You’ve done your research. You’ve talked to Dr. McJunkin. You’ve decided the SNM trial is the right next step for your overactive bladder, urge incontinence, or non-obstructive urinary retention. Now what?
The SNM trial period — typically lasting 3 to 14 days — is one of the most important phases of the entire treatment journey. It’s your personal proof-of-concept: a chance to experience sacral neuromodulation’s effects before committing to a permanent implant. Understanding exactly what to expect, day by day, means you’ll get better data, feel less anxious, and be prepared to make an informed decision at the end of the trial.
This guide walks you through the entire SNM trial process, from preparation through evaluation — so you know precisely what’s coming.
Before the Trial — What to Prepare
The week before your trial procedure, a little preparation goes a long way:
Medical Preparation
- Voiding diary baseline: Dr. McJunkin’s office will provide a voiding diary. Complete at least 3 days of baseline tracking before your procedure — recording how often you urinate, urgency levels (0-5 scale), any leakage episodes, and fluid intake. This baseline is critical for comparing results during the trial.
- Medications: Inform the team of all medications. Some anticoagulants or blood thinners may need to be paused before the procedure. Do NOT stop any medication without specific instructions.
- Arrange transport: You will not be able to drive after the procedure on Day 1. Plan for someone to bring you home.
- Comfortable clothing: Loose-fitting pants or skirts are ideal post-procedure. Tight waistbands and compression garments should be avoided during the trial period.
Home Preparation
- Set up a comfortable rest area with easy access to the bathroom
- Have your voiding diary and pen accessible at all times — ideally near the toilet
- Download any apps or set reminders to help with consistent diary tracking
- Plan for lighter activity levels for the first 2-3 days
- Stock your bathroom with supplies so you’re not stretching or reaching during the early recovery phase
Day 1-2: The Implant Procedure and Recovery
The Procedure
The SNM trial uses a temporary lead (a thin wire electrode) implanted near the S3 sacral nerve, which governs bladder, bowel, and pelvic floor function. Unlike the permanent implant, the trial uses an external stimulator worn outside the body — clipped to clothing or worn in a small pouch.
The procedure itself:
- Performed under local anesthesia with light sedation (you’re relaxed but not fully under)
- Takes approximately 30 to 45 minutes
- You lie face-down on a fluoroscopy table; Dr. McJunkin uses real-time X-ray guidance to precisely position the lead
- During placement, you may feel tingling, pressure, or a mild pulling sensation in your lower back, pelvis, or leg — this helps confirm correct lead placement
- The lead is secured with medical tape and a small dressing; the external stimulator is attached
- No general anesthesia, no hospital stay
Day 1 Recovery
After the procedure, expect:
- Soreness at the implant site (similar to a mild bruise) — manageable with acetaminophen (Tylenol). Avoid NSAIDs like ibuprofen unless specifically directed.
- The sensation from the stimulator — often described as a mild tingling, buzzing, or pulsing in the lower pelvis or between the legs. This is normal and is the device working.
- Fatigue from the procedure and mild sedation
- Light activity only: walking around the home is fine; no driving, heavy lifting, or bending/twisting
Day 2
The soreness typically peaks on Day 2 and then begins to improve. Most patients find the stimulation sensation becomes less noticeable as the nervous system adapts. Continue your voiding diary — even if you feel like nothing is happening yet, record everything. Begin to notice whether urgency episodes are different in character or frequency than your baseline.
Days 3-7: Tracking Your Results
This is the core data-collection phase of your trial. Your voiding diary is your most important tool during these days.
What to Track in Your Voiding Diary
- Time of each void: Record every bathroom trip, including the time
- Volume voided: If possible, use a measuring cup to record output in milliliters or ounces. This is one of the most objective data points you can provide.
- Urgency level (0-5): 0 = no urgency (routine void), 3 = significant urgency (had to hurry), 5 = couldn’t hold it
- Leakage episodes: Note any leakage — when, how much (drops/small/large), what triggered it
- Nocturia: Record nighttime wake-ups to use the bathroom
- Fluid intake: What you drank and approximately how much
- Activities and notes: Exercised? Felt particularly stressed? Traveled? These contextual notes help interpret patterns
What You Might Notice
Patients vary considerably in how quickly they notice changes. Some report improvement within the first 24-48 hours. Others take 4-5 days to see clear differences. Common early signs the trial is working:
- Longer intervals between bathroom trips
- Urgency that arrives less suddenly and feels more manageable
- Fewer nocturia episodes
- Leakage episodes become less frequent or smaller in volume
- Voiding volumes increase (you’re holding more before voiding)
Stimulator Settings
Your external stimulator will be programmed before you leave the office. You may be given ability to adjust the stimulation amplitude (intensity) within a prescribed range. Guidelines:
- The sensation should be perceptible but comfortable — not painful
- If you feel pain, discomfort, or muscle twitching in your leg, call the office; the lead may need repositioning or the settings adjusted
- The stimulator should run continuously (24/7) during the trial
Week 2: Evaluating Progress
If your trial extends to two weeks (some protocols run 10-14 days for more definitive results), use the second week for honest evaluation and any fine-tuning:
- Compare your voiding diary data against your pre-trial baseline — look at average voids per day, average urgency scores, and leakage frequency
- Report back to Dr. McJunkin’s office with an interim update — many patients have a mid-trial phone check-in
- If results are borderline, a reprogramming session can adjust stimulation parameters to optimize effectiveness
- Note quality-of-life improvements beyond just the numbers: Are you sleeping better? Planning activities differently? Feeling less anxious about bathroom access?
