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Rectal Spacer Placement in Prostate Cancer: A Procedural Guide

Author Javier Prieto III covers Rectal Spacer Placement in Prostate Cancer: A Procedural Guide on BackTable Urology

Javier Prieto III • Feb 22, 2024 • 142 hits

The radio-protective effects of rectal spacer technology have helped to minimize the damaging side effects of radiation therapy in prostate cancer patients. Accordingly, rectal spacer placement has become quite prevalent in the prostate cancer treatment algorithm. UC San Diego urologic oncologist Dr. Javier-Desloges and University of Pennsylvania radiation oncologist Dr. Neil Taunk joined BackTable Urology to describe the essential features of rectal spacing placement, including a step by step guide to help fellow clinicians succeed with rectal spacer procedures. The doctors also analyze the similarities and dissimilarities between SpaceOAR and Barrigel hydrogel spacers, as well as the required operational equipment and antibiotic protocol options for surgical success.

This article features excerpts from the BackTable Urology Podcast. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.

The BackTable Urology Brief

• Setup and preparation for rectal spacing procedures is less complex than one might believe, considering the flexibility of anesthesia options, the simplicity of patient positioning, and the opportunity for improved needle mobility if floor or rail steppers are utilized for spacer probe purposes.

• Clinical trials have demonstrated the efficacy of both SpaceOAR and Barrigel for rectal spacing. While these two gels possess their strengths and weaknesses, both are trusted by physicians to protect prostate cancer patients from radiotherapy.

• The standard protocol for the majority of surgeries and procedures is the administration of antibiotics to prevent infection and post-op complications, which also applies to rectal spacing. However, the medical community has yet to cement an ubiquitous antibiotic regimen for rectal spacing, resulting in treatment diversity amongst physicians.

Rectal Spacer Placement in Prostate Cancer: A Procedural Guide

Table of Contents

(1) Rectal Spacing Equipment & Orientation Protocol

(2) SpaceOAR vs Barrigel: Advantages & Disadvantages in Rectal Spacing

(3) Antibiotic Regimen & Infection Risk in Rectal Spacing Procedures

Rectal Spacing Equipment & Orientation Protocol

Rectal spacing procedures offer patients and physicians the convenience of incorporating different forms of anesthesia depending on patient history or presenting symptoms. Attending physicians or medical institutions typically determine the primary anesthesia selection since the field of rectal spacing has not universally agreed on a preferred anesthesia route for prostate cancer treatment. General and local anesthesia with an oral anxiolytic are popular, but accommodations can be made for certain clinical cases.

For patient positioning, the lithotomy position is the standard for rectal spacing, allowing easy access to the perineum. After applying a sterile solution to the area, Tegaderm is placed on the scrotum to gently move it aside, ensuring clear access for the insertion of the rectal spacer. If local and regional anesthesia is administered, periapical triangle or lateral blocks with lidocaine are both acceptable options.

In terms of handling the rectal spacer probe, transperineal biopsy equipment can be used for rectal spacing procedures, but floor or rail steppers offer many advantages. While floor or rail steppers are expensive, they allow ultrasounds to be fixed and immobile while allowing the freedom of not requiring the needle to be attached to the ultrasound probe. This separation between probe and needle empowers physicians to maneuver the angle of the needle freely with a steady image and insert the spacer successfully. In contrast, the biopsy protocol mandates that the needle be attached to the probe, which limits needle flexibility.

[Dr. Neil Taunk]:
When I trained, we learned under general anesthesia, which offers some conveniences in terms of patient comfort as well as a lot of time. There's a feeling that you really don't have to rush. As much as you want to get out of the OR as quickly as possible, there's a feeling that you can take your time to do this. Currently in our practice at Penn, we place around 200 spacers per year and it's done entirely by radiation oncologists. We do it entirely in the office under straight local anesthesia and an oral anxiolytic. That's been successful for the vast majority of patients.

How do you say, there are instances where some type of anesthesia is preferred, whether that's sedation or general anesthesia, due to patients with significant discomfort, perhaps significant poor experiences with a prior prostate biopsy, or developmental disabilities. Maybe a handful of patients per quarter, we will book special time in our ASC and perform those procedures there, but otherwise entirely outpatient office based under straight local.

[Dr. Juan Javier-Desloges]:
In terms of patient positioning, dorsal lithotomy, stirrups, maybe tape the scrotum out of the way with some paper tape there or a pep stick. Where are you putting the block usually when you do these patients? What are you using?

