What is the most common type of uterine polyp, specifically among women of reproductive age, particularly those over 40, presenting with symptoms such as abnormal uterine bleeding or infertility?

Most Common Type of Uterine Fibroid (Leiomyoma)

Intramural fibroids are the most common type of uterine leiomyoma, occurring in approximately 52% of cases among women with fibroids undergoing assisted reproductive technology, compared to 37% with subserosal and 10% with submucosal fibroids. 1

Epidemiology and Classification

• Uterine fibroids (leiomyomata) are the most common tumors found in women, occurring in 20-50% of women over age 30 years, with prevalence increasing with age. 1

• The three main anatomic types are classified by their relationship to the uterine wall:

  • Intramural (IM): Located within the myometrial wall without cavity distortion 1
  • Subserosal (SS): Projecting outward from the uterine serosa 1
  • Submucosal (SM): Protruding into the endometrial cavity 1

• The FIGO classification system provides standardized nomenclature for leiomyomas based on their relationship to the endometrium and serosa, which is critical for determining optimal therapeutic approach. 2

Clinical Significance by Location

Intramural Fibroids (Most Common)

• Intramural fibroids significantly impair fertility outcomes, with pregnancy rates of only 16.4% per transfer compared to 30.1% in women without fibroids, even when there is no visible cavity distortion. 1

• Implantation rates are markedly reduced at 6.4% with intramural fibroids versus 15.7% in women without fibroids. 1

Submucosal Fibroids (Least Common but Most Symptomatic)

• Submucosal fibroids, though least common at approximately 10% prevalence, are most strongly associated with abnormal uterine bleeding, spontaneous abortion, preterm delivery, and infertility. 1

• Pregnancy rates with submucosal fibroids are only 10% per transfer with implantation rates of 4.3%. 1

Subserosal Fibroids

• Subserosal fibroids do not significantly impact pregnancy or implantation rates (34.1% pregnancy rate, 15.1% implantation rate), which are comparable to women without fibroids. 1

Important Clinical Pitfalls

• Most fibroids are asymptomatic, with symptomatology depending on size, position, and number present. 1

• Pedunculated or broad ligament fibroids can be mistaken for solid ovarian or adnexal masses on imaging; careful identification of normal ovaries and blood supply from uterine vessels helps avoid this error. 1

• The presence of fibroids on ultrasound does not exclude concurrent endometrial pathology, including cancer or endometrial stromal neoplasms—tissue diagnosis remains mandatory when indicated. 3, 4

• Preoperative GnRH-agonist treatment may soften small intramural leiomyomata, making them impossible to palpate during myomectomy, leading to incomplete removal and apparent "rapid recurrence." 1

Treatment Implications

• Surgical or medical treatment should be considered in infertile patients with intramural and/or submucosal fibroids before assisted reproductive technology. 1

• Myomectomy recurrence rates approach one-third of patients, depending on the number of tumors present and length of follow-up. 1

• Leiomyomas are prevalent in approximately 20-30% of women over 30 years of age, making them the most common uterine neoplasm. 1