What this is
A refresher on the stab-technique SPC. We do these occasionally, not often enough to be on autopilot, often enough to know what good prep looks like. These are working notes on what’s happening on the table, what the team is asking for, and what to keep an eye on afterwards.
Why This Procedure Works at All
The bladder sits right behind the pubic bone, very close to the surface. When it fills up, it rises out of the pelvis like a balloon being inflated underneath the abdominal wall. Picture pushing a beach ball up against the inside of a tarp, the tarp stretches, everything that was sitting on top of it slides off to the sides, and you’ve got a clear line straight down to the ball.
That’s the trick the whole procedure runs on. A full, distended bladder pushes the loops of bowel up and out of the way, creating a clear corridor through skin, fat, and muscle straight into the bladder dome. A small stab in that corridor reaches the bladder without touching anything else.
The whole logic, in one line
Fill the bladder until it lifts the bowel out of the way, then go straight down through the cleared corridor.
That single fact is what every step exists to protect. The ultrasound at the start, the careful angling, the “is it still full?” check before the stab, all of it is in service of making sure the corridor is actually clear before anything sharp goes in.
The patients sent for this fall into a handful of camps. Men whose prostate is so enlarged that a urethral catheter won’t pass. Trauma cases where the urethra has been injured. People with strictures (scarred narrowings) of the urethra. Patients with neurogenic bladders (where the nerves controlling bladder emptying don’t work) who need long-term drainage. Some post-surgical urinary diversions. And the long-term comfort case. For someone who’ll be catheterised for years, an SPC is gentler than a urethral catheter and carries a lower risk of urethral injury and stricture over time.
The Anatomy
The screen during the case is essentially a sagittal ultrasound view through the lower abdomen. You’ll see the pubic bone as a curved bright line with shadow behind it, the bladder as a black (fluid-filled) oval sitting on top of it, and the abdominal wall as the layered tissue between the skin and the bladder.
A textbook safe puncture site looks like this:
Skin ← the stab here
Subcutaneous fat
Rectus sheath (front)
Rectus muscles
Rectus sheath (back) — thinner below the arcuate line
Transversalis fascia
Extraperitoneal fat ← peritoneum should be pushed up and out of the way
Bladder dome ← target
The target is the midline, two to four finger-breadths above the pubic bone, angled slightly downwards toward the pelvis.
The bladder must be palpable or visible on ultrasound before anyone goes near it with a trocar
If you can’t feel a tight, full bladder above the pubic bone and you can’t see it on the screen pushing the bowel out of the way, the procedure stops. A blind stab into a poorly distended bladder is how people end up with a hole in their sigmoid colon. BAUS guidelines and the older NPSA alert both hinge on this single rule.
A few anatomical traps worth knowing. Previous lower abdominal surgery can stick loops of bowel down to the bladder dome with adhesions, so they don’t slide out of the way even when the bladder fills. Pregnancy lifts everything. Obesity makes the working distance longer and the bladder harder to feel. Bladder cancer is a soft contraindication because of a theoretical risk of seeding tumour cells along the catheter track. All of these are reasons the doctor may convert to an open approach in theatre with a urology team instead.
The Two Ways In
Two techniques, both percutaneous. The difference is what goes through the abdominal wall.
The stab (trocar) technique is the fast one. The whole kit (a sharp metal trocar inside a peelable plastic sheath, with the catheter already loaded) goes into the bladder as a single unit, in one push. Skin nick, one firm controlled advance, you’re in.
The Seldinger technique is the careful one. A fine needle goes in first, then a guidewire is threaded through it into the bladder, then the needle comes out and progressively larger dilators are passed over the wire to make a track, then finally a peel-away sheath and catheter go down the wire. More steps, more time, more controlled.