[Dr. Neil Taunk]:
Yes. Juan, just like you said, our setup is not particularly creative or inventive dorsal lithotomy legs up. We use a jumbo tegaderm to hold the scrotum out of the way. Then we prep with ChloraPrep sticks. Our block is a pretty traditional periapical triangle block. A superficial skin wheel, and then followed by deeper infiltration of lidocaine into the periprostatic tissue, but virtually entirely near the prostate apex and on either side of it. We have tried lateral blocks as well, and anecdotally those are roughly equal, but since most of us trained with the standard periapical triangle block, that's what we've stuck to.

[Dr. Juan Javier-Desloges]:
Then in terms of holding the probe, are you using a stepper in the clinic? Is it attached to the bed or is it a mobile stepper?

[Dr. Neil Taunk]:
We use a CIVCO floor stepper. We do have two rail steppers as part of our brachytherapy program, but we try to keep those for those procedures. You can use a rail stepper or you can use a floor stepper. The nice thing about the floor stepper is that it just has some less moving parts. It's a little bit less cumbersome when the patient's awake. Maybe that's just something that makes us feel better, but we've liked using the floor stepper for ours.

[Dr. Juan Javier-Desloges]:
Yes. To give the audience a little bit more background, I basically follow the same setup as Neil, not just as common as you can make it. We do use a bed mount for the stepper. We actually use the same rail mount as the machine that we use for the Uronav. When we bought the Uronav, we had planned to do the transmetabolistic biopsies and we bought the stepper with it, which was actually quite small. It's the nice thing about it compared to some of the steppers out there. It can be bulky for the room, but the one that we purchased from Uronav is a little bit smaller and compact and can fit in a small procedural room.

One of the things I want to get your thoughts on is the necessity of needing a stepper for those. It's an expensive purchase. I personally have tried to use some of the biopsy attachment equipment. There's two companies out there, SureFire and PrecisionPoint, and I have not had a lot of success with it. I think that one of the differences between doing a biopsy and doing a spatial replacement is in a biopsy, you want the needle to be fixed in a sense. It should be fixed to the ultrasound and you want that mobility with your hand. In spacing placement, I found that it's more about you want the ultrasound to be fixed. You don't want the ultrasound to move during the procedure and you want your needle to be mobile. When it's attached to the biopsy, when the needle's attached to the probe, you just do not have that same level of flexibility. I don't know if you've experimented with using biopsy attachments over steppers or not.

[Dr. Neil Taunk]:
Juan, I think you've characterized it really expertly. In the way that you've generally framed those two different types of setups I agree with you completely that in spacing, you want a very stable image and then you want essentially complete freedom with your needle.

In a transperineal prostate biopsy, your needle's often following the pathway of the ultrasound, like how a flashlight would be pointing. Wherever your ultrasound's pointing, that's where you're going to go get your prostate needle biopsy. I have experimented with the precision point device from Paraneologic. I think that offers some great advantages for maybe learning users or users that may be experiencing or want to gain some additional proficiencies in the transperineal technique. My challenges are I've been trained and I've learned to really like that stable image that a stepper provides. Having the ability to control the angle of the needle, which you can do much better if you have a stable image and a freehand needle, is a little bit easier than if the needle is say fixed to the probe. We've tried it, and we've stuck with what we know.

[Dr. Juan Javier-Desloges]:
Yes, I completely agree with you. The one thing I would say to anybody that's new to learning how to do which is basically a completely freehand placement of a fiducial marker or a spacer is to keep in mind where the buttons are on the ultrasound because the needle or the needle tip will always come out over the buttons. I'd imagine you'd use fiducial markers also, but when I teach it to the residents, I have them practice with getting the fiducial markers over the buttons, make sure they can visualize their needle. Then as they get more comfortable with that free-handed technique, then we start to get them into doing the spacing, the hydro dissection, and placing another gel.

[Dr. Neil Taunk]:
Yes, absolutely. Orientation is key, and really nailing those basic ultrasound skills. It's fantastic that you teach them to the trainees because they'll have the confidence to do them in practice. It's really critical. If you have confidence in your equipment and your orientation, it'll really help you be set up for success in the future.

