Operative animation, Nephrostomy

Percutaneous nephrostomy: decompression of the obstructed kidney

A hydronephrotic, obstructed system decompressed through a posterior calyx: ultrasound-guided puncture, urine for culture, wire, tract, pigtail. The neighbours decide the danger: retrorenal colon laterally, pleura above the 12th rib, segmental vessels inside the kidney.

Core tier FRCS endourology, emergency drainage Interactive 3D
Schematic scene preview: Percutaneous nephrostomy
Preparing the 3D anatomy…

UrOops3D · UroRef · © Nity G

Click me next Section 2 of 8 Anatomy The structures this operation works between, and the one it must not cross.

The structures in the scene

Nephrostomy: how the structures relateProne, the needle line from skin to posterior calyx. Posterior calyx: urine efflux confirms you are inside Dilated pelvis and calyces. Posterior calyx: a supracostal line enters the chest Pleural reflection (danger). Posterior calyx: can swing behind the kidney onto the line Retrorenal colon (danger). Posterior calyx: puncture along the axis, never across it Infundibulum and segmental arteries (danger).Posterior calyxDilated pelvis andcalyces!Pleural reflection!Retrorenal colon!Infundibulum andsegmental arteriesurine effluxconfirms you areinsidea supracostal lineenters the chestcan swing behindthe kidney onto thelinepuncture along theaxis, never acrossitTargetDanger
Prone, the needle line from skin to posterior calyx. Schematic, not to scale; relationships only.
  • The needle line runs skin to posterior calyx with three neighbours to clear: the pleura above the 12th rib, the colon on the lateral line, and the segmental arteries running along the calyceal infundibula inside the kidney.
  • ›Posterior calyx - the target: through parenchyma, along the infundibular axis, away from the hilar vessels.
  • ›Dilated pelvis + calyces - the system you are decompressing; efflux of urine is the confirmation you are inside it.
  • ›Retrorenal colon - thin patient or previous surgery can swing it behind the kidney and across the line.
  • ›Pleural reflection - rises above the 12th rib; a supracostal line enters the chest.
Click me next Section 3 of 8 Steps The operation in order, with the landmark that guards each move.

Operative steps

  1. Ultrasound survey The side is confirmed, the clotting and platelets are acceptable or corrected, antibiotics are given or already running, and the patient is positioned prone; the flank is surveyed with ultrasound before the skin is prepped with intent. The scan confirms the dilated system and a posterior calyx is chosen below the 12th rib, on a line that clears colon laterally and pleura above. The same images show whether liver or spleen dips into the corridor, the depth of parenchyma the needle will cross, and the axis of the infundibulum. The line is decided here, on the scan: a corridor negotiated after the needle is inserted is already a compromised one.
    where it bites: the line is chosen on the scan, not with the needle.
  2. Calyceal puncture + aspiration The needle advances along the anaesthetised line through the parenchyma and into the chosen calyx, entering through the papilla along the infundibular axis. Urine is aspirated and sent for culture before anything else follows, because that sample is one of the reasons this route was chosen. Efflux at the needle hub confirms the tip sits in the collecting system, and the needle is steadied for the wire. The system is decompressed deliberately, not emptied: aspirating an infected pelvis dry before the wire is in risks collapsing the very space the next pass must find.
    where it bites: aspirating the pelvis dry before wire placement risks losing the system.
  3. Wire (Seldinger) A guidewire is passed through the needle and advanced under screening until it coils in the pelvis with spare length inside the system. The coil is the security: it holds the wire in the kidney when the needle comes out and through every exchange that follows. The wire is controlled at the skin by one person throughout, and every pass over it happens with the wire visible at both ends. A wire advanced against resistance perforates the collecting system, and a wire left unattended is a wire that will perforate.
  4. Tract + pigtail drain The tract is dilated over the wire in graded steps, staying exactly on the line the needle made, and the pigtail is railroaded into the pelvis over the same wire. Screening shows the pigtail curl before the stiffener is released, because the coil is the only thing holding the drain in place. Every movement is small, deliberate and on the image, and nothing is advanced against resistance. Dilation off the needle axis, or over a wire with no intra-renal purchase, displaces the kidney or tears the parenchyma.
    where it bites: dilating off-axis or over a wire with no intra-renal purchase displaces the kidney or tears the parenchyma.
  5. Secure + check The drain is aspirated to confirm free flow, a final sample is sent, and the drain is secured to skin at its entry site without tension or kinking. Position is confirmed on a film or CT before the patient leaves the table, because a pigtail that looks right at the skin can sit outside the system. Output and its colour are documented, and the ward plan names what the drain is for and who acts on it. The operation was decompression, not stone clearance, and it is finished when the kidney is draining, not when the dressing is on.
Click me next Section 4 of 8 Danger zones Where this operation bites, and why it bites there.
Critical relationship

Danger zones

The spatial relationships the animation is built to make automatic. Before you read each one, ask yourself: at this point in the operation, what is about to go wrong, and what is my first move? The save for each sits in the Complications tab.

