# Abnormal Uterine Bleeding

Evaluate abnormal uterine bleeding by first excluding pregnancy and nonuterine bleeding, then stratifying endometrial cancer risk, identifying PALM-COEIN causes, and selecting imaging, sampling, medical therapy, or uterine intervention according to bleeding pattern and reproductive goals.

**Clinical question:** How should clinicians evaluate and manage abnormal uterine bleeding in reproductive-aged and perimenopausal patients?

Updated: 2026-08-21T02:39:42.585510+00:00

## What matters in practice
- Use PALM-COEIN to organize the differential into structural causes requiring imaging or histopathology and nonstructural causes that often receive medical management. [8][11][14][17]
- Do not label bleeding as AUB-O or AUB-E until structural disease, coagulopathy, iatrogenic causes, and relevant endocrine disorders have been considered or excluded. [9][16][17]
- For postmenopausal bleeding, transvaginal ultrasound showing an endometrial thickness of 4 mm or less identifies a very low malignancy-risk group; persistent bleeding after a negative biopsy still warrants further evaluation. [2][22]
- Use saline infusion sonohysterography when a focal intracavitary lesion is suspected or the endometrial echo is not adequately characterized on transvaginal ultrasound; it improves detection of polyps and submucosal fibroids. [18][21][24]
- For idiopathic heavy menstrual bleeding, oral tranexamic acid 3.9 to 4 g/day for 4 to 5 days beginning on day 1 of menses reduces menstrual blood loss by 26% to 60%; avoid it with active thromboembolic disease and consider U.S. thrombosis-related contraindications. [20]
- Endometrial ablation is a uterine-sparing option only after evaluation of the bleeding cause and for patients who have completed childbearing; hysterectomy remains definitive surgical management. [15]

## Triage bleeding severity and establish the diagnostic branch

Classify the bleeding pattern while excluding pregnancy and an extrauterine source before assigning a uterine cause.

AUB applies to nongravid reproductive-aged patients with bleeding abnormal in regularity, frequency, duration, or volume. A normal cycle interval is 24 to 38 days, duration is 2 to 7 days, and estimated blood loss is 5 to 80 mL; deviations should prompt a structured AUB assessment rather than use of obsolete terms such as dysfunctional uterine bleeding. [8][11]

At the initial encounter, determine whether bleeding is uterine rather than cervical, vaginal, vulvar, urinary, or rectal. Speculum examination should identify cervical lesions, vaginitis, trauma, foreign body, ulceration, atrophy, prolapse-related erosion, or genital neoplasia; these entities require cause-specific evaluation rather than a uterine bleeding algorithm. [16][17]

Document cycle timing, duration, volume, intermenstrual or postcoital bleeding, medication exposure, and reproductive goals. Irregular, unpredictable, heavy, or prolonged bleeding favors ovulatory dysfunction, whereas predictable cyclic heavy or prolonged bleeding after exclusion of other causes supports endometrial dysfunction. [9][17] In perimenopause, intervals shorter than 21 days are more common early in the transition and intervals longer than 36 days later in the transition, but physiologic transition does not eliminate the need to evaluate hyperplasia or cancer risk. [10]
- Obtain pregnancy testing before classifying bleeding as nongravid AUB.
- Obtain a CBC when bleeding history suggests clinically important blood loss or anemia; anemia is a recognized consequence of AUB. [9]
- Use the PALM-COEIN framework at the outset: polyp, adenomyosis, leiomyoma, malignancy/hyperplasia; coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not otherwise classified. [8][11][14]
- Escalate promptly for hemodynamic compromise or ongoing severe bleeding; stabilize before completing outpatient etiologic testing.