[Dr. Juan Javier-Desloges]:
To those that are listening out there that are working with trainees, I have to admit, found it a little bit easier to work with the interns. I think one of the parts of our training, which is switching over a little bit, is we are so used to the visualization on transrectal for visualizing the prostate, and you have to unbreak their mentality of viewing the prostate in a different plane. When you're working actually with an intern, I found the interns are the twos that really haven't done many transrectal biopsies. They actually pick it up pretty quickly because they're seeing the prostate for the first time on an ultrasound, and it's a little bit more easier for them to pick it up as opposed to the graduating chief resident in June of their chief year.

[Dr. Neil Taunk]:
Some excellent characterization. I think one of the reasons that prostate brachytherapists find comfort in doing these transperineal procedures is that's largely how we've been entirely trained from the start. We haven't had to learn say one and then switch to the other. I've tried to learn transrectal procedures to round out that skill, but it's like unlearning transperineal to learn transrectal visualization in different planes.

Listen to the Full Podcast

Perfecting Rectal Spacer Placement for Optimal Care with Dr. Neil Taunk on the BackTable Urology Podcast)
Ep 123 Perfecting Rectal Spacer Placement for Optimal Care with Dr. Neil Taunk
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SpaceOAR vs Barrigel: Advantages & Disadvantages in Rectal Spacing

The two most popular gel products for rectal spacing are Barrigel and SpaceOAR, and clinical trials have shown good patient outcomes for both treatment options. Both gels offer their unique advantages and disadvantages. SpaceOAR is more time-consuming since it requires mixing powder and liquid to create a hydrogel, while Barrigel is pre-packaged and ready for use. Another setback for SpaceOAR is that the gel can only be visualized on CT, not ultrasound, compared to Barrigel, which can be visualized on both. However, the doctors agree that injecting gel with SpaceOAR is more straightforward than Barrigel, which involves more needle repositioning for proper gel application. Considering the differences between gels, SpaceOAR and Barrigel both aim to provide enough separation by injecting gel via needle between the prostate and rectal wall before radiation. When treating prostate cancer, radiotherapy can damage nearby organ structures, like the rectum, if a spacer is not in place.

[Dr. Juan Javier-Desloges]:
There's two gels out there now. As we all know, there have been two trials that have been-- The most recent one published with bare gel and SVRT patients, and then the older trial from Boston Scientific for spacer looking at IMRT patients. They've both shown benefits in terms of rectal toxicity, but the gels they're different. I think it's a little nuanced to anybody that's getting into rectal spacing. I was hoping that we could maybe talk about both and what their differences is and you could maybe add to what I have to say. For Boston Scientific, the SpaceOAR gel, it's visible on CT, it's not visible on ultrasound. Once you place the gel, it blocks out the prostate, so you can't see that well. You do a hydro dissection prior to spacer placement, which I believe is an advantage because I have had a number of patients that just do not have a lot of pararectal fat. We didn't really get into placement of the gel and the needle position at all.

Generally, when you try to put these gels in, you take the needle from an anterior approach, to come down towards the pararectal fat plane. If you've done a prostatectomy, you know that just some patients don't have much pararectal fat. You're right on the rectum sometimes. The same is true when you're doing an ultrasound. I don't really feel that this is a learning curve issue, but rather an anatomy issue. You need that sometimes hydro dissection to spread apart that area and make sure that you are placing the gel in the right area because you can get it into the navigated fascia, you can get it into the prostate, you can get it into the rectal wall. While none of that has happened to me personally, I do feel that leaning on the hydro dissection has prevented that.

The other major difference is, for SpaceOAR, you're a little bit under a time crunch, which is good or bad, depending on how you look at it. You want to get the gel in and you want to get that patient a radiation usually pretty quickly. The way that our protocol here works is we put patients on hormone therapy for six to eight weeks, and then they'll get the SpaceOAR gel. Then usually within a week after that, they'll get their sim and then they'll get their radiation. I think it's controversial whether or not you really necessarily need to give anybody ADT prior to radiation or when you start it. I think from a scheduling perspective because we just have so many patients. I don't think it matters if they get it when they start ADT or when they're six to eight weeks in, but that has been the general protocol that we've followed.

For Barrigel, the major benefit I think is it's visible on ultrasound and it also lasts longer. There have been concerns raised about how long does it actually last. In the trial, there were a number of patients that I think had absorption times beyond nine months or even 12 months, but majority absorbed within nine months. Now we do know that the gel is safe. I think it's pretty popular for lip filler. I think that's where they got most of their safety data. That longer time, if there's a misplacement of the gel, I'm not sure how I would mitigate it, but would like to get your thoughts on the differences between the two.

