Potential causes of abnormal uterine bleeding described using the PALM-COEIN classification system13
| Pathology | Description | Ambulatory test* |
|---|---|---|
| Polyps (AUB-P) | Endometrial polyps are focal outgrowths that can occur anywhere within the uterine cavity.8 13 | OPH/SIS (TVS) |
| Adenomyosis (AUB-A) | Adenomyosis is the presence of heterotopic endometrial tissue within the myometrium.13 | MRI/TVS (OPH) |
| Leiomyoma (AUB-L) (also known as myoma or fibroids) | Benign smooth muscle tumours of the uterus.15 Leiomyomas can be categorised using a numeric scale to denote the proportion of a leiomyoma found in different anatomical positions within the uterus, ranging from 0 (fibroid is completely within the uterine cavity) to 7 (fibroid extra uterine, attached to serosa by a stalk).13 | Submucous fibroids (Grade 0–2) OPH/SIS/MRI (TVS) Fibroids (Grade 3–8) TAS and TVS/MRI (OPH) |
| Malignancy and hyperplasia (AUB-M) | Endometrial hyperplasia is a proliferation of endometrial glands with structural abnormalities and crowding and is considered atypical where glands exhibit cytological atypia. Endometrial stromal invasion is seen with malignancy.49 | EB/OPH+EB (TVS) |
| Coagulopathy (AUB-C) | Systemic disorders of haemostasis, with von Willebrand disease being the most common.50 This group also includes women with iatrogenic coagulopathies associated with anticoagulant medication. | Haematological testing |
| Ovulatory dysfunction (AUB-O) | Ovulatory dysfunction tends to result in unpredictable timing of bleeding and variable flow. It may be caused by polycystic ovary syndrome, hypothyroidism, hyperprolactinaemia, mental stress, obesity, anorexia, weight loss, or extreme exercise.13 | TVS/biochemical endocrine testing |
| Endometrial (AUB-E) | Endometrial causes of AUB refer mainly to the condition previously known as ‘dysfunctional uterine bleeding’, which is a diagnosis of exclusion, used when no other identifiable cause can be found and usually manifesting as heavy menstrual bleeding. It also includes inflammation and infection of the endometrium which are more likely to manifest as intermenstrual bleeding.13 | TVS/EB/OPH |
| Iatrogenic (AUB-I) | Iatrogenic causes of AUB include hormonal medications (systemic or intrauterine) and other drugs associated with AUB, apart from anticoagulant therapy.13 | − |
| Not yet classified (AUB-N) | The role of chronic endometritis, arteriovenous malformations and myometrial hypertrophy in the development of AUB is yet to be accurately defined and thus these conditions have been included in this group.13 | TVS/MRI/EB/microbiological swabs |
*Ambulatory tests shown in parentheses are those that can be used to aid diagnosis of particular pathologies but are considered second best.
AUB, abnormal uterine bleeding; DB, hysteroscopically-directed biopsy; EB, endometrial biopsy; MRI, magnetic resonance imaging; OPH, outpatient hysteroscopy; SIS, saline infusion sonography; TAS, transabdominal ultrasound scan; TVS, transvaginal ultrasound scan.