*PALM-COEIN directs whether the next discriminating test is uterine imaging or evaluation for systemic and functional causes. [8][11][14][17]*

| Etiologic branch | Pattern or discriminator | Next diagnostic action |
| --- | --- | --- |
| PALM: polyp, adenomyosis, leiomyoma, malignancy/hyperplasia | Structural lesions are demonstrable by imaging or histopathology. [11][17] | Start with transvaginal ultrasound; use saline infusion sonohysterography or hysteroscopy for suspected intracavitary disease and obtain tissue when malignancy or hyperplasia is a concern. [18][21][24] |
| C: coagulopathy | Bleeding disorder is a nonstructural AUB cause. [11][16] | Use targeted bleeding history and hemostatic evaluation when the history suggests a systemic bleeding tendency. |
| O: ovulatory dysfunction | Absent ovulation causes progesterone deficiency and unopposed estrogen stimulation; bleeding is typically irregular and unpredictable. [9][17] | Evaluate for endocrine or life-stage contributors, including thyroid disorders, puberty, perimenopause, and polycystic ovary syndrome; exclude competing AUB causes before assigning AUB-O. [16][17] |
| E: endometrial dysfunction | Predictable cyclic heavy or prolonged bleeding after exclusion of structural, ovulatory, and coagulation causes. [9] | Treat as a diagnosis of exclusion; reconsider endometritis or other inflammatory contributors when clinically suggested. [9][16] |
| I/N: iatrogenic or not otherwise classified | Medication or device exposure, or no established PALM-COEIN category. [11][16] | Review hormones, anticoagulants, and other treatments; reassess for an overlooked structural or systemic diagnosis. |

## Prioritize endometrial assessment when cancer or hyperplasia is plausible

The key early diagnostic decision is whether outpatient imaging can safely triage the patient or tissue diagnosis is needed.

In perimenopausal AUB, hormonal transition can mimic or conceal pathologic bleeding; use PALM-COEIN and pursue evaluation for hyperplasia or cancer when clinical context warrants. FIGO-associated literature identifies endometrial tissue testing as a first-line approach in perimenopausal AUB, particularly before hormonal treatment when a premalignant or malignant endometrial process must be excluded. [10][13]

For postmenopausal bleeding, transvaginal ultrasound can triage endometrial evaluation. An endometrial thickness of 4 mm or less is associated with a malignancy risk of approximately 1 in 917; pooled data cited in this review found 3 cancers among 2,752 patients with bleeding and an endometrial echo of 4 mm or less. [22] A technically unreliable or nonvisualized endometrial echo should not be treated as a negative test; saline infusion sonohysterography can clarify the cavity. [22]

Outpatient endometrial biopsy is useful when an adequate specimen is obtained, particularly for ruling in endometrial cancer: pooled positive and negative likelihood ratios were 66.48 and 0.14, respectively. [2] A benign or negative blind biopsy does not end the evaluation of persistent AUB, because focal lesions may be missed; proceed to cavity-focused imaging or hysteroscopy when bleeding continues or imaging suggests focal pathology. [2][3][24]
- Use transvaginal ultrasound to assess uterine architecture and the endometrial echo; do not rely on it alone when tissue diagnosis is clinically required. [3][22]
- Proceed from a globally thickened endometrium to blind sampling, but direct sampling visually when the abnormality is focal, including a suspected polyp. [22]
- Use hysteroscopy when diagnostic accuracy for intrauterine pathology must be improved after ultrasound suspicion, inadequate evaluation, or persistent symptoms. [3][5]
- In postmenopausal bleeding with persistent symptoms after negative biopsy, continue evaluation rather than accepting the negative result as definitive. [2]

*Choose the endometrial test according to menopausal status, endometrial visualization, and whether disease appears diffuse or focal. [2][18][21][22][24]*

| Clinical finding | Interpretation | Next step |
| --- | --- | --- |
| Postmenopausal bleeding and endometrial thickness ≤4 mm | Very low observed malignancy-risk group when the endometrial echo is reliably measured. [22] | Expectant management may be appropriate initially; investigate recurrent or persistent bleeding. [2][22] |
| Postmenopausal bleeding and thickness >4 mm or globally thickened endometrium | Requires assessment for diffuse endometrial pathology. [22] | Perform endometrial sampling. [22] |
| Focal endometrial thickening, suspected polyp, or suspected submucosal fibroid | Blind sampling can be less informative for localized cavity disease. [18][22] | Perform saline infusion sonohysterography or hysteroscopy with visually directed sampling or treatment. [18][21][22] |
| Persistent bleeding after negative outpatient biopsy | Negative biopsy decreases but does not eliminate the probability of endometrial cancer or focal pathology. [2] | Perform further uterine-cavity evaluation, generally with imaging that defines focal lesions or hysteroscopy. [2][3][24] |

## Use imaging to distinguish focal intracavitary disease from diffuse uterine pathology

Imaging should answer whether bleeding is driven by a lesion that requires directed sampling or procedural therapy.

