Table 1 The efficacy of the various types of tissue blocks to detect VI.

	Frequency (%)	Yield (%)	Efficacy
Perpendicular	24.8	51.7	2.088
Tangential	22.1	24.1	1.092
Across the mesentery	8	17.2	2.151
From mesenteric vessels	5.1	0	0
From mesenteric LNs	40	6.9	0.172

Frequency refers to the percentage of the total number of tissue blocks. Yield refers to the percentage of the total number of blocks in which VI was detected. Efficacy refers to the ratio of yield to frequency.

LN, lymph node; VI, venous invasion.