Abnormal uterine bleeding and mass per abdomen theory and clinical

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Abnormal Uterine Bleeding (AUB) and Mass Per Abdomen (Uterine Fibroids)

PART 1: ABNORMAL UTERINE BLEEDING (AUB)

Definition and Normal Parameters

AUB is defined as any change in the frequency, regularity, duration, or volume of uterine bleeding outside normal parameters. A normal menstrual cycle:

Frequency: every 24-38 days
Duration of flow: 4-8 days
Cycle shorter than 21 days or longer than 35 days is abnormal
Flow <2 days or >7 days is abnormal

The older terms "menorrhagia," "metrorrhagia," "menometrorrhagia," and "dysfunctional uterine bleeding (DUB)" are obsolete and replaced by the PALM-COEIN system. The term DUB should no longer be used.

The PALM-COEIN Classification (FIGO 2011)

Established by the FIGO Working Group on Menstrual Disorders. Each letter represents a cause:

PALM - Structural Causes (diagnosed by imaging or histology)

Letter	Cause	Notes
P	Polyp (AUB-P)	Endometrial or endocervical polyp
A	Adenomyosis (AUB-A)	Ectopic endometrial glands in myometrium
L	Leiomyoma (AUB-L)	Submucosal (AUB-LSM) vs. other (AUB-LO)
M	Malignancy & Hyperplasia (AUB-M)	Endometrial carcinoma, hyperplasia

COEIN - Non-structural Causes (medical/functional)

Letter	Cause	Notes
C	Coagulopathy (AUB-C)	Von Willebrand disease, thrombocytopenia
O	Ovulatory Dysfunction (AUB-O)	PCOS, perimenopause, anovulation
E	Endometrial (AUB-E)	Endometritis, endometrial defects
I	Iatrogenic (AUB-I)	IUCD, exogenous hormones, tamoxifen
N	Not yet classified (AUB-N)	Arteriovenous malformations, etc.

(Source: ROSEN's Emergency Medicine; Sabiston Textbook of Surgery)

AUB by Age Group (Robbins Basic Pathology)

Age Group	Causes
Prepuberty	Precocious puberty (hypothalamic, pituitary, or ovarian origin)
Adolescence	Anovulatory cycle, coagulation disorders
Reproductive age	Pregnancy complications (abortion, ectopic, trophoblastic disease), anatomic lesions (leiomyoma, adenomyosis, polyps, hyperplasia, carcinoma), dysfunctional uterine bleeding
Perimenopause	Anovulatory cycles, ovulatory dysfunction, inadequate luteal phase
Postmenopause	Anatomic lesions (carcinoma, hyperplasia, polyps), endometrial atrophy

Normal Menstrual Cycle - Hormonal Basis

Normal Menstrual Cycle - Hormones, Ovarian and Endometrial Changes

The menstrual cycle begins on Day 1 of menses. Estrogen dominates the follicular phase, causing endometrial proliferation. After ovulation (Day ~14), the corpus luteum produces progesterone, which matures the endometrium. If implantation does not occur, the corpus luteum degenerates, progesterone and estrogen fall sharply, and menstruation occurs. This normally occurs ~14 days after ovulation.

Pathophysiology of Dysfunctional/Ovulatory AUB

Approximately 50% of excessive menstruation falls under ovulatory dysfunction (AUB-O):

If a woman does not ovulate, there is no corpus luteum and therefore no progesterone
Unopposed estrogen causes the endometrium to proliferate until it becomes unstable and breaks down
Results in irregular, unpredictable, and often heavy bleeding
Anovulatory cycles are most common at menarche and perimenopause due to HPO axis fluctuations

Other causes of anovulation include:

PCOS (polycystic ovary syndrome)
Pituitary tumors secreting prolactin (disrupts GnRH)
Hyperprolactinemia, hypothalamic dysfunction (anorexia nervosa)
Obesity, malnutrition, chronic systemic disorders (liver, thyroid disease)

(Source: Robbins Basic Pathology; ROSEN's Emergency Medicine)

