Abnormal uterine bleeding

• Abnormal uterine bleeding (AUB) is bleeding from the uterus in a woman of reproductive age that is abnormal in volume, regularity, frequency or duration. It is a symptom, not a diagnosis.
• "Heavy menstrual bleeding" means bleeding heavy enough to disrupt life. Counting millilitres is not practical in clinic, so the diagnosis rests on the woman's report and its impact ^[2].
• Normal parameters are agreed by FIGO and most texts: a cycle of 24 to 38 days, bleeding for up to 8 days, total blood loss under 80 ml, and cycle length varying by under 9 days (18-25 and 42-45 years) or under 8 days (26-41 years) ^[1][2].
• Causes are organised by PALM-COEIN: structural causes (polyp, adenomyosis, leiomyoma, malignancy or hyperplasia) and non-structural causes (coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, not yet classified) ^[1].
• Ovulatory dysfunction is the commonest overall cause. Endometrial cancer must be excluded in women aged 45 years or older, and in younger women with risk factors ^[2][4].
• In the stable woman, long-term control usually starts with a levonorgestrel-releasing intrauterine system. Acute heavy bleeding is controlled first with uterine tamponade, high-dose hormones and tranexamic acid ^[4][5].

By the end of this page you should be able to:

1. Define abnormal uterine bleeding in FIGO terms and give the normal menstrual parameters.
2. Work through PALM-COEIN, distinguishing structural from non-structural causes, with an example for each.
3. Take a focused history and perform a pelvic examination that points toward a cause.
4. Order investigations sensibly, and state the indications for endometrial sampling.
5. Manage an acutely bleeding woman, stable or unstable, with drug, route and dose.
6. Select long-term medical and surgical treatment for each cause, respecting fertility wishes.
7. Recognise the red flags that require urgent referral.

Abnormal uterine bleeding is a very common reason to see a gynaecologist. Population studies estimate 10 to 30% of reproductive-aged women affected, and one clinical summary notes that about one third of outpatient gynaecology visits are for AUB, which accounts for more than 70% of gynaecologic consultations in the perimenopausal and postmenopausal years ^[4][6]. Questionnaire studies of HMB alone suggest prevalence over 50% in women of reproductive age, with FIGO System 1 adopted to make these figures comparable ^[1].

The term applies only to non-pregnant women of reproductive age. Bleeding in pregnancy is a different problem. Older, vague labels such as "menorrhagia", "metrorrhagia" and "dysfunctional uterine bleeding" are discouraged because they were used inconsistently ^[4].

To name bleeding abnormal you must know what normal is. The FIGO systems give normal parameters and the four primary descriptors of pattern: frequency, duration, regularity and flow volume ^[1]. These are agreed by the major references in the field ^[2].

• Frequency (cycle length, first day of one bleed to first day of the next): normal 24 to 38 days. Frequent is under 24 days, infrequent over 38 days. Absence of bleeding (without an iatrogenic cause) is amenorrhoea. ^[1]
• Duration of a bleed: up to 8 consecutive days is normal; longer is prolonged and abnormal. ^[1]
• Regularity (variation between the shortest and longest cycle): for women aged 18 to 25 and 42 to 45 years, a variation of up to 9 days is normal; for women aged 26 to 41, up to 7 days. Norms are not well defined below 18 and after 45. ^[1]
• Flow volume is subjective and patient-determined, described as light, normal or heavy. Counting ml is rarely done in practice. Heavy bleeding is likely when a pad or tampon is saturated within 3 hours, or clots larger than 2.5 cm are passed ^[2]. The NICE/FIGO figure used for study purposes is 80 ml per cycle ^[2].
• Intermenstrual bleeding (any bleeding between regular cycles) is always abnormal, and may be early-follicular (dark spotting), periovulatory or late-luteal.
• Unscheduled bleeding while on oestrogen or progestin contraception, GnRH analogues or selective progesterone receptor modulators is also abnormal.

Abnormal uterine bleeding is chronic when it has occurred in most of the preceding 6 months, or acute when an episode of heavy bleeding, in the clinician's opinion, is of sufficient quantity to need immediate intervention to prevent further loss ^[1][4].

