01Principles and purposeThe professional or clinical skill and the decisions it supports.
Obstruction prevents effective urine drainage and can reduce filtration in the affected kidney. When infection is present above the blockage, pressure and the retained infected focus can sustain systemic illness despite an antibiotic that is active in the laboratory. The emergency decision is therefore about restoring drainage while treating sepsis. Manipulating and definitively fragmenting an infected obstructing stone during uncontrolled sepsis can increase physiological risk; decompression and later clearance are separate phases.
The urgency depends on infection, renal reserve, output and clinical trajectory, not just the number of millimetres on CT. A small obstructing stone can be dangerous in a solitary functioning kidney. Bilateral obstruction can cause anuria, and unilateral obstruction may coexist with hypovolaemia or other causes of AKI. A bladder catheter can measure output and treat a lower-tract obstruction, but it does not bypass a blocked ureter; absence of improvement requires upper-tract assessment.
Timing statements need their correct population. EAU calls for urgent decompression in sepsis with obstructing stones. NICE NG148 says that suspected pyonephrosis with AKI needs immediate ultrasound, performed within six hours, and that stenting or nephrostomy for upper-tract obstruction with AKI is performed as soon as possible and within twelve hours of diagnosis. These are escalation requirements, not permission to wait until a deadline when the patient is deteriorating. The separate NICE forty-eight-hour stone-treatment recommendation for intolerable colic is not a sepsis drainage window.
Retrograde stenting crosses the obstruction internally from the bladder, while nephrostomy enters the collecting system percutaneously and drains externally. Neither is universally superior for emergency infected-obstruction decompression. Access anatomy, ability to tolerate the proposed anaesthetic, coagulopathy or antithrombotic exposure, available staff and the likelihood of prompt success guide the joint decision. If an attempted route fails, move to an effective alternative instead of allowing repeated attempts to defer source control.
Key points
- An obstructed kidney with infection or anuria is a urological emergency. Start assessment, resuscitation and indicated antibiotics while obtaining urgent urological source control; neither cultures nor response to an antibiotic should postpone drainage.
- NICE AKI guidance requires immediate urological referral for pyonephrosis, an obstructed solitary kidney, bilateral upper-tract obstruction or obstruction causing AKI complications. When stenting or nephrostomy treats obstruction with AKI, do it as soon as possible and within 12 hours of diagnosis.
- A ureteric stent and percutaneous nephrostomy are both effective decompression options. Choose the promptly achievable safe route from anatomy, physiology, bleeding risk and expertise, and defer definitive infected-stone removal until infection has resolved.
- In nonpregnant adults managed under NG253, an indicated initial isotonic fluid bolus is 250 mL over 10–15 minutes, followed by reassessment; high-risk suspected sepsis needs broad-spectrum IV antibiotics within one hour of risk identification.
- Continued anuria, hypotension, fever or worsening renal function after device placement requires reassessment of drainage, obstruction and infection; a technical procedure entry is not proof of clinical success.
- Before discharge, identify who owns culture review, stone treatment and dated device removal or exchange. A symptom-free patient with a retained stent still has an unfinished treatment pathway.
02Situations and prioritiesThe context, relevant information and actions that matter most.
Fever or rigors, systemic deterioration, flank symptoms and upper-tract dilation raise concern for an infected obstructed kidney. Older or immunosuppressed patients may lack a striking fever. Judge the whole physiological picture; negative nitrites or an initially reassuring blood count cannot safely exclude this emergency.
Establish whether the patient has one functioning kidney, bilateral disease, anuria or a creatinine rise from baseline. An obstructed solitary kidney and bilateral obstruction require immediate referral under NG148. Review potassium and other AKI complications in parallel with the mechanical obstruction.
Assess blood pressure, perfusion, mental state, lactate, respiratory status and urine output. Improvement after a fluid bolus may be temporary while obstruction persists. Escalate to senior urology, anaesthesia and critical care according to physiology, with a documented source-control decision.
A stent can migrate or fail to drain adequately, while a nephrostomy can kink, block or dislodge. New fever, recurrent flank pain, absent external drainage or worsening renal function requires assessment of device function and the underlying kidney. Do not dismiss these as expected postoperative discomfort without examining the patient.
03Assessment and interpretationHow to gather information, assess the situation and recognise uncertainty.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Urgent upper-tract imaging - Why
- Confirm the site and consequence of obstruction while resuscitation proceeds.
- Interpretation and limitations
- Use the fastest appropriate study for the actual question and patient. In suspected pyonephrosis with AKI, apply the NG148 immediate ultrasound within-six-hour requirement. CT can define a stone and alternative pathology when needed, but diagnostic sequencing must not create an avoidable delay in source control.
