Renal tuberculosis

Aetiology and pathology

Tuberculosis of the urinary tract arises from haematogenous infection from a distant focus which is often impossible to identify. The lesions are 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. Untreated, the lesions enlarge and 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 of pyonephrosis or tuberculous renal abscess 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). Less commonly the kidneys may be bilaterally affected as part of the generalised process of miliary tuberculosis (Fig. 64.34).

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

Renal tuberculosis usually occurs between 20 and 40 years of age, and is twice as common in men as in women; also, the right kidney is affected slightly more often than the left.

Urinary frequency is often the earliest symptom and may be the only one. The patient complains that, over a period of months, there has been a progressive increase in both day­time and night time frequency.

‘Sterile’ pyuria. In early cases the urine is pale and slightly opalescent. 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 pain accompanies 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

In 5 per cent of cases the first symptom is haematuria occurring from an ulcer on a renal papilla. The tuberculous lesion may be difficult to detect radiologically and mycobacteria may not be cultured from the urine until the onset of more suggestive symptoms some months later.

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 but 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

A plain abdominal radiograph may show the calcified lesions described above.

Intravenous urography

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 (Fig. 64.35) 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 (Fig. 64.36). 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

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

A 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 (Fig. 64.37). 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 bowel in a substitution cystoplasty.