Types of Bleeding Pattern by Cause

Pattern	Causes
Menstrual (heavy)	Endometrial polyp/malignancy, fibroids
Intermenstrual	Vaginal/cervical trauma or malignancy, cervical polyp, endometrial polyp/malignancy
Postcoital	Cervical ectropion, cervical polyp/malignancy, vaginal malignancy
Postmenopausal	Endometrial atrophy (most common), endometrial carcinoma, polyps, hyperplasia

Special Cause: Tamoxifen

Women on tamoxifen (used for breast cancer) are a special group:

Tamoxifen can induce endometrial abnormalities in 10-40% of women
Causes: endometrial polyps, hyperplasia, cancer, and rarely uterine sarcomas
Risk doubles in the first year and quadruples after 5 years
Risk is time-dependent but dose-independent
Aromatase inhibitors (anastrozole, letrozole, exemestane) have less endometrial effect and may reverse tamoxifen-induced abnormalities

(Source: Bailey and Love's Short Practice of Surgery)

Clinical Evaluation

History:

Volume, frequency, duration, and relationship to menstrual cycle
Age of menarche or menopause
Sexual history, risk factors for STIs
History of easy bruising/bleeding (family history of coagulopathy)
Medications (hormonal contraceptives, IUCD, tamoxifen)
Systemic disease: thyroid, liver, metabolic syndrome, obesity
Prior cesarean section (cesarean scar defect)

Physical Examination:

Signs of hypovolemia and anemia in acute bleeding
PCOS signs: obesity, acne, hirsutism, acanthosis nigricans
Thyroid examination (nodules)
Skin: petechiae, ecchymoses (coagulopathy)
Speculum: vaginal/cervical lesions
Bimanual exam: uterine enlargement, tenderness, palpable fibroid

Investigations:

Pregnancy test (urine or serum β-hCG) - first and always
Full blood count - hemoglobin, platelets
Pelvic ultrasound - first-line imaging (2D/3D, saline sonogram)
Thyroid function tests, prolactin level
Coagulation studies - if heavy bleeding since menarche, family history, or signs of systemic bleeding
Cervical cancer screening if not up to date
STI screening
Endometrial biopsy (Pipelle or hysteroscopic)

Indications for endometrial biopsy:

All women >45 years with AUB (including intermenstrual bleeding)
Women <45 years with: obesity/unopposed estrogen, persistent AUB, AUB refractory to medical treatment, elevated familial cancer risk
Any postmenopausal bleeding
Suspected endometrial pathology
Failed medical treatment

Postmenopausal bleeding is its own diagnosis - the most common cause is endometrial atrophy, but endometrial carcinoma must be excluded.

(Source: Sabiston Textbook of Surgery; Bailey and Love's Short Practice of Surgery)

Endometrial Hyperplasia (precursor to carcinoma)

Mechanism: Prolonged unopposed estrogen causes exaggerated endometrial proliferation.

Risk factors for estrogen excess: obesity (adipose converts steroids to estrogens), exogenous estrogens without progesterone, estrogen-producing ovarian lesions (PCOS, granulosa-theca cell tumors).

Types:

Hyperplasia without atypia: increased gland-to-stroma ratio; low risk of progression to carcinoma (1-3%)
Hyperplasia with atypia (Endometrial Intraepithelial Neoplasia - EIN): complex gland proliferation with nuclear atypia + PTEN mutations; considered true precancer. Treatment: hysterectomy (fertility desired: high-dose progestins)

Endometrial Carcinoma

Most common gynecologic cancer in high-income countries
Type 1 (Endometrioid): 80% of cases; estrogen-related; arises from hyperplasia; PTEN and mismatch repair gene mutations; associated with Lynch syndrome, Cowden syndrome
Type 2 (Serous): 15% of cases; arises in atrophic endometrium of older postmenopausal women; TP53 mutations; far more aggressive

PART 2: MASS PER ABDOMEN - UTERINE FIBROIDS (LEIOMYOMA)

Definition and Epidemiology

Uterine fibroids (leiomyomata) are benign, well-circumscribed smooth muscle tumors of the uterus. They are the most common pelvic tumors in women.

