Understanding Irregular Periods vs Abnormal Bleeding

Menstrual bleeding can vary from person to person. Occasional changes in cycle length or flow are often normal. But sometimes bleeding patterns signal an underlying issue. Below, you’ll find clear, straightforward guidance to help you distinguish between irregular periods and abnormal bleeding, when to consider further evaluation, and how to take the next steps.

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What Is a Normal Menstrual Cycle?

• Cycle length: 24–38 days from the first day of one period to the first day of the next
• Bleeding duration: 4–8 days
• Flow volume: 5–80 mL (about 1–6 tablespoons)
• Consistent pattern: variation in cycle length of ≤7–9 days across 12 months

If your cycle and flow generally stay within these ranges, you likely have a normal pattern.

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Defining Irregular Periods

“Irregular periods” usually means your cycle length, timing or flow changes beyond typical limits—but without extreme heaviness or worrying symptoms. Key features:

• Cycle-to-cycle variation over months repeatedly exceeds 7–9 days
• Occasional missed or extra periods
• Flow still within about 5–80 mL per cycle
• No heavy bleeding (soaking a pad/tampon every hour for 2+ hours)
• No significant large blood clots (bigger than a quarter)
• No bleeding between periods or after sex

Common causes of irregular periods include:

• Stress, weight changes, intense exercise
• Hormonal fluctuations (thyroid issues, polycystic ovary syndrome)
• Breastfeeding, perimenopause
• Medications (some birth control, antidepressants)

In most cases, tracking your cycles for a few months will reveal patterns. If you’re concerned about unpredictable periods, consider a free, online symptom check for to gather more personalized guidance.

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Recognizing Abnormal Uterine Bleeding

According to the International Federation of Gynecology and Obstetrics (FIGO), abnormal uterine bleeding (AUB) covers bleeding that differs in frequency, regularity, duration or volume from normal menstruation. FIGO’s PALM-COEIN classification (Munro et al., 2011) organizes causes:

Structural (PALM)
 • Polyps
 • Adenomyosis
 • Leiomyoma (fibroids)
 • Malignancy & hyperplasia

Non-structural (COEIN)
 • Coagulopathy (bleeding disorders, liver disease)
 • Ovulatory dysfunction (anovulation, perimenopause)
 • Endometrial (local endometrial disorders)
 • Iatrogenic (medications, devices)
 • Not yet classified

Signs of abnormal bleeding include:

• Heavy menstrual bleeding (menorrhagia):
 – Soaking through one or more pads/tampons every hour for 2+ hours
 – Needing to change protection overnight
 – Large blood clots (>2.5 cm)
• Bleeding between periods (metrorrhagia)
• Prolonged bleeding: lasting >8 days
• Postcoital or postmenopausal bleeding
• Symptoms of anemia: fatigue, dizziness, shortness of breath
• Bleeding with pain or significant cramping

If you have any of these features, it’s important to seek medical evaluation. Even if symptoms seem mild, they can affect quality of life and hint at conditions like fibroids, endometrial hyperplasia or systemic issues such as thyroid disease or von Willebrand’s disease.

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Special Considerations: Bleeding Disorders & Liver Disease

Bleeding that is unusually heavy or difficult to control may relate to an underlying coagulopathy. References (Kamath et al., 2001; Garcia-Tsao et al., 2017) emphasize that people with end-stage liver disease or portal hypertension are at higher risk for severe bleeding, including gastrointestinal bleeding. While menstrual bleeding patterns differ, an impaired ability to clot can make periods much heavier and longer.

If you have a known bleeding disorder, cirrhosis, or symptoms like easy bruising, petechiae (tiny red spots), or gastrointestinal bleeding (dark or tarry stools, vomiting blood), speak to a doctor right away.

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Tracking & When to Seek Help

1. Track your cycles for at least three months:

   • Start each entry with Day 1, the first day of bleeding.
   • Note flow volume, number of pads/tampons used, presence of clots, and any spotting.

2. Watch for red-flag symptoms:

   • Passing clots larger than a quarter
   • Changing protection every hour for 2+ consecutive hours
   • Bleeding lasting more than 8 days
   • Sudden heavy bleeding after normally light periods
   • New bleeding after menopause
   • Severe pain, dizziness, palpitations, fainting

3. Consider a free, online symptom check for to clarify your main concerns and prepare for a medical appointment.

4. Speak to a doctor if you notice any worrying signs or if your irregular periods interfere with daily life, regardless of whether you think it’s “serious.” Early evaluation can stop potential problems before they worsen.

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Diagnosis & Treatment Options

Diagnosis often involves:

• Medical history & physical exam
• Blood tests (hormones, thyroid, complete blood count, clotting factors)
• Transvaginal ultrasound or MRI (to detect fibroids, polyps, adenomyosis)
• Endometrial biopsy (for suspected hyperplasia or cancer)
• Hysteroscopy (direct visual assessment of the uterine cavity)

Treatment depends on the cause:

• Lifestyle changes: stress reduction, healthy weight, moderate exercise
• Hormonal therapy: birth-control pills, progestin IUDs
• Non-hormonal medications: tranexamic acid, NSAIDs
• Surgical options: polypectomy, fibroid removal, endometrial ablation, hysterectomy
• Treat underlying conditions: thyroid disease, clotting disorders, liver disease

Your doctor will tailor the approach based on your age, fertility desires, symptom severity and test results.

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Bottom Line

• Irregular periods involve unpredictable timing or flow but stay within safe volume and duration limits.
• Abnormal bleeding includes heavy, prolonged or unexpected bleeding, often signaling structural, hormonal or systemic causes.
• Use the FIGO PALM-COEIN system to understand potential causes.
• Track your cycles, note red-flag symptoms and consider an online symptom check for initial guidance.
• Speak to a doctor about any bleeding pattern that worries you or is accompanied by pain, anemia or systemic symptoms. Early evaluation ensures timely, effective treatment.