Abnormal Uterine Bleeding in Perimenopause Explained

Understanding Abnormal Uterine Bleeding in Perimenopause

Up to one-third of women will experience abnormal uterine bleeding (AUB) in their lifetime, with perimenopause being one of the most common times for irregularities to appear. This transition phase, marked by hormonal fluctuations before periods stop completely, often brings unpredictable, heavy, or prolonged bleeding. Modern clinical frameworks now provide clearer ways to classify and address these menstrual changes.

Ovulatory Dysfunction Drives Most Irregular Bleeding

During perimenopause, the primary culprit behind irregular periods is a condition classified as AUB-O, or “Abnormal Uterine Bleeding due to Ovulatory Dysfunction.” Research by Jewson, Purohit, and Lumsden explains this mechanism. In a typical cycle, estrogen builds the uterine lining (endometrium), and ovulation triggers progesterone release, which stabilizes and then sheds that lining predictably. As ovarian function declines in perimenopause, ovulation becomes infrequent and irregular. The body may produce estrogen without the balancing effect of progesterone, a state called “unopposed estrogen.” This leads to continuous, unstable endometrial growth without the organized signal to shed. The result can be missed periods followed by episodes of heavy, prolonged, or unpredictable breakthrough bleeding.

Ruling Out Structural Causes with the PALM-COEIN System

While hormonal imbalance is common, it is not the only possible cause. The International Federation of Obstetrics and Gynecology (FIGO) developed the PALM-COEIN system to guide a thorough evaluation. As outlined by Mikes, Vadakekut, and Sparzak, “PALM” covers structural causes: Polyps, Adenomyosis, Leiomyoma (fibroids), and Malignancy/hyperplasia. “COEIN” covers non-structural causes: Coagulopathy, Ovulatory dysfunction (AUB-O), Endometrial disorders, Iatrogenic (medication-induced), and Not otherwise classified. This system ensures clinicians methodically check for issues like fibroids, which are common and can worsen bleeding, or more serious concerns like endometrial hyperplasia, before attributing changes solely to perimenopause.

Progesterone is the Cornerstone of Hormonal Management

For AUB driven by ovulatory dysfunction, treatment aims to reintroduce the stabilizing effect of progesterone. Evidence shows that cyclical progesterone or progestin therapy is a first-line option. It works by opposing estrogen’s growth signal, triggering regular shedding of the endometrium and preventing its over-accumulation. This can regulate cycles, reduce heavy flow, and protect against the endometrial hyperplasia that unopposed estrogen can cause. Options include oral pills, levonorgestrel-releasing intrauterine systems (IUS), or cyclical progestin. The choice depends on individual symptoms, need for contraception, and patient preference, but the principle remains restoring hormonal balance.

Navigating Evaluation and Personalized Treatment Plans

A clinical evaluation for perimenopausal AUB starts with a detailed history tracking cycle parameters against the normal range: frequency of 24 to 38 days, duration of 2 to 7 days, and a volume under 80 mL. Doctors then perform a physical exam and may order blood tests to check for anemia or thyroid issues. Ultrasound is often used to look for “PALM” structural causes. For women over 45, or those with persistent bleeding despite treatment, an endometrial biopsy is frequently recommended to rule out hyperplasia or cancer. Management is then individualized. For acute, heavy bleeding, short-term high-dose hormones may be used. For chronic AUB-O, long-term cycle regulation with progesterone, combined hormonal contraceptives, or a levonorgestrel IUS are evidence-based paths. Non-hormonal options like tranexamic acid can reduce blood loss. Importantly, the stress of managing unpredictable bleeding can affect quality of life, and approaches like cognitive behavioral therapy may help cope with this aspect.

When to Seek Medical Guidance

Understanding that perimenopause brings change is important, but normalization should not prevent medical assessment. Bleeding that soaks through a pad or tampon every hour for several hours, periods lasting more than 7 days, or cycles occurring more frequently than 24 days are clear signs to consult a doctor. Similarly, any bleeding after menopause (12 months without a period) requires prompt investigation. A structured approach using the PALM-COEIN framework ensures that treatable conditions are identified and that appropriate management, often starting with progesterone, can restore control and safety during this transition.

Sources:
https://pubmed.ncbi.nlm.nih.gov/30422508/
https://pubmed.ncbi.nlm.nih.gov/32698992/