- 02
Blood and urine cultures - Why
- Identify the organism and allow directed antibiotic treatment.
- Interpretation and limitations
- Obtain blood and an appropriate urine sample before antibiotics if this causes no meaningful treatment delay. Send urine obtained above the obstruction during drainage, because it can add information beyond a bladder sample. Review susceptibility results against the clinical response rather than filing them as an isolated laboratory result.
- 03
Renal, metabolic and sepsis tests - Why
- Measure organ injury and follow response to drainage and treatment.
- Interpretation and limitations
- Compare creatinine with baseline; assess electrolytes, potassium, blood count, inflammatory markers and lactate as indicated. Persistent hyperkalaemia, acidosis, shock or renal deterioration needs active management as well as decompression. Repeat results answer whether the kidney and the patient are recovering.
- 04
Procedural preparation - Why
- Choose a feasible drainage route without overlooking modifiable risk.
- Interpretation and limitations
- Review anticoagulants, antiplatelets, coagulation, relevant anatomy, allergy history and anaesthetic risk. Percutaneous access has a different bleeding profile from retrograde stenting. Discuss reversal or interruption with the responsible teams where needed; an unexamined medication list should not determine the route by accident.
04Worked approachesCases with ordered reasoning, an action and a check of the outcome.
01Worked caseDrain an infected system and verify recoveryA sixty one year old man presents with rigors, right flank pain, systolic pressure 88 mmHg and creatinine 198 micromol/L from a baseline 92.+
- 1He is recognised as having high-risk suspected sepsis. Ultrasound demonstrates right hydronephrosis, and urgent CT available during stabilisation identifies an eight-millimetre proximal ureteric stone. Blood and urine cultures are obtained promptly. Senior urology and anaesthesia agree urgent decompression while monitored resuscitation continues; the team does not wait for culture growth or a twelve-hour limit.
- 2An indicated 250 mL isotonic crystalloid bolus is given over 10–15 minutes with assessment of perfusion and breathing, and a second bolus is given after reassessment. For this individual, the microbiologist selects ceftriaxone 2 g IV every twenty four hours, infused over at least thirty minutes, using his recent susceptible urinary isolate and local resistance assessment after checking beta-lactam allergy and liver function. The first dose is administered within one hour; this selection is not a universal empirical regimen for every obstructed septic patient.
- 3A retrograde stent is placed promptly because access is feasible and this is the immediately available safe drainage route. Urine from above the obstruction is sent for culture; the stone is left for later treatment. Blood pressure rises to 112/70 mmHg, lactate falls on repeat testing and urine output recovers during monitored care. These observed changes support effective source control, while ongoing observations check for recurrent deterioration.
- 4Susceptibility confirms the selected ceftriaxone. At forty eight hours, route and response are reviewed and 2 g IV daily is continued while the total course is assessed against the systemic illness, the selected agent and effective drainage. At the eventual treatment-stop review, rigors and flank pain have resolved, perfusion and urine output remain normal, inflammatory markers have fallen and creatinine is 94 micromol/L. The record confirms that ceftriaxone continued for a further seventy two hours after documented defervescence. The completed course reflects the whole disease course and source-control assessment; it was not calculated simply by adding seventy two hours to the first normal temperature. This satisfies the afebrile branch of the product continuation instruction without claiming a universally sufficient total. EAU distinguishes the inferior seven-day result in male systemic UTI from limited beta-lactam evidence, so these observed stopping conditions are not presented as a fixed course for every man with an infected obstructed stone.
- 5After infection has resolved, planned ureteroscopy clears the stone. A dated device plan is fulfilled, with stent removal recorded and later assessment showing no residual obstruction and renal function at baseline. The completed record therefore demonstrates sepsis recovery, stone clearance and device removal as three separate outcomes.
02Anuria without infectionRestore drainage in a threatened functioning systemA patient with a solitary kidney develops anuria and an obstructing ureteric stone.+
- 1Confirm catheter patency if present and exclude simple lower-tract retention, but request immediate urological review for an obstructed solitary kidney. Assess electrolytes, ECG when hyperkalaemia is possible, volume status and other AKI complications. Absence of fever does not make anuria safe for routine outpatient observation.
- 2Arrange decompression as soon as possible. Where upper-tract obstruction with AKI is treated by stenting or nephrostomy, meet the NG148 within-twelve-hour diagnosis requirement while responding faster to deterioration. Select the route that can relieve the actual obstruction promptly and safely.
- 3Monitor urine output, electrolytes and fluid balance after relief because a marked diuresis can follow. Replace losses according to measured physiology and renal-team advice rather than a fixed unexamined volume. Verify improving renal function, then make a definite stone and device plan before the acute team relinquishes care.
