Postmenopausal bleeding and endometrial assessment

• Postmenopausal bleeding (PMB) is any vaginal bleeding that begins after the menopause, defined as 12 months without a period. It is always abnormal and always investigated ^[1][4].
• The most common cause (about 60% of cases) is genitourinary atrophy, a benign consequence of low oestrogen ^[1]. However, 1 in 10 women with PMB has malignant cells in the uterine lining, so cancer must be excluded first ^[4].
• The assessment is directed at excluding endometrial hyperplasia and cancer: transvaginal ultrasound for endometrial thickness and endometrial sampling for tissue diagnosis ^[1][3].
• An endometrial thickness of 4 mm or less on transvaginal ultrasound has a greater than 99% negative predictive value for endometrial cancer in a woman with PMB, and is usually enough to reassure after an initial episode ^[3].
• Any bleeding after the menopause needs an urgent appointment with a clinician, not reassurance or watchful waiting ^[4].

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

1. Define postmenopausal bleeding and list its common and serious causes in the order in which they are considered.
2. Select the appropriate initial investigations (transvaginal ultrasound, endometrial sampling, hysteroscopy) and justify each.
3. Apply the 4 mm endometrial thickness cut-off correctly, including when not to rely on it.
4. Plan the evaluation of a woman taking tamoxifen or hormone replacement therapy.
5. Interpret an endometrial biopsy showing hyperplasia with and without atypia and outline its management.
6. Decide when to re-investigate recurrent postmenopausal bleeding.

A woman is postmenopausal when 12 months have passed since her last natural menstrual period. Any vaginal bleeding after that point is called postmenopausal bleeding (PMB) ^[4]. Bleeding that is confined to pelvic examination or to intercourse is not PMB but needs its own assessment.

PMB is common: it is the reason for roughly two-thirds of all gynaecological office visits in postmenopausal women ^[1]. The average age of menopause in the United States is 51 years ^[1]. Most causes are benign, and the 5-year survival of endometrial cancer, when it is eventually diagnosed, is about 90%, because bleeding prompts early presentation ^[1]. That favourable statistic must not be used to reassure a woman before the cause is known.

The order below reflects how often each cause occurs and how urgent it is. Several causes can coexist, for example an atrophic vagina with an incidental submucosal fibroid.

Atrophy deserves emphasis. Because it is so common, there is a temptation to attribute light PMB to atrophy and to skip investigation. That is unsafe. Atrophy is a diagnosis of exclusion made after cancer and hyperplasia have been ruled out, or after a documented thin endometrial echo on transvaginal ultrasound with a reassuring clinical picture ^[1][3].

Treat the following as urgent (same day or next outpatient slot, depending on local pathways):

• Any postmenopausal bleeding in an untreated woman, including a single episode. NICE recommends a suspected cancer pathway referral for women aged 55 and over with unexplained postmenopausal bleeding that cannot be attributed to hormone replacement therapy (HRT) ^[2]. For women under 55 a suspected cancer pathway referral should be considered ^[2].
• Bleeding that is heavy, prolonged or repeated, or accompanied by large clots.
• Postmenopausal bleeding in a woman with risk factors for endometrial cancer: age over 55 years, obesity, polycystic ovary syndrome, anovulation, postmenopausal oestrogen-only therapy, tamoxifen for more than 2 years, Lynch or Cowden syndrome, or type 2 diabetes ^[3][8].
• A thickened endometrium on ultrasound, or a uterus that is enlarged, irregular or fixed on examination.
• Cervical lesions seen on speculum examination.
• Bleeding that persists or recurs after a first, reassuring evaluation.
• Anticoagulation does not need to be stopped to investigate a bleed sensibly, but active bleeding with anaemia or instability requires stabilisation first.

A focused history separates the categories before any test is ordered.

• Pattern. When did it start, how much, single episode or recurrent, spotting or frank bleeding, intermenstrual before the menopause, postcoital.
• Quantity. Light spotting suggests atrophy or a polyp; larger volumes raise concern for hyperplasia or malignancy.
• Menopausal timing and HRT. Date of last period; whether she has ever taken oestrogen-only or combined therapy, its route, and recent changes; tamoxifen and its duration.
• Risk factors for endometrial cancer. Age, body mass index, diabetes, anovulation/PCOS, early or late menopause, parity, family history of colorectal, endometrial or ovarian cancer, prior tamoxifen.
• Bleeding pattern on HRT. Unscheduled bleeding that is new or persistent may need adjustment of progestogen or urgent assessment depending on risk factors ^[6].
• Other bleeding sources. The urine, cervix, vagina, vulva, anus and rectum can mimic uterine bleeding. Postcoital bleeding points at the cervix or vagina.
• Symptoms of obstruction or organ involvement are late (pelvic pain, weight loss, urinary symptoms) and should prompt careful examination for advanced disease.