Transvaginal ultrasound is the initial anatomic test for suspected PALM causes, but a suspected lesion on ultrasound should prompt a test that better defines the cavity when management depends on focal versus diffuse disease. Diagnostic hysteroscopy improves diagnostic accuracy for uterine pathology beyond ultrasound in selected patients with AUB or suspicious sonographic findings. [3]

Saline infusion sonohysterography provides real-time transvaginal imaging during sterile saline instillation and is particularly useful for differentiating focal from diffuse endometrial and subendometrial lesions. It is more accurate than transvaginal sonography for submucosal fibroids and endometrial polyps and can clarify endometrial or periendometrial processes. [18][21]

Where pathology must be established, the combination of saline infusion sonohysterography and endometrial biopsy offers a high-sensitivity office approach. In a prospective cohort completing definitive reference testing, the combined strategy had 97.0% sensitivity and 94.3% negative predictive value for abnormal pathologic findings, although specificity was 70.2%. [24] A positive or persistent focal finding still requires a directed procedural plan rather than reassurance from a nonspecific test result. [3][24]
- Suspected endometrial polyp: define the intracavitary lesion with saline infusion sonohysterography or hysteroscopy; use directed sampling when malignancy evaluation is needed. [18][21][22]
- Suspected submucosal fibroid: saline infusion sonohysterography helps establish cavity involvement, which is relevant to hysteroscopic treatment planning. [21]
- Adenomyosis or noncavity myometrial pathology: transvaginal ultrasound identifies uterine structural abnormalities, but a normal cavity study does not establish AUB-E until other branches are excluded. [9][11]
- Suspected malignancy or hyperplasia: imaging informs lesion localization, but histology guides management. [13][17]

## Confirm nonstructural AUB only after competing causes are addressed

Nonstructural diagnoses change treatment selection but should not obscure missed structural disease or endometrial pathology.

AUB-O results from absent ovulation and consequent lack of progesterone exposure. Continuous unopposed estrogen stimulation produces an endometrium that is proliferative, fragile, vascular, and insufficiently supported by stroma, yielding irregular, often heavy or prolonged bleeding. [9][17] The next step is to identify the driver of anovulation, including puberty, perimenopause, polycystic ovary syndrome, or thyroid disease, while excluding pregnancy, structural disease, and other PALM-COEIN causes. [16][17]

AUB-E is an exclusion diagnosis. The usual pattern is predictable, apparently ovulatory cycles with heavy or prolonged bleeding after exclusion of structural lesions, ovulatory dysfunction, and coagulopathy. Proposed mechanisms include altered local vasoconstrictors, accelerated endometrial clot lysis, and altered prostaglandin balance; infection or inflammation may also contribute. [9] A noncyclic pattern should redirect evaluation toward AUB-O, iatrogenic bleeding, structural pathology, or a nonuterine source. [9][16][17]

AUB-C requires deliberate recognition because coagulopathy is a distinct FIGO category and changes both procedural planning and medication choices. [11][16] Review the personal and family bleeding history, anticoagulant exposure, and prior hemostatic challenges; if concerning, arrange targeted laboratory evaluation and coordinate management before endometrial procedures or surgery.
- Do not equate perimenopause with benign anovulation: persistent or concerning AUB still requires assessment for hyperplasia and cancer. [10][13]
- Do not diagnose AUB-E solely because ultrasound is normal; exclude ovulatory dysfunction and coagulopathy first. [9]
- Review medications and exogenous hormones in every patient because iatrogenic bleeding is a separate COEIN branch. [11][16]

## Match treatment to lesion, thrombosis risk, and fertility goals

Treat anemia and active bleeding while planning therapy that addresses the assigned PALM-COEIN cause.