Once bleeding is defined as abnormal, the cause or causes are classified with PALM-COEIN (pronounced "palm-koin") ^[1]. "PALM" are structural causes that can be seen on imaging or histology; "COEI" are non-structural. The categories are not mutually exclusive, and a woman often has more than one ^[4].

Points worth knowing for each letter:

• Polyp. Lifetime prevalence 8 to 35%, increasing with age. Intermenstrual bleeding is the commonest symptom and many are asymptomatic. Around 95% of symptomatic polyps are benign, with lower malignancy risk in premenopausal women ^[4]. ^[1]
• Adenomyosis. Prevalence ranges from 5 to 70%; many women have none. Symptomatic women report painful, heavy or prolonged bleeding and a dense, enlarged uterus ^[4].
• Leiomyoma. Present in up to 80% of women eventually, increasing with age. Most are asymptomatic; bleeding, when present, is heavy or prolonged menses, more likely with larger or submucosal fibroids ^[4]. TVUS diagnoses fibroids with 90 to 99% sensitivity ^[1].
• Malignancy and hyperplasia. AUB is the most common presenting symptom of endometrial cancer; close to one quarter of new diagnoses are in women under 55 ^[4]. Long-term unopposed oestrogen is the main risk (relative risk 10 to 20, compared with hereditary non-polyposis colorectal cancer 6 to 20, oestrogen-producing tumour over 5) ^[4]. Precursor change (atypical hyperplasia or endometrial intraepithelial neoplasia) is in this category ^[1].
• Coagulopathy. About 20% of women with heavy menstrual bleeding, and more among adolescents, have a bleeding disorder. Von Willebrand disease and platelet dysfunction are the most common ^[4].
• Ovulatory dysfunction. Anovulation or oligo-ovulation. Common at the extremes of reproductive life (perimenarche and perimenopause), and in PCOS, thyroid disease, hyperprolactinaemia and hypothalamic causes ^[2].
• Endometrial. A diagnosis of exclusion: ovulatory women with normal investigations, presumed primary disorder of local haemostasis. There is no clinical test; it is arrived at only after other causes are excluded ^[2][4].
• Iatrogenic. Breakthrough bleeding on hormonal contraception is the commonest; also tamoxifen, anticoagulants, copper IUDs, corticosteroids, antipsychotics ^[4]. Failed medical management, including failed benefit of gonadal steroids, is a risk factor for malignancy and should prompt endometrial sampling ^[1].
• Not otherwise classified. Uterine arteriovenous malformations (rare, can be life-threatening) and caesarean scar defects (early-cycle intermenstrual spotting) ^[1].

Leiomyomas are subclassified by location relative to the endometrium and serosa (FIGO types 0 to 8) ^[1]. Only submucosal fibroids are directly linked to objectively measured increased blood loss. MRI and ultrasound can suggest sarcomatous change, but diagnostic certainty about malignancy remains limited ^[1].

A woman with apparently ovulatory, regular cycles and heavy bleeding has a disorder of haemostasis: systemic (coagulopathy) or local (primary endometrial, AUB-E, or bleeding secondary to adenomyosis or a submucosal fibroid) ^[1]. HMB is frequently associated with iron deficiency and iron deficiency anaemia, which should be investigated at the same time ^[1].

Treat these as urgent:

• Haemodynamic instability: hypotension, tachycardia, syncope, postural symptoms, or soaking through protection hourly with clots.
• Pregnancy, including ectopic pregnancy and gestational trophoblastic disease: exclude in every woman of reproductive age with abnormal bleeding ^[2][4].
• Suspected cancer or risk factors: age 45 years or older, postmenopausal bleeding, persistent/recurrent bleeding despite treatment, unopposed oestrogen exposure (obesity, PCOS, tamoxifen), or failed medical management.
• Cervical lesions seen on speculum examination.
• Bleeding in an adolescent with anaemia or hospitalisation, or with a personal/family history suggestive of a bleeding disorder ^[2].
• Bleeding that does not stop despite adequate medical therapy.