Offer abdominal, pelvic, speculum and bimanual examination early in the pathway, because cervical and vaginal lesions are visible at once ^[4].

• Speculum: look for atrophy, polyps at the cervical os, infection, foreign body, and cervical or vaginal lesions.
• Bimanual: uterine size, shape and mobility, adnexal masses or tenderness.
• General: body mass index, signs of anaemia, PCOS or other endocrine disease, and family history of cancer.
• Consent and preparation. Many older women have had little previous gynaecological examination. Explain each step, offer a chaperone, and have pain relief available for biopsy or hysteroscopy.

Transvaginal ultrasonography is the first investigation. It is quick, safe and widely available, and it measures the endometrium and shows polyps, fibroids, adnexal masses and structural causes ^[1][3].

How it is measured. Endometrial thickness is measured as the maximum anterior–posterior thickness of the endometrial echo on a long-axis (sagittal) transvaginal view of the uterus ^[3]. In a postmenopausal woman the endometrium should be thin and well-defined.

The 4 mm cut-off. An endometrial thickness of 4 mm or less has a greater than 99% negative predictive value for endometrial cancer in a woman with PMB ^[3]. Therefore transvaginal ultrasound is usually sufficient for an initial evaluation if the images reveal a thin endometrial echo of 4 mm or less ^[3]. An echogenically "thickened", irregular, cystic or poorly visualised endometrium is not reassuring, even if a single number is 4 mm or less.

When the endometrium is thicker than 4 mm. An endometrial thickness above 4 mm is an indication for endometrial sampling in a woman with PMB, with or without risk factors ^[1][3]. Other indications are persistent or recurrent bleeding despite a thin stripe on ultrasound, or the presence of risk factors such as obesity, smoking or unopposed oestrogen exposure ^[1].

When ultrasound is insufficient alone. If a thin, distinct endometrial echo cannot be identified clearly, the approach is triggered to sonohysterography, office hysteroscopy or direct endometrial sampling ^[3]. A retroverted uterus, leiomyomata, or body habitus can make a postmenopausal woman's endometrium hard to see.

Do not use ultrasound as cancer screening. Transvaginal ultrasonography is not an appropriate screening tool for endometrial cancer in postmenopausal women without bleeding ^[3]. An endometrial thickness above 4 mm found incidentally in a postmenopausal patient without bleeding need not routinely trigger evaluation, although an individualised assessment based on patient characteristics and risk factors is appropriate ^[3]. A number on an image in a symptom-free woman is not a diagnosis.

Endometrial sampling is the first-line test for evaluating PMB in any patient, because it supplies tissue for histological diagnosis, which is what detects and excludes malignancy ^[1]. It is performed in clinic through a small cannula (for example a Pipelle) with or without local anaesthesia, or at hysteroscopy. ^[3]

Indications in a woman with PMB:

• Endometrial thickness above 4 mm on transvaginal ultrasound ^[1].
• Any woman in whom PMB persists after a thin stripe on ultrasound, even repeated ^[3].
• Any woman with risk factors for endometrial cancer, such as obesity, diabetes, hypertension, PCOS or chronic anovulation, unopposed oestrogen exposure, or tamoxifen ^[1].
• A biopsy that is insufficient or non-diagnostic: sampling can be repeated, and the result combined with ultrasound.

Interpretation and limits. An office biopsy detects most endometrial cancers, but a negative result does not completely exclude disease if the clinical picture is suspicious ^[3]. If blind sampling does not reveal endometrial hyperplasia or malignancy, further testing such as hysteroscopy with dilation and curettage is warranted in a woman with persistent or recurrent bleeding ^[3]. Persistent or recurrent bleeding after a negative blind biopsy is a serious signal, not a reassurance.

Office hysteroscopy complements sampling rather than replacing it. It is offered when the history suggests submucosal fibroids, polyps or endometrial pathology, when ultrasound is inconclusive, or when bleeding persists or recurs despite an initially normal evaluation ^[1]. Polyps and small submucosal fibroids are focal lesions that a blind biopsy can miss completely.

Key points in practice:

• The hysteroscope is inserted through the cervix, usually without or with short-acting analgesia, with a small-calibre instrument (3.5 mm or smaller is typical for outpatient work) ^[10].
• A targeted biopsy of any focal lesion is taken under direct vision.
• A "see-and-treat" single-visit polypectomy is possible in many departments.
• Hysteroscopy also treats (polypectomy, resection of fibroid), so the diagnostic and therapeutic steps may be combined.
• If office hysteroscopy is uncomfortable, a general or regional anaesthetic may be needed, particularly after cervical stenosis.

