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Renal agenesis (unilateral usually asymptomatic), horseshoe kidney (fusion of the lower poles, prone to obstruction, stones and infection), ectopic (pelvic) kidney, duplex collecting system (with ureterocele or ectopic ureter opening), pelviureteric junction obstruction (the commonest cause of hydronephrosis in children), vesicoureteric reflux (graded on cystography; causes recurrent pyelonephritis and scarring). Polycystic kidney disease is described with renal cysts.

Causes: stones, pelviureteric junction obstruction, ureteric strictures, tumours, retroperitoneal fibrosis, bladder outlet obstruction (BPH), pregnancy, neurogenic bladder. Consequences: pain, infection, and progressive loss of renal function if the obstruction is not relieved. Diagnosis: ultrasound, CT, diuretic renography. An infected obstructed system (pyonephrosis) is an emergency needing urgent drainage (ureteric stent or percutaneous nephrostomy).

Types: calcium oxalate (commonest), calcium phosphate, uric acid (radiolucent; acidic urine), struvite (infection stones with urease-producing bacteria such as Proteus; staghorn), cystine (inherited). Risk factors: low fluid intake, hypercalciuria, hyperoxaluria, hypocitraturia, gout, hyperparathyroidism, recurrent infection. Presentation: renal colic (severe loin-to-groin pain, haematuria, vomiting). Diagnosis: non-contrast CT (gold standard), ultrasound. Treatment: analgesia (NSAIDs), alpha-blockers for medical expulsive therapy of distal ureteric stones, stones up to about 5 mm usually pass; extracorporeal shock wave lithotripsy, ureteroscopy with laser lithotripsy, percutaneous nephrolithotomy for large stones. Prevention: fluids above 2.5 L/day, dietary measures, thiazides, potassium citrate, allopurinol.

Organisms: E. coli (most), Klebsiella, Proteus, Enterococcus, Staphylococcus saprophyticus. Uncomplicated cystitis in women: dysuria, frequency, urgency; short course of nitrofurantoin, fosfomycin or trimethoprim. Pyelonephritis: fever, loin pain, vomiting; urine culture and imaging if severe or not improving; treated with fluoroquinolones, cephalosporins or aminoglycosides according to sensitivities. Complicated UTI (men, pregnancy, obstruction, catheters, diabetes) needs longer courses and imaging. Renal abscess: persistent fever despite antibiotics; drained percutaneously. Emphysematous pyelonephritis in diabetics is an emergency. Asymptomatic bacteriuria is treated only in pregnancy and before urological procedures.

1. Which stone is radiolucent? 2. What is the gold-standard imaging for suspected renal colic? 3. When is an obstructed infected kidney an emergency and how is it treated? 4. Which organism is the commonest cause of UTI?

1. Uric acid stones. 2. Non-contrast CT. 3. Infection above an obstruction (pyonephrosis): urgent drainage by stent or nephrostomy plus antibiotics. 4. Escherichia coli.

Simple cysts: very common with age, asymptomatic, thin wall, anechoic on ultrasound: no treatment. Complex cysts are classified by the Bosniak system (I-IV) on CT or MRI according to septa, calcification and enhancement; Bosniak III and IV carry a significant risk of malignancy and are resected. Autosomal dominant polycystic kidney disease (PKD1, PKD2): bilateral enlarging cysts, hypertension, haematuria, infection, cerebral aneurysms, progression to kidney failure; tolvaptan can slow progression.

Risk factors: smoking, obesity, hypertension, dialysis, von Hippel-Lindau disease. Types: clear cell (most, loss of VHL), papillary, chromophobe. Classic triad (haematuria, flank pain, mass) is now rare. Paraneoplastic syndromes: polycythaemia, hypercalcaemia, hypertension. Spread into the renal vein and inferior vena cava; metastases to lung, bone and brain. Diagnosis: CT with contrast. Treatment: partial nephrectomy for small tumours (T1), radical nephrectomy for larger, ablation or surveillance for small masses in frail patients, and systemic therapy (tyrosine kinase inhibitors, immune checkpoint inhibitors) for metastatic disease. Benign masses: angiomyolipoma (fat on CT) and oncocytoma.

Risk factors are like bladder cancer (smoking, aromatic amines), plus Lynch syndrome and aristolochic acid. Presentation: painless haematuria, flank pain, hydronephrosis. Diagnosis: CT urography, ureteroscopy with biopsy, cytology. Treatment: radical nephroureterectomy with removal of the bladder cuff for high-risk disease; kidney-sparing endoscopic management for low-risk tumours. Bladder recurrence is common, so cystoscopic surveillance is needed.

1. What system classifies complex renal cysts? 2. Which genetic syndrome predisposes to clear cell renal carcinoma? 3. What is the standard surgery for high-risk upper tract urothelial carcinoma?

1. The Bosniak classification. 2. Von Hippel-Lindau disease. 3. Radical nephroureterectomy with a bladder cuff.

Symptoms: storage (frequency, urgency, nocturia) and voiding (weak stream, hesitancy, incomplete emptying); scored with the International Prostate Symptom Score. Assessment: history, digital rectal examination, urinalysis, frequency-volume chart (nocturia and nocturnal polyuria), PSA, flow rate and post-void residual, ultrasound. Treatment: watchful waiting and lifestyle, alpha-blockers (tamsulosin), 5-alpha reductase inhibitors (finasteride, dutasteride; for prostates over 30-40 mL), antimuscarinics or beta-3 agonists for overactive bladder, desmopressin for nocturnal polyuria, and surgery (transurethral resection, laser enucleation, simple prostatectomy) for retention, recurrent infection, stones, renal impairment or failure of medical therapy.

Screening and suspicion: PSA (age-dependent, affected by BPH, prostatitis and instrumentation) and digital rectal examination. Multiparametric MRI (PI-RADS score) identifies suspicious lesions; MRI-targeted plus systematic transrectal or transperineal biopsy gives the grade (ISUP grade group). Staging: MRI, bone scan or PSMA-PET. Risk groups (low, intermediate, high) guide management: active surveillance for low-risk disease, radical prostatectomy or radiotherapy with androgen deprivation for higher risk, and systemic therapy for metastatic disease.

Erectile dysfunction: inability to achieve or maintain an erection sufficient for intercourse; causes vascular, neurogenic, hormonal (hypogonadism), drug-induced (antihypertensives, antidepressants), diabetes and psychological. Assessment includes cardiovascular risk. Treatment: lifestyle, phosphodiesterase-5 inhibitors (sildenafil, tadalafil; contraindicated with nitrates), intracavernosal alprostadil, vacuum devices and penile prosthesis. Foreskin diseases: phimosis, paraphimosis (emergency: reduce the foreskin), balanitis and balanitis xerotica obliterans (lichen sclerosus), treated with topical steroids or circumcision. Penile squamous cell carcinoma: risk factors HPV, phimosis and poor hygiene, lichen sclerosus; treated by excision or penile-sparing surgery with inguinal lymph node management.

1. Name two drug classes for BPH and their mechanism. 2. Describe the diagnostic pathway for prostate cancer. 3. Which drug class for erectile dysfunction is contraindicated with nitrates? 4. What is paraphimosis?

1. Alpha-blockers relax prostatic smooth muscle; 5-alpha reductase inhibitors shrink the gland by blocking dihydrotestosterone synthesis. 2. PSA and examination, multiparametric MRI (PI-RADS), targeted plus systematic biopsy with ISUP grading, staging imaging. 3. Phosphodiesterase-5 inhibitors. 4. A retracted foreskin that cannot be returned over the glans, an emergency.