26th June 2023

Urinary Tract Disorders

Renal Calculi

Clinical Presentation

Renal calculi most commonly present as renal colic accompanied by microscopic haematuria. Renal colic is typically an abrupt onset of severe unilateral abdominal pain originating in the loin or flank and radiating to the labia in women or to the groin or testicle in men. It occurs in intervals lasting minutes to hours, often accompanied by nausea and/or vomiting.

Fever and rigors might indicate a concurrent urinary tract infection. Whereas intermittent urine stream may suggest obstruction.

Risk factors for stone formation

• Age and gender – highest risk is in men aged 40-60 years
• Ethnicity – urinary stones primarily occur in white people, followed by Hispanics, black people, and Asians
• Diet – excessive intake of oxalate, urate, sodium and animal protein
• Chronic dehydration
• Obesity
• Family history

There are also medical conditions which can predispose to stone formation, including:

• Anatomical abnormalities of the urinary tract, e.g. horseshoe kidney, ureteral stricture, vesico-uretero-renal reflux
• Gastrointestinal conditions, e.g. jejunoileal bypass, intestinal resection, Crohn’s disease, malabsorptive conditions
• Genetic conditions, e.g. cystinuria, primary hyperoxaluria, renal tubular acidosis, cystic fibrosis
• Conditions altering urinary volume or pH, e.g. hyperparathyroidism, nephrocalcinosis, diabetes, hypertension, polycystic kidney disease, gout, sarcoidosis, neurogenic bladder, spinal cord injury, increased levels of vitamin D

Management

The most useful imaging to confirm diagnosis is a non-contrast CT Kidney Ureter and Bladder (KUB).
First line management of pain associated with renal calculi is with NSAIDs, e.g. diclofenac.
Further management of renal calculi depends on the size of stone, location, severity of symptoms and age. Options include:

• Watchful waiting if stone is less than 5mm
• Medical expulsive therapy – using an alpha blocker to help stone passage if it is in the distal ureter and less than 10mm
• Surgical options are offered when pain is ongoing or stone is unlikely to pass. Options include:
  • Shock wave lithotripsy
  • Percutaneous nephrolithotomy
  • Ureteroscopy
  • Open surgery

Biochemical composition of renal calculi

• Calcium oxalate stones – most common and most opaque. Oxalate from food is found in urine, and it forms a salt with calcium that precipitates out of solution very easily, thus even mild dehydration can predispose the individual with high urine oxalate levels to develop renal stones.
• Calcium phosphate
• Uric acid – radiolucent
• Struvite stones – magnesium ammonium phosphate, typically in patients with multiple UTIs
• Cysteine – often in a patient with the rare genetic disorder cystinuria

Urinary Tract Infections

Presentation

A lower urinary tract infection (UTI) is an infection of the bladder typically caused by bacteria from the gastrointestinal tract.

Lower UTIs can present with increased urinary frequency, nocturia, urgency, dysuria, suprapubic pain, foul-smelling urine, or haematuria. In the elderly or those with cognitive impairment, UTIs may present with non-specific features such as delirium, anorexia, nausea, and vomiting.

A lower UTI can be complicated by persistent infection, treatment failure or recurrent infection. The risk factors for complications include structural or neurological abnormalities of the urinary tract, external sources of infection such as catheters and immunosuppressive comorbidities such as diabetes. A further complication is the spread of infection to the upper urinary tract giving rise to pyelonephritis. This presents with fever, rigors, and loin pain with renal angle tenderness on examination.

Investigation and treatment

In adults below the age of 65 with risk factors for complicated UTI, urine dipstick can be a basis to start treatment. A dipstick positive for nitrites or leucocytes and blood suggests a UTI. The sample should then be sent for microscopy and culture. Asymptomatic bacteriuria (the presence of bacteria in urine) should be treated in pregnancy as it increases the risk of preterm rupture of membranes. Note that the presence of bacteriuria is common in those over 65 and usually does not need to be treated unless symptomatic.