• Full blood count and ferritin, particularly if bleeding has been repeated or heavy ^[1].
• Pregnancy test if the woman is not clearly postmenopausal (perimenopausal bleeding is a different problem and may be a normal early menopausal event, but atypical bleeding should still be clarified).
• Cervical sampling when the cervix looks abnormal; cervical cancer can present as postmenopausal bleeding and must be excluded by colposcopy if suspected.
• MRI pelvis for staging or surgical planning when cancer is found.
• Chest X-ray or CT only when advanced disease is suspected.

Tamoxifen is a selective oestrogen receptor modulator used in breast cancer that acts as an oestrogen agonist on the endometrium. Using tamoxifen for more than 2 years increases the risk of endometrial cancer, and that risk is greater after the menopause ^[8]. Raloxifene, by contrast, does not have oestrogen-like effects on the uterus and has not been shown to increase endometrial cancer risk ^[8].

Practical points:

• Any woman taking tamoxifen who reports bleeding needs a full endometrial assessment. Do not attribute it to a "normal" tamoxifen effect ^[1].
• The approach is the same as for PMB generally, but the threshold for hysteroscopy is lower, because tamoxifen can produce diffuse cystic thickening of the lining that is hard to sample blindly. If atypia is found, the lesion is managed as atypical hyperplasia or cancer ^[9].
• Routine transvaginal ultrasound screening without bleeding is not useful in asymptomatic tamoxifen users; investigation follows a bleeding episode ^[3].
• Combined oestrogen–progestin therapy taken for postmenopausal symptoms does not increase endometrial cancer risk, although it does increase breast cancer risk; oestrogen-only therapy raises endometrial cancer risk and the risk rises the longer oestrogen is used ^[8].

Women on HRT are a distinct group, because HRT itself commonly causes unscheduled bleeding, especially in the first months after starting or changing the preparation ^[4][6]. Whether the bleeding is "expected" or not should be judged against the regimen:

• Sequential (cyclical) combined HRT given to perimenopausal or postmenopausal women should produce a predictable monthly withdrawal bleed.
• Continuous combined HRT given 12 months or more after the last period should usually produce no bleeding after the first few months. ^[4]
• Bleeding after that, or any heavy or persistent bleeding, needs assessment ^[6].

The BMS joint guideline on unscheduled bleeding on HRT sets endometrial thickness thresholds that differ from the 4 mm postmenopausal cut-off ^[6]:

• With continuous combined HRT, a fully visualised uniform endometrium measuring 4 mm or less makes endometrial cancer unlikely; a measurement above 4 mm needs referral for endometrial assessment (biopsy or hysteroscopy). ^[6]
• With sequential HRT, the corresponding values are 7 mm or less (reassuring) and above 7 mm (referral).
• A woman on HRT with major risk factors (BMI 40 or more, Lynch or Cowden syndrome) needs urgent assessment regardless of bleeding pattern, and a woman with 3 or more minor risk factors (BMI 30 to 39, diabetes, PMOS) in a similar category ^[6].
• Offer an urgent scan if the first presentation with bleeding occurs more than 6 months after starting HRT or more than 3 months after changing it, or if bleeding is prolonged or heavy ^[6].

After a normal biopsy on HRT, adjust the progestogen and provide reassurance for 3 months; after a normal hysteroscopy and biopsy, reassurance can extend to 6 months ^[6].

NICE notes that the evidence for unscheduled bleeding on sequential or continuous HRT is limited ^[2]. This is a case of guideline disagreement stated plainly: the BMS thresholds are expert-derived standards that you should apply with clinical judgement and knowledge of the woman's risk profile.

Postmenopausal bleeding often leads to an endometrial biopsy showing hyperplasia. Its management depends entirely on the presence of atypia.

• Hyperplasia without atypia is a reversible hormonal state rather than a premalignant clone. It progresses to cancer in less than 5% of women over 10 years ^[7]. Regressions occur in 89% to 96% with progesterone, against 74% to 81% with expectant management ^[7]. First-line medical treatment is a levonorgestrel-releasing intrauterine system, which reaches higher tissue levels than oral progesterone and has a 92% regression rate in complex hyperplasia without atypia (vs 66% with oral progesterone) and a 90% rate in atypical hyperplasia (vs 69%) ^[7]. Oral alternatives are medroxyprogesterone 10 to 20 mg daily or norethindrone (norethisterone) 10 to 15 mg daily ^[7]. Weight loss and glycaemic control improve regression ^[9].
• Atypical hyperplasia / endometrial intraepithelial neoplasia (EIN) is the precursor of endometrioid cancer. About 33% of women diagnosed with atypical hyperplasia already have concurrent endometrial cancer, and untreated progression is about 8.2% per year ^[7]. Total hysterectomy is the definitive treatment, with bilateral salpingo-oophorectomy in postmenopausal women ^[5][7]. In women who wish to preserve fertility, high-dose progestin under specialist supervision with close hysteroscopic follow-up is possible, with completion surgery after childbearing ^[9].
• RCOG Green-top Guideline No. 67 (2016, reviewed 2019 and 2022) lists postmenopausal bleeding among the common presentations of endometrial hyperplasia and supports this two-track management ^[5].

