HYDATIFORM DEGENERATION IN UTERINE PREGNANCY. 211 



sands also must be taken into consideration. But in any case, the estimated 

 incidence of hydatiform degeneration in the Carnegie Collection, calculated 

 without regard to those contained among specimens classed as normal, is 8.7 

 per cent, and the actual incidence hence is probably more than 1 in every 10 acces- 

 sions. 



Estimated on the basis of hydatiform degenerations found among the uterine 

 and tubal specimens classed as pathologic alone, the incidence would be 12.5 

 per cent of the first 3,000 accessions. Upon this basis the incidence among the 

 uterine specimens alone would be 9.9 per cent, and among the tubal alone 28.1 

 per cent. This difference of 200 per cent between the tubal and uterine specimens 

 may have some significance in connection with the cause of hydatiform degenera- 

 tion. That this estimate is not altogether too high is indicated also by the last 

 392 accessions, the first gross examination of which, made by others than myself, 

 revealed 21 hydatiform degenerations, or an incidence of 5.3 per cent. Since 

 these accessions contained a disproportionately large number of older, naked 

 fetuses unaccompanied by secundines, aborted during influenza, this incidence of 

 hydatiform degeneration undoubtedly is too low. Moreover, no histologic exam- 

 ination has as yet been made. Nevertheless, the incidence among those accom- 

 panied by secundines and classed as pathologic was about 14 per cent and among 

 those classed as normal about 4 per cent. 



If, as alleged by various investigators, the great majority of abortions occur 

 in the first three months, it is highly probable that many of these early conceptuses 

 are lost and never come to the attention of anyone, and that therefore the propor- 

 tion of early specimens in this or any other collection is no doubt too small. More- 

 over, in quite a number of specimens of the first 1,000 accessions the chorionic 

 vesicles were too degenerate for examination and in others they were absent, but 

 we have reason to believe that this is not true to the same extent in the material 

 beyond the first 1,000 accessions. Then, too, since only a few relatively large 

 sections from a single portion of the chorionic vesicles were examined, it is evident 

 that some cases in which the degeneration may have been purely local were prob- 

 ably overlooked. Hence the actual as compared with the recorded incidence of 

 hydatiform degeneration in this collection is probably not merely 8 times but 240 

 times as great as that given by Williamson (1900), and 33.3 times as great as that 

 given by Essen-Moller. 



Most persons will, I presume, be willing to regard an increase of 700 per cent 

 above that of Williamson as possible, but one of 24,000 per cent above Williamson, 

 or even 3,333 per cent above that of Essen-Moller, as wholly out of the question. 

 Yet, strange as it may seem at first sight, this is not a random guess, but an estimate 

 based upn the actual incidence of hydatiform degeneration as determined by a 

 careful gross and microscopic examination of mounted and unmounted material 

 from over 400 abortuses. However, I lay no special emphasis on these percentages, 

 and am using them merely to emphasize the great frequency of hydatiform degenera- 

 tion. It matters little whether we shall ultimately determine an incidence of 10 

 or 5 per cent, but it does matter considerably whether we regard the frequency as 

 5 or 0.05 per cent, for this is a difference in frequency of 10,000 per cent. 



