Urology: Retention, Stones, Haematuria and the Acute Scrotum
Surgery — Urology, NMC MBBS licence examination syllabus (Nepal Medical Council).
Urology: retention, stones, haematuria and the acute scrotum
Four presentations, two of which are emergencies measured in hours.
Urological presentations are common, and most are straightforward once you know which question decides the answer. Is the retention acute or chronic? Does the haematuria hurt? Is the scrotum acutely painful, and how quickly did it start? Each of those single questions separates something routine from something that needs acting on today.
Two conditions in this chapter are true time-critical emergencies: testicular torsion, where delay costs the testis, and an obstructed infected kidney, where delay costs the patient. Both are diagnosed clinically and both are made worse by waiting for imaging.
🩺 Where this lives: Painless visible haematuria that stops on its own is one of the most dangerous reassurances in medicine. Bladder tumours bleed intermittently, so the blood clearing is exactly what a cancer does — and patients, understandably, take it as the problem resolving. A single episode of visible haematuria without pain warrants investigation in full, regardless of whether it recurs. The number of advanced bladder cancers that had one ignored episode years earlier is the reason this rule is stated so absolutely.
💡 A note on numbers. This chapter gives no doses and no PSA threshold values. PSA interpretation is age-specific, rises with benign enlargement, infection and instrumentation, and guidance on when to test differs between countries — so a threshold quoted here would mislead. Take it from current national guidance. Acute kidney injury and chronic kidney disease are covered in their own chapter, and the acute abdomen in its own.
Urinary retention
The distinction that matters is painful acute versus painless chronic retention, because the second carries two risks the first does not: renal impairment from long-standing back pressure, and post-obstructive diuresis after the catheter goes in. A patient whose bladder has been distended for weeks can pour out litres of urine over the following hours, becoming volume-depleted and electrolyte-deranged if nobody is watching. Check renal function in every patient with retention, and monitor output after relieving a chronic one.
WHY RETENTION HAPPENS — AND THE DRUG CAUSES PEOPLE FORGET
OBSTRUCTIVE
Prostatic enlargement (much the commonest in older men)
Urethral stricture · stone · clot · constipation
— a loaded rectum genuinely causes retention
NEUROLOGICAL
Cord compression, cauda equina, diabetic or other
neuropathy, post-operative and post-epidural
DRUGS — always review the chart
ANTICHOLINERGIC drugs of any kind
OPIOIDS
Some antidepressants and antipsychotics
Sympathomimetics in cold remedies
AND ALWAYS ASK ABOUT THE BACK. Retention with back pain,
leg weakness or saddle sensory loss is CAUDA EQUINA
SYNDROME until proven otherwise — a neurosurgical
emergency, not a urological one.
After catheterisation, document the residual volume: it
distinguishes acute from chronic retention and guides what
happens next.
Renal colic
💡 Exam angle: two traps recur. The first is the obstructed, infected kidney — fever with an obstructing stone is not a stone that also has a urinary infection; it is pus behind an obstruction, and it needs urgent drainage alongside antibiotics. The same source control logic as an abscess. The second is the patient over 50 with a "first attack of renal colic", where a leaking abdominal aortic aneurysm can present identically — and is the diagnosis you cannot afford to miss.
Haematuria
SORTING OUT HAEMATURIA
FIRST QUESTION: IS IT PAINFUL?
PAINLESS VISIBLE HAEMATURIA
→ urinary tract CANCER until excluded (bladder,
kidney). Refer for full investigation even if it
settles. Settling means nothing.
PAINFUL HAEMATURIA
→ more often stones or infection — but cancer is not
excluded by pain.
SECOND QUESTION: IS IT FROM THE KIDNEY ITSELF?
Clues pointing to a GLOMERULAR cause:
PROTEINURIA as well as blood
Red cell casts on microscopy
Oedema, hypertension, impaired renal function
That combination is a renal problem, not a urological
one — see the kidney chapter.
