper

The patients were divided into three groups according to the measured gap length as Group A: Gap length >2.1 cm (long); Group B: Gap length >1–≤2 cm (intermediate); and Group C: Gap length ≤1 cm or less (short). The gap length measured during surgery was subsequently compared with the previously recorded radiography groups.

The variables were summarized using frequency tables and supplemented by appropriate graphs. P < 0.05 was considered statistically significant. SPSS version 15.0 software (IBM, NY, USA) was used for statistical analysis.

RESULTS

A total number of 118 cases were included over a period of 3 years. As per the preoperative radiographic assessment, patients were grouped into T1-T2 (n = 9), T2-T3 (n = 51), T3-T4 (n = 56), and T4 (n = 2) groups [Figure 2]. The number of patients in the three groups according to the intraoperative measurement of gap length were Group A (n = 41; 34.7%), Group B (n = 44; 37.3%), and Group C (n = 33; 28%) [Figure 3].

Figure 2

Radiographic assessment group of patients

Figure 3

Gap length groups as per intra operative recording of gap length

In gap length Group A, the arrest of the tube at T1-T2 level was noted in 9/41 (21.9%) patients and at T2-T3 level in 30/41 (73.2%) patients. In gap length Group B, the arrest of the tube was noted at T2-T3 level in 19/44 (43.18%) and T3-T4 level in 25/44 (56.82%) patients. In gap length Group C, the arrest of the tube was noted at T3-T4 level in 29/33 (87.88%) patients [Figures 4 and 5].

Figure 4

Chest X-ray showing different levels of arrest of nasogastric tube (black arrow) (a) Arrest at T1-T2 level (gap length - 2.1 cm), (b) Arrest at T3-T4 level (gap length - 1 cm), (c) Arrest at T4 level (gap length - nil)

Figure 5

Correlation between gap length groups versus radiographic assessment groups

The arrest of nasogastric tube at T1-T2 and T2-T3 vertebral level corresponded to gap length Group A in 39/41 (95.12%) * patients. In gap length Group B, the arrest of tube at T2-T3 and T3-T4 vertebral level was seen in 44/44 (100%) * patients and in gap length Group C the arrest of tube was noted at T3-T4 and T4 vertebral level in 31/33 (93.93%) * patients (*P < 0.001) [Table 1 and Figure 5].

Table 1

Comparison of intra-operative gap length group verses radiographic assessment group

Gap length Radiographic assessment	A, n (%)	B, n (%)	C, n (%)
T1-T2	9 (21.95)	0 (0)	0 (0)
T2-T3	30 (73.18)	19 (43.18)	2 (6.06)
T3-T4	2 (4.87)	25 (56.82)	29 (87.88)
T4	0 (0)	0 (0)	2 (6.06)
Total	41 (100)	44 (100)	33 (100)

Primary repair was done in 100 cases and diversion by cervical esophagostomy and feeding gastrostomy was done in 18 cases where primary repair was not feasible. Re-operation and diversion with cervical esophagostomy and gastrostomy was performed in 12 cases which were long gap length and the anastomosis was performed under tension.

DISCUSSION

The desired outcome from a surgeon's perspective in cases of EA is to achieve a primary tension free anastomosis which depends on the gap length between the two esophageal pouches. Some recent studies proposed that gap length between the two esophageal pouches is an important predictor of outcome.[345]

Gap length is a measure of anatomical difficulty faced by a surgeon during surgery. It can be conveniently measured in centimeters during surgery. Preoperatively, the gap may be predicted as equivalent to the number of vertebral bodies in a plain skiagram with a tube in the upper esophagus, considering that the lower esophagus has a relatively constant level of termination. To validate the accuracy of prediction of gap length from a preoperative chest X-ray, we undertook this study by comparing it with open measurement of gap length at surgery. Although we followed a standardized technique for performing the plane radiograph with nasogastric tube in upper esophageal pouch, the possibility of slight change in the position due to stretching of upper esophageal pouch remained. However, as seen from our results comparing the two groups, it did not affect gap length prediction from a plane radiograph.

Pure EA cases were excluded from our study because intra thoracic measurement of gap length was not possible.

Our patients were divided in three groups based on intraoperative measurement of gap length (Group A – long gap 34.7%, Group B – intermediate gap 37.3%, and Group C – short gap 28%). Brown and Tam reported an increased incidence of all complications with increasing gap length in a series of 66 neonates.[3] They also proposed that a classification based on gap length was more relevant in the modern era. Upadhyaya et al. reported similar findings in a series of 50 patients.[5] Mansur et al., in their study also concluded that gap length is an important factor in the outcome of patients.[6]

Our study shows that there exists a correlation between the preoperative radiological assessments of gap length with intra operatively measured gap length. A plain radiograph done routinely with a catheter in situ can provide useful information regarding the level of upper pouch, although the level of the lower fistula cannot be assessed by this method. The assessment by a plain radiograph correlated significantly with the actual gap length measured at open surgery. Our four preoperative radiological groups based on vertebral level of arrest of the esophageal tube correlated well with the intraoperatively measured three gap length groups namely short, intermediate and long [Table 1, P < 0.001]. Similar results were indicated in an earlier preliminary study by the authors while studying factors affecting the gap length and its effect on the final outcome of the patients.[10] Factors such as birth weight gestational age, age at presentation, associated anomalies and postoperative outcome have earlier been studied by authors. Birth weight had direct reciprocal relationship with the gap length. Higher gap length was also associated with increased need for postoperative ventilation and poor outcome.[10]

Such a correlation between preoperative radiographic assessment and actual gap length measured at surgery has not been studied before. This finding obviates the need for a preoperative CT scan and prevents unnecessary radiation exposure in a neonate as advised by some authors.[6789]

It is pertinent to reemphasize that gap length plays a significant role in the operative outcome as it directly correlates with the feasibility of doing a primary anastomosis without undue tension.

Although a delayed primary repair is recommended and preferred management for long gap EA, a significant number of our cases with long gap or failed anastomosis were managed by (30/118, 25.4%) cervical esophagostomy and feeding gastrostomy as per institutional practice due to limited resources. This resulted in significant morbidity and mortality in those patients of EA-TEF. Preoperative radiographic assessment can facilitate in predicting such an eventuality.

CONCLUSION

Preoperative assessment of gap length by vertebral level of arrest of the nasogastric tube in the upper pouch in a chest X-ray correlated well with intra operatively measured gap length in cases of EA-TEF. Hence the preoperative radiograph with a tube in the esophagus should be carefully studied for assessment of gap length in the preparedness toward surgical management of the patients of EA-TEF.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.