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Abnormal uterine bleeding

Abnormal uterine bleeding (AUB) describes bleeding from the uterus that differs from the expected pattern in amount, timing, frequency or duration. It is a symptom pattern with many possible causes rather than a single diagnosis.

At a glance

Quick facts

Condition snapshot
Category
Menstrual / uterine bleeding disorder
Patterns
Heavy · irregular · intermenstrual
Key first step
Exclude pregnancy when relevant
Common test
CBC + targeted evaluation
Imaging
Pelvic ultrasound when indicated
Emergency pattern
Heavy bleeding with instability

Names & terminology

How this entity may be named or searched

Canonical name
Abnormal uterine bleeding (AUB).
Heavy menstrual bleeding
A specific pattern of excessive menstrual bleeding; not identical to all AUB.
Intermenstrual bleeding
Bleeding or spotting between expected periods.
Postmenopausal bleeding
Any uterine bleeding after menopause requires evaluation.

Structured entity profile

Clinical profile

Condition data
DefinitionBleeding outside an expected patternAmount, timing, frequency and duration can all be abnormal.
CourseAcute or chronicA sudden severe episode differs from a recurrent pattern over months.
ConsequencesIron-deficiency anemiaOngoing blood loss can cause fatigue, breathlessness and reduced function.
CausesStructural and non-structuralFibroids, polyps, adenomyosis, ovulatory dysfunction, medication and bleeding disorders are examples.
PregnancyMust be considered when possibleEctopic pregnancy and miscarriage can present with bleeding.
Cancer riskContext-dependentPostmenopausal bleeding and selected risk profiles need endometrial evaluation.

Overview

AUB includes bleeding that is unusually heavy, lasts longer than expected, occurs between periods, follows sex, happens at irregular intervals or occurs after menopause. ACOG notes that acute AUB can occasionally be severe enough to require immediate treatment and stabilization. [1]

The purpose of evaluation is to identify the pattern, assess the effect of blood loss and find the underlying cause. Structural uterine conditions, ovulatory or hormonal problems, bleeding disorders, medications, infection, pregnancy-related conditions and cancer can all be relevant. [1] [2]

Symptoms and warning signs

The visible symptom is bleeding, but the clinically important pattern includes how much blood is lost, how long it lasts, when it occurs and whether there are signs of anemia or instability. Soaking pads or tampons very rapidly, dizziness, shortness of breath or chest symptoms can signal significant blood loss. [1]

SYMPTOM MATRIX

Bleeding pattern and systemic impact guide urgency

The same amount of bleeding can have different significance depending on pregnancy possibility, age and symptoms of blood loss.

Menstrual health
Common AUB patterns
  • Heavy menstrual bleeding
  • Bleeding longer than 7 days
  • Bleeding between periods
  • Irregular cycle timing
  • Bleeding after sex
Effects / associated clues
  • Fatigue or reduced exercise tolerance
  • Pelvic pain or pressure
  • Easy bruising or nosebleeds
  • Thyroid or ovulation symptoms
  • Medication-related bleeding
Urgent warning signs
  • Soaking a pad or tampon every hour for several hours
  • Dizziness, fainting or marked weakness
  • Shortness of breath or chest pain
  • Heavy bleeding with possible pregnancy

Severe acute bleeding with symptoms of blood loss needs urgent medical assessment.

Diagnosis

Assessment starts with the bleeding history, pregnancy possibility, medications, contraception, medical conditions and family history of bleeding disorders. A physical and pelvic examination may be needed. A complete blood count helps identify anemia, and pregnancy testing is appropriate when pregnancy is possible. [1]

Further testing depends on age and presentation. It can include pelvic ultrasound, STI testing, thyroid or coagulation studies, hysteroscopy or endometrial biopsy. The goal is not to order every test for every patient, but to target the most likely and most important causes. [1] [2]

Diagnostic pathway

Stabilize first if bleeding is severe, then identify the cause

AUB is a presentation; the final diagnosis may be structural, hormonal, hematologic, medication-related or pregnancy-related.

Cause-directed work-up
1Assess severityCheck for hemodynamic symptoms, pregnancy possibility and acute blood loss.
2Characterize the patternDocument timing, duration, flow, pain, medications and cycle history.
3Basic testingUse CBC and pregnancy testing when relevant; add targeted laboratory tests based on history.
4Target the uterine causeUse ultrasound, hysteroscopy or endometrial sampling when indicated by age, risk or symptoms.
Common blood testCBCanemia / blood loss
When relevantPregnancy testexclude pregnancy-related bleeding

Postmenopausal bleeding and severe acute bleeding require a lower threshold for prompt evaluation.

Common causes of abnormal uterine bleeding

Common causes include ovulatory dysfunction, fibroids, polyps, adenomyosis, bleeding disorders, hormonal contraception, anticoagulant medicines, thyroid disorders, pregnancy-related conditions and infection. Endometrial cancer is less common but must be considered in the appropriate age and risk context. More than one cause can coexist. [1]

Treatment and management

Treatment depends on whether bleeding is acute or chronic, the cause, severity of anemia, contraceptive needs and reproductive goals. Hormonal therapies and nonhormonal medicines such as tranexamic acid can reduce bleeding in selected patients. Iron replacement may be needed when iron deficiency is present. [1] [2]

Procedures or surgery may be appropriate for structural causes or persistent bleeding that does not respond to medication. Options can include hysteroscopic treatment, myomectomy, endometrial ablation in selected patients or hysterectomy. The underlying diagnosis and future pregnancy goals determine which options are appropriate. [1] [2]

Treatment & care hub

Control bleeding while treating the underlying cause

Acute stabilization, long-term symptom control and cause-specific treatment are separate decisions.

Cause-directed care
Acute careIf severe

Stabilize significant bleeding

Urgent treatment may include fluids, medicines and occasionally transfusion or procedural control.

MedicationCommon

Reduce ongoing bleeding

Hormonal options and tranexamic acid are among treatments used for selected causes and patient goals.

Treat deficiencyWhen present

Correct iron deficiency

Iron replacement and follow-up of anemia are important when chronic blood loss has depleted iron.

ProceduresSelected

Treat structural causes

Polyps, fibroids or persistent endometrial bleeding may require targeted procedures or surgery.

Assess severity→Identify pattern→Find cause→Match treatment

AUB treatment should not be chosen without considering pregnancy possibility, age and the cause of bleeding.

Tracking bleeding over time

A calendar or cycle-tracking record can help document frequency, duration, spotting and heavy-flow days. It is also useful to track symptoms of anemia and response to treatment. Persistent new changes should be reassessed rather than assumed to be a normal variation. [1]

Clinical context

AUB is common, but prevalence depends on the definition

Studies use different thresholds for heavy, irregular or prolonged bleeding, so a single global prevalence number can obscure important differences.

ACOG abnormal uterine bleeding FAQ ↗
Clinical patternCommon presentationmultiple causes across the reproductive life course
Normal cycle reference21–35 days
Typical period durationup to 7 days
Interpretation: The purpose of these reference ranges is to recognize a changed bleeding pattern, not to label every variation as disease.

Common questions

Frequently asked questions

Reference content

Sources

  1. ACOG — Abnormal Uterine Bleeding FAQ, reviewed August 2025
  2. NICE — Heavy menstrual bleeding: assessment and management (NG88)

This article is based on trusted medical sources and is awaiting clinician review. It is not a substitute for personalized medical advice.