A caesarean scar niche in plain language
After a caesarean birth, the incision in the lower part of the womb heals with a scar. Sometimes the scar heals with a small pouch or indentation on its inner side, where the muscle is thinner. This is called a niche, an isthmocele or a caesarean scar defect. All three names describe the same thing.
- Lining of the womb (endometrium)
- Pouch in the caesarean scar (niche)
- Thinner muscle over the niche
- Bladder
- Wall of the womb (muscle)
- Cervix (neck of the womb)
- Vagina
Niches are common. Many women who have had a caesarean have a small niche visible on a scan, and most have no symptoms from it. In some women, menstrual blood or fluid collects in the niche and drains slowly, which can cause the symptoms described below.
Symptoms
A niche can cause:
- brown spotting or prolonged light bleeding for several days after a period has finished
- pelvic pain, or pain during a period that is worse than before the caesarean
- pain during sex
- difficulty conceiving, which may be linked to fluid collecting in the niche and the cavity of the womb
These symptoms have other possible causes too, which is why a careful assessment matters before any treatment.
How I assess a niche
I start with your history: your periods before and since the caesarean, the number of caesareans you have had, your symptoms and whether you are planning another pregnancy. At Parkside Hospital and the CRP Clinic I can perform a transvaginal ultrasound scan during the consultation, so we can usually discuss the findings at the same visit.
The scan shows the size and shape of the niche and, importantly, the thickness of the muscle that remains over it (the residual myometrium), which guides the choice of treatment. Sometimes I introduce a little sterile saline into the womb during the scan to outline the niche more clearly, and sometimes a hysteroscopy (looking inside the womb with a slim telescope) adds useful information.
Treatment options
I counsel women about niches in a deliberately balanced way, because the evidence about who benefits from treatment is still developing. I will describe what the niche is doing, set out every reasonable option including no treatment, and advise you whether repair is likely to help you.
- No treatment. If the niche causes few symptoms, or none, leaving it alone is often the right choice.
- Hormonal treatment. For women who are not planning a pregnancy, treatment that makes periods lighter, such as the contraceptive pill or a hormonal coil, can reduce spotting.
- Hysteroscopic repair (niche resection). Carried out through the cervix, this trims the edges of the niche to improve drainage and reduce spotting. It does not rebuild or thicken the wall, so it is suitable when there is enough muscle over the niche, and it is usually a day case.
- Keyhole repair (laparoscopic or robotic). This removes the thinned scar from outside the womb and rebuilds the wall in layers. It is usually preferred when the remaining muscle is thin, or when you are planning another pregnancy and a thicker wall is the aim.
What the evidence shows
A randomised trial found that hysteroscopic repair shortened post-period spotting for some women, although the average benefit was modest. Studies of keyhole repair report that the wall of the womb is thicker afterwards and that symptoms improve for many women, but these studies are smaller and did not compare repair with no treatment. Whether repair improves the chance of pregnancy is not yet known. I will go through what this means for you, so that you can make the decision that is right for you.
What surgery involves and recovery
Hysteroscopic repair is carried out as a day case, usually under general anaesthetic or sedation, and takes around twenty to thirty minutes. Mild cramping and light bleeding for a few days are normal, and most women return to work within a few days.
Keyhole repair is carried out under general anaesthetic through several small incisions. I free the bladder from the front of the womb, remove the thinned scar, often guided by a hysteroscope to locate the niche precisely, and close the wall of the womb in layers. Most women stay one night in hospital and return to desk-based work after two to three weeks. If you are planning a pregnancy, I will advise you how long to wait after the repair, usually several months.
The risks include bleeding, infection, injury to the bladder or nearby organs, the niche forming again, and, for keyhole repair, the small possibility of converting to an open operation. I will explain how these apply to you, and you will receive full written information well before any operation.
Planning a pregnancy
If you are planning another pregnancy, I will explain what is known about niches and pregnancy, including the uncommon situation of a pregnancy implanting in the caesarean scar, and recommend an early scan to confirm where the pregnancy has implanted. You can read more about my work in this area on the fertility and miscarriage surgery page.