NICE advises taking into account the range and natural variability in cycles and blood loss, discussing this with the woman, since women and clinicians often underestimate blood loss ^[3]. HMB has a major impact on quality of life, and the aim of treatment is to improve that, not to focus on blood loss alone ^[3].

When taking the history, think first of pregnancy, then of non-uterine sources: bladder, urethra, anus, perineum, vagina or cervix, as women may not tell them apart ^[4].

Offer a physical and pelvic examination (speculum and bimanual) when there are symptoms beyond the bleeding itself, and always before investigation or LNG-IUS fitting ^[3]. Examination may be deferred in adolescents who are not sexually active, when no trauma or infection is suspected and the response to initial treatment is adequate ^[4]. A physical examination is not needed before starting pharmacological treatment for women with HMB alone and a low-risk history, unless a LNG-IUS is to be fitted ^[3].

Look for:

• Evidence of haemodynamic compromise: pallor, tachycardia, hypotension, postural change.
• Thyroid gland, signs of androgen excess, galactorrhoea, cushingoid features, nutritional status.
• Abdominal or pelvic masses; an enlarged or irregular uterus suggests fibroids; a dense, tender, bulky uterus suggests adenomyosis; cervical lesions need biopsy.
• Pallor, bruising, petechiae.

1. Pregnancy test (urine hCG, then serum quantitative hCG if negative) ^[2][4].
2. Full blood count and ferritin for every woman with HMB, in parallel with treatment ^[2][3].
3. Coagulation screening if there has been HMB since menarche or a personal or family history suggestive of a bleeding disorder: platelet count, PT and APTT (fibrinogen or thrombin time optional; bleeding time not needed), sometimes von Willebrand factor and ristocetin cofactor, often with haematology ^[2][4]. The FIGO screening tool (90% sensitive) looks at HMB since menarche plus previous postpartum, surgical or dental bleeding, bruising 1 to 2 times a month, epistaxis 1 to 2 times a month, frequent gum bleeding, or a family history ^[1]. Roughly one in five women with heavy bleeding has a bleeding disorder, and more among adolescents ^[4].
4. Hormonal tests only if indicated: TSH and prolactin (always reasonable in AUB-O even without galactorrhoea); androgens/DHEAS, glucose, lipids, blood pressure and BMI if PCOS suspected; FSH and oestradiol if primary ovarian insufficiency ^[2]. NICE says do not do routine female hormone or thyroid testing for HMB ^[3].
5. Cervical screening and STI testing when due or when infection is suspected ^[2].
6. Transvaginal ultrasound is the first-line imaging for suspected structural lesions, inadequate examination, women 45 years or older, postmenopausal women, women with cancer risk factors (obesity, diabetes, hypertension, PCOS, chronic anovulation), or bleeding that persists despite empiric hormone treatment ^[2]. Ultrasound detects fibroids with 90 to 99% sensitivity and polyps or intrauterine lesions with about 97 and 100% sensitivity when sonohysterography is used ^[1]. Endometrial thickness varies through the cycle in premenopausal women (2 to 4 mm in menstruation, 5 to 7 mm early proliferative, up to 11 mm late proliferative, 7 to 16 mm secretory), so a single measurement cannot reassure ^[2]. Uterine (endometrial) thickness is not a reliable cancer screen in Black women ^[2]. ^[4]
7. Sonohysterography improves detection of focal intrauterine lesions; MRI is a second-line or planning tool, not first line; D&C alone should not be used as a diagnostic tool ^[3].
8. Outpatient hysteroscopy is offered when the history suggests submucosal fibroids, polyps or endometrial pathology (persistent intermenstrual bleeding or cancer risk factors), using miniature hysteroscopes of 3.5 mm or smaller with vaginoscopy, with progressed see-and-treat ^[3]. MRI can clarify fibroid number, position and vascularity before embolisation or myomectomy ^[3].
9. Endometrial sampling, as below.

If the history suggests low risk of structural disease, NICE allows starting pharmacological treatment before investigating ^[3]. TVUS is preferred over transabdominal ultrasound or MRI for suspected adenomyosis, where direct and indirect MUSA features give sensitivities of about 84, 85 and 94% for 2D, 3D and colour Doppler ultrasound ^[1].