For idiopathic heavy menstrual bleeding in a hemodynamically stable patient, medical therapy is generally first-line. [20] Oral tranexamic acid reduces menstrual blood loss by 26% to 60%; the reviewed regimen is 3.9 to 4 g/day for 4 to 5 days beginning on the first day of menses. [20] Do not use tranexamic acid with active thromboembolic disease; in the United States, a history of thrombosis or thromboembolism or an intrinsic thrombosis risk is also considered a contraindication. [20]

The levonorgestrel-releasing intrauterine system reduces menstrual blood loss more than tranexamic acid in heavy menstrual bleeding. [20] Select uterine-directed hormonal therapy only after completing the appropriate assessment for endometrial neoplasia or hyperplasia when the patient’s age, bleeding pattern, or clinical context makes tissue evaluation necessary. [13]

When an intracavitary lesion is identified, hysteroscopy provides a diagnostic and potentially therapeutic route because it can improve recognition of uterine pathology and permits visually directed evaluation. [3][5] For persistent heavy AUB in patients who have completed childbearing, endometrial ablation is a minimally invasive option only after the underlying cause has been evaluated; it destroys the functional endometrium to reduce subsequent menstrual blood loss. [15] Hysterectomy is definitive surgical management and has high patient satisfaction, but it is not fertility-sparing. [12][15]
- Treat the identified cause rather than applying empiric therapy indefinitely to persistent AUB with uncharacterized endometrial or intracavitary findings. [1][2][22]
- Choose tranexamic acid for cyclic heavy bleeding when thrombosis-related contraindications are absent; dose only during menses as reviewed. [20]
- Consider a levonorgestrel-releasing intrauterine system when a reversible contraceptive and menstrual blood-loss reduction strategy is desired. [20]
- Reserve endometrial ablation for patients with desired parity complete after appropriate evaluation; counsel that hysterectomy is the definitive alternative. [15]

*Treatment selection for heavy AUB depends on whether a focal lesion is present and whether future fertility is desired. [3][15][20]*

| Option | Best-fit setting | Critical limitation or decision point |
| --- | --- | --- |
| Tranexamic acid | Idiopathic heavy menstrual bleeding in a stable patient; 3.9-4 g/day for 4-5 days from day 1 of menses. [20] | Contraindicated with active thromboembolic disease; U.S. contraindications also include prior thrombosis/thromboembolism or intrinsic thrombosis risk. [20] |
| Levonorgestrel-releasing intrauterine system | Heavy menstrual bleeding when a reversible intrauterine therapy is acceptable. [20] | Reduces menstrual blood loss more than tranexamic acid; complete indicated endometrial assessment first. [13][20] |
| Hysteroscopy-directed management | Suspected or confirmed focal intracavitary pathology. [3][5][18] | Use directed assessment because focal pathology can be missed by blind sampling. [2][22] |
| Endometrial ablation | Heavy AUB after evaluation in a patient who has completed childbearing. [15] | Not a fertility-preserving procedure; underlying cause must be assessed before treatment. [15] |
| Hysterectomy | Definitive treatment when symptoms, pathology, or patient preference justify uterine removal. [12][15] | Definitive but eliminates fertility. [15] |

## Escalate persistent bleeding, inadequate samples, and discordant results

A negative initial test is not a final diagnosis when symptoms and anatomy remain discordant.

Reassess the bleeding pattern, CBC when blood loss has been clinically significant, treatment adherence, and adverse effects after initiating medical therapy. Continued intermenstrual, irregular, or heavy bleeding should trigger diagnostic reconsideration rather than repeated empiric treatment, especially if anovulatory bleeding was presumed without definitive exclusion of endometrial pathology. [9][13][17]

Escalate to saline infusion sonohysterography or hysteroscopy when transvaginal ultrasound does not adequately visualize the endometrium, a focal lesion is suspected, outpatient biopsy is inadequate, or bleeding persists after a negative biopsy. [2][3][21][22] This approach addresses the principal blind-sampling limitation: a focal lesion may remain untreated or unsampled despite a nondiagnostic or benign global specimen. [2][22]

For patients proceeding to ablation or hysterectomy, confirm that the diagnostic workup has accounted for PALM-COEIN causes and that reproductive plans are documented. Endometrial ablation should follow, not substitute for, evaluation of the underlying AUB cause. [15]
- Persistent bleeding after negative biopsy: investigate further. [2]
- Unreliable endometrial echo on transvaginal ultrasound: use saline infusion sonohysterography to characterize the cavity. [22]
- Suspected focal lesion: favor hysteroscopic or other visually directed evaluation rather than relying solely on blind sampling. [3][22]
- Completed childbearing is a prerequisite consideration before endometrial ablation. [15]

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.