Page 296, August 12, 1933.
Pregnancy Diagnosis Station: Report of Fourth Year's Working
by
B.P. Wiesner
Macaulay Laboratory, Institute of Animal Genetics, University of Edinburgh
Previous reports1 dealt with the cases diagnosed by the station up to the end of January, 1932. The present report refers to the work carried out between the end of January, 1932, and January 31st, 1933. As previously, only cases submitted by practitioners, hospitals, or public health authorities are considered. There will be a separate report on the results of tests undertaken on selected samples in connexion with certain clinical studies. In all 2,368 cases have been dealt with in the period of the report this figure does not include repeat tests. The total number of cases diagnosed since 1929 thus exceeds 5,500.
The modifications of the original technique which were introduced previously (routine detoxication with sulphocalicylic acid, etc.) were retained; detoxication was generally successful. Gradation of dosage was abolished, and equal doses of urine (0.4 c.cm. per injection) are now given to all mice.
Reports from senders numbered 1,452. Of these, 1,432 contained a confirmation of the diagnosis, which had been "positive" in 772 cases and "negative" in 660. There were twenty reports in which the ultimate clinical diagnosis differed from the diagnosis submitted by the station; this would appear to give an error of 1.37 per cent. Analysis of the data, however, shows that in several cases the error was only apparent in the sense in which this term was used in previous reports. For instance, a "negative" and seem- ingly misleading reaction is obtained when the ovum has died, even though expulsion has not occurred. If cases of this and similar nature be eliminated, a "real" error of 0.89 per cent. is found. Of the "real" errors all but one were "negative errors" that is, the station gave a "negative" diagnosis in the presence of pregnancy. In five cases of "negative error" pregnancy had been in its very early stages; repetition of the test (in two cases) three to four weeks later gave positive results. On the other hand, "positive" tests were obtained (and confirmed by clinical observation) as early as four days after the first missed period. In the case of samples collected very soon after the last menstrual period, it thus seems advisable (1) to regard a "positive" diagnosis as almost certainly correct, and (2) to have the test repeated after an interval of two to four weeks if the reaction is "negative" and the clinical diagnosis continues to be doubtful.
When this year's results are compared with those of previous years a not inconsiderable increase in accuracy is found. This year's data show that the test was correct in 99.11 per cent. of all those cases where clinical control was obtained; the highest previous figure was 97.8 per cent. It is possible that the improvement was due to the higher dosage used in last year's tests on the other hand, the decrease in the incidence of errors may be spurious. By drawing conclusions from the data controlled by clinical findings it is implied that the distribution of errors in the whole group of tests is the same as in the controlled group. As has been mentioned in a previous report, this assumption may be mistaken. It is hoped that in future all those who avail themselves of the services of the station will fulfil the request to inform us of the ultimate clinical finding, and thus help to eliminate a possible source of erroneous conclusions.
This year's "errors" again contain several cases in which a "negative"diagnosis with definite clinical signs of pregnancy was followed by abortion. The data are now sufficiently numerous to justify more detailed investigation; this is now in progress, and the results will be published shortly.
The station has carried out a number of Friedmann tests (rabbit tests-see last year's report) during the last six months. The results seem very satisfactory, but the number of tests controlled by clinical reports is still small. A report on the results will appear when the numbers justify an analysis.
The fee charged by the station for the Zondek-Aschheim reaction carried out on behalf of private practitioners will remain unchanged at 10s. The fee for hospitals or public institutions will be raised by 1s. to 4s. It is necessary to make this increase because the number of hospital cases rose during the last year to a surprising extent, and the fee of 3s. involved a considerable loss. As in previous years, the station was secured against deficit by a guarantee from the Medical Research Council.
Careful packing of the specimen is essential, and the name and address of the doctor should be put on the parcel. It has occurred on several occasions that parcels were destroyed by the Post Office (in accordance with its regulations) when the bottle containing the sample was broken, so that fluid escaped. In several such cases the station was unable to trace the sender. It is therefore particularly requested that details regarding the case, and the name of the sender, should be forwarded to the station under separate cover, and that the fee accompany this information in order to save un- necessary expenditure and work. It may also be mentioned that the station does not send out or return containers for samples any clean bottle will serve the purpose. Finally, clients are urged to comply with the following requests: (1) to give full particulars of every case; (2) to inform the station of the ultimate result. The scientific value of the data collected by the station would be greatly enhanced if detailed information were given in a greater number of cases.
British Medical Journal, 1930, i, 662; i, 890; 1932, ii, 759. ↩