  • RiskInfundibular axis - a puncture across the infundibulum, not along it, is the classic segmental artery injury.
  • RiskRetrorenal colon - seen on the pre-procedure CT or scan; if it sits behind the kidney, choose the line with it in mind.
  • RiskSupracostal line - above the 12th rib the pleura is on the path; hydrothorax and haemothorax live here.
Practise it Take me into the scene Opens the animation at a danger moment and asks you to predict the mechanism and your first move before it reveals.
Click me next Section 5 of 8 Complications The save for each one: the first move, the escalation trigger, the op-note line.

Complications and immediate saves

Trigger each of these live in the Animation tab, then read the save: the first move, the escalation trigger, and the line that goes in the op note.

Colonic transfixion

  • the needle or drain passes through a retrorenal colon into the kidney.
The save
  1. Recognise it: faeculent efflux, gas from the needle, or urine draining per rectum; a CT nephrostogram settles the anatomy. first move
  2. Do not rip the drain out blind - if bowel and kidney are bridged, leaving the tube controlled separation is safer.
  3. Withdraw the drain back into bowel under imaging, or reposition a new drain correctly, so the renal and colonic streams separate.
  4. Antibiotics, cultures, nil by mouth and serial observation: most extraperitoneal injuries close with the tract managed.
  5. Peritonism, intraperitoneal injury or deterioration → general surgical review; may need formal repair or diversion. escalation trigger
  6. Op note: needle passes, imaging used, drain positions, cultures, antibiotic plan and follow-up imaging. document

Segmental artery injury / delayed haemorrhage

  • deep parenchymal puncture or an infundibular line opens a segmental artery; bleeding is immediate or delayed by days.
The save
  1. Immediate: leave a larger drain or sheath for tamponade; do not keep re-puncturing a bleeding kidney. first move
  2. Cross-match, monitor haemodynamics and haemoglobin; most acute ooze settles with tamponade.
  3. Heavy persistent bleeding or haemodynamic change → angioembolisation is the treatment, not open surgery.
  4. Delayed haematuria days later suggests pseudoaneurysm or arteriovenous fistula: angiography first, embolisation at the same sitting. escalation trigger
  5. Op note: number and axis of punctures, bleeding observed, imaging and embolisation plan. document

Transpleural puncture (hydrothorax)

  • a supracostal line crosses the pleural reflection; urine or blood enters the chest.
The save
  1. Suspect it with post-procedure chest or shoulder-tip pain, breathlessness or desaturation. first move
  2. Chest film or CT after any supracostal puncture, symptomatic or not.
  3. Small hydrothorax: observe with oxygen and analgesia.
  4. Significant collection, breathlessness or hydro/pneumothorax → intercostal chest drain. escalation trigger
  5. Op note: puncture level relative to the 12th rib, chest imaging done, drain or follow-up plan. document
Click me next Section 6 of 8 Troubleshooting When the case turns: the problem, then the next move.

Intra-operative troubleshooting

When the case turns: the problem, then the next move.

  • ActionNo efflux from a correctly placed-looking needle - re-image; do not advance deeper hoping for urine - the calyx may be septated or the tip intraparenchymal.
  • ActionWire will not coil in the pelvis - rotate and withdraw slightly; a wire wedged in an infundibulum perforates if pushed.
  • ActionKidney pushed away by the needle - stop, withdraw to the capsule and re-advance with a firmer, more perpendicular line.
  • ActionBloody efflux obscuring the system - aspirate gently, leave the needle for tamponade, re-image before any further puncture.
Click me next Section 7 of 8 FRCS viva Say it out loud, then mark yourself against the model answer.

FRCS viva questions

The examiner stems this scene prepares you for. Try to answer out loud first, then reveal, and learn the discriminator, the detail that turns a pass into a strong pass.

QA septic patient with an obstructed kidney: stent or nephrostomy, and why?reveal answer
  • The emergency is decompression of an infected obstructed system, and both routes achieve it.
  • My choice depends on what is available out of hours and on the anatomy.
  • A percutaneous nephrostomy gives reliable, large-bore drainage, a sample for culture directly from the system, and a route for later stone treatment; it needs imaging equipment and a prone patient.
  • A retrograde JJ stent avoids a flank puncture and its bleeding and bowel risk, but the obstructed system may be impossible to cannulate, drainage around the stent is narrower, and it usually needs a general anaesthetic in a septic patient.
  • If I cannot clear the obstruction from below within minutes, or the patient cannot tolerate a prolonged attempt, I stop and go percutaneous.
  • Either way, antibiotics and resuscitation run in parallel; drainage is the definitive sepsis source control.
Strong pass