What “Working” Looks Like
The standard clinical benchmark for trial success is a 50% or greater improvement from baseline in your primary symptom measure — whether that’s urgency episodes, leakage events, daily void frequency, or nocturia. However, this threshold is a guideline, not an absolute rule.
If your primary burden was severe urgency incontinence (multiple leaks per day), a 50% reduction means you’re going from perhaps 6 leaks/day to 3. That’s meaningful. If you were also getting up 4 times per night and now wake once, that’s the kind of quality-of-life change that can feel transformative even if the numbers seem modest.
A productive follow-up conversation with Dr. McJunkin will look at:
- Your objective diary data (frequency, volumes, urgency scores)
- Your subjective experience (quality of life, confidence, sleep quality)
- Whether any settings adjustments during the trial could improve results further
- Your overall comfort with the experience and technology
What If It’s Not Working?
Don’t panic if results are unclear or disappointing in the first several days. Several options exist before concluding the trial has failed:
Reprogramming
The external stimulator’s settings can be adjusted — amplitude, pulse width, stimulation frequency, and which electrode configurations are active. Many patients experience significantly better results after a programming adjustment. Contact the office anytime during the trial if symptoms aren’t improving or the stimulation feels uncomfortable.
Lead Repositioning
If reprogramming doesn’t solve the issue, the lead position may need minor adjustment. This is a straightforward in-office procedure that can be done during the trial period.
Extending the Trial
In some cases, extending the trial by a few additional days provides more time for the nervous system to adapt and for clearer results to emerge. This is a conversation to have with Dr. McJunkin based on your specific pattern.
When to Call the Office Immediately
- Pain (not just soreness) at the implant site
- Signs of infection: redness, warmth, swelling, or discharge at the lead site
- Fever
- Electric shock sensations or painful stimulation
- Lead dislodgement (the wire comes loose)
- Inability to urinate
The Permanent Implant Decision
At the end of the trial period, you’ll return to the office to remove the temporary lead and review your diary data with Dr. McJunkin. If the trial showed meaningful improvement, the conversation turns to the permanent implant.
The permanent SNM system uses a small implantable pulse generator (IPG) — about the size of a silver dollar — placed just beneath the skin in the upper buttock area, with a permanent lead positioned at the S3 nerve. The procedure is typically done under light sedation as an outpatient procedure.
The Axonics device used at Bladder Centers of America is rechargeable, MRI-compatible, and engineered to last 15+ years. Unlike older SNM devices that required battery replacement surgery every 3-5 years, the Axonics system dramatically reduces the long-term surgical burden. Most patients manage rechargeable sessions of about 30-60 minutes once per week.
Explore the full SNM and Axonics treatment information on our website, and don’t hesitate to ask questions before your decision. For more on the Axonics device specifically, visit the Axonics therapy page.
Frequently Asked Questions About the SNM Trial
Can I shower or bathe during the SNM trial?
You can shower with precautions — the implant site and external stimulator must be kept dry. Most patients use waterproof dressings (provided by the office) over the lead site and keep the external stimulator outside the shower. Baths, swimming, and hot tubs are not allowed during the trial period, as submerging the equipment or wound in water risks infection and device damage.
Will I be able to go to work or exercise during the trial?
Most patients return to desk work or light activity within 1-2 days of the procedure. Heavy lifting (over 10 pounds), vigorous exercise, bending, and twisting should be avoided for the entire trial period to prevent lead dislodgement. Walking, light stretching, and normal daily activities are generally fine by Day 2-3. Always follow Dr. McJunkin’s specific activity restrictions, which may vary based on your procedure details.
What happens if the trial doesn’t work for me?
If the SNM trial does not produce meaningful improvement (less than 50% reduction in symptoms), the temporary lead is simply removed in the office — a quick, straightforward procedure. You are not committed to a permanent implant. Other treatment options remain available, including Botox bladder injections, medication adjustments, or additional evaluation. A failed trial is not a dead end; it’s information that helps guide the next step in your care.
Ready to Start Your SNM Trial?
The SNM trial is designed to remove uncertainty from a significant treatment decision. You don’t have to wonder if sacral neuromodulation will work for you — you get to find out, firsthand, before committing to the permanent system.
Dr. Tory McJunkin and the team at Bladder Centers of America guide patients through this process every week in our Phoenix and Scottsdale locations. If you’ve been living with overactive bladder, urge incontinence, or urinary retention and conventional treatments haven’t given you adequate relief, the SNM trial may be the most important 2 weeks of your treatment journey.
Take the next step. Schedule a consultation with Dr. McJunkin to discuss whether you’re a candidate for the SNM trial — and get your questions answered by one of the most experienced SNM specialists in the Phoenix metro area.