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kidney infection-2nd lecture

   U/S-ultrasonogram will demonstrate dilatation of the renal pelvis and calyces.

IVU-The intravenous urogram will show poor function and the features of hydronephrosis on the affected side.  

Treatment 

  Pyonephrosis is a surgical emergency because the patient is threatened with permanent renal damage and a potentially lethal septicaemia.

-Parenteral antibiotics should be given immediately and

-the kidney drained( nephrostomy),

 -Nephrectomy may be considered when long-standing obstruction is known to have destroyed the kidney, and function on the other side is good.

Renal carbuncle

    An abscess may form in the renal parenchyma as the result of  blood-borne spread of organisms, especially coliforms or Staphylococcus aureus, from a focus elsewhere in the body. commonly seen in diabetic patients, intravenous drug abusers, those debilitated  by chronic disease and patients with acquired immunodeficiency. 

Pathology.

     The renal parenchyma contains an encapsulated necrotic mass.

Clinical features.

    There is an ill-defined tender swelling in the loin, persistent pyrexia and leucocytosis, signs that closely simulate those of perinephric abscess.

GUE/ In early cases there is no pus or bacteria in the urine but they appear after a day or so.

IVU/ Urography shows a space occupying lesion in the kidney which may be confused with a renal adenocarcinoma on ultrasonography and CT. 

Treatment.

 Resolution by antibiotic treatment alone is unusual. Formal open incision of the abscess may be necessary if the pus is too thick to be drained by percutaneous aspiration.

Perinephric abscess: 

      The common causes of perinephric abscess are –extension from cortical abscess  –haematogenous –via periuretral lymphatics –adjacent organ like appendix . ascending aerobic gram-negative enteric infection (especially E. coli)is more common than staphylococcal infection from hematogenous spread. Other causes are infection of a perirenal haematoma and perinephric discharge of an untreated pyonephrosis or renal carbuncle. A mycobacterial perinephric abscess may arise by extension from a nearby tuberculosis vertebra.

Clinical features 

               The classical symptoms and signs of perinephric abscess are a high swinging pyrexia, abdominal   tenderness and fullness in the loin.. The white cell count is always markedly raised but there are characteristically no pus cells or organisms in the urine. 

Imaging 

        (KUB)The psoas shadow is obscured on the plain abdominal radio­graph. There may be a reactionary scoliosis — with the concavity toward the abscess — and elevation and immobility of the diaphragm on the affected side. A calculus may be present.

 Ultrasonography and CT are diagnostic. 

Treatment 

    Open drainage may be necessary if the abscess cannot be aspirated through a large percutaneous needle. A specimen of pus is sent for culture and the wound is closed over a tube drain. 

Renal tuberculosis:

Aetiology and pathology: 

     Tuberculosis of the urinary tract arises from haematogenous infection from a distant focus , usually confined to one kidney. A group of tuberculous granulomas in a renal pyramid coalesces and forms an ulcer. Mycobacteria and pus cells are discharged into the urine.a tuberculous abscess may form in the parenchyma. The necks of the calyces and the renal pelvis stenosed by fibrosis confine the infection so that there is tuberculous pyonephrosis which is sometimes localised to one pole of the kidney. Extension  leads to perinephric abscess and the kidney is progressively replaced by caseous material (putty kidney) which may be calcified (cement kidney). At any stage the plain radiograph may show areas of calcification (pseudocalculi) 

Renal tuberculosis is often associated with tuberculosis of the bladder and typical tuberculous granulomas may be visible in the bladder wall. In the male, tuberculous epididymo­orchitis may occur without apparent infection of the bladder. 

Clinical features 

    Usually occurs between 20 and 40 years of age, and is twice as common in men as in women;

Urinary frequency is often the earliest symptom and may be the only one.

‘Sterile’ pyuria.. Routine urine culture is negative. 

Painful micturition is a feature as soon as tuberculous cystitis sets in.

 First there is a suprapubic pain if voiding is delayed; later a burning  micturition. When there is secondary infection a superadded agonising pain referred to the tip of the penis or to the vulva is often associated with haematuria and strangury. 

Renal pain is often minimal but there may be a dull ache in the loin.

Haematuria

.A tuberculous kidney is oedematous and friable and is more liable to damage than a normal kidney.

Constitutional symptoms are common. Weight loss is usual and a slight evening pyrexia is typical. A high temperature suggests secondary infection or dissemination, i.e. miliary tuberculosis. 

On examination 

It is unusual for a tuberculous kidney to be palpable. The prostate, seminal vesicles, vasa and scrotal contents should be examined for nodules or thickening. 

Investigation

Bacteriological 

       Bacteriological examination of at least three full specimens of early morning urine should be sent for microscopy and culture before specific chemotherapy is started.

Staining of the urine sediment with the Ziehl—Neilsen stain occasionally shows the presence of acid-fast bacilli.

 To proof that these are pathological mycobacteria must await prolonged culture on Lowenstein—Jensen medium. Where the clinical picture is convincing it is permissible to start antituberculous therapy in anticipation of the culture results which will come some 6 weeks later. 

Radiography 

   KUB/A plain abdominal radiograph may show the calcified lesions. 

IVU/  In the very earliest stages of the disease the normally clear cut outline of a renal papilla may be rendered indistinct by the presence of ulceration. Later there may be evidence of calyceal stenosis and/or hydronephrosis caused by stricture of the renal pelvis or the ureter draining the affected kidney; this may be more easily demonstrable by retrograde ureterography. A tuberculous abscess appears as a space-occupying lesion which causes adjacent calyces to splay out. The bladder may appear shrunken with its wall irregular or thickened. In late stages there may be dilatation of the contralateral ureter from obstruction where the ureter passes through a thickened and oedematous bladder wall. 

Cystoscopy is not indicated as a routine part of the investigation of urinary tuberculosis but is often performed  because there has been haematuria or unexplained bladder symptoms. There may be little to see in the first stages of the disease but later the bladder urothelium is found to be studded with granulomas which cluster particularly around the ureteric orifices. The tubercles may coalesce to produce a tuberculous ulcer. As the bladder wall fibroses the bladder capacity decreases. Contraction of the fibrosed ureter tugs at the ureteric orifice which is displaced upwards, its mouth wide open (the so-called ‘golf-hole’ ureteric orifice). 

Chest radiograph  is indicated to exclude an active lung lesion. 

Treatment 

    Antituberculous chemotherapy is best managed by a physician with experience of the most modern drug regimens and their potential adverse effects. The surgeon must ensure that the state of the urinary tract is reviewed during the first few weeks of therapy because stricturing of the renal pelvis and ureter may continue after treatment has started. 

Prognosis in renal tuberculosis is good and there should be no recrudescence of the disease if the patient completes the course of chemotherapy. 

Operative treatment 

    Operative treatment should be as conservative as possible. The aim is to remove large foci of infection, which are difficult to treat with drugs, and to correct the obstruction caused by fibrosis. The optimum time for surgery is between 6 and 12 weeks of the start of antituberculous chemotherapy. 

The surgeon needs a repertoire of procedures to deal with various potential effects of urinary tuberculosis. An obstructed lower pole calyx may be drained into the upper ureter. A strictured renal pelvis needs a pyeloplasty. Ureteric stenosis and shortening may require a Boari operation or a bowel interposition, depending on the level and extent of the fibrosis. If the kidney has no function it is best to perform a nephroureterectomy . A bladder which is so contracted that it can no longer function as a reservoir for urine may need to be replaced with a neobladder fashioned from a loop of s bowel in a substitution cystoplasty.