Study guide for medical terminology & coding · Bleeding between periods? Read the patient guide
Metrorrhagia.com

Lesson 5

Causes of metrorrhagia: PALM-COEIN

The classification gynecologists use to work out why the bleeding is happening.

By the Metrorrhagia.com editorial teamUpdated Medical review pending
Illustration of a calm clinic room with an ultrasound machine, an exam chair and a rack of empty test tubes.

Educational content for students. Not medical or coding advice. Having symptoms? See the patient guide.

On this page
  1. PALM: structural causes
  2. COEIN: non-structural causes
  3. Always rule out pregnancy first
  4. Other causes students should list
  5. Sources

Metrorrhagia describes the bleeding pattern. Clinicians then look for the cause. FIGO's PALM-COEIN system sorts causes of abnormal uterine bleeding in non-pregnant people of reproductive age into structural (PALM) and non-structural (COEIN) groups [FIGO 2018] [StatPearls].

PALM-COEIN classification chart: structural causes polyp, adenomyosis, leiomyoma, malignancy and hyperplasia; non-structural causes coagulopathy, ovulatory dysfunction, endometrial, iatrogenic and not otherwise classified.
FIGO's PALM-COEIN system (as updated in 2018) for abnormal uterine bleeding in non-pregnant patients of reproductive age.

PALM: structural causes

LetterCauseNotes
PPolypBenign growths of the endometrium or cervix. Can cause irregular bleeding or bleeding after sex [ACOG].
AAdenomyosisEndometrium growing into the uterine wall. Heavy, painful periods [ACOG].
LLeiomyoma (fibroids)Benign muscle tumours of the uterus [ACOG] [NHS].
MMalignancy and hyperplasiaEndometrial hyperplasia or cancer, more likely around and after menopause [ACOG] [ACOG].

COEIN: non-structural causes

LetterCauseNotes
CCoagulopathyBleeding disorders such as von Willebrand disease [StatPearls] [ACOG].
OOvulatory dysfunctionIrregular or absent ovulation, common in adolescence and perimenopause and in PCOS or thyroid disease [ACOG].
EEndometrialPrimary disorders of the endometrium, including inflammation or infection [StatPearls].
IIatrogenicCaused by treatment: hormonal contraception, IUDs, anticoagulants, tamoxifen and others [ACOG] [Cleveland Clinic].
NNot otherwise classifiedRare or poorly defined causes [FIGO].
Labeled schematic front view of the uterus showing the fundus, body, endometrium (lining), myometrium (muscle wall), uterine cavity, cervix, fallopian tubes, ovaries and upper vagina.
Metr/o means uterus: metrorrhagia is bleeding from the uterus at irregular times, between expected periods. Schematic, not to scale.

Always rule out pregnancy first

PALM-COEIN applies to non-pregnant patients. Pregnancy-related bleeding (including miscarriage and ectopic pregnancy) is considered first, which is why a pregnancy test is a standard early step [StatPearls] [ACOG] [NHS].

Other causes students should list

  • Infections, including sexually transmitted infections such as chlamydia, cervicitis and PID [NHS] [Cleveland Clinic].
  • Cervical causes such as ectropion or polyps, especially for bleeding after sex [NHS].
  • Systemic conditions: thyroid, liver or kidney disease [Cleveland Clinic].
Memory trick

"PALM you can see (on imaging or biopsy); COEIN you can't."

Patient-facing version: bleeding between periods.

Sources

  1. The two FIGO systems for normal and abnormal uterine bleeding symptoms and classification of causes of AUB in the reproductive years: 2018 revisions Munro MG et al., Int J Gynecol Obstet 2018
  2. Abnormal Uterine Bleeding StatPearls, NCBI Bookshelf (NBK532913)
  3. Perimenopausal Bleeding and Bleeding After Menopause American College of Obstetricians and Gynecologists
  4. Abnormal Uterine Bleeding (FAQ095) American College of Obstetricians and Gynecologists, reviewed Aug 2025
  5. Fibroids NHS
  6. Menometrorrhagia (Abnormal Uterine Bleeding) Cleveland Clinic Health Library, Nov 2024
  7. Vaginal bleeding between periods or after sex NHS, reviewed Aug 2024

We link to primary medical sources so you can check our work. See the editorial policy and the full reference list.