The honest comparison: in a recent IR comparative series, trocar took about 12 minutes against 26 for Seldinger, with less sedation and a fifth of the radiation dose. When the bladder is well distended and easily palpable, the trocar approach is faster and just as safe. Seldinger comes into its own when the bladder is small or partly emptied, or when the doctor wants the extra control, like a patient who’s been catheterised for years and the bladder won’t hold much volume.
Stab vs Seldinger in one line
Stab is the right tool when the bladder is big and easy. Seldinger is the right tool when it isn’t.
How the Case Unfolds
The patient comes in supine, often with a urethral catheter already in place that the team will use to fill the bladder before they start (sterile saline up the urethral catheter, drainage clamped). Sometimes the bladder is filled simply by the patient drinking water and waiting. If the patient is in retention with no catheter, the bladder is usually already enormous and no extra filling is needed.
The doctor scans the lower abdomen with ultrasound, finds the bladder, measures how thick the abdominal wall is, picks a midline puncture site, and looks carefully for any bowel between skin and bladder. If they’re happy, the area is prepped and draped, and the site is numbed with local anaesthetic (lignocaine 1%, sometimes with a small amount of adrenaline). The local goes all the way down to the rectus sheath in a fine track, which the trocar will follow.
A finder needle, a long thin needle attached to a syringe, goes in next. The doctor advances it under ultrasound and pulls back on the plunger as they go. The moment urine flashes back into the syringe, they know two things: the bladder is exactly that deep, and they’re definitely in the bladder and not somewhere else. The angle and depth of that needle become the template for the trocar.
Then the moment that really decides how safe the procedure will be: the stab itself. A small skin incision is made with a scalpel, usually 5 to 10 mm, just enough for the sheath to slide through. The trocar-and-sheath assembly, with the catheter already loaded, is held like a dart and advanced through the abdominal wall in one firm controlled push, following the angle the finder needle showed. A sudden give signals entry into the bladder.
This step matters more than any other
The trocar must stop the instant it enters the bladder. Going too far drives the sharp tip into the back wall of the bladder, sometimes through it, sometimes into bowel sitting behind. A controlled advance with the non-dominant hand braced against the abdomen is what stops that overshoot.
Urine should drain immediately. The sharp trocar is then withdrawn while the sheath is held in place, the catheter is fed deeper into the bladder, and the peelable sheath is split and peeled away around it. The catheter balloon is inflated with about 10 mL of sterile water, and the catheter is gently pulled back until the balloon sits snug against the inside of the bladder wall.
Sometimes a quick cystogram finishes the case. A small volume of Omnipaque (iohexol, the practice’s standard iodinated contrast) diluted with saline is injected down the catheter and a fluoroscopic image is taken. The bladder should fill cleanly with no contrast extravasation (leakage outside the bladder), which confirms the catheter is sitting in the bladder and the bladder isn’t perforated. Not every operator does this. If the ultrasound was clean and drainage looks good, the cystogram is often skipped. Worth having Omnipaque drawn up just in case it’s called for. Then the catheter is connected to a drainage bag, the entry site is dressed, and the catheter is anchored to the skin with a suture or a securement device.
The kits you’ll see named are BD Bonanno (a small-calibre 14G FEP catheter on a Bonanno-type trocar, the original and still common one), Cook One-Step Suprapubic Introducer (a peel-away sheath system, 14 to 24 Fr, with the catheter pre-loaded), and Mediplus S-Cath (Seldinger-based, less of a stab kit). The catheter that gets left in is usually a 14 to 16 Fr silicone or hydrogel-coated Foley.
What’s Worth Anticipating
A few things tend to come up in the room that are worth knowing before they’re asked for.
The bladder filling step is the one that goes wrong most often. If the patient comes in with an indwelling urethral catheter and a drainage bag, the bag gets clamped and the bladder filled either by drinking time or by retrograde instillation of sterile saline up the urethral catheter. Some operators ask for around 300 to 500 mL. If the patient is in retention with no catheter and a tender, palpable bladder, that step’s already done. The thing to confirm before draping is that the ultrasound still shows a clearly distended bladder, bladders can deflate during prep, especially with anxiety and movement.
