How to read merged cell from word document

You could try the following:

Table table = Globals.ThisDocument.Tables[1];
Range range = table.Range;
for (int i = 1; i <= range.Cells.Count; i++)
{
    if(range.Cells[i].RowIndex == table.Rows.Count)
    {
        range.Cells[i].Range.Text = range.Cells[i].RowIndex + ":" + range.Cells[i].ColumnIndex;
        MessageBox.Show(range.Cells[i].Range.Text);
    }
}