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BackTable / OBGYN / Article
Identifying Isthmocele: Symptoms, Causes & Diagnostic Methods
Faith Taylor • Updated Oct 31, 2024 • 38 hits
Isthmocele is an anatomical defect at the site of a previous C-section that causes abnormal bleeding, pain, and even infertility. Because C-sections are so frequent, isthmocele affects a significant number of women, making accurate diagnosis and management essential in restoring postpartum women to full reproductive health. Despite its prevalence, isthmocele remains under-recognized in routine OB/GYN care.
Expert gynecologic surgeon Dr. Chuck Miller explains how to identify isthmocele after C-section, covering symptoms, risk factors, and imaging techniques. This article features excerpts from the BackTable OBGYN Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable OBGYN Brief
• Isthmocele is a common defect found at C-section scars, with a prevalence increasing from 30% after the first C-section to nearly 100% after the third.
• Isthmocele was first identified in 1995, with laparoscopic repairs starting in the early 2000s.
• The primary symptom of isthmocele is abnormal bleeding, particularly where bleeding continues after menstruation, with additional symptoms including fluid buildup, pain, and infertility.
• Isthmocele is diagnosed using imaging techniques like transvaginal ultrasound, saline-infused sonogram (SIS), MRI, and hysteroscopy.
• Fluid retention in the endometrial cavity and inflammation at the C-section site disrupt implantation, contributing to infertility.
• Factors like retroverted uterus, prolonged labor, diabetes, and C-section repair techniques can increase the risk of developing isthmocele.
• While there is speculation that two-layer closures may reduce risk, there is no conclusive data, and further research is needed on techniques to prevent isthmocele.
Table of Contents
(1) Isthmocele Definition & Diagnosis
(2) Isthmocele Symptoms: Bleeding, Fluid Retention & Infertility
(3) Isthmocele Causes: Does C-Section Technique Play a Role?
Isthmocele Definition & Diagnosis
Isthmocele is a common but historically under-recognized condition. First discussed in 1995 as a defect or niche at the site of a previous C-section, it affects approximately 30% of women after their first C-section, with the incidence rate increasing with each subsequent C-section. Despite its prevalence, it was not widely identified until abnormal bleeding and fluid retention in the endometrial lining was associated with C-section scars.
The diagnosis of isthmocele relies on imaging techniques such as transvaginal ultrasound, saline-infused sonogram (SIS), hysterosalpingogram, MRI, and hysteroscopy. Dr. Miller prefers SIS when working up an isthmocele, as it effectively accentuates and enlarges the defect.
[Dr. Mark Hoffman]
Talk to us about isthmocele, like how this became a thing in your practice, like what it is, how it happens, how we diagnose it and like a little background just on what isthmocele is.
[Dr. Chuck Miller]
It's an interesting entity because the first time it was talked about was 1995. That's an amazing thing when you think that this is such a very common problem. If you look on ultrasound and you look at where the C-section was performed, roughly 30 percent of women will have a niche, a defect in their C-section after their first, upwards to 60% and nearly 100% after their third. Yet, it was never really identified.
Interestingly enough, Mark and Amy, years ago I did a hysterectomy on a lady for abnormal bleeding. I couldn't figure out where the bleeding was coming from. We finally did the hyst, and pathology came back and said there's a defect in the lower uterine segment. I still wasn't smart enough to correlate that it was from her C-section scar. Well, I know that Cam Nezhat in the early 2000s did a laparoscopic repair of isthmocele. Started doing more reading, started doing more, having more concern with patients in my own practice having fluid in their endometrial lining and couldn't do transfer.
Found out that others were having the same problem and looked back and said, "Oh my gosh, this is the C-section scar. This is the niche. This is the isthmocele." Lo and behold, with treatment, we have had very-- we've had excellent success. Of the patients that I have done and looked back on since I started doing the procedure in 2014, we have a 70 percent delivery rate. That obviously is quite high. It is a procedure that you can correct and have great success with the correction.
[Dr. Mark Hoffman]
Talk to us about how we diagnose it and then also about signs and symptoms, because I think we-- I read ultrasounds as part of my practice, we see it all the time. How do we differentiate isthmocele as a cause of symptom and how do we differentiate isthmocele as a cause of infertility?
[Dr. Chuck Miller]
I think that's a good one, because that always comes back at me, especially infertility part. From a standpoint of diagnosis, one can either use a transvaginal ultrasound, I have a tendency to look at the saline-infused sonogram. Understand that an SIS will enlarge the defect, the isthmocele. You can look at hysterosalpingogram, you can look at MRI, and finally you diagnose it hysteroscopically.
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Isthmocele Symptoms: Bleeding, Fluid Retention & Infertility
The primary symptoms of isthmocele include abnormal bleeding, fluid accumulation, and infertility. Abnormal bleeding is a common manifestation, and it often presents as continuous, heavy bleeding after menstruation due to blood trapped in the niche at the C-section scar. Patients may also present with fluid retention in the endometrial cavity, which can disrupt implantation and contribute to infertility. In some cases, a thin myometrium is observed above the isthmocele defect, raising concerns for future pregnancies. While pain has been reported, it is less frequent and can often be attributed to scarring at the C-section site.
[Dr. Chuck Miller]
…Ultimately, the symptoms that I probably care about the most is the fluid, the inflammation at that C-section defect at the isthmocele backs up into the endometrial cavity and disrupts implantation. Perhaps the most common symptom that isthmocele causes is abnormal bleeding. If that patient, Mark, says to you, "I'm bleeding, and then after my period, I still continue to bleed," and has a history of C-section, think about isthmocele.
