The diagnosis should be as certain as possible. Rarely nodules which are not cancerous appear in the cervix during pregnancy, and these are to be examined microscopically. Snipping out of a piece of the nodule for examination does not cause abortion. Vaughan of Michigan University, who is a skilful and careful observer, said[116] that in an investigation of 200 cases of cancer, upon which more than 30,000 differential blood-counts were made, he discovered a method of diagnosing the operability of a cancer as follows: He makes a blood-count and then injects intraperitoneally one c.c. of placental residue. The next day he begins a series of blood-counts, and if the number of polymorphonuclear cells _decreases_ the case is operable, no metastasis has occurred; if there is no change in the number of the polymorphonuclears, or an _increase_ with a corresponding decrease of the large mononuclears, the case is inoperable, metastasis has begun. [116] _Jour. Amer. Med. Assoc._, December 8, 1917. In cancer of the cervix operability does not mean curability always. Inoperability signifies that the woman has no chance at all for life and that it is useless to do anything; operability means that she has one chance in four and that it is worth while taking the chance. The following conditions may be met: 1. The case may be operable and the child inviable. 2. The case may be operable and the child viable. 3. The case may be inoperable and the child inviable. 4. The case may be inoperable and the child viable. In the first case the supposition is that the case is operable but the child inviable. To save the woman the uterus, with its adnexa, must be removed, and this, of course, kills the fetus. The case differs from the enucleation of a gangrenous myoma which involves the death of an inviable fetus. In the myoma case the woman has practically every chance for her life through operation; in this cancer case the woman has only one chance in four, as 75 per cent. of such operations fail through recurrence of the cancer. The child has about one chance in two of going on to viability, owing to the tendency to abortion, if no operation is done; but the mother loses her chance for life if the operation is not done at once, as the cancer will spread beyond cure. Zweifel has seen such a growth extend a finger's breadth in one week. The one chance in four in immediate operation gives the mother a solid ground for hope, and the probability is sufficient, in my opinion, to permit the operation with a permissive loss of the fetus. In the second case the cancer is operable and the child is viable. The child should at once be delivered by cesarean section, and the uterus with its adnexa removed. The third case is that of an inoperable cancer and an inviable child. There the operation should be deferred, if possible, until the child becomes viable.