Urology
Monday 20/11/2017
Upper Urinary Tract Infections
Introduction:
Urinary Tract Infection (UTI) is currently defined as the inflammatory response of the urothelium to bacterial invasion. This inflammatory response causes a constellation of symptoms depending on the part involved.
Bacteriuria is the presence of bacteria in the urine. Bacteriuria may be asymptomatic or symptomatic. Bacteriuria without pyuria indicates the presence of bacterial colonization of the urine, rather than the presence of active infection.
Pyuria is the presence of white blood cells in the urine (implying an inflammatory response of the urothelium to bacterial infection or, in the absence of bacteriuria, some other pathology such as carcinoma in situ, TB infection, bladder stones, or other inflammatory conditions – sterile pyuria).
An uncomplicated UTI is one occurring in a patient with a structurally and functionally normal urinary tract.
A complicated UTI is one occurring in the presence of an underlying anatomical or functional abnormality, eg, stone, fistula. Complicated UTIs take longer to respond to antibiotic treatment than uncomplicated UTIs, and if there is an underlying anatomical or structural abnormality they will usually recur within days, weeks, or months.
Routes of infection
Ascending: The vast majority of UTIs result from infection ascending retrogradely up the urethra. The bacteria, derived from the large bowel, colonize the perineum, vagina, and distal urethra. They ascend along the urethra to the bladder (increased risk in females as urethra shorter) causing cystitis, and from the bladder they may ascend, via the ureters, to involve the kidneys (pyelonephritis).Haematogenous: Uncommon, but is seen with Staph. aureus, candida fungaemia, and TB.
Infection via lymphatics.
Natural Defense Mechanisms of The Urinary Tract:
Normal Body Flora
Urine Composition (low pH and high osmolarity)
Mechanical flushing effect of urine.
Risk Factors :
Stasis and obstruction: Residual urine due to impaired flow e.g. BPH, stricture.
Foreign body.
Decreased resistance to micro-organisms e.g. DM, malignancy
Other factors: trauma, anatomic abnormalities, female gender.
Bacteriology:
Escherichia coli and other Gram-negative organisms are commonly responsible. When Streptococcus faecalis is present it is usually accompanied by other organisms. In E. coli and streptococcal infections the urine is acidic. Proteus spp. and staphylococci split urea to form ammonia, which makes the urine alkaline and promotes the formation of calculi.
Atypical organisms may also be involved e.g. TB, Chlamydia, Candida, Mycoplasma.
Acute Pyelonephritis
Overview: Acute pyelonephritis is a potentially organ- and/or life-threatening infection that characteristically causes scarring of the kidney. An episode of acute pyelonephritis may lead to significant renal damage.
Acute pyelonephritis is more common in females, especially during childhood, at puberty, after intercourse (as a complication of ‘honeymoon cystitis’), during pregnancy and during menopause. It occurs more on the right and is frequently bilateral.
Pathophysiology: Acute pyelonephritis results from bacterial invasion of the renal parenchyma. Bacteria usually reach the kidney by ascending from the lower urinary tract. Bacteria may also reach the kidney via the bloodstream.
Clinical Presentation: The condition is more common in women. The classic presentation in acute pyelonephritis is the triad of fever, costovertebral angle pain, and nausea and/or vomiting. Pain is usually sudden, and may be associated with rigor. There is tenderness in the loin and sometimes in the hypochondrium.
Symptoms of cystitis may or may not be present to varying degrees. These may include urinary frequency, hesitancy, lower abdominal pain, and urgency. Hematuria may also present but pyuria is more common. Rarely, in cases of severe bilateral pyelonephritis, especially when there is an associated obstruction, renal dysfunction may be sufficient to cause uremia. The risk of life-threatening septicemia is always present.
Investigations:
Urinalysis:
Bacteriuria.
Pyuria: defined as more than 5-10 WBCs per high-power field (hpf). Almost all patients with pyelonephritis have significant pyuria.
Hematuria: microscopic or, less commonly gross.
Proteinuria.
Urine culture with/without blood culture.
Imaging may be required if there is suspicion of underlying and/or associated conditions that impair the healing, affects immunity or aggravate the renal damage. Imaging is also indicated in cases of no response to treatment.
Management: The treatment of acute pyelonephritis should be prompt, appropriate and prolonged.
Bed rest.
Antibiotics with a broad spectrum while waiting for the culture and sensitivity results..
Analgesia in the form of NSAID or even opioids.
Adequate hydration through oral or intravenous route.
Despite the efficacy of modern antibacterial drugs, recurrent infection is likely if there is an untreated underlying abnormality of the urinary tract such as a stone, vesicoureteral reflux, fistula to the gastrointestinal tract or retention of urine.
Special Cases:
Pyelonephritis in Pregnancy: Pyelonephritis of pregnancy usually occurs between the fourth and sixth months of gestation in women who have a past history of recurrent urinary infection. In about 10% of cases the disease runs a severe and protracted course and occasionally leads to abortion or premature birth.
