01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Colic develops when a stone impedes ureteric drainage and raises pressure above the obstruction. Distension, local inflammation and ureteric muscular activity generate intense pain. The intensity may fluctuate, but many patients describe a sustained background ache with severe exacerbations. A person who is moving continually to find relief fits the usual pattern; a still patient with guarding requires particular attention to peritoneal disease. These behaviours are clues rather than diagnostic tests.
Pain commonly begins in the flank and may radiate towards the lower abdomen, groin, testis or labium as the ureter is involved. A distal stone can produce urinary urgency or dysuria and resemble bladder infection. Nausea and vomiting may dominate the presentation. Visible or dipstick blood supports urinary tract irritation, but its absence does not exclude a stone and its presence does not exclude an aortic, malignant or infectious cause. Previous stones increase plausibility without closing the differential.
The acute decision has two linked parts: identify the cause and determine whether drainage can safely wait. A healthy person with two functioning kidneys, controlled pain, preserved renal function and a small uncomplicated stone may choose observation. The same measured stone with rigors, rising creatinine or obstruction of a solitary kidney requires a different pathway. Normal overall urine output does not exclude unilateral obstruction because the opposite kidney may continue producing urine.
Explain the uncertainty as findings arrive. A suspected stone is a working diagnosis until imaging and the clinical course support it. Analgesia should start during assessment and should not be withheld to preserve examination signs. Equally, pain relief is an effect of treatment, not proof that the original diagnosis was correct. Re-examine after analgesia, reconcile the scan with the side and pattern of symptoms, and document the plan for unresolved findings.
Key points
- Acute loin pain radiating towards the groin with restlessness suggests ureteric colic, but neither pain location nor haematuria establishes the diagnosis.
- NICE recommends low-dose noncontrast CT within twenty four hours for adults with suspected colic; use ultrasound instead during pregnancy and as the initial examination in people under sixteen.
- Give an appropriate NSAID first; if it is contraindicated or insufficient, offer intravenous paracetamol, then consider an opioid if both earlier choices are unsuitable or inadequate.
- Assess observations, renal function, urine findings and the number of functioning kidneys before choosing observation; stone diameter cannot override infection or renal danger.
- A distal small stone is more likely to pass than a large proximal one, but continuing pain, obstruction or renal deterioration can make waiting inappropriate.
- Confirm the outcome through recovered stone or appropriate follow-up assessment; disappearance of pain does not by itself prove that the ureter is clear.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Migration from the kidney
Most symptomatic ureteric stones have formed within the kidney before entering the ureter. A stone may intermittently obstruct drainage as it moves, so the acute pain episode reflects its location and effects rather than the time when crystallisation began.
Predisposition to stone formation
Concentrated urine, relevant metabolic abnormalities, infection, inherited disorders and urinary tract anatomy contribute differently between patients. Stone composition and recurrence history guide later assessment; the acute presence of colic does not identify the underlying biochemical mechanism.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Pressure above an obstruction
Impaired urine flow increases pressure within the ureter and collecting system. Stretch and local inflammatory signalling activate pain pathways, while the degree and duration of obstruction influence renal consequences.
- 2Ureteric activity and referred pain
Smooth-muscle contraction around an obstruction contributes to painful episodes. Shared sensory pathways help explain radiation towards the groin or genital region, while distal irritation may also cause urinary urgency.
- 3Infection behind impaired drainage
An obstructed infected collecting system provides a source that antimicrobial treatment may not adequately control without drainage. Systemic inflammation and circulatory disturbance can progress rapidly even when the stone is small.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Ask about onset, radiation, previous episodes and the ability to drink or pass urine. Record fever, rigors and symptom duration, and specifically seek a history of one functioning kidney, renal transplantation or known urinary reconstruction. Establish pregnancy possibility where relevant before selecting imaging or medicines.
Fever, chills, tachycardia, hypotension or new confusion with hydronephrosis can indicate infected obstruction. A negative bladder nitrite result cannot reliably describe organisms trapped above a complete blockage. Treat the physiological emergency and involve the team that can decompress the collecting system.
Assess the abdomen, circulation and relevant genital or pelvic symptoms. Sudden testicular pain needs testicular examination and urgent torsion assessment; pregnancy-related pain or bleeding needs an ectopic-pregnancy pathway. An older person with collapse and back pain needs immediate consideration of aortic pathology rather than reassurance from microscopic haematuria.
Repeated vomiting, uncontrolled pain, recurrent attendance, uncertain follow-up or inability to understand return advice may make admission appropriate even without sepsis. Separate these practical barriers from the anatomical probability of passage, and reassess whether the patient can actually carry out the proposed home plan.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Urine testing and indicated cultureFirst step - Why
- Look for urinary inflammation or bleeding and identify evidence that changes the infection pathway.
