Fibroids are uterine smooth muscle tumours each developed from a single muscle cell.
It is estimated that more than 30% of women would have one or more fibroids after the age of 30 but are not common in younger age groups. Accordingly increasing age up to the menopause is considered as one of the risk factors for increased prevalence of fibroids together with family history, racial origin, obesity as well as nulliparity.
There is a 3-fold increased risk of developing fibroids with similar first degree family history. Furthermore fibroids
are more common, multiple and larger in Afro-Caribbean women compared to other ethnic groups. As well body habitat is considered to be a predisposing factor. Women who weigh > 70 kg are 3 times more likely to develop fibroids than women <50 kg heavy.
An association between nulliparity, infertility and fibroids has been known or suspected for many years. Nulliparous women are more likely to have fibroids than parous women. In fact there is a inverse relationship between the number of pregnancies and fibroids. A nulliparous women is 4 times more at risk of developing fibroids than a woman who had 5 children. As well there is a double risk of fibroids in infertile woman but a causal relationship is still vague and needs stronger evidence.
Fibroids could be found totally or partly within the uterine cavity [submucous], within the muscle wall [intramural] or just underneath the serosal outer covering of the uterus [subserosal]
In many if not most cases fibroids give no symptoms and are chance findings during pelvic or ultrasound scan examinations. However when present symptoms usually depend on the number, size and location of the fibroids.
It has been reported that 30% of women with uterine fibroids have menstrual abnormalities. Both intracavitary and intramural fibroids could increase the endometrial surface area. However vascular defects and impaired endometrial haemostasis could also be contributing factors. Heavier menstrual blood loss >200 ml is more associated with fibroids [40%] than blood loss in the region of 80-100 ml [10%] as shown in one study. This is reflected by the fact that anaemia is more common in women with heavy menstrual loss associated with fibroids than menorrhagia due to other factors.
Pressure symptoms on neighbouring structures especially the urinary bladder leading to increased urinary frequency and urgency.
Dysmenorrhoea or pelvic pain due to degeneration and torsion of a fibroid or possibly an associated adenomyosis could be a presentation. On the other hand red degeneration of fibroids during pregnancy could cause pain of different intensities mainly during the second trimester in up to 10% of the cases. However despite contradictory teaching prospective studies showed that in 80% of the cases fibroids showed reduction or no change in size during pregnancy.
Repeated miscarriages and infertility have been attributed mainly to submucous fibroids. There are no randomised controlled studies to examine the effect of myomectomy on infertility. However few case series showed that removal of fibroids was followed by pregnancies in 30-80% of the cases.
Abdominal mass or just increase in abdominal girth might be the only presenting symptoms.
Pelvic ultrasound scan examination is the most commonly used technique for diagnosing fibroids. They are often seen as hypoechoic masses with well defined margins and ring-like vascularisation on colour Doppler mapping.
Fibroids may be identified according to their location as:
These are located either totally or partially within the uterine cavity and cause most of the bleeding and miscarriage problems encountered in the gynaecology clinic. Different investigators reported the presence of submucous fibroids in 6-34% of patients with abnormal uterine bleeding, 2-7% of women investigated for infertility and 1.5% of asymptomatic women undergoing hysteroscopic sterilisation.
They are graded into 3 subgroups
This is a practical classification as both grade 0 and 1 could be removed hysteroscopically without difficulty in most cases. As for grade 2 difficulties could be encountered as most of the fibroid is not within the cavity.
The thickness of myometrial mantle between the fibroid and the overlying serosa should be considered as the controlling factor in offering or denying hysteroscopic resection for safety reasons.
The above 3D ultrasound images show grade 0, 1 and 2 fibroids, respectively. All 100%, >50% and <50% of the fibroids fall within the the uterine cavities respectively.
The first picture above is a rendered view of a uterus with a submucous fibroid with an overlying polyp. The neighbouring hysteroscopic picture confirmed the diagnosis as shown by ultrasound.