Because if you think about it, that blood is trapped in the niche. Then after a woman is done with her menses, that trapped blood comes out as a discharge. Not only that, some women will present with heavy menstrual flow and then there's times when someone will present with pain related to the niche. I'm not sure, some of that may also be due to oftentimes we see a lot of scarring at the C-section site with these patients. Bleeding, fluid, infertility, and also pain, probably most important symptoms.
[Dr. Mark Hoffman]
You're seeing C-section scars on ultrasound, but then you're seeing fluid in the cavity as well. Is that really your red flag that this is what's going on?
[Dr. Chuck Miller]
My red flag is going to be a couple things. Generally, number one is fluid. Most of the patients that I do perform surgery on have fluid in their cavities. The second most common reason that I do this is looking at this and their myometrium above the defect is so thin that one is concerned about the possibility of how they'll fare with pregnancy. Now these are patients that have only a couple millimeters of myometrium.
Now, obviously, Mark, Amy, there's not great data to say that, but I think it's only clinical-- you just have to think through this, that that area becomes so very thin as the uterus grows. That's another reason where I will offer isthmocele repair, although most of the patients are presenting with infertility usually due to fluid.
[Dr. Amy Park]
Wait, so I just want to ask as somebody who doesn't really see this at all, the main symptoms and signs-- we reviewed the signs, so the symptoms are bleeding and pain, right?
[Dr. Chuck Miller]
Yes, less so pain.
[Dr. Amy Park]
Oh, more bleeding?
[Dr. Chuck Miller]
Really bleeding is the most very common symptom and then the concern about fertility. I would say pain is probably the third issue. Not all that pain is related to the inflammation of the isthmocele. It can be due to scar tissue at the C-section site. I would tell you the two main would be bleeding, bleeding, bleeding, and then fertility.
Isthmocele Causes: Does C-Section Technique Play a Role?
Several factors may contribute to the development of an isthmocele after C-section. Prolonged labor, particularly during second-stage arrest, increases the likelihood of developing isthmocele. A retroverted uterus also increases isthmocele risk due to the heavier corpus of the gravid uterus applying additional tension to the C-section scar. A patient with diabetes also may experience a heightened risk of an isthmocele due to impaired wound healing [1].
Whether or not specific C-section techniques cause isthmocele or help to prevent it is an area of ongoing inquiry. Dr. Miller suggests that a two-layer uterine closure may reduce the risk of isthmocele formation compared to a single-layer closure, yet no definitive studies confirm this. Furthermore, the potential influence of different suture materials on inflammation highlights another area for future investigation in isthmocele prevention.
[Dr. Amy Park]
Can I just ask, and I don't know if there's data on this, but I guess I'm dating myself, but that whole thing when I was a resident, single layer versus double-layer uterine closure, now it's so different. Everybody's just ripping through and not doing a bladder flap. Do any of these techniques make a difference?
[Dr. Chuck Miller]
That's a very good question, Amy. We believe that two-layer closure will minimize the risk, not take it away, obviously, but would lessen the risk. There's no study, no study that really has been able to compare. It would be a great study for us to all do across the United States and really invest the time to do one-layer and two-layer repairs and then look and see this. Other things that have been mentioned are retroverted uteruses. If you think about it, the heavier corpus of the gravid uterus is splitting that C-section site in the retroverted uterus. Prolonged labor, especially when you're in a prolonged second stage labor or you've really thinned out that area, can be a factor.
Togas Tulandi did a nice study where he looked at factors, came up with women with diabetes are at greater risk of C-section defects, C-section niches. Makes sense, they may have healing issues. Those also interplay as well. Obviously, with my patients, I always ask, "Tell me about your C-section." Most people in infertility said, "Okay, you have a C-section, check. Next question." No, I want to know, was there arrest? Were they dilated to 10? Were they pushing for three hours? These are all setups for isthmoceles.
[Dr. Amy Park]
How about use of suture? I trained with Vicryl, are people using PDS now? I have no idea. Is that less inflammatory? I have no idea.
[Dr. Chuck Miller]
Yes. I don't know.
[Dr. Amy Park]
The barbed suture or something, like how people do myomectomy.
[Dr. Chuck Miller]
Hey, the last baby I delivered was my daughter in 1984 with the obstetrician yelling at me. I looked at him, I said, "Artie, I trained at Parkland. I've delivered 10,000 kids. Back off." [laughs] I wouldn't know.
[Dr. Amy Park]
Yes, yes. No, I was just wondering, because it's like, once the problem's here, it would be great if we could just prevent it, right?
[Dr. Chuck Miller]
Oh, it would be the best.
[Dr. Amy Park]
It sounds like we don't know. Yes, we don't know the-- If you're talking about secondary infertility, obviously, it's somebody who's had a C-section before.
[Dr. Chuck Miller]
Right.
Podcast Contributors
Dr. Chuck Miller
Dr. Charles (Chuck) Miller is the president and founder of the Advanced IVF Institute and the Advanced Gynecologic Surgery Institute in Naperville, Illinois.
Dr. Amy Park
Dr. Amy Park is the Section Head of Female Pelvic Medicine & Reconstructive Surgery at the Cleveland Clinic, and a co-host of the BackTable OBGYN Podcast.
Dr. Mark Hoffman
Dr. Mark Hoffman is a minimally invasive gynecologic surgeon at the University of Kentucky.
Cite This Podcast
BackTable, LLC (Producer). (2024, April 2). Ep. 50 – Decoding Isthmocele: Causes and Considerations [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com 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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