03Drainage appears unsuccessfulReassess continuing illness after decompressionFever, shock, pain, anuria or renal deterioration persists after stent or nephrostomy placement.+
- 1Reassess the patient first, repeat relevant sepsis and renal investigations and review whether resuscitation or critical-care support needs escalation. Check the procedure record, external tubing if present and the possibility of an undrained or contralateral obstructed system.
- 2Request urgent urological reassessment and imaging appropriate to suspected device position or persistent obstruction. Correct a blocked, displaced or ineffective drain through the responsible procedural service; do not assume that escalating antibiotics alone will fix ongoing mechanical obstruction.
- 3Review upper-tract and blood cultures with microbiology, reconsider resistant organisms or another focus, and adjust treatment to the actual findings. Record the physiological and drainage response to the second intervention so that apparent technical success is tested against patient recovery.
05Relevant medicines and safetySpecific regimens and precautions when the skill involves prescribing.
Ceftriaxone, selected 2 g UK injection product
For an adult complicated urinary infection when selected using susceptibility and local policy: 1–2 g IV once daily; the worked high-risk case uses 2 g every 24 hours by infusion over at least 30 minutes. Review IV treatment at 48 hours. The selected SmPC states that duration varies with the disease course and ceftriaxone continues for 48–72 hours after the patient becomes afebrile or evidence of bacterial eradication is achieved. Assess that continuation criterion within the total-course decision, alongside source control, response and the population; it does not itself define a short total course. EAU reports seven days inferior to fourteen in male systemic UTI, while evidence for other agents is limited and older beta-lactam studies showed no clear benefit beyond ten days. Neither finding establishes a universal fixed ceftriaxone course for this male shock/obstruction context. The worked case records a completed course, sustained recovery and seventy two hours of treatment after defervescence, as an individual endpoint rather than a fixed course for other patients.Check allergy before administration: ceftriaxone or other cephalosporin hypersensitivity and previous severe hypersensitivity to another beta-lactam are contraindications. Do not mix with calcium-containing diluents or give simultaneously with IV calcium solutions; adult sequential use requires compatible line management and thorough flushing. Never inject a lidocaine-containing IM preparation intravenously. Renal impairment alone usually needs no reduction if hepatic function is satisfactory; CrCl below 10 mL/min limits the dose to 2 g/day. Severe combined renal and hepatic dysfunction requires close specialist monitoring. Check INR with vitamin K antagonists and monitor renal function, blood count and hepatic tests as the course requires. Stop and treat severe allergy or severe skin reactions; assess significant diarrhoea, new anaemia, confusion or myoclonus for drug toxicity. Renal or biliary precipitation is a recognised risk, so reassess new relevant symptoms. This is an adult example; pregnancy and neonates require their own restrictions.
06Feedback, follow-up and evidenceReview outcomes, seek feedback and identify what to improve.
- Trend perfusion, consciousness, respiration, temperature and urine output during resuscitation and after drainage; reassess after each fluid bolus and obtain senior help for inadequate response or overload.
- Check creatinine and electrolytes after relief, including a possible post-obstructive diuresis; recovery is measured against the previous baseline rather than an arbitrary normal range.
- Review every blood, bladder and upper-tract culture with the antibiotic choice and clinical trajectory, documenting any change in agent, route or completion date.
- Name the clinician or service responsible for each stent or nephrostomy, planned stone procedure and removal or exchange date; reconcile those plans at discharge and confirm completion.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Time limits are not waiting targets
The NG148 six-hour imaging and twelve-hour decompression statements apply within its AKI scope. A patient with septic shock may need a much faster response, and immediate urological contact should occur before a scheduling deadline becomes the focus.
Culture location can matter
Urine trapped above an obstruction may differ from a bladder sample. Sampling at decompression informs subsequent targeted treatment, but neither that useful sample nor its final result should delay the initial antibiotic and drainage response.
A route is selected for this patient
Retrograde and percutaneous drainage each have practical advantages and limitations. Team expertise, access, anaesthetic tolerance and bleeding risk can determine which succeeds soonest; a universal preference would hide the decision that matters.
Acute recovery is only one milestone
Renal function and sepsis can improve with a stone still present. Closing the episode also requires a deliberate clearance strategy and prevention of a forgotten temporary device, including action when a patient misses the removal appointment.
08Common pitfallsFrequent interpretation and management errors.
- 01
Using the forty-eight-hour intolerable-colic treatment recommendation to delay drainage in sepsis confuses two different indications and timescales.
- 02
Waiting for antibiotic response before referring an infected obstructed kidney can leave the infectious focus undrained.
- 03
Assuming a urethral catheter relieves a ureteric obstruction can give false reassurance while an upper tract remains blocked.
- 04
Discharging after successful stenting without an owned stone and device plan converts a temporary solution into a preventable later complication.