Antibiotic choice should be guided by sensitivities from culture, but the following are often used:

• Nitrofurantoin 100mg modified-release twice a day for three days
  • must be avoided if eGFR ≤45ml/minute
  • must be avoided in the last trimester of pregnancy due to the risk of haemolytic anaemia of the newborn
  • poor penetration of the kidney so not for complicated UTI
• Trimethoprim 200mg twice a day for three days (if low risk of resistance)

In pregnancy, cefalexin 500mg twice a day can also be considered. Men and pregnant women should be treated for seven rather than three days.

Urinary Tract Obstruction

Causes of urinary tract obstruction

The most common causes of urinary tract obstruction in young adults are stones in a kidney or ureter (see Renal Calculi section). In older adults, benign prostatic hyperplasia (BPH), prostate cancer, tumours (see Urinary Tract Tumours section) and stones are all common causes.

Other causes of urinary tract obstruction include tumours, abscesses, and cysts of the bladder, cervix, uterus, prostate, or other pelvic organs.

People who have slowly progressive obstruction causing hydronephrosis may have no symptoms, or they may have attacks of dull, aching discomfort in the flank on the affected side. Chronic obstructive nephropathy typically leads to the development of end stage renal disease (ESRD) and can be complicated by chronic UTI.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) typically presents with a gradual reduction in urinary flow, hesitancy, frequency, and nocturia. It may also present with acute retention of urine. Management depends on the extent to which lower urinary tract symptoms affect quality of life; this is often classified using the International Prostate Symptom Score (IPSS).

Initial management options include lifestyle changes:

• Reducing fizzy drinks and liquid input before bed
• Bladder training
• Double voiding techniques

Medical management constitutes:

• Alpha blockers, e.g. tamsulosin
  • By inhibiting alpha-1 receptors, the smooth muscle of the prostate and the base of the bladder are relaxed, making it easier for urine to flow.
  • Common side effects include orthostatic hypotension, nasal congestion, ejaculation changes, and weakness.
• Anticholinergics, e.g. oxybutynin
  • Specifically relax bladder detrusor muscle and are also used in overactive bladder.

Prostate cancer

(See Urinary Tract Tumours below)

Management of Acute Obstruction

Early diagnosis is important because most cases of obstruction can be corrected and a delay in treatment can lead to irreversible kidney damage. Doctors may suspect obstruction based on a patient’s symptoms, such as renal colic, symptoms of bladder distention, or a decrease in the volume of urine. A distended bladder can sometimes be felt in the lower part of the abdomen just above the pubic bone.

The first step in the management of acute obstruction is with urethral catheterisation.
Urethral catheterisation (insertion of a hollow, soft tube through the urethra) is often the first diagnostic test done in people with symptoms that suggest the bladder is distended, such as pelvic pressure or distention. If the catheter drains a large amount of urine from the bladder, this suggests that either the bladder outlet or the urethra is obstructed.

The next step is to investigate the cause of the obstruction with investigations which may include renal tract ultrasound, CT KUB or micturition studies.

The cause of the obstruction is targeted. If the cause of obstruction cannot be rapidly corrected or relieved by urethral catheterisation, particularly if there is infection, kidney failure, or severe pain, the urinary tract is drained via nephrostomy or suprapubic catheter, depending on the level of obstruction.

Urinary Tract Tumours

Common cancers of the renal tract

Renal Cancer

Benign renal tumours include angiomyolipomas, hamartomas and renin-secreting tumours.

Renal cell carcinoma arises from the tubular epithelium. Risk factors include smoking, obesity, hypertension, acquired cystic renal disease and genetic conditions such as Von Hippel Lindau syndrome or tuberous sclerosis. It can present with flank pain and, once the collecting duct system has been invaded, haematuria. It may also present with non-specific symptoms such as weight loss or fevers.

Renal cell carcinoma has a propensity to invade the renal veins with two possible complications: emboli to the lung or occlusion of the left testicular vein causing left varicocele.

Other complications include those of associated paraneoplastic syndromes, such as:

• Hypercalcemia (secondary to parathyroid hormone-related peptide)
• Hypertension (secondary to increased renin levels)
• Erythrocytosis (secondary to increased erythropoietin levels)

Bladder Cancer

The predominant histological type is transitional cell carcinoma. Risk factors include smoking, nitrosamines, aniline dyes, phenacetin, and cyclophosphamide. Schistosoma haematobium is a parasite that increases the risk of squamous cell carcinoma. The most common presentation is painless haematuria, either microscopic or macroscopic. Pain suggests invasive and/or metastatic disease. Haematuria towards the end of voiding suggests bladder neck or prostatic urethra source. Lower urinary tract symptoms can also be present such as urgency, frequency, and dysuria. Gold standard imaging for diagnosis and staging is cystoscopy. Provided the tumour does not invade muscle, surgical treatment is via transurethral resection of bladder tumour.