- Interpretation and limitations
- Dipstick blood is neither compulsory nor specific. White cells can accompany stone irritation; use fever, systemic findings and culture to evaluate infection. Obtain a culture when infection is suspected or intervention is planned, and do not delay urgent treatment to obtain a perfect specimen.
- 02
Creatinine electrolytes and blood count - Why
- Identify renal impairment, complications and abnormalities that alter analgesic or procedural choices.
- Interpretation and limitations
- Compare creatinine with a documented baseline and interpret it alongside volume status and imaging. Marked unilateral obstruction can coexist with a normal creatinine when the opposite kidney is healthy. Add inflammatory markers and, when sepsis is suspected, blood cultures and lactate without making laboratory confirmation a prerequisite for escalation.
- 03
Low-dose noncontrast CT in an adult - Why
- Confirm a ureteric stone, its dimensions and location and examine the alternative causes of pain.
- Interpretation and limitations
- Under NG118, offer CT within twenty four hours for suspected adult renal colic. The report should describe the side, maximum stone dimensions and obstruction rather than provide only a stone count. A stone-protocol scan is not a substitute for the appropriate vascular study when the leading question is aortic disease.
- 04
Ultrasound for pregnancy or children - Why
- Use the initial imaging pathway appropriate to radiation-sensitive populations.
- Interpretation and limitations
- NICE uses ultrasound instead of CT for pregnant patients and urgent ultrasound within twenty four hours for children and young people under sixteen. If the diagnosis remains uncertain after paediatric ultrasound, consider low-dose noncontrast CT with specialist discussion. Nonvisualisation of a ureteric stone on ultrasound does not settle a persistently concerning presentation.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Vascular abdominal disease
Aortic aneurysm or dissection may produce back or abdominal pain with collapse or circulatory change. Age, vascular risk and examination findings alter suspicion, and urinary blood does not rule out a vascular emergency.
Abdominal pelvic and genital emergencies
Appendicitis, diverticulitis, ectopic pregnancy, ovarian torsion and testicular torsion can overlap with colic symptoms. Focused examination and imaging should address the most concerning alternative rather than follow a stone pathway by default.
Infection without a stone
Pyelonephritis may cause flank pain, fever and vomiting without mechanical obstruction. Imaging and the clinical course determine whether the infection also requires drainage, while cultures support antimicrobial selection.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Worked caseVerify an uncomplicated small distal stoneFirst stepA thirty six year old man presents with abrupt left loin pain radiating towards his groin.+
- 1He is restless but afebrile and circulatorily stable, passes urine normally and has no solitary-kidney history. Creatinine is 82 micromol/litre against a baseline of 80, and urine has blood without nitrites. Examination finds no peritonism or testicular abnormality. His medication history contains no NSAID, anticoagulant or relevant allergy, and he has no ulcer, vascular or hepatic disease.
- 2AlternativeHe receives diclofenac sodium 75 mg as the selected 3 ml preparation by deep intragluteal injection. Pain falls from eight to two out of ten within the observed treatment period and he retains oral fluids. Low-dose noncontrast CT demonstrates a four millimetre distal left ureteric stone with mild upstream dilation and a normal right kidney; it identifies no alternative acute cause.
- 3Following urological review he chooses observation, with an agreed analgesia plan, urine strainer and a named review appointment. He understands that fever, inability to pass urine, repeated vomiting or recurrent uncontrolled pain requires urgent return. The small distal position supports the choice, while normal renal function and reliable access to reassessment make it practicable.
- 4He retrieves a stone in the strainer eight days later and delivers it for analysis. At the arranged review he is pain-free, creatinine remains at baseline and follow-up ultrasound shows resolution of dilation. The recorded outcome is concordant recovered stone, symptom recovery and restored drainage, rather than a telephone assumption based only on pain relief.
02Changed clinical stateEscalate infection or renal riskEscalationA patient initially suitable for observation develops a new high-risk feature.+
- 1Reassess observations and urine output promptly and repeat the relevant blood tests. Establish whether the known stone still obstructs drainage, and tell urology about fever, anuria, the baseline renal state and whether the other kidney functions. Do not allow a previous small-stone label to delay this reassessment.
- 2DefinitiveWhen obstruction is infected, take appropriate cultures while starting systemic antibiotics and resuscitation, and arrange urgent stenting or nephrostomy. Definitive stone fragmentation usually follows infection clearance. When the danger is anuria or loss of the only functioning renal drainage, decompression is urgent even if there is no fever.
- 3AlternativeCheck the response after intervention through physiology, urine output, renal function and drain performance. A stent insertion note alone does not establish successful source control; continued deterioration requires reassessment of the device, residual obstruction and alternative pathology.