Say all three

  • Framing both as source control
  • Choosing by what the obstruction and the patient tolerate
  • Not by operator preference
Examiner note
Framing both as source control, and choosing by what the obstruction and the patient tolerate, not by operator preference.
QWhere exactly do the renal vessels run relative to your puncture, and why does the axis matter?reveal answer
  • The segmental and interlobar arteries run along the calyceal infundibula and then dive alongside the papillae as arcuate vessels at the corticomedullary junction.
  • A puncture through a papilla, along the infundibular axis, passes between the segmental branches, which is why the papilla is the avascular plane of entry.
  • A puncture that crosses an infundibulum, or enters the system through the renal pelvis directly, transects those branches and bleeds, sometimes into a pseudoaneurysm that presents days later.
  • The same axis logic is why a posterior calyx is chosen: posterior parenchyma is thicker, the avascular line is longest, and the tract lies behind the hilar vessels.
Strong pass

Say both

  • Naming the papilla as the avascular entry point and the infundibular axis as the bleeding risk
  • Not just "avoid the hilum"
Examiner note
Naming the papilla as the avascular entry point and the infundibular axis as the bleeding risk, not just "avoid the hilum".
QCloudy urine under pressure on aspiration - what is your sequence?reveal answer
  • That is an infected obstructed system and the pressure tells me handling matters.
  • I would aspirate enough to decompress and send the sample for culture, but not aggressively empty the system, because sudden decompression of an infected kidney can drive bacteraemia.
  • I would complete the nephrostomy with the lowest number of exchanges over the wire, avoid forceful flushing, and sample bloods and cultures around the procedure.
  • Antibiotics already running is the ideal; if not, they start immediately.
  • I would watch for post-decompression sepsis - the patient can transiently worsen after source control - with early warning scoring and escalation to critical care if needed.
Strong pass

Say both

  • Controlled rather than complete decompression of the infected system
  • Anticipating post-drainage sepsis
Examiner note
Controlled rather than complete decompression of the infected system, and anticipating post-drainage sepsis.
QYour nephrostomy drain has stopped draining on day 2. What do you do?reveal answer
  • I would not flush it reflexively.
  • First, check the patient: fever, flank pain or rising inflammatory markers say the system is obstructed again or infected.
  • Then check the tube for kinking or dislodgement at the skin, and the collection bag and tubing for obstruction.
  • If the drain is simply blocked or malpositioned, imaging - a nephrostogram or CT - tells me whether the pigtail is still in the pelvis; I would reposition or exchange it over a wire in imaging rather than blind-flush.
  • If the kidney is decompressed - for instance the obstruction has been bypassed or stented - reduced output may be expected, and the imaging confirms that too.
  • The decision is imaging-led, and persistent undrained obstruction goes back to theatre or interventional radiology the same day.
Strong pass

Say all three

  • Patient before tube
  • Imaging before flushing
  • Same-day re-intervention for a blocked infected system
Examiner note
Patient before tube, imaging before flushing, and same-day re-intervention for a blocked infected system.
Click me next Section 8 of 8 Evidence The guidance each of these answers is built on.

Evidence and guidance

EAU Guidelines
Urolithiasis
Decompression of the obstructed infected system: timing, route and stent versus nephrostomy.
Open guideline
EAU Guidelines
Urological infections
Source control and antibiotic strategy around emergency urinary drainage.
Open guideline
EAU Guidelines
Urological trauma
Management of iatrogenic renal injury and pseudoaneurysm after percutaneous procedures.
Open guideline
Two minutes

Close the lap: recall it before you leave.

Say it aloud, then reveal. Reading is not remembering.

  1. 01 The relationship Say the critical spatial relationship out loud, then reveal. reveal
    Memory frame

    The needle line runs skin to posterior calyx with three neighbours to clear

    Why?
    The needle line runs skin to posterior calyx with three neighbours to clear: the pleura above the 12th rib, the colon on the lateral line, and the segmental arteries running along the calyceal infundibula inside the kidney.
  2. 02 The first move Colonic transfixion. Your first move? reveal
    First move

    Recognise it: faeculent efflux, gas from the needle, or urine draining per rectum; a CT nephrostogram settles the anatomy.

  3. 03 The escalation trigger Colonic transfixion. What makes you call for help? reveal
    Escalate when

    Peritonism, intraperitoneal injury or deterioration → general surgical review; may need formal repair or diversion.

  4. 04 The discriminator What turns a pass into a strong pass? reveal
    Strong pass

    Say all three

    • Framing both as source control
    • Choosing by what the obstruction and the patient tolerate
    • Not by operator preference
    Examiner note
    Framing both as source control, and choosing by what the obstruction and the patient tolerate, not by operator preference.
  5. 05 The pitfall Where does this operation bite first? reveal
    Pitfall

    Infundibular axis

    Why?
    a puncture across the infundibulum, not along it, is the classic segmental artery injury.

Revision practice with self-marked answers, not an assessment of clinical competence. Kept in this browser only; it does not sync between devices.