Pyonephrosis

Pyonephrosis (pyonephrosis), the final stage of the suppuration process in the kidney, wherein the kidney takes the form of a sac filled with pus. In a number of cases, P. develops on the basis of a preceding hydronephrosis, or else, developing as an independent disease, it is complicated by sequentially developing difficulties in outflow through the ureter. Usually, a pyonephrotically altered kidney is increased in volume. The reverse phenomenon, i.e., shrinkage of the kidney with marked sclerotic changes and deposits of fat in its immediate vicinity, is rarely encountered. Externally, a pyonephrotic kidney either appears as a smooth-walled sac or else its surface shows a series of bulges corresponding to pathologically stretched renal calyces. The origin of these two varieties of P., which do not exclude transitional forms, is connected with the method of infection penetration into the kidney. Unilocular or forms similar in structure to them are connected with the ascending (urogenic) type of kidney infection. In these cases, the initial disease is most often cystitis, with the infection ascending along the lumen of the ureter (more rarely in the thickness of its wall - the lymphogenous route of infection), successively affecting the ureter, renal pelvis, and calyces. Stagnation of infected urine leads to expansion of the renal cavity system with compression and atrophy of the renal parenchyma. As a final result, wide mutual communication between the expanded pelvis and calyces is obtained, with the disappearance of the intervening layers of renal tissue and the formation of a unilocular sac. If the infection is hematogenically introduced into the kidney, it more often forms a focus in the renal parenchyma than in the mucosa of the pelvis. Replacement of the kidney tissue in the spaces between the calyces with fibrous tissue and adipose tissue leads to narrowing of their outlets, as a result of which the pyonephrotic kidney is found to consist of a series of cavities containing pus, some completely closed and some communicating with a slightly distended pelvis. In both forms of P., the amount of preserved renal tissue is minimal, and sometimes entirely absent. This explains both the fact that the contents of P. are usually more or less pure pus without admixture of urine, and that seemingly paradoxical phenomenon that after surgical incision of P., a fistula discharging purulent urine may result. In secondarily infected hydronephrosis, the contents are more or less turbid urine with an admixture of pus. The anatomical connection between the lymphatic vessels of the large intestine and the lymphatic vessels of the renal fat capsule and the kidney itself has been established with certainty. Thus, the possibility of a lymphogenous route of infection (Franke) stands beyond doubt; only the frequency of this particular route of infection penetration is unknown. In the cavities of a pyonephrotically altered kidney, deposits of lime or stones can often be encountered. Those of them that are secondary in origin are usually phosphates. The process taking place in the kidney cannot remain without effect on neighboring tissues. With the exception of those cases where pus, violating the integrity of the fibrous capsule of the kidney, spills into the perirenal fat, causing the development of purulent paranephritis, the changes in the vicinity of the kidney are of a chronic sclerosing, resp. sclero-fatty nature, leading 1) to more or less dense adhesion of the pyonephrotic sac and 2) to a sharp decrease in the caliber of the renal pedicle, surrounded by a significant amount of newly formed dense adipose tissue. Similar sclerosing changes also occur in the ureter of the affected side, which causes changes in the thickness of its wall, caliber and uniformity of the lumen, and leads to its firm adhesion to the peritoneum. P., the drainage of which has completely ceased, is called closed P., in contrast to open P. In the presence of a duplex kidney, it is possible to encounter involvement of only one pelvis and the corresponding part of the kidney, i.e., partial pyonephrosis. P. is most often unilateral, which undoubtedly has significant importance from the point of view of accessibility to surgical treatment. Nevertheless, sequential involvement of the second kidney is always possible - either as ascending infection from the infected bladder or as toxic nephritis caused by absorption of toxic material from the diseased kidney and its excretion through the healthy kidney. Mild degrees of this toxic nephritis (albuminuria, hyaline casts) can exist with undiminished functional capacity of the kidney, therefore do not contraindicate removal of the diseased kidney and are capable of subsequent regression. In contrast to this, subsequent amyloidosis of the healthy kidney is only a partial expression of the general amyloidosis of internal organs on the basis of prolonged suppuration and excludes the possibility of a favorable outcome of the operation. P. are most often encountered between the ages of 30 and 40 years, which (according to Israel) is connected with the acquired nature of the disease, having its bacteriological roots in diseases of the urogenital sphere. In women, these are gonorrheal infection, pyelitis of pregnancy, postpartum cystitis, cystocele, etc.; in men - cystitis, prostatitis, pyelitis, strictures of the urethra. In addition, stones in the kidney, movable kidney, its dystopia, etc., undoubtedly have significance as predisposing factors to the development of P., as factors causing either trauma to the kidney or disturbance of free outflow from it, or disorders of normal blood circulation in it. P. can be the result of infection by the most diverse microbes, and mixed infection apparently occurs more often. An especially important role belongs to the colon bacillus, gonococcus, staphylo- and streptococcus, tubercle bacillus, as the most frequently encountered. Melchior has drawn attention to the comparative frequency of P. caused by typhoid infection and developing on the basis of hydronephrosis, specifically - during the convalescent period from typhoid fever. This variety of P. is characterized by slight expressiveness of symptoms (pain, fever may be entirely absent), and the disease attracts attention only by pyuria and the formation of a renal tumor. Just as in pyosalpinx, in some chronically occurring closed pyonephroses, sterility of the purulent contents can be established. The symptomatology of open P. amounts to marked pyuria in the presence of a little or completely immobile renal tumor. In such cases, even in the absence of pain and elevated temperature, diagnosis of P. presents no particular difficulties. Nevertheless, it