03Persistent symptomsReconsider the observation decisionPain remains intolerable or a stone is judged unlikely to pass despite initial treatment.+
- 1Check what analgesia has actually been given, its effect and any adverse reaction. Revisit imaging for size, location and a competing diagnosis, and assess ongoing vomiting or renal deterioration. A request for more analgesia may signal persistent obstruction rather than an inadequate explanation of the expected course.
- 2NICE recommends surgical treatment, including shockwave lithotripsy where appropriate, within forty eight hours of diagnosis or readmission when pain is ongoing and not tolerated or the stone is unlikely to pass. This is a treatment-timing recommendation for adult ureteric stones, distinct from immediate source control in infected obstruction.
- 3EscalationAgree the intervention and follow-up with the patient, including whether a temporary stent is likely and how it will be removed. The choice depends on the stone and available timely procedures; escalating treatment need not mean that every patient requires the same operation.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
Voltarol diclofenac sodium 75 mg per 3 ml ampoule
For an eligible adult with renal colic, give 75 mg intramuscularly by deep intragluteal injection; a second 75 mg may be given after thirty minutes if needed, with a maximum of 150 mg from all diclofenac formulations in twenty four hours. Do not use ampoules beyond two days.Exclude renal or hepatic failure, active or recurrent peptic ulcer/bleeding, previous NSAID-related bleeding, established ischaemic heart or cerebrovascular disease, peripheral arterial disease and NYHA II–IV heart failure. Do not use after NSAID-triggered asthma, angioedema or urticaria, or with diclofenac or metabisulphite allergy. Review dehydration, renal function, anticoagulants, other NSAIDs, lithium, methotrexate and ACE inhibitor/diuretic combinations. Stop for bleeding, renal decline or hypersensitivity. This ampoule is not recommended for children; avoid routine use in pregnancy, with particular fetal risk from twenty weeks and contraindication in the third trimester. Its IV indication concerns postoperative pain, and it must never be injected as an IV bolus. The selected Voltarol label states that it should not be administered during breastfeeding.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Loss of renal function
Sustained obstruction may damage the affected kidney. Bilateral obstruction or obstruction of a solitary functioning kidney can reduce total filtration and cause anuria, making the available renal reserve central to urgency.
Obstructive infection and sepsis
Bacterial infection behind a stone can progress to sepsis and shock. The treatment problem includes both systemic infection and the trapped urinary source, with reassessment needed after any drainage procedure.
Treatment-related harm
NSAIDs can cause renal, gastrointestinal or cardiovascular adverse effects; opioids can impair respiration and alertness. Instrumentation adds risks such as infection, bleeding and stent symptoms, so the selected treatment needs an explicit benefit and monitoring plan.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Observe the response to analgesia and repeat abdominal and physiological assessment; an improvement score should accompany, not replace, a reviewed diagnosis.
- Track creatinine, hydration and urine output when impairment or continued obstruction is suspected; a worsening trend changes the observation plan.
- Provide written return symptoms and a named follow-up route, especially when a patient is discharged before demonstrated passage.
- Review the recovered stone or appropriate follow-up imaging and renal recovery, then discuss recurrence assessment and prevention using the actual composition and risk factors.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Two kidneys can conceal unilateral loss
Serum creatinine reflects combined filtration and may remain normal despite a significantly obstructed ureter. Use anatomical findings and symptom course to judge the affected side; do not require a creatinine rise before contacting urology about a persistently obstructed kidney.
Restlessness is useful but imperfect
Colic often makes patients move, whereas peritoneal irritation can make movement painful. Neither behaviour reliably excludes another emergency. A patient with a stone history can also develop appendicitis, an aortic event or torsion, so the present examination matters.
A negative urine test has limits
Absence of haematuria cannot exclude a ureteric stone. Conversely, a positive dipstick should not anchor the diagnosis when the circulation, pain pattern or scan suggests another cause. Infection assessment requires the whole clinical context, particularly if drainage is blocked.
Prevention begins after the acute answer
Recovering and analysing a passed stone can direct later care, but fluid and diet advice cannot replace confirming resolution of an acute obstruction. Separate the immediate endpoint of safe drainage from the longer-term goal of reducing recurrence.
11Common pitfallsFrequent interpretation and management errors.
- 01
Reassuring a patient about a small stone before checking fever, renal reserve and the ability to maintain oral intake can miss a dangerous obstruction.
- 02
Treating pain relief as proof of passage can leave a silent obstruction without follow-up; confirm an appropriate clinical and anatomical endpoint.
- 03
Combining several NSAIDs or repeating diclofenac without counting earlier tablets and suppositories can exceed the selected product maximum.
- 04
Using a routine stone CT as the only investigation when vascular or pregnancy-related pathology is the leading concern can answer the wrong clinical question.