[Reprinted from The American Journal of Obstetrics and Diseases of 
Women and Children, Yoi. XL , No 4, 1899.] 
THE REFLUX OF AIR INTO THE URETERS THROUGH THE AIR- 
DISTENDED BLADDER IN THE KNEE-BREAST POSTURE. 
BY 
HOWARD A. KELLY, M.D., 
Baltimore. 
The important practical question as to the possibility of a 
reflux of fluids from the bladder into the ureters has been raised 
of recent years in contradiction to the views of the older 
writers. 
The distinguished French surgeon, J. L. Petit, who lived 
from 1674 to 1750, in his great surgical work posthumously 
published, makes a declaration with which all subsequent 
writers and observers have substantially agreed until recently. 
He states 1 that there can be no escape of urine from the blad- 
der into the ureters, because the ureters run obliquely between 
the coats of the bladder; and as the latter becomes distended 
and the inner coat is pressed against the outer coat, the ureter 
is necessarily compressed between them and so a reflux is pre- 
vented. He further states that it is well known that under con- 
tinued over-distension of the bladder the ureters and the renal 
pelves also undergo great distension; but this is due, not to the 
hack flow into the ureters, hut because the urine which is se 
creted after the bladder has been filled, is now no longer able 
to enter that organ, and for this reason accumulates in the 
upper urinary tracts. 
Lewin and Goldschmidt, in a paper published first in the 
Berliner Minische Wochenschrift (1893, vol. xxx., page 776) 
and later in extenso in Virchow’s Archives (1893, vol. cxxxiv,, 
page 33), called this accepted dogma into question upon the 
basis of a series of experiments upon rabbits, in which they 
found that colored fluids such as milk and methylene solutions, 
in the intact bladder moderately distended, with active mus- 
cular contractile power, were taken up into the ureters as far 
as the renal pelves by an active antiperistaltic movement, to be 
again discharged downward by peristalsis. 
’Petit; “Traite des maladies ohirurgicales, etc.,” 1790, vol. iii., p. 4. 2 
kelly: the reflux of air into the ureters. 
These experiments were repeated and verified by Courtade 
and Guyon,1 who showed, however, that the phenomenon was 
far less likely to occur in dogs, where the muscular power of 
the bladder was greater and exercised a more efficient control 
over the ureteral extremities. 
As a result of these experiments, the possibility of such a 
reflux into the human ureters has been admitted; upon the 
practical results, flowing from such an admission I need not 
dwell. I wish here to record my own observations regarding 
the entrance of air into the ureters. 
When the patient is put in the knee-breast position and a 
catheter introduced as far as the renal pelves, a little air some- 
times enters and escapes later in bubbles with the discharge of 
the urine. 
Sometimes, however, the air enters the ureter spontaneously 
before the ureteral orifice is touched, and, entering at the tem- 
perature of the room, it shortly becomes heated within the 
ureter to the body temperature, when it is forced out of the 
ureteral orifice in the form of a little bubble. This bubble has 
guided me to the position of the ureteral orifice in several in- 
stances where it was difficult to find. 
More frequently the air enters spontaneously into an inflamed 
ureteral orifice on a side which is discharging pus (pyuria); in 
these cases, when the ureteral opening is concealed in the 
puffy, hyperemic mucosa, the little tell-tale bubble is a wel- 
come sign which marks the site of the hole. 
I have witnessed this phenomenon not less than twelve 
times. In one instance the bubbles of air and pus which 
marked the ureter escaped in a continuous stream; this, how- 
ever, proved to be a case of pathological pneumaturia due to 
the presence of a large gas-forming bacillus in the kidney. 
The fact that a gas will enter the ureters simply shows that 
they are not air-tight under some conditions, and does not 
prove in any way that they are not water-tight under physio- 
logical conditions. 
I have never seen any harm come from the entrance of air, 
and it causes the patient no pain. 
1 Ann, des mal. des org. gen.-ur., Paris, vol. xii., p. 561.