Prostate Cancer

The most common prostate malignancy is adenocarcinoma, which typically occurs in the posterior lobe of the prostate. Risk factors include increasing age and family history. It is asymptomatic in most cases but can present with lower urinary tract symptoms, including urinary retention. Digital rectal examination might identify asymmetry, lack of sulcus, induration and/or nodules of the prostate. The blood marker, prostate specific antigen, is not specific for malignancy and so, if only mildly raised, is typically repeated after six weeks before investigation for malignancy. Metastatic prostate cancer can cause spinal cord compression from bony metastases.

Micturition difficulties

Types of urinary incontinence

Evaluation of urinary incontinence is based on clinical history, including the situation in which incontinence occurs, bowel and bladder habits, symptoms, lifestyle behaviours, and past medical history. Investigations include urine culture, blood tests including renal and thyroid function, and glucose tests. Further tests may include postvoid residual volumes, renal ultrasound, and urodynamic studies. Renal ultrasound can be used to rule out hydronephrosis and kidney stones, and postvoid residual volumes can monitor urinary retention secondary to obstruction or neurogenic bladder.

Urge Incontinence

Urge incontinence is a subset of overactive bladder (OAB). Overactive bladder is defined as urinary urgency with or without incontinence, accompanied by increased frequency and nocturia. Risk factors include:

• Systemic neurological conditions such as Parkinson’s disease, multiple sclerosis, or injury to pelvic or spinal nerves
• Comorbidities such as obesity, type 2 diabetes, and chronic urinary tract infection can increase urgency symptoms
• Drugs such as parasympathomimetics, antidepressants, and hormone replacement

The first step in management is behavioural interventions such as prompted voiding, scheduling toileting, bladder training and pelvic muscle exercises. Following this, medical therapy includes alpha-1 blockers and anti-muscarinic acetylcholine drugs such as darifenacin.

Stress Incontinence

Stress incontinence is defined as involuntary leakage on effort or exertion, for example, on sneezing or coughing. Risk factors include:

• Increasing age
• Pregnancy and vaginal delivery — muscles and connective tissue can be weakened during delivery, and damage may occur to pudendal and pelvic nerves.
• Obesity — due to pressure on pelvic tissues and stretching and weakening of muscles and nerves from excess weight
• A deficiency in supporting tissues, for example:
  • Prolapse — not a cause of stress urinary incontinence but may be caused by the same underlying deficiency of supporting tissues
  • Hysterectomy — surgery may damage the pelvic floor muscles
  • Lack of oestrogen at the menopause — oestrogens keep tissues that influence normal pressure transmission in the urethra healthy and maintain urethral secretions that help to create a ‘seal’.
• Smoking — smoking is associated with chronic cough, which may contribute to stress urinary incontinence.
• Drugs — for example, angiotensin-converting enzyme (ACE) inhibitors (can cause cough and worsen stress incontinence)

Managing contributing factors, such as weight loss, smoking cessation and reducing oral liquid intake, can help improve symptoms. Other management options include supervised pelvic floor muscle training, or surgical options such as colposuspension, sling surgery or vaginal mesh surgery. If surgical options are not viable, selective serotonin inhibitors can be utilised as pharmacotherapy.

Neurogenic Bladder

Neurogenic bladder refers to disorders of the urinary bladder relating to dysfunction of the central nervous or peripheral nervous system, affecting the nerves involved in control of urination. This can present as urge incontinence, urinary frequency, and urinary retention. Causes include injury to the spinal cord, multiple sclerosis, stroke, and neurodegenerative diseases. Children with spina bifida often have urethral sphincter dyssynergia which leads to incomplete bladder emptying or incontinence. This can be worsened with superadded frequent UTI bs leading to reflux causing upper tract dilatation which in turn can cause chronic kidney disease (CKD).