Fibroids may be completely asymptomatic and chance findings at an ultrasound scan carried out for some unrelated condition. About 20-25% women with fibroids have fibroid related symptoms. The two most common symptoms are abnormal uterine bleeding and pelvic pressure.

Prolonged or profuse uterine bleeding (menorrhagia) is seen with all types and sizes of fibroids although it is more common with submucous fibroids. Normal periods typically last for four to five days whereas women with fibroids have periods lasting longer than seven days, sometimes weeks. Bleeding may be heavy requiring frequent change of sanitary protection. Bleeding between periods is not usually associated with fibroids and should always be investigated by a physician.

Pelvic pressure results from an increase in size of the uterus. Most women with leiomyomas have an enlarged uterus; in fact doctors describe the size of a uterus with fibroid as they would a pregnant uterus, for example as a 12 week size fibroid uterus. It is not unusual for a uterus with leiomyomas to reach the size of a four to five month pregnancy. Presssure on adjacent structures in the pelvis including the bowel and bladder can result in difficulty with bowel movement, and constipation or urinary frequency and incontinence. Rarely, fibroids can press on the ureters (tubes which carry urine from the kidney to the bladder) which can lead to kidney dysfunction.

Leiomyomas are also associated with a range of reproductive dysfunction including recurrent miscarriage, infertility, premature labor, fetal malpresentations, and complications of labor. Although few studies exist regarding fibroid-related reproductive dysfunction, the prevailing clinical perspective is that these complications most often occur when fibroids physically distort the uterine cavity. Therefore women with large or symptomatic fibroids may choose to undergo assessment of the uterine cavity (such as by hysteroscopy or hysterosalpingography, see below) before attempting pregnancy. If fibroids are detected on the inside of the uterus and distort the uterine lining, they are a significant cause of reproductive problems and should be removed. It is less clear whether fibroids in the wall of the uterus cause reproductive problems although there is a shift in the opinion now, especially with fibroids more than 4 cm, towards treating these before attempting a pregnancy.