Differential Diagnosis for Irregular Bleeding between Periods in a 35-year-old

Single Most Likely Diagnosis

• Hormonal Imbalance: This is often due to anovulatory cycles, which are common in women of reproductive age, especially around the age of 35 when hormonal fluctuations can occur more frequently. It can lead to irregular bleeding patterns, including bleeding between periods.

Other Likely Diagnoses

• Uterine Fibroids: These are common in women of reproductive age and can cause irregular bleeding, including bleeding between periods, due to their potential to disrupt the normal uterine lining.
• Endometrial Polyps: Similar to fibroids, polyps can cause irregular bleeding by disrupting the normal endometrial lining and its shedding process.
• Intrauterine Device (IUD) Complications: If the patient has an IUD, especially a non-hormonal one, it could be a cause of irregular bleeding between periods.
• Thyroid Dysfunction: Both hyperthyroidism and hypothyroidism can affect menstrual regularity and cause irregular bleeding.

Do Not Miss Diagnoses

• Endometrial Cancer: Although less common, endometrial cancer is a critical diagnosis not to miss. It can present with irregular vaginal bleeding, including bleeding between periods, especially in women over 35.
• Cervical Cancer: Similarly, cervical cancer can cause irregular vaginal bleeding and must be considered, especially if the patient has not had regular cervical screening.
• Pregnancy Complications: Ectopic pregnancy or a miscarriage can present with irregular bleeding and must be ruled out, especially if there's a chance the patient could be pregnant.

Rare Diagnoses

• Adenomyosis: A condition where tissue similar to the lining inside the uterus grows into the muscular walls of the uterus, which can cause heavy or irregular bleeding.
• Bleeding Disorders: Such as von Willebrand disease, which can cause irregular or heavy menstrual bleeding due to clotting issues.
• Ovarian Tumors: Although rare, some ovarian tumors can produce hormones that lead to irregular bleeding patterns.

Each of these diagnoses has a different set of risk factors, symptoms, and diagnostic approaches. A thorough medical history, physical examination, and appropriate diagnostic tests (such as ultrasound, endometrial biopsy, and blood tests) are essential for determining the underlying cause of irregular bleeding between periods in a 35-year-old woman.