A normal first evaluation does not end the story. Recurrent bleeding should be investigated rather than dismissed; a polyp is a common explanation, and cancer must be re-excluded if the picture has changed.

Cycle of good sense:

1. Ask whether the original bleeding has clearly stopped and for how long. A woman who never stopped bleeding has failed investigation, not a normal one.
2. Repeat transvaginal ultrasound; an endometrium that was 3 mm three months ago may be 9 mm today, or a polyp may now be visible.
3. If bleeding recurs and no focal lesion is seen, perform hysteroscopy with targeted biopsy rather than repeating a blind biopsy. Persistent or recurrent bleeding after a negative biopsy is a direct indication for hysteroscopy ^[3].
4. Consider risk-factor review: weight gain, new tamoxifen, new HRT, or new diabetes might have changed the priors in the months since the first visit.
5. If cancer is still a concern, fast-track referral is appropriate even with a thin stripe, because a thin stripe is reassurance about cancer recurrence in one snapshot, not forever.

• Older adults and frail women. Investigation still proceeds to tissue diagnosis, but surgical fitness may push definitive cancer treatment toward radiotherapy or systemic therapy instead of hysterectomy. Do not skip the diagnosis because treatment will differ.
• Women who do not have a uterus (after hysterectomy). Bleeding from the vagina is not PMB. It should prompt examination for atrophy, infection, polyp or neoplasm of the vagina or vault; the 4 mm cut-off no longer applies.
• Women on tamoxifen after breast cancer. Investigate every bleed, and hysteroscopy is preferred because the tamoxifen-induced endometrium is hard to sample blindly (see above).
• Low-resource settings. The tests that change management are cheap and robust: a careful speculum examination, transvaginal ultrasound with an endometrial thickness measurement, and an endometrial biopsy. If hysteroscopy is unavailable, dilation and curettage in a theatre with a trained operator is the fallback, but only when it is clinically necessary; do not subject women to D&C as a routine diagnostic when ultrasound plus office biopsy can answer the question. A thin stripe of 4 mm or less remains reassuring. Drugs (progestins) and surgery (hysterectomy) for hyperplasia or cancer usually require referral up the chain.

A short list to anchor the reading:

• Any bleeding after the menopause -> investigate for cancer and hyperplasia first ^[1][2].
• Heavy, prolonged or repeated bleeding.
• Risk factors (age above 55, obesity, PCOS, unopposed oestrogen, tamoxifen, Lynch or Cowden syndrome).
• An endometrium above 4 mm on TVUS.
• A non-diagnostic biopsy with persistent bleeding.
• Bleeding that recurs after reassurance.

• Postmenopausal bleeding is any bleeding after 12 months without a period; it is abnormal and must be investigated ^[4].
• The commonest cause (about 60%) is genitourinary atrophy, but about 1 in 10 women with PMB has malignant cells in the endometrium ^[1][4].
• The aim of investigation is to exclude endometrial hyperplasia and cancer, not to confirm atrophy.
• Transvaginal ultrasound is first line; an endometrial thickness of 4 mm or less has a greater than 99% negative predictive value and is usually enough to reassure after a single episode ^[3].
• An endometrium over 4 mm, persistent or recurrent bleeding, or risk factors are indications for sampling ^[1][3].
• A biopsy that is negative in a woman with persistent or recurrent bleeding deserves hysteroscopy with guided biopsy rather than repeated reassurance ^[3].
• Tamoxifen for over 2 years increases endometrial cancer risk, especially after menopause; every bleed in a tamoxifen user needs assessment ^[8].
• HRT regimens have their own, less familiar endometrial thickness cut-offs (4 mm on continuous combined, 7 mm on sequential) ^[6].
• Atrophy is a diagnosis of exclusion; do not diagnose it by assumption.
• Combined oestrogen–progestin HRT does not increase endometrial cancer risk; oestrogen-only therapy does ^[8].
• Most causes of PMB are benign and treatable, with a good prognosis for endometrial cancer when found ^[1]; that must not shorten the work-up.

Postmenopausal bleeding sits alongside endometrial cancer and hyperplasia, abnormal uterine bleeding in the premenopause, uterine leiomyoma, cervical cancer, abnormal vaginal discharge, the menopause and hormone replacement therapy, and cervical screening. They are listed here as plain text until their pages are verified.