[Dr. Neil Taunk]:
Juan, you've really nailed the highlights of what they are. Some additional differences regarding the products, they have very different setups. SpaceOAR from Boston Scientific requires a multi-step process where you have to mix a powder vial into a powder gel into a liquid and then they mix that all around to essentially create the hydrogel versus Barrigel, now part of Teleflex, comes pre-packaged in single-use syringes, ready to use. There's no mixing and they're stable. The setup time is different.

There's a little bit of preparation with SpaceOAR versus Barrigel, you can use right out of the box. I did make the point regarding injecting say all of it at once with SpaceOAR could be good and bad. Some of our doctors like when they place it, you place it over 10 to 30 seconds, whatever you choose to do. There's different ways to apply it. It's done. It's over. if you've hydro-dissected, you've created the pocket effectively, which I also agree with you is a really nice safety check to have, to know that you are in fact in the right space, and gives you an out to abort that procedure. If you're not in the right space, you put in the gel, and then the whole thing is done.

Barrigel, you do have to be a lot more thoughtful in terms of where you put the gel and then where you reposition the needle. There's a lot more repositioning required. Our more experienced users tend to be more successful because they're just so much more savvy at moving the needle around where they want it to go. On the whole, I can't really say that one is significantly faster than the other. You borrowed time from one aspect of it and maybe just put it in another aspect of the procedure. Really, our turnover time is the thing that dictates most all of it. The safety data for the NASHA that's used in Barrigel, yes, did mostly come from lip filler products. These products are used all over the body already and get very impressive long-term safety data for this. There is also a similar product that the company has, which is specifically used to bulk the rectum for patients with say, fecal incontinence. Deliberately placing this NASHA product into the rectum. Now, granted, those patients were not treated with radiation, so we can't necessarily infer that it's safe to radiate when that stuff is inside the rectum.

SpaceOAR will take around six months fairly consistently to go. I think reliably we say we have about 12 weeks of stability. There is a bit of time. We place it basically right before we want the radiation to happen. Say during the COVID-19 pandemic, patients who had spacers placed and then our clinic shut down, we kept them on ADT because we weren't treating non-emergent patients with prostate radiation for a while. Some patients we either did another procedure on or they just went ahead and did their treatment even after the gel resorbed. The Barrigel is supposed to resorb I think mostly within six to nine months, but there are data suggesting that you will still have gel at 12 to 18 months afterwards. There is a reversibility aspect of Barrigel that is offered. You would use hyaluronidase to do that, but I think the experience is very limited and there would be a fair amount of counseling to be done to tell a patient, "Hey, it wasn't in the right place, but we need to do another procedure to reverse it and then maybe fix it." I don't really have a good grip on how widely it's done, except I think I've just heard about a single case of it really. That's another potential aspect of it, but you hope you just do it right the first time so you never have to go back.

[Dr. Juan Javier-Desloges]:
Yes. I think this is one of the things that goes back into the pre-op counseling session I tell patients about. In urology, we do a lot of different types of implants. We do penile implants, we do prosthesis of the testicle, AUS, and if those devices get infected or if they're misplaced, we can take them out. You can't really do that with the gel. The gel becomes this amorphous material within the peri-rectal space and it is not whether you're injecting something into it to dissolve it or you're trying to suction it out. It's just not possible. Once it's in there, it's in there. It's not coming out. You just got to wait until it absorbs. Going back all the way to when I was a trainee and we first started doing these, there were some patients that had infiltration of the rectal wall, and the guidance at that time, and I haven't seen it in a while, has been just to wait for about three to four months before offering them radiation. Is that generally what you've done when that does happen?

[Dr. Neil Taunk]:
Yes. The management of patients who have a suboptimal placement is very imperfect and very heterogeneous. In the original trial, I believe 7% of patients on a post-hoc analysis had some degree of rectal wall infiltration using the SpaceOAR Classic. The SpaceOAR Vue and SpaceOAR Classic, neither of them are particularly visible in ultrasound, but the SpaceOAR Vue is what we prefer at Penn. That is available on CT. All these patients had an MRI in the original study because that's what was required. I think 7% had rectal wall infiltration, but there was no high-grade subsequent toxicities that were experienced by these patients. In terms of how we tend to manage it is most of our patients that are treated at our main campus, we have a distributed model. We have around 60 doctors in our radiation oncology practice spread across our various sites. In these patients, the ones that are treated at the main campus, they all get an MRI anyway. We do have that to reference.