Endometrial sampling exists to exclude hyperplasia or cancer ^[2]. It is recommended in:

• Premenopausal women aged 45 years or older ^[2][4].
• Women under 45 with risk factors for endometrial cancer (obesity, diabetes, hypertension, PCOS, chronic anovulation, unopposed oestrogen, tamoxifen) ^[2][4].
• Abnormal bleeding that persists or recurs after an initially normal evaluation and despite treatment ^[2][4].
• Postmenopausal women with risk factors or worrying ultrasound findings (endometrial thickness over 4 to 5 mm, or focal or irregular thickening) ^[2].
• Inconclusive ultrasound when neoplasia is suspected ^[2].
• Women for whom treatment for HMB has been unsuccessful, or with persistent intermenstrual bleeding, or infrequent heavy bleeding who are obese or have PCOS, or taking tamoxifen, per NICE hysteroscopy indications ^[3].

Contraindications include pregnancy, uncontrolled bleeding disorders and acute pelvic infection ^[2]. Sampling should be done in the context of diagnostic hysteroscopy, not as a "blind" biopsy, and hysteroscopic directed biopsy is used when symptoms persist despite a normal biopsy ^[3][4]. Office biopsy detects 78% of endometrial cancers and 76% of atypical hyperplasia ^[2]. For a 49-year-old with new irregular bleeding, uterine imaging and endometrial sampling are needed; a 19-year-old with presumed AUB-O may only need iron studies and thyroid tests ^[1].

Acute AUB is heavy bleeding that requires immediate intervention ^[1]. A committee opinion on nonpregnant reproductive-aged women (ACOG No. 557, 2013, reaffirmed 2026) summarises the approach ^[5]. After pregnancy is excluded, treat in the same way as any haemorrhage: close monitoring of vital signs, haemodynamic stabilisation with IV crystalloid and blood products, and tests including CBC and DIC screen ^[2]. Airway, physiological monitoring and adequate IV access come before anything else. ^[4]

Control of bleeding, once stable, combines procedures and drugs ^[2][4]:

• Uterine tamponade (a bladder catheter inflated with 30 to 60 ml of fluid or gauze packing) gives rapid but temporary control.
• Dilation and curettage, uterine artery embolisation, or hysterectomy (last resort, especially if fertility is wanted) may be needed if bleeding continues.
• Hormone therapy is started once bleeding is controlled.

Drugs for stable severe bleeding (choice depends on contraindications; all increase thrombosis risk) ^[2][4]:

• High-dose oestrogen-progestin oral contraceptive: one monophasic pill containing 35 micrograms of ethinyl oestradiol, three times daily for 7 days. ^[2]
• High-dose oral progestin: medroxyprogesterone acetate 20 mg three times daily for 7 days; or norethindrone 5 mg three times daily for 7 days. ^[2][4]
• Tranexamic acid: 10 mg per kg IV every 8 hours, or 20 to 25 mg per kg orally every 8 hours. ^[4]
• IV oestrogen: conjugated (equine) estrogens 25 mg IV every 4 to 6 hours, up to 4 doses (for unstable patients; contraindicated with increased thrombosis risk). ^[2]

After the acute regimen, a daily oestrogen-progestin oral contraceptive is continued until bleeding has been controlled for a few months ^[2].

Treatment depends on cause, acuity, fertility and contraceptive wishes, comorbidity, cost and effectiveness. When the underlying cause can be treated, symptoms may resolve without further therapy. Anaemia and bleeding that affects quality of life are clear indications for treatment ^[4]. Anovulatory bleeding is treated by inducing ovulation or giving progestin to oppose unopposed oestrogen (the risk of endometrial cancer) ^[4].