Urinary infection in childhood: Urinary infection in childhood is important to recognize because it may damage the growing kidney. The possibility of urinary sepsis should always be considered if a child fails to thrive or suffers unexplained pyrexia. Pain or screaming on micturition may occur. The older child may complain of loin pain and may develop urinary frequency and secondary enuresis. Vesicoureteral reflux of urine is detectable in about 35% of children with recurrent urinary infection.
Chronic Pyelonephritis
Chronic pyelonephritis is characterized by renal inflammation and fibrosis induced by recurrent or persistent renal infection, vesicoureteral reflux, or other causes of urinary tract obstruction. The diagnosis of chronic pyelonephritis is made based on imaging studies such as ultrasound or CT scanning. It occurs almost exclusively in patients with major anatomic anomalies, most commonly in young children with vesicoureteral reflux (VUR).Clinical Presentation:
More common in women than men (3:1) especially young women.
May be asymptomatic (clinically silent).
Dull aching lumbar or loin pain.
Urinary frequency and dysuria.
Hypertension: malignant HT.
Constitutional symptoms: fever, malaise, headache and anorexia.
Treatment: Treatment is aimed at eradicating predisposing contributory factors such as obstruction or stones and treating the infection, often with repeated courses of antibiotic. Surgical treatment is indicated only when the disease is confined to one kidney. Patients with end-stage renal failure require renal replacement therapy.
Renal Carbuncle:
Renal carbuncle is a term used to describe an abscess or an encapsulated necrotic mass that may form in the renal parenchyma. It results from hematogenous spread of bacteria from a primary extrarenal focus of infection. Staphylococcus aureus is the etiologic agent in 90% of cortical abscess cases, coliforms may also be implicated.
Occasionally, the condition results from infection of a haematoma following a blow to the kidney.
Predisposed People:
Diabetics,
Intravenous drug abusers,
Those debilitated by chronic disease
Patients with acquired immunodeficiency.
Clinical Presentation:
Common symptoms include:
Fever, chills, nausea/vomiting,
Flank or abdominal pain.
Dysuria and other urinary tract symptoms.
Nonspecific constitutional symptoms (eg, malaise, fatigue, weight loss) may occur in patients with a chronic process.
On examination.. ill appearance with fever and there may be an ill-defined mass in the loin. Costovertebral angle tenderness is usually present.
Investigations:
Urinalysis: bacteria and pyuria are common features.
Leucocytosis.
Imaging: USS, CT & MRI.
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:
A perinephric abscess is a collection of suppurative material in the perinephric space.Causes:
Haematogenous
Extension of cortical abscess
Extension of appendix abscess
Via periureteral lymphatics
Infection of a perirenal haematoma
Perinephric discharge of an untreated pyonephrosis or renal carbuncle.
Presentation:
Typically, the onset of symptoms is insidious, The most common symptoms include high fever with chills and flank or abdominal pain.
Physical findings include flank or costovertebral tenderness. A flank mass is palpable if the abscess is large or located in the inferior pole of the kidney space.
Investigations:
Leucocytosis, high ESR.
There may or may not be pyuria.
Imaging.
Treatment:
Open drainage may be necessary if the abscess cannot be aspirated through a large percutaneous needle.
Renal Tubeculosis:
Tuberculosis of the upper urinary tract arises from haematogenous infection from a distant focus. It is often associated with tuberculosis of the bladder and typical tuberculous granulomas may be visible in the bladder wall. In the male, tuberculous epididymo-orchitis may occur without apparent infection of the bladder.Clinical Features: The presentation of renal tuberculosis is often vague, and physicians must have a high degree of awareness to make the diagnosis. Renal tuberculosis usually occurs between 20 and 40 years of age, and is twice as common in men as in women; the right kidney is affected slightly more often than the left.
The most common symptoms, in descending order of frequency, include increased frequency of urination (during the day initially but at night later in the disease course), dysuria, flank pain, suprapubic pain, blood or pus in the urine, and fever.
Sterile Pyuria.
Pain: painful micturition and suprapubic pain on full bladder.
Hematuria:
Malaise and weight loss are usual and a low-level evening pyrexia is typical. A high temperature suggests secondary infection or dissemination, i.e. miliary tuberculosis.
Investigations:
Bacteriological: Bacteriological examination of at least three complete specimens of early-morning urine should be sent for microscopy and culture for the detection of M.tuberculosis.Radiography:
Plain abdominal X ray may show calcifications.
IVU may reveal calyceal stenosis, hydronephrosis or a space-occupying lesion (tuberculous abscess). Bladder may be irregular.
A chest radiograph is indicated to exclude an active lung lesion.
Cystoscopy: may be required. Urothelium may appear studded with granulomas. TB ulcer may be seen.
Treatment:
Anti-tuberculous chemotherapy.The urinary system should be reviewed during the first few weeks of therapy because the renal pelvis and ureter may stricture after treatment has started.
Prognosis in renal tuberculosis is good if the patient completes the course of chemotherapy.
Surgery, if required should be minimal. It includes removal of large foci of infection and correction of obstructions.