Patients with minor infiltrations, which is really just the superficial layers of the rectum, we'll go ahead and we'll continue to treat without issue. Any patients with say any deep infiltration deeper into the submucosa or we've seen some patients from outside that have had gel placements that have even intraluminal gel, we absolutely will not treat. There's some thought to say that if you say, do an anoscopy and check if there's no gel in the lumen, you can proceed forward. It's hard to say if that's correctly the data-driven approach. If there is a sufficient amount of physician worry, I think it's reasonable to wait. Most patients can comfortably wait for prostate cancer treatment, particularly if they're on ADT. Superficial infiltrations, if we see it, we're generally comfortable proceeding forward with it. Again, we take a nuanced look and make sure to look carefully. That's only just a little bit. How do you guys manage these and your practice?

[Dr. Juan Javier-Desloges]:
Again, we don't do 200 a year. We probably do about 70. We just haven't had one. I actually was just taking notes here with my microphone on mute on how you are managing the rectum because I know it's bound to happen. going back to the way that we talked about how the gel is placed. if there's just not a giving periorectal flat pad, even if you follow all the maneuvers, sometimes you get a little bit of superficial infiltration. It's just not something you could avoid.

Antibiotic Regimen & Infection Risk in Rectal Spacing Procedures

Antibiotic regimens are variable amongst physicians performing rectal spacer procedures across the country. Most hospitals and health clinics currently administer antibiotics for rectal spacers, but heterogeneity lies in duration, time frame, and type. Cefpodoxime and ciprofloxacin are two recommendations by certain antibiotic governance committees; however, transperineal and transrectal procedures are not limited to these two antibiotic options. The standard timeframe for oral antibiotics after rectal spacer placement is about one to five days. IV antibiotics such as ceftriaxone also serve as an option while operating.

It is rare for no antibiotics to be given to patients receiving a rectal spacer. The purpose of antibiotics for these clinical cases is more preventive than curative. Physicians acknowledge the proximity of the rectal wall when inserting the spacer, and there is a slight risk of violating the wall. The probability of violating the rectal wall is very low, but physicians consider administering antibiotics as beneficial in case the rectal wall is ever breached.

[Dr. Juan Javier-Desloges]:
For infection, are you giving antibiotics now or are you giving a day or three days? Originally, I think it was five days. We have tailored our antibiotic program. Originally, I was doing the three days of Cipro and then I didn't really see a benefit to it so I cut it down to one day. I know a number of centers are not doing anything, but I've always been afraid to do that. Sometimes I'll do some periop Cipro. I don't know what you're normally doing.

[Dr. Neil Taunk]:
I think there's a lot of heterogeneity in this practice, particularly as the excitement around transperineal prostate biopsy continues to roll up and really compelling data about antibiotic-free prostate biopsy, which I think is tremendously exciting. I think it's phenomenal for patients and physicians.

For spacing, since there still technically really is the possibility of violating that rectal wall, even though it should rarely if ever happen, we've chosen to give antibiotics. We worked with our local antibiotic governance committee at our hospital to come up with guidelines and our patients will get three days of cefpodoxime, which is concordant with most of our other transperineal or transrectal urologic procedures.

Again, there is some heterogeneity. Some physicians will just do a single day of pre-procedural cefpodoxime. There are some clinics that particularly if the patient's asleep, will offer IV ceftriaxone as part of the procedure. The last one will do a rectal swab and then offer tailored antibiotics. I would say most clinics are offering antibiotics. It's rare to actually probably have an encountered one that's not doing it for these spacing procedures. We've taken maybe just a quite uniform approach, ceftepidoxime, but that's concordant with our local antibiotic resistance guidelines.

Podcast Contributors

Dr. Neil Taunk discusses Perfecting Rectal Spacer Placement for Optimal Care on the BackTable 123 Podcast

Dr. Neil Taunk

Dr. Neil Taunk is an assistant professor of radioation oncology and radiology at University of Pennsylvania School of Medicine in Philadelphia.

Dr. Juan Javier-Desloges discusses Perfecting Rectal Spacer Placement for Optimal Care on the BackTable 123 Podcast

Dr. Juan Javier-Desloges

Dr. Juan Javier-DesLoges is a urologic oncologist at UC San Diego in California.

Cite This Podcast

BackTable, LLC (Producer). (2023, September 29). Ep. 123 – Perfecting Rectal Spacer Placement for Optimal Care [Audio podcast]. Retrieved from

Disclaimer: The Materials available on are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.



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