• Levonorgestrel-releasing intrauterine system (52 mg, 20 micrograms per day) reduces menstrual volume by about 70 to 95%, is the most effective medical therapy, and performs as well as hysterectomy in quality-adjusted life years ^[4]. NICE recommends it as first treatment for HMB with no identified pathology, fibroids under 3 cm not distorting the cavity, or suspected or diagnosed adenomyosis ^[3]. ^[2]
• Alternatives if LNG-IUS is declined or unsuitable: tranexamic acid (500? no: 1 to 1.5 g orally three times daily), NSAIDs (e.g. naproxen 500 mg twice daily), combined hormonal contraception (about 35 to 69% reduction), cyclical oral progestins (norethindrone 2.5 to 5 mg once daily, or medroxyprogesterone acetate 10 mg daily for 21 days), and progestin-only methods that suppress menstruation ^[3][4]. ^[2]
• Tranexamic acid reduces menstrual blood loss by roughly 50% over up to 5 days during menstruation; NSAIDs reduce it by 25 to 35% and relieve dysmenorrhoea ^[2].
• For adenomyosis with HMB, similar hormonal options apply, with MRI and specialist input for surgical planning.

NICE allows starting pharmacological treatment without investigating, if the history and examination suggest low risk of structural disease ^[3].

Refer to specialist care. Larger fibroids limit the effectiveness of drugs ^[3]. Options, tailored to size, number, location and fertility wishes, include tranexamic acid, NSAIDs, LNG-IUS, combined hormonal contraception, cyclical progestins, GnRH agonists or antagonists (to shrink fibroids and stop bleeding before surgery, limited to 6 months because of hypo-oestrogenic side effects), uterine artery embolisation, hysteroscopic removal for submucosal fibroids, myomectomy and hysterectomy ^[3][2]. GnRH agonists produce an initial oestradiol surge then amenorrhoea after 7 to 14 days ^[2]. For some premenopausal women with fibroids 3 cm or more and HMB with haemoglobin 102 g per litre or under, ulipristal acetate 5 mg for up to 4 courses is an option when surgery or embolisation is unsuitable or declined, with liver monitoring; note hepatotoxicity warnings ^[3].

Hysteroscopic polypectomy (often see-and-treat) is both diagnostic and therapeutic. About 95% of symptomatic polyps are benign, with cancer risk around 1% in premenopausal women ^[4][1].

AUB due to suspected or diagnosed adenomyosis is managed similarly to HMB without structural pathology (LNG-IUS first line), with hysterectomy definitive. MRI helps plan surgery; uterine artery embolisation may be offered in some settings.

Atypical endometrial hyperplasia or carcinoma is referred for specialist oncological management. Failed medical management is a risk factor for malignancy and requires investigation ^[1].

Treat the disorder (often with haematology), with tranexamic acid and hormonal control of bleeding, and screen adolescents appropriately ^[4].

Treat the underlying cause and the unopposed oestrogen: lifestyle and endocrine management, combined hormonal contraception, or cyclic progestins. Progestin-only pills do not control heavy bleeding ^[2]. If pregnancy is desired and bleeding is not heavy, ovulation induction with clomiphene may be used ^[2].

Review the drug or device. For unscheduled bleeding on hormonal contraception, advise on timing and copper IUD effects; failed response raises cancer risk. Arteriovenous malformations causing life-threatening bleeding need urgent interventional radiology or surgery.

Endometrial ablation reduces bleeding in most women and is about as effective as the LNG-IUS, but is contraindicated when future fertility is desired and makes future sampling difficult ^[2][4]. Hysterectomy is the definitive and most effective treatment, with high satisfaction, but risks, ovarian function and the implications should be discussed fully ^[3][4]. Except for myomectomy and polypectomy, surgery for AUB is contraindicated if fertility is to be preserved ^[4]. Dilatation and curettage alone is not a treatment option for HMB ^[3]. Consider GnRH analogue pretreatment before hysterectomy or myomectomy when fibroids enlarge or distort the uterus ^[3].

