Experience with a Simplified, Standardized 4-Hour Gastric-Emptying Protocol

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FIGURE 1.
ROC curves for 1-h (▴), 2-h (○), and 3-h (▪) retention, with 4-h retention of more than 10% as the standard for delayed emptying. AUC values were 0.75, 0.93, and 0.97 at 1, 2, and 3 h, respectively. FPF = false-positive fraction; TPF = true-positive fraction.
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FIGURE 2.
ROC curves for lag defined as first appearance of bowel activity (○), and lag defined as 5% emptying from peak activity (▪). FPF = false-positive fraction; TPF = true-positive fraction.

TABLE 3

Sensitivity, Specificity, and Predictive Values of Abnormal Emptying at 1 and 2 Hours Compared with 4 Hours

Gastric retention	Sensitivity	Specificity	Positive predictive value	Negative predictive value
>90% at 1 h	31% (14/45)	97% (123/127)	78% (14/18)	80% (123/154)
>60% at 2 h	59% (26/44)	94% (122/130)	76% (26/34)	87% (122/140)

The standard for a 4-h abnormal value was a retention of greater than 10% (Tougas et al. (1)). The data in parentheses were used for the calculation. The numerator is the number of patients correctly assigned by the intermediate time criterion to the same category as the 4-h criterion (e.g., abnormal emptying), and the denominator is the total number of patients from that category evaluated at the given time. One true-positive was not evaluated at 2 h, and 3 true-negatives were not evaluated at 1 h; hence, only 44 of the 45 patients with abnormal emptying at 4 h were evaluated at 2 h, and only 127 of 130 patients with normal emptying at 4 h were evaluated at 3 h.