should be supplemented and detailed by modern methods of urological diagnosis. The urinary bladder, despite prolonged contact with infected urine, often remains unaffected or the inflammatory changes are moderate and are limited mainly to the side of the diseased kidney. The opening of the ureter of the affected side may be altered: inflammatory infiltrated, edematous, gaping or funnel-shaped retracted. In some of such cases, a characteristic feature is the possibility of palpating through the vagina, resp. rectum, the lower segment of the thickened, hardened and painful ureter. Liquid poured into a thoroughly washed bladder becomes turbid very quickly due to liquid pus being expelled from the ureter, which is clearly visible in the cystoscope. Especially characteristic are the cystoscopic pictures when from the ureter of the affected side thick pus descends into the bladder in the form of a worm, similar to that being squeezed from a tube of an ointment cylinder. The question of the functional suitability of the second kidney is decided by the indigo carmine test with ureteral catheterization. This catheterization, which carries the danger of infecting the healthy kidney, can be considered unnecessary where observation through the cystoscope shows the discharge of completely transparent liquid from it. It is understood that the discharge of the blue dye on the affected side is often entirely absent or lags markedly in time of appearance, saturation of the discharge and force of the expelled stream. Catheterization of the ureter on the side of P. under these conditions can also serve for subsequent pyelography. Pyelography, although it essentially clarifies the picture of the changes present in the renal cavity system, cannot be considered as indicated in all cases of P. Myshe considers it contraindicated in the presence of very thick purulent contents in the sac of P., as well as in febrile patients and those suffering from pain. A simple X-ray of the kidney and ureter, as being able to detect the presence of stones in the kidney and especially in the ureter, is always desirable. In connection with the acute or chronic course of the process, as well as depending on temporary exacerbations of it, temperature varies in the most diverse ways: from hectic to completely normal. In cases of intermittent P., a deterioration of the general condition during periods of complete or relative (in the presence of cystitis) clearing of the urine is characteristic. Closed P. can (outside periods of exacerbation) proceed without fever. Complication in the form of purulent paranephritis leads to the formation of abscesses, some located around the kidney, others taking the nature of migrating abscesses (in the fossa iliaca and under Poupart's ligament on the thigh). Pain is not obligatory, but more often exists and sometimes reaches the degree of renal colic.

Palpation of the tumor and shaking of the lumbar region on the affected side are often painful. The size of the palpable renal tumor does not yet give a clear idea of the size of the actual purulent renal sac due to its masking by powerful inflammatory layers on the outside. Treatment of P. is only possible by surgical means, since drainage of the purulent renal sac by catheterization through the ureter and irrigation of it are as a rule ineffective. Of the two possibilities (nephrostomy, nephrectomy), removal of the diseased kidney should be considered more appropriate, and moreover by primary nephrectomy. By freeing the patient immediately from the focus of infection and intoxication and placing the body in the best conditions for the most rapid recovery, nephrectomy in the end is not heavier than nephrostomy, the negative aspects of which are the radical nature of the intervention, which eventually requires a secondary nephrectomy, which cannot be regarded as technically more difficult than primary nephrectomy, and therefore more difficult for a weakened body to tolerate. Nephrostomy as such can find application only where the function of the second kidney at the time of the necessary operation itself is insufficient or doubtful, or in the presence of bilateral P. In all other cases, primary nephrectomy is the method of choice. In this connection, it should be borne in mind that the phenomena of toxic parenchymatous nephritis of the 'healthy' side, usually not sharply expressed and capable of rapidly regressing after removal of P., are not contraindications to the operation. When proceeding to nephrectomy for P., it is necessary to keep in mind the frequent difficulties and dangers associated with it (dense adhesion of the tumor, possible violation of the integrity of the peritoneum, pleura, damage to the v. cavae, rupture of P.). The normal surgical approach is lumbar with sufficiently wide access to the kidney. The large Israel-Bergmann incision is very good, supplemented in case of difficult accessibility of the upper pole of the kidney and especially with dense adhesions by resection of the XII and even XI ribs. The renal tumor can be dissected extracapsularly or subcapsularly. The subcapsular method should be used more often than is done, and in any case where extracapsular dissection of the tumor encounters great difficulties. If in these cases one passes to subcapsular dissection of the tumor and at the same time hits the proper layer, then the dissection, performed exclusively by blunt means, i.e., by hand and by feel, proceeds very easily. To prevent rupture of the purulent sac, all manipulations of dissection by hand should be directed away from the sac; in very large fluctuating P., it may be advantageous to preliminarily empty the sac. The moment of best isolation of the vascular-renal pedicle is substantially facilitated by the method strictly regulated by Fedorov: retreating about 1 cm from the hilum of the kidney, a semicircular incision is made through the already turned aside fibrous capsule of the kidney from front and back, thus turning into a circular incision bordering the hilum of the kidney; through it it becomes possible to free the renal pedicle by blunt means with the help of a finger and to ligate the vessels and ureter separately; - to find and ligate the latter separately, it is sometimes necessary in addition to the circular incision mentioned to make an incision downward from its lower end through the same fibrous capsule, where in the thickness of the altered 'periureteric cellular tissue the ureter is found' (Fedorov). In case of difficult accessibility of the renal pedicle, instead of ligation, one can use the application of a reliable renal clamp a demeure, removed after 48-72 hours. - Transperitoneal nephrectomy finds its main indication in P., developing in dystopic kidneys.