• Adolescents. Anovulation is common and often physiological. Heavy bleeding since menarche, or family history, should prompt coagulation work-up, since bleeding disorders are more common in this group. Pelvic examination can be deferred when not sexually active and response to treatment is adequate ^[4]. Endometrial sampling is reserved for persistent bleeding or risk factors, not age alone.
• Perimenopausal women. Ovulatory dysfunction becomes more common. Because endometrial cancer risk rises with age, women 45 or older (or younger with risk factors) need sampling ^[2][4].
• Postmenopausal bleeding. Always investigate for neoplasia; an endometrial thickness over 4 to 5 mm or focal thickening requires sampling. This topic's guide (Merck Manual) also summarises ACOG/RCOG approaches ^[2].
• Women wanting pregnancy. Avoid definitive surgery; use medical therapy compatible with conception (e.g. tranexamic acid, ovulation induction) and hysteroscopic removal of structural lesions.
• Women with obesity, PCOS, diabetes. Higher risk of endometrial pathology; lower threshold for sampling and imaging; consider comorbidity-guided choice of hormone (e.g. avoid oestrogen in increased thrombosis risk) ^[3][4].
• Low-resource settings. HMB is common and often untreated. Where hysteroscopy, MRI and embolisation are unavailable, use a symptom-focused history, pelvic examination and TVUS; heavy prolonged bleeding responds to tranexamic acid, NSAIDs and hormonal therapy; tamponade controls acute bleeding; refer for surgical care when possible. FIGO's classification allows a common language for referral.

• Calling it "menorrhagia". Use "heavy menstrual bleeding"; the FIGO terms reduce confusion and support comparable research ^[1].
• Assuming regular equals normal. Heavy regular periods still need assessment for structural and haemostatic causes.
• Treating bleeding without considering cancer. Sampling is indicated by age and risk, not just severity.
• Trusting an endometrial thickness measurement in a premenopausal woman. It changes across the cycle; a "normal" value does not exclude pathology ^[2].
• "Blind" endometrial biopsy. NICE advises sampling only in the context of diagnostic hysteroscopy for HMB ^[3].
• Missing coagulopathy. Ask the bleeding history and use the FIGO screening tool, especially in adolescents ^[1].
• Staying with medical therapy after it has failed. Failed management is a reason to investigate (including hysteroscopy and sampling), not to repeat the same prescription ^[1][3].
• Performing hysterectomy or ablation before completing PALM-COEIN assessment. Non-structural causes (e.g. coagulopathy, ovulatory dysfunction) must be treated too.
• Using D&C alone as diagnosis or treatment for HMB ^[3].

Refer urgently with unstable patients, suspected pregnancy complications, suspected malignancy, or failure of conservative control of bleeding. Non-urgent referral is appropriate for fibroids 3 cm or more, structural lesions needing surgery, uncertain diagnosis, or when first-line therapy fails ^[3].

• Abnormal uterine bleeding is a symptom, not a diagnosis: nongestational bleeding outside normal volume, regularity, frequency or duration, classified with PALM-COEIN.
• Normal: 24 to 38 day cycle, up to 8 days' bleeding, under 80 ml; irregularity suggests ovulatory dysfunction.
• Structural causes (PALM) are diagnosed on imaging or histology; non-structural causes (COEI) on history and tests. Several may coexist.
• Ovulatory dysfunction is the commonest overall cause and presents with irregular bleeding; regular heavy bleeding suggests structure or haemostasis.
• Pregnancy is excluded first; non-uterine bleeding sources are common mimics.
• Haemodynamic instability, cancer risk and persistent/recurrent bleeding are red flags.
• Investigations proceed from pregnancy test, FBC, ferritin, coagulation screen, focused hormones, to transvaginal ultrasound, hysteroscopy and endometrial sampling.
• Endometrial sampling is indicated at 45 years or older, and earlier with risk factors or treatment failure. Sample in the context of hysteroscopy.
• Acute heavy bleeding: IV fluids and blood, tamponade, then high-dose hormones and tranexamic acid; surgery or embolisation if unstable.
• Long-term: LNG-IUS is most effective, followed by COCs, progestins, tranexamic acid and NSAIDs; ablation and hysterectomy for refractory cases.
• Surgery for AUB except myomectomy and polypectomy is contraindicated when fertility is desired.
• D&C alone is not a treatment for HMB.

AUB is a presentation rather than a disease, so the relevant related topics are problem- and disease-based: iron deficiency anaemia, uterine fibroids, endometrial cancer, polycystic ovary syndrome, von Willebrand disease and bleeding disorders, contraception and intrauterine systems, and premature ovarian insufficiency. These are linked on MedGrasp once their own pages are verified; until then they are listed here as plain text.