FIGURE 1.

Measured parameters of the sacral hiatus. 1) height of sacral hiatus; 2) width of sacral hiatus at the level of sacral cornua; 3) distance from hiatus apex to the level of S2 foramina; 4) distance between the left superolateral sacral crest and sacral hiatus apex; 5) distance between the right superolateral sacral crest and sacral hiatus apex; and 6) distance between two superolateral sacral crests (base of the triangle)