When I consult with men before they get a vasectomy, I go through the details of how to prepare for the surgery, what to expect during the procedure and how to recover at home. Of course, it’s the perfect opportunity for patients to express questions and concerns. I often get inquiries about safety, potential pain and recovery time. The answers, in short, are that vasectomies are very safe, well tolerated and you’ll only need a few days to recover.

However, some of us have heard the occasional story about a vasectomy that didn’t take. As a urologist, these stories usually find their way to my pre-procedure consultations, leading to the often-asked question – is a vasectomy absolutely effective? More to the point, is there any chance that I can get my partner pregnant afterwards?

How effective is a vasectomy?

A vasectomy is a very effective and permanent form of birth control. In fact, with a 99.85% effective rate, it’s practically the gold standard.

Between the method we use to cut the vas deferens and the follow-up tests that ensure all sperm has left your semen, a vasectomy is designed to work completely and permanently. So, what about the two in 1,000 men who have a failed vasectomy?

Why do vasectomies fail?

I assure you, like I do all my patients, that failed vasectomies are extremely rare. If a vasectomy fails, it usually happens in the first year following the procedure and often for one of three reasons.

1. Having sex too soon after surgery

When we look at why a vasectomy failed, this is the cause that comes up the most. Fortunately, it’s also the cause that’s the most preventable. While a vasectomy is effective birth control, it isn’t an instant fix – even if we remove a section of highway for sperm to move, there will still be travelers left on the road. If you have sex while you still have sperm in your system, you can still get your partner pregnant after you’ve had a vasectomy.

It takes about three months, or 25 ejaculations, for any remaining sperm to leave your body completely. That’s why having your semen tested for remaining sperm is such an essential part of your post-procedure care. A few months after surgery, you’ll make a scheduled visit to the lab to leave a sample. We’ll analyze it to make sure that your sperm count is zero, confirming that your vasectomy is a success.

Until that time, you’ll still need to operate under normal, pre-vasectomy procedures – continuing to use birth control when you have sex with your partner. After around three months, or 25 ejaculations, you should be ready for a successful test. Once you get the final confirmation of zero sperm from the lab and your urologist, you will know your vasectomy worked.

2. Your snipped tubes reconnect

There is a remote possibility that the cut vas deferens will reattach on their own. When this happens, the cut ends of your tubes find their way back to each other and fuse. Then, small channels form in the scar tissue, allowing sperm to wiggle through.

If that sounds concerning, don’t worry. We take great care to perform the procedure in a way that makes it extremely difficult for reattachment to happen. When I perform a vasectomy, I use a technique that’s triply redundant: along with the actual cut and removal of a segment of the vas deferens from each side, I also cauterize the ends to “seal” them shut and separate the two cut ends with a barrier of healthy tissue. This provides several almost insurmountable obstacles for the ends to reattach and carry sperm again.

However, under extremely extraordinary circumstances, the two ends can still reattach at any point following the procedure. In my 14 years of experience and nearly 1500 vasectomies, I have yet to see this happen with any of my patients. If it does, it usually occurs soon after the procedure. If you have a zero sperm count when your semen is analyzed three months after your vasectomy, you are, for all intents and purposes, in the clear.

3. An error happens during surgery

Vasectomies are very simple and routine outpatient surgeries that are often performed in your doctor’s office with no hospital visit or overnight stay. Doctors like me who specialize in vasectomies pride themselves on performing hundreds, even thousands of procedures over years of experience – a surgical error is extremely rare.

However, an error can occur when the procedure doesn’t go according to plan, for example, if the doctor misses a procedural step or accidently makes the wrong incision. It can also happen when your internal parts aren’t quite “textbook,” meaning that you have an anatomical variation that the doctor doesn’t usually see. Having a previous surgery in or near your groin can also increase the odds of this happening.

Fortunately, your doctor’s surgical experience and the routine nature of the procedure overwhelmingly put the odds for success in your favor. There are many checks and safeguards before, during and after the procedure to make sure that your vasectomy is performed correctly and safely.

A thorough examination before your surgery can identify any potential issues and help your doctor prepare for the procedure appropriately. In addition, your post-vasectomy sperm count can provide definitive proof of the success of the surgery. If there are any sperm that remain in your semen several months beyond your procedure, you and your doctor can discuss possible next steps.

Patience is the key to a successful vasectomy

The best way to make sure that your vasectomy is as successful as possible is to be patient. It’s tempting to think that the procedure itself is the finish line, but you still have a few more months before you know that your vasectomy was 100% successful. Just keep using birth control after your vasectomy until you have a confirmed result of zero sperm from an analysis of your semen. Once that step is complete, you can be assured that the procedure was successful.

Your next steps

If you have additional questions about vasectomies or already know you want one, we recommend that you schedule a consultation with a urologist. A specialist can answer your questions, tell you what to expect and create a plan for your surgery.

You can also learn more about vasectomies and clinics that perform the procedure at HealthPartners and Park Nicollet Urology.