Local anaesthetic is almost always lignocaine 1%, sometimes plain, sometimes with adrenaline if the operator wants longer-lasting infiltration and less bleeding from the skin nick. A 10 or 20 mL syringe with a green needle for the deep tissue track, a smaller orange needle for the skin wheal.
Sedation varies. Most of these are done with light conscious sedation (midazolam, sometimes a small amount of fentanyl). The IR series above used about 1 mg of midazolam for the trocar approach on average. Generous local makes a real difference. Worth flagging if the patient looks like they’d struggle to tolerate this awake. That’s a conversation for before the patient is on the table, not during.
The kit on the trolley is mostly what you’d expect for any percutaneous case: sterile drapes, gown and gloves, prep solution (chlorhexidine in alcohol), local anaesthetic and syringes, a scalpel for the skin nick, the SPC kit itself, sterile water for the balloon (10 mL syringe pre-drawn), a leg bag or drainage bag, suture or securement device, and a transparent dressing. The contrast for a possible cystogram (Omnipaque diluted maybe 50:50 with saline) is worth having drawn up but doesn’t always get used.
The catheter going in is sterile but the patient’s urine isn’t. Anyone with a long-term catheter is colonised, so the first dribble of urine out of the trocar is bacterial. Standard splash-protection, and a kidney dish ready to catch the initial flow. Antibiotic prophylaxis (often a single dose of gentamicin) is usually given before the procedure starts, not after.
One small detail that gets missed
Make sure the patient has actually gone to the toilet not to empty, they’re meant to be coming in full. It sounds obvious but the booking instructions don’t always make it through to the patient clearly. If they arrive empty, the case is delayed until the bladder fills again.
Why We See These Occasionally
Most suprapubic catheters in the country are put in by urology, either at the bedside or in theatre. The ones that come to us tend to be the awkward cases: patients with previous abdominal surgery and adhesions, scarred or thickened bladders that won’t distend easily, larger-bore drainage needs, or anyone where the bedside team wanted real-time ultrasound and fluoroscopy in the same room rather than ultrasound alone.
What makes image guidance worth the trip is in the numbers. Historically, blind insertions had a bowel injury rate of around 2.5%, with mortality close to 2% when bowel was hit. Once ultrasound (and on-demand fluoroscopy) became the norm, the bowel injury rate dropped to somewhere between 0 and 0.2%. Image guidance is the entire reason this procedure has a place in IR at all.
The flipside is that because we don’t do many of these, the team is sometimes a bit cold when one is booked. That’s the actual reason for keeping notes like this. The procedure is straightforward when it’s set up well, but the setup details (a properly distended bladder, the right kit on the trolley, knowing when the cystogram might be asked for) are the bits that fade between cases.
What Follows the Procedure
The most common thing in the first day isn’t really a complication, it’s transient haematuria. The bladder doesn’t enjoy being punctured and a small amount of blood in the urine for the first 24 to 48 hours is expected. Bladder spasms are also common early on, especially as the balloon presses against the trigone (the sensitive triangle at the base of the bladder).
The thing the team is genuinely watching for is bowel injury. It can be obvious (faeculent material in the catheter, peritonitis with severe abdominal pain and rigidity, or sepsis), or it can be subtle, declaring itself a few days later as fever, ileus (the bowel going quiet), or unexplained deterioration. Any of those signs after an SPC needs to be taken seriously and worked up with a CT.
The other late complication is dislodgement before the tract has matured
The track from skin to bladder takes about four to six weeks to form a proper epithelialised channel. If the catheter falls out or is pulled out in that window, the track collapses and reinsertion through the same hole becomes much harder, sometimes impossible without a fresh percutaneous procedure. The first scheduled catheter change is almost always done by the inserting team (urology or IR), not by community nursing.
