Table 1.

Calculation table to determine diagnostic value of axillary ultrasound.

	SLNB /ALND
Axillary Ultrasound	Pathological Node Positive	Pathological Node Positive
Positive	True Positive (TP)	False Positive (FP)
Negative	False Negative (FN)	True Negative (TN)
Sensitivity	= TP / TP + FN
Specificity	= TN / TN + FP
Positive Predictive Value	= TP / TP + FP
Negative predictive value	= TN / TN + FN
Accuracy	= TP + TN / TP + FP + TN + FN

ALND = axillary lymph node dissection, FN = false negative, FP = false positive, SLNB = sentinel lymph node biopsy, TN = true negative, TP = true positive.