These are fibroids located just underneath the outer serosa. They could grow to very large size and retain connection to the uterus with only a narrow stalk. Usually they cause no menstrual or infertility problems but might cause pressure symptoms related to neighbouring organs. Broad ligament fibroids may fall into this group. This later group may be especially significant during assisted reproduction treatment, making it difficult to access the ipsilateral ovary during transvaginal oocytes collection.
The above 4 images respecively show:
- Transverse ultrasound image showing anterior subserous fibroid pushing into the bladder and causing increased frequency and urgency of micturition.
Longitudinal plane of the uterus showing a posterior subserous fibroid near the lower part of the body of the uterus. Larger fibroids in the same position may push on the rectum causing defaecation difficulty.
The third ultrasound image shows a pedunculated fibroid attached to the uterus by a thick vascular stalk
These are fibroids located totally or maximally within the muscle wall itself and form the majority of diagnosed fibroids. They could be small or large, single or multiple. They are often associated with adenomyosis. It is reported that fibroids, adenomyosis and polyps could be found together and the presence of one would increase the chance to 80% of finding one of the other two.
Fibroids have different ultrasound echogenicity depending on their content of muscular or fibrous tissue, degeneration or calcification.
The first ultrasound image shows two small fibroids with different echogenicity. One of them has some calcification which is causing distant shadowing. The other one is almost iso echoic to the neighbouring myometrium with curtain-like foldings
- The second image shows a fibroid with two degenerated areas with hypoechoic pattern relative to the rest of the tumour.
- The third image shows almost complete degeneration of a posterior wall fibroid. The patient had no related symptoms
In recent years research showed that intramural fibroids larger than 5 cm in diameter and those close to the cervix and fallopian tubes could affect fertility without involvement of the uterine cavity. As well some recent work showed a negative effect of these fibroids on IVF success rate as well, without any distortion of the cavity. However subserous fibroids have no such negative impact on the fertility potential. Accordingly more patient are advised to have their submucous and intramural fibroids removed before undergoing IVF or ICSI treatment.
The first image above shows a large fibroid not reaching the cavity as revealed by saline infusion hysterography. This patient had 3 unsuccessful IVF attempts, and conceived after laparoscopic myomectomy. The most plausible explanation is that, such large fibroids syphon blood away from the endometrial cavity, as shown by a previous study from Japan.
The second 2D image above shows a uterus with a posterior wall fibroid and another one occupying the uterine cavity anteriorly. Note the difference in the echogenicity between the two fibroids.
- The third image shows an intramural fibroid showing curtain folds appearance, marked by arrows, and distant shadowing; both are common characteristics of large fibroids. With such large fibroids, other parts of the image and distant organs may not be easily visible, because of ultrasound absorption and attenuation. In such cases 3D rendering may be useful.
| ||Sometimes 3D rendering can be very useful when large or multiple fibroids are seen. It can be used for mapping the uterus for the exact position of the fibroids in relation to the endometrial line, as seen in the neighbouring image.|
This is a separate entity and could be found without the involvement of the uterine body. Anterior cervical fibroids stretch the bladder and can cause urinary symptoms where as a large posterior one may press on the rectum.
Alternatively they may lead to cervical distortion with extreme displacement of the cervical canal which may interfere with sperm deposition and migration. They can also interfere with cervical dilatation and child birth.
The neighbouring image shows anterior and posterior cervical fibroids clamping the cervical canal. The patient needed caesarean section to deliver her baby.
Other important points
- Women with asymptomatic fibroids should not be denied low dose oral contraceptives for family planning as there is no evidence that they cause benign fibroids to grow.
- Infertile women with fibroids affecting the uterine cavity should be offered myomectomy where no other factors are identifiable.
- Fibroids usually regress by 50% after the menopause. Accordingly rapidly growing or symptomatic fibroids in this age group should raise the suspicion of sarcomatous changes.
- HRT may cause fibroids to grow especially during the first 2 years of their use, but usually cause no related symptoms. This is more so for transdermal oestrogen HRT than oral medication with oestrogens and progestogens or livial. Accordingly, patients with excessive bleeding or pain should be investigated as if they are not on HRT to exclude more sinister causes.
Doppler scanning and fibroids