Other things that come up. Urinary tract infection is common with any indwelling catheter, managed when it becomes symptomatic, not just on the basis of dipstick changes. The skin site can get inflamed, and granulation tissue (a small fleshy lump of healing tissue) often forms around the catheter entry, usually managed with simple care, occasionally with silver nitrate. Catheter blockage from debris or encrustation is the routine reason these get changed earlier than scheduled.
For long-term SPC patients, the catheter is changed every six to twelve weeks, depending on the catheter material and the patient’s tendency to encrust.
What's worth getting onto the discharge sheet
The catheter brand and size, the balloon volume, the date inserted, when the first change is due (usually six weeks, by the inserting team), and a clear instruction that the catheter is not to be removed accidentally before the tract has matured. Add a contact number for the IR team if it does come out. The patient and their community nurse won’t always know to escalate fast. That one line on the discharge sheet matters.
Numbers Worth Knowing
| Stat | Value | Why it matters |
|---|---|---|
| Bowel injury rate, blind technique (historical) | ~2.5% | The reason image guidance is now standard |
| Bowel injury rate with image guidance | 0–0.2% | The reason this procedure has shifted into IR |
| Mortality when bowel is injured | ~1.8% | Why the bladder-must-be-full rule is non-negotiable |
| Technical success, primary insertion | ~99.6% | When the rules are followed, it almost always works |
| Trocar vs Seldinger procedure time | ~12 min vs ~26 min | Why trocar is preferred when conditions allow |
| Trocar vs Seldinger radiation dose | ~20 mGy vs ~100 mGy | Trocar uses far less fluoroscopy |
| Typical depth from skin to bladder dome | 3–6 cm (more in obese patients) | What sets the trocar advance distance |
| Tract maturation time | 4–6 weeks | Catheter must not be lost before this |
| Routine catheter change interval | 6–12 weeks | After the tract is mature |
How the Approach Gets Chosen
No single answer
The choice between stab and Seldinger depends on how full the bladder is, how thick the abdominal wall is, what catheter size is needed, and whether there’s previous surgery or scarring to work around.
A rough sketch of the decision space: if the bladder is clearly distended, the wall is normal thickness, there’s no surgical history, and a standard 14 to 16 Fr catheter is enough, the trocar approach is faster and lower-dose. If the bladder is small or partly emptied, the wall is scarred, a larger-bore catheter is needed, or the doctor wants the safety of a guidewire, Seldinger takes over. If the bladder can’t be confirmed full and clear of bowel even with ultrasound, neither percutaneous approach goes ahead — the patient gets referred to urology for an open insertion in theatre.
Related
- Fiducial Insertion into Deep Organs — another stab-based percutaneous procedure where bladder distension and ultrasound clearance of bowel both matter
- CT-Guided Spinal Injections — similar principle of finding a safe corridor through anatomy under image guidance
- Septic Shower — what can happen when an infected urinary tract is instrumented, relevant to prepping SPC patients with chronic UTIs
Sources
- Imaging-Guided Suprapubic Bladder Tube Insertion: 549 Patients — AJR
- IR Image-Guided Suprapubic Cystostomy: Trocar vs Seldinger Comparative Analysis — ScienceDirect
- Suprapubic Catheter Insertion Using an Ultrasound-Guided Technique — BJU International
- BAUS Suprapubic Catheter Practice Guidelines — Revised (2020)
- National UK Audit of SPC Insertion Practice and Bowel Injury Rate — Wiley
- Suprapubic Bladder Catheterization — StatPearls (NIH)
- Safety of Ultrasound-Guided Percutaneous SPC Insertion in SCI Patients — PMC
- Imaging-Guided Percutaneous Large-Bore Suprapubic Cystostomy — American Journal of IR
- Cook Medical One-Step Suprapubic Introducer — product overview
- S-Cath System for Suprapubic Catheterisation — NICE
Last updated May 18, 2026.