Synopsis
Organise abnormal uterine bleeding into structural and non-structural mechanisms, use pattern and risk to select imaging or hysteroscopy, and recognise when more than one cause is contributing.
- PALM describes structural causes: polyp, adenomyosis, leiomyoma, and malignancy or hyperplasia; COEIN describes coagulopathy, ovulatory dysfunction, endometrial dysfunction, iatrogenic causes and causes not otherwise classified.
- The framework organises mechanisms rather than declaring one final diagnosis; fibroids and anticoagulation, adenomyosis and anovulation, or a polyp and hormonal contraception can coexist.
- Pregnancy-related, cervical, vaginal, vulval, urinary and rectal bleeding sit outside non-pregnant uterine classification and must be localised first.
- Polyps often cause intermenstrual or postcoital bleeding, submucosal fibroids distort the cavity, and adenomyosis commonly combines heavy bleeding with substantial dysmenorrhoea.
- Ovulatory dysfunction produces irregular timing and prolonged unopposed endometrial proliferation; causes include adolescence, perimenopause, PCOS, thyroid disease, hyperprolactinaemia, weight change and systemic illness.
- Primary endometrial dysfunction is considered when ovulation appears regular and no structural or systemic explanation is found; it reflects local haemostatic and inflammatory mechanisms.
- Iatrogenic bleeding includes hormonal-method adjustment, copper intrauterine contraception, anticoagulants, tamoxifen and medicines affecting ovulation or endometrium; temporal association does not exclude disease.
- Use hysteroscopy when a focal cavity or endometrial lesion is suspected and ultrasound when myometrial enlargement, adenomyosis or pelvic mass is the leading question.
- Endometrial histology, not thickness alone, diagnoses hyperplasia or malignancy; select biopsy based on bleeding pattern and risk and obtain it within an appropriate cavity pathway.
- Treat the contributor that matches the patient’s goal while maintaining surveillance for unresolved or changing bleeding rather than forcing every case into a single category.
Key red flags
Postmenopausal bleeding, persistent intermenstrual bleeding, suspicious cervix, new pelvic mass or unexplained weight loss requires prompt cancer-pathway assessment.
Abnormal bleeding with pregnancy possibility may represent ectopic pregnancy, miscarriage, gestational trophoblastic disease or placental pathology and belongs in a pregnancy pathway.
Sudden pain, vomiting and an adnexal mass suggests torsion, while fever and pelvic tenderness raises infection or abscess; bleeding classification must not delay urgent care.
Heavy bleeding from menarche with mucosal bleeding or affected relatives raises an inherited bleeding disorder even when uterine imaging is normal.
Tamoxifen, prolonged anovulation, obesity, PCOS or previous endometrial hyperplasia increases endometrial risk and changes the threshold for hysteroscopy and sampling.
Investigation priorities
Remove pregnancy-related and non-uterine bleeding from the classification before uterine testing.
Management branches
Bleeding is heavy, irregular, intermenstrual, postcoital or prolonged.
- Establish pregnancy status and anatomical source, then describe cycle regularity, duration, volume impact, pain and non-menstrual bleeding.
- Review pelvic symptoms, examination, bleeding history, endocrine phenotype and treatment exposure to populate plausible PALM and COEIN categories.
- Retain more than one contributor when evidence supports it and state which uncertainty each planned test will resolve.