Abnormal uterine bleeding: HMB, IMB, PCB and PMB

Overview

Abnormal uterine bleeding (AUB) is any bleeding from the uterus that is abnormal in amount, timing or frequency. It is one of the commonest reasons women see a doctor, and it peaks at the two ends of reproductive life (adolescents and the perimenopause), when cycles are often anovulatory.

Key questions in every case:

• Is she pregnant? (Always check.)
• Is there a structural cause (polyp, fibroid, cancer)?
• Is there a red flag for cancer (PMB, persistent IMB, PCB, age over 45)?

Terminology

Causes: PALM-COEIN (FIGO)

• Endometrial dysfunction is a diagnosis of exclusion: when no other cause is found. Abnormal local prostaglandins, blood vessel growth and repair are blamed.
• Submucosal fibroids bleed most, even when small, because they enlarge and distort the bleeding surface.
• Heavy anovulatory bleeding: without ovulation there is no progesterone, so the endometrium grows unchecked under oestrogen and breaks down irregularly.

Heavy menstrual bleeding (HMB)

About 20-30% of women of reproductive age report HMB.

History

• How heavy: flooding, clots, changing protection at night, days off work or school, symptoms of anaemia.
• Since menarche? HMB from the first period suggests a bleeding disorder rather than structural disease.
• Regular or irregular (irregular suggests anovulation: PCOS, early puberty, perimenopause).
• Bleeding history: bruising, nosebleeds, bleeding after dental extraction or surgery, postpartum haemorrhage, family history. A coagulation disorder is found in about 20% of women with otherwise unexplained HMB.
• Associated IMB or PCB (polyp, cervical lesion, cancer); pressure symptoms (fibroids); pain (adenomyosis, endometriosis); weight change, acne, hirsutism, fatigue (PCOS, thyroid).
• Contraception, fertility wishes, drugs (anticoagulants).

Examination

• Pallor, abdominal mass, speculum (cervix: polyp, ectropion, cancer), bimanual (bulky uterus, fibroids, adnexal mass).
• Young girls with HMB and no other symptoms can be treated medically without a pelvic examination.

Investigations

When to take an endometrial biopsy

• HMB at age over 45 years
• HMB with IMB
• Treatment failure
• Before endometrial ablation (to confirm normal histology)
• PMB with endometrium over 4 mm, or persistent PMB whatever the thickness

Medical treatment (in the usual order of preference)

Surgical and other treatment

• Endometrial ablation: destroys the endometrium down to the basalis so it cannot regrow.
  • Suitable if the uterus is no bigger than 10 weeks' size and fibroids are under 3 cm.
  • Only for women whose family is complete (later pregnancy risks prematurity and placenta accreta spectrum).
  • Second-generation methods (thermal balloon, radiofrequency, microwave) are now used and should be offered before hysterectomy.
• Myomectomy (laparoscopic, open or hysteroscopic) for fibroids in women wanting fertility.
• Uterine artery embolisation for fibroid-related HMB; symptoms improve in over 80%, but effects on fertility are uncertain.
• Hysterectomy: definitive; first-line when large fibroids cause severe pressure symptoms or with uterine prolapse.
  • Usually laparoscopic; ovaries kept if normal, but the fallopian tubes are removed (most aggressive ovarian cancers start in the tube).
  • Even with ovaries kept, about 25% develop premature ovarian failure.

Acute heavy bleeding

1. Admit; IV access, resuscitate, transfuse if needed.
2. Pelvic examination (exclude a prolapsing fibroid or cervical lesion).
3. FBC, coagulation screen, biochemistry, group and save.
4. Tranexamic acid (oral or IV).
5. High-dose progestogen (for example norethisterone 5 mg three times a day) to stop bleeding.
6. TVUSS; consider GnRH analogue for medium-term control.
7. Surgery for causes such as a prolapsing fibroid polyp; long-term plan to prevent readmission.

Intermenstrual bleeding (IMB)

Causes to think of:

• Cervical: ectropion, cervicitis (Chlamydia), polyp, cervical cancer.
• Endometrial: polyp, hyperplasia, cancer, submucosal fibroid, endometritis.
• Hormonal: unscheduled bleeding on the pill, progestogen-only methods or HRT; mid-cycle bleeding at ovulation.
• IUD, pregnancy complications (always do a pregnancy test).

Assess with speculum examination, swabs for STIs, cervical screening if due, and TVUSS with hysteroscopy if bleeding persists. Endometrial polyps are found in about 10-20% of women with AUB; risk factors include obesity, late menopause and tamoxifen.

Post-coital bleeding (PCB)

Postmenopausal bleeding (PMB)

• Definition: bleeding more than 12 months after the last period.
• It is a red flag: about 5-10% have a gynaecological cancer, most often endometrial cancer.
• Causes: vaginal atrophy (commonest benign cause), unscheduled bleeding on HRT, endometrial or cervical polyps, endometrial hyperplasia, endometrial cancer, cervical or vulval cancer, oestrogen-secreting ovarian tumours (granulosa cell), tamoxifen.

Investigation pathway

1. Inspect vulva, vagina and cervix (speculum) to exclude lower genital tract cancer.
2. Transvaginal ultrasound for endometrial thickness.
3. Endometrium under 4 mm: cancer very unlikely; no further test needed if bleeding does not recur.
4. Endometrium over 4 mm, or recurrent bleeding at any thickness: hysteroscopy and endometrial biopsy (outpatient Pipelle or directed biopsy).

Dysmenorrhoea (brief)

Pakistani practice note

Anaemia is common in Pakistani women, so HMB often presents late with very low haemoglobin. Treat the cause and the iron deficiency together. Local availability of the LNG-IUS and outpatient hysteroscopy varies; follow your hospital and current national guidance.

Quick revision

• HMB = loss that affects quality of life (old cut-off 80 mL).
• PALM (structural) - COEIN (non-structural).
• Coagulation screen if HMB since menarche or bleeding history.
• Biopsy: over 45, IMB, failure, pre-ablation, PMB over 4 mm or persistent.
• Treatment order: LNG-IUS → tranexamic/mefenamic acid, pill → progestogens → GnRH → surgery.
• Ablation: uterus 10 weeks or less, fibroids under 3 cm, family complete.
• PCB: ectropion, cervicitis, polyp, cervical cancer; always inspect the cervix.
• PMB: 5-10% cancer; TVUSS under 4 mm reassuring.

Written by The House Job from standard references (Gynaecology by Ten Teachers).

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