ASK ABOUT SMOKING: it is a major risk factor for bladder
cancer and the association is frequently overlooked.
Occupational exposure to certain dyes and chemicals also
matters.
AND EXCLUDE THE MIMICS: beetroot, some drugs, and
myoglobinuria discolour urine without blood. A dipstick
positive for blood with no red cells on microscopy should
prompt thought about rhabdomyolysis.
The prostate
Lower urinary tract symptoms divide usefully into voiding symptoms (hesitancy, poor stream, terminal dribbling) and storage symptoms (frequency, urgency, nocturia). On rectal examination, a smooth, firm, symmetrical gland with a preserved central groove suggests benign enlargement, whereas a hard, irregular, nodular gland with a lost groove is suspicious of cancer. And remember where prostate cancer goes: bone. New back pain in a man with prostate cancer is metastasis until proven otherwise — and back pain with leg weakness or retention is cord compression, an emergency.
The acute scrotum
💡 Exam angle: testicular torsion is a clinical diagnosis that goes straight to theatre. The examinable trap is a stem offering "urgent ultrasound" as the next step — a normal scan does not exclude torsion, and the time spent obtaining it is time the testis does not have. Sudden severe pain in an adolescent, often with vomiting, a high-riding testis and an absent cremasteric reflex, means surgical exploration. Epididymo-orchitis is more gradual, with fever and urinary symptoms, usually in an older man.
Clinical reasoning: four presentations
🔍 Case 1 — the blood that stopped
PresentationA 64-year-old smoker had one episode of visible painless haematuria three weeks ago. It cleared within a day and has not recurred. He is told this was probably an infection and to return if it happens again.
ErrorTreating resolution as reassurance.
ReasoningPainless visible haematuria is urinary tract cancer until excluded, and bladder tumours characteristically bleed intermittently — so stopping is what a cancer does. His age and smoking history raise the risk further.
AnswerUrgent referral for full investigation of the upper and lower urinary tract, regardless of the fact that the bleeding settled.
🔍 Case 2 — colic with a fever
PresentationA woman with loin-to-groin pain has an obstructing stone on imaging. She is febrile at 39°C, tachycardic and hypotensive. She is started on antibiotics and admitted for observation and analgesia.
Missing stepDrainage.
ReasoningThis is an obstructed, infected kidney — infected urine behind an obstruction, which antibiotics cannot sterilise. It is the same problem as an undrained abscess, and it progresses to septic shock quickly.
AnswerResuscitate, antibiotics, and urgent decompression of the obstructed system per local pathway. This is an emergency, not an admission for observation.
🔍 Case 3 — litres after the catheter
PresentationAn elderly man with months of poor stream and nocturia is found to have a large painless palpable bladder and impaired renal function. A catheter drains a very large volume. He is sent to the ward with routine observations only.
RiskPost-obstructive diuresis.
ReasoningThis is chronic retention with renal impairment. After decompression, the kidneys may produce very large volumes for hours, causing volume depletion and electrolyte disturbance if unmonitored.
AnswerMonitor urine output closely, replace fluid as needed per protocol, and recheck electrolytes and renal function. Then plan definitive management of the obstruction.
🔍 Case 4 — an adolescent with sudden pain
PresentationA 15-year-old wakes with sudden severe left scrotal pain and vomiting. The testis is high-riding and exquisitely tender, and the cremasteric reflex is absent. The team arranges an ultrasound, expected in two hours.
TrapImaging before theatre.
ReasoningThis is torsion until proven otherwise. The testicular blood supply is twisted, viability falls with every hour, and a normal ultrasound does not exclude the diagnosis.
AnswerImmediate surgical referral for exploration. Do not wait for imaging when torsion is clinically suspected.
Commonly confused
Confusion
The distinction
Why it matters
Acute vs chronic retention
Painful and sudden versus painless and gradual
Chronic carries renal impairment and diuresis risk.
