Fertility, miscarriage and the shape of the womb
Most miscarriages happen because of a chance problem with the developing pregnancy, and many women who have had a miscarriage go on to have a healthy pregnancy without any treatment. When miscarriages recur, or when good-quality embryos repeatedly fail to implant, I look carefully for a cause, including a structural problem of the womb or the fallopian tubes.
Structural problems that can play a part include:
- a uterine septum, a wall of tissue present from birth that divides the cavity of the womb
- polyps and fibroids that bulge into the cavity
- adhesions (scar tissue) inside the womb, as in Asherman’s syndrome
- a caesarean scar niche, where fluid may collect in the cavity; we have published our keyhole technique for repairing one [6]
- a hydrosalpinx, a blocked fallopian tube filled with fluid
- endometriosis, which can affect fertility in several ways
Rarer problems in the shape of the womb are present from birth. One is a small second horn of the womb that does not connect to the cavity (a non-communicating rudimentary horn), which can cause pain and affect fertility; we have published a step-by-step keyhole technique for removing one [4]. An unusual shape does not rule out pregnancy: we have also published a case of twins conceived naturally in a woman with a double womb (uterus didelphys) [5].
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A normal cavity
The cavity is a smooth, triangular space lined by the endometrium.
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A polyp
A soft overgrowth of the lining, attached to the wall of the cavity.
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A uterine septum
A wall of tissue present from birth that divides the cavity.
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Scar tissue (Asherman's syndrome)
Bands of scar tissue join the walls and close off part of the cavity.
Symptoms and situations
- two or more miscarriages (UK guidance defines recurrent miscarriage as three or more first-trimester miscarriages, but supports looking for a cause after two)
- repeated failed embryo transfers despite good-quality embryos (recurrent implantation failure)
- a scan showing an abnormal shape of the cavity, a polyp, a fibroid or a blocked tube
- light periods or spotting that began after surgery or a caesarean
How I assess structural causes
I begin with your history, including previous pregnancies, procedures and fertility treatment, and review any reports from your fertility clinic. At the CRP Clinic and at Parkside Hospital I can perform an ultrasound scan during the consultation, including a three-dimensional view of the cavity, which shows its shape very clearly.
Where the scan suggests a problem, a hysteroscopy (looking inside the womb with a slim telescope) can confirm and often treat it at the same time. When a tubal problem is suspected, I review or arrange a test of the tubes.
At the CRP Clinic I work alongside colleagues who investigate the other causes of recurrent miscarriage, so that your care covers the whole picture.
I was one of the authors of the International Federation of Gynecology and Obstetrics (FIGO) good practice recommendations on the use of progesterone in recurrent miscarriage [1], guidance written for doctors worldwide, and of the practice recommendations for couples with recurrent miscarriage that followed it [2]. With the same colleagues, I published a study of more than 1,000 women, which found that clotting conditions (thrombophilia) were no more common in women with recurrent miscarriage than in women in general, so routine testing for them is not needed [3].
Treatment options
I will explain every reasonable option, including no treatment, and be clear where the evidence is uncertain. The decision weighs the possible benefits of surgery against its risks and the uncertainty in the evidence.
Surgery inside the womb (hysteroscopic)
- Polyps and fibroids bulging into the cavity can be removed through the cervix.
- Adhesions can be divided, with ultrasound guidance when they are dense.
- A septum can be divided through the cervix (hysteroscopic septum resection). The evidence is set out below.
You can read more on the hysteroscopy page.
Removing a septum: what the evidence shows
Reviews pooling the results of many, mostly observational, studies have found fewer miscarriages after a septum is removed, particularly in women who have had recurrent miscarriages [7] [8]. American guidance concludes that removing a septum improves outcomes for women with recurrent miscarriage [9].
The evidence is not all in one direction. A randomised trial of 80 women did not find more live births after a septum was removed [10], and UK guidance (RCOG) suggests that it is ideally done within an audit or research setting. The trial was designed to detect a doubling of the live birth rate, however, so it could have missed a smaller benefit, and it was too small to show whether particular groups, such as women with a larger septum, do better.
How a septum is defined is important too. The European definition labels many more wombs as septate than the American criteria or the stricter criteria agreed more recently by an international specialist group (CUME), so studies do not always describe the same thing [11] [12]. I measure the shape of the womb carefully on a three-dimensional scan, and I will explain what the evidence means for you, so that you can decide.
Surgery on the tubes
A hydrosalpinx is a fallopian tube that is blocked at its far end and swollen with fluid. The fluid can flow back into the womb and is thought to make an embryo less likely to implant. Good-quality evidence shows that removing the tube (salpingectomy) or blocking it before IVF improves the chance of pregnancy. I usually do this by keyhole surgery, taking care to preserve the blood supply to the ovary.
- Normal fallopian tube
- Ovary
- Womb
- Swollen, blocked tube (hydrosalpinx)
- Ovary
Surgery for fibroids and endometriosis
Fibroids within the wall of the womb, and endometriosis, can also affect fertility. Whether surgery helps depends on their size, position and type, and on your fertility plans. You can read more on the fibroids and endometriosis pages.
Working with King’s Fertility and the CRP Clinic
As an honorary consultant at King’s Fertility, I see women referred from the fertility unit and plan surgery around their treatment cycles. At the CRP Clinic (Centre for Reproductive Immunology and Pregnancy) in Epsom, where I run a Friday morning clinic, I look after women whose miscarriages may be linked to a structural problem of the womb.
What surgery involves and recovery
Most hysteroscopic procedures are day cases, and most women return to work within a day or two. Keyhole surgery on the tubes usually means going home the same day or the next morning, with one to two weeks before returning to work. You will receive full written information well before any procedure, and I will explain the risks as they apply to you.
After treatment I will advise you on when it is safe to try to conceive or to have an embryo transfer, and I will share that advice with your fertility team.
