Abnormal Uterine Bleeding

Abnormal uterine bleeding encompasses any deviation from normal menstrual frequency, regularity, duration, or volume.

The FIGO PALM-COEIN classification structures the differential into structural causes (Polyp, Adenomyosis, Leiomyoma/fibroids, Malignancy and hyperplasia) and non-structural causes (Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not otherwise classified), and this same framework underlies the Menorrhagia entry covered earlier in this atlas, with this entry addressing the broader pattern of abnormality (irregular timing, intermenstrual bleeding, postcoital bleeding) rather than heavy flow specifically.

Presentation varies by underlying pattern: intermenstrual bleeding (between otherwise normal periods, raising concern for a structural or cervical cause), irregular cycles (suggesting anovulation, common with PCOS or perimenopause), postcoital bleeding (raising specific concern for cervical pathology, including cervicitis or, less commonly, cervical malignancy), and postmenopausal bleeding (any bleeding after 12 months of amenorrhea in a menopausal woman, which is a red flag requiring urgent investigation to exclude endometrial malignancy until proven otherwise).

• Pregnancy test in any woman of reproductive age presenting with abnormal bleeding, essential first step
• FBC (anemia assessment), coagulation screen if history suggests a bleeding disorder, TSH
• Pelvic ultrasound (transvaginal preferred) for structural assessment: fibroids, polyps, adenomyosis, and endometrial thickness
• Postmenopausal bleeding: urgent referral pathway with endometrial thickness above 4 to 5 mm on transvaginal ultrasound as the threshold prompting endometrial biopsy (thresholds vary slightly by guideline); endometrial biopsy (pipelle or hysteroscopic) is the definitive test
• Endometrial biopsy in premenopausal women is indicated for persistent intermenstrual bleeding, age 45 or above with abnormal bleeding, or younger women with risk factors for endometrial hyperplasia (obesity, PCOS, tamoxifen use, or unopposed estrogen exposure)
• Hysteroscopy for direct visualization and targeted biopsy where focal pathology (polyp) is suspected
• Cervical cytology/HPV testing per routine screening schedule if due, and cervical examination for any visible lesion, particularly with postcoital bleeding

Directed by the underlying cause once identified:

• Anovulatory bleeding: combined oral contraceptive, cyclical progestogen, or the levonorgestrel-releasing IUD to regulate cycles
• Structural causes (polyp, fibroid, adenomyosis): managed per the Endometriosis and Uterine Fibroids entries, and hysteroscopic polypectomy for endometrial polyps
• Endometrial hyperplasia without atypia: progestogen therapy (oral or LNG-IUS) with surveillance biopsy; atypical hyperplasia or confirmed malignancy is managed per gynae-oncology pathways, generally with hysterectomy
• Intermenstrual bleeding with a normal workup: often managed with hormonal regulation (COCP or progestogen) alongside reassurance, with reassessment if bleeding pattern changes further
• Iron replacement for associated anemia (see Iron Deficiency Anaemia entry)

Referral: urgent (typically 2 week wait pathway) gynecology referral for any postmenopausal bleeding; gynecology for persistent abnormal bleeding despite initial management, or where hysteroscopy/biopsy is indicated.