Relieving vs monitoring afterwards
Post-obstructive diuresis follows decompression
Unmonitored patients become depleted.
Retention vs cauda equina
Back pain, leg weakness, saddle sensory loss
A neurosurgical emergency.
Stone with infection vs obstructed infected kidney
Fever with obstruction needs DRAINAGE
Antibiotics alone cannot sterilise it.
Renal colic vs aortic aneurysm
First attack over 50 is suspicious
The diagnosis you cannot miss.
Haematuria settling vs resolving
Bladder tumours bleed intermittently
Stopping is what a cancer does.
Urological vs glomerular haematuria
Protein, casts, oedema, hypertension
Sends you to the kidney chapter instead.
Torsion vs epididymo-orchitis
Sudden in an adolescent versus gradual with fever
One goes straight to theatre.
Rapid revision
MUST-KNOW FACTS
1. ACUTE retention is PAINFUL and sudden.
2. CHRONIC retention is PAINLESS, gradual, with large volumes.
3. Chronic retention may cause RENAL IMPAIRMENT.
4. After relieving chronic retention, expect POST-OBSTRUCTIVE DIURESIS.
5. Monitor urine output, fluids and electrolytes afterwards.
6. Check RENAL FUNCTION in every patient with retention.
7. Retention causes: prostate, constipation, DRUGS, neurological, infection.
8. Anticholinergics and OPIOIDS are common drug causes.
9. Retention with back pain or leg weakness = CAUDA EQUINA until excluded.
10. Document the residual volume after catheterisation.
11. RENAL COLIC: loin to groin, waves, patient CANNOT KEEP STILL.
12. RESTLESS with colic · STILL with peritonitis.
13. FEVER with an obstructing stone = OBSTRUCTED INFECTED KIDNEY.
14. That needs URGENT DRAINAGE plus antibiotics — source control.
15. First "renal colic" over 50 — EXCLUDE AORTIC ANEURYSM.
16. PAINLESS VISIBLE HAEMATURIA = urinary tract cancer until excluded.
17. Refer even if the bleeding settles — settling means nothing.
18. SMOKING is a major risk factor for bladder cancer.
19. Glomerular clues: PROTEINURIA, red cell casts, oedema, hypertension.
20. Beetroot, some drugs and myoglobin discolour urine without blood.
21. LUTS divide into VOIDING and STORAGE symptoms.
22. Benign prostate: smooth, firm, symmetrical, groove preserved.
23. Suspicious prostate: HARD, irregular, NODULAR, groove lost.
24. Prostate cancer metastasises to BONE.
25. Back pain with leg weakness or retention = CORD COMPRESSION.
26. PSA rises with benign enlargement, infection and instrumentation.
27. Take PSA thresholds from current national guidance.
28. TESTICULAR TORSION: sudden severe pain, often adolescent, vomiting.
29. High-riding testis, absent cremasteric reflex.
30. DO NOT DELAY SURGERY FOR IMAGING — a normal scan excludes nothing.
31. Epididymo-orchitis: gradual, fever, dysuria, usually older.
💡 Exam angle: this chapter is mostly about which presentations cannot wait. Torsion and the obstructed infected kidney go to theatre or to drainage today. Painless haematuria goes for investigation regardless of settling. And retention with back pain goes to the neurosurgeons, not the urologists.
Syllabus points
Acute versus chronic retention
Post-obstructive diuresis
Drug and neurological causes of retention
Retention and cauda equina syndrome
Renal colic and the restless patient
The obstructed infected kidney
Aortic aneurysm mimicking colic
Painless visible haematuria
Glomerular versus urological haematuria
Voiding and storage symptoms
Benign versus suspicious prostate findings
Bone metastasis and cord compression
Testicular torsion and why imaging waits
Create a free account to tick topics off, take notes as you read, watch the video lessons and get a day-by-day study plan built around your exam date.