Present in up to 40% of women during reproductive years
Present in 70-80% of women by age 50
Black/African-Caribbean women are disproportionately affected (2-3x higher rates)
Incidence highest in women aged 45-49 years
Require estrogen and progesterone to grow; grow rapidly in early pregnancy; shrink after menopause
Malignant transformation to leiomyosarcoma in <1% (approximately 1 in 1100-1500 women under 45)

Genetics:

Germline mutations in FH (fumarate hydratase) gene - associated with early onset uterine + cutaneous leiomyomas + renal cell cancer
Somatic mutations in MED12 gene (X chromosome)

(Source: Goldman-Cecil Medicine; Bailey and Love's Short Practice of Surgery)

Classification by Location

Type	Location	Clinical Significance
Submucosal	Projects into uterine cavity	Heavy/irregular periods, infertility, recurrent pregnancy loss; if pedunculated, may extrude through cervical os
Intramural	Within myometrial wall	Pressure symptoms; heavy periods if distorts endometrium; infertility
Subserosal	On outer surface of uterus	Pressure symptoms; if pedunculated, may mimic ovarian tumour
Broad ligament / Cervical	Rare locations	Unusual presentations

The submucosal fibroid is most responsible for AUB because it increases endometrial surface area and prevents adequate uterine contractions from compressing endometrial vessels.

Clinical Presentation

Symptoms (many fibroids are asymptomatic):

Menstrual disturbance: heavy and/or irregular menstrual bleeding (most common symptom)
Anaemia (from chronic blood loss)
Pelvic/abdominal mass - may present as mass per abdomen
Pressure symptoms:
- Pelvic discomfort and fullness
- Urinary frequency, urgency, retention (anterior fibroids compressing bladder)
- Constipation, backache (posterior fibroids)
- Varicosities (due to back-pressure from large fibroids)
Infertility (especially with submucosal or intramural fibroids distorting the cavity)
Recurrent pregnancy loss
Acute pain (rare): torsion of pedunculated fibroid, red degeneration (especially in pregnancy due to rapid growth outstripping blood supply)

Examination Findings - Mass Per Abdomen

On abdominal examination:

Enlarged uterus felt arising from the pelvis
Smooth, firm, irregular ("knobby") surface
Non-tender (unless red degeneration)
Cannot get below the mass (it's arising from the pelvis)

On bimanual/vaginal examination:

Enlarged uterus with attached firm swellings
The uterus and mass move together
Cervix moves with the mass (differentiates from ovarian tumour)

Differential diagnosis of mass per abdomen (uterine vs. ovarian):

In an ovarian tumour: uterus is felt separately from the mass on vaginal examination (unless adherent)
In a fibroid uterus: the uterus and swelling move as one unit
Pedunculated subserosal fibroid may closely mimic an ovarian tumour

Investigations

Pelvic ultrasound (first-line) - high sensitivity and specificity for fibroids
MRI - if ultrasound is inconclusive or declined; better delineation of fibroid size, number, and location
Saline infusion sonogram (SIS/SHG) - for submucosal fibroids
Hysteroscopy - for submucosal fibroids; combines diagnosis + treatment
FBC - assess anaemia
Tumour markers (CA-125) - if ovarian pathology needs to be excluded
Endometrial biopsy - if AUB present and malignancy suspected

Treatment

Choice depends on: age, fertility intentions, size/number/location of fibroids, and severity of symptoms.

Conservative (Asymptomatic)

Watchful waiting - fibroids shrink after menopause

Medical (Reduce Bleeding, Symptom Control)

Drug	Mechanism/Use
NSAIDs (mefenamic acid, naproxen)	Reduce dysmenorrhoea and heavy bleeding
Combined OCP / Progestins	Suppress endometrial proliferation
Levonorgestrel-IUS (Mirena)	Reduces menstrual blood loss
Mifepristone (anti-progesterone)	5 mg/day x 6 months or 10 mg/day x 3 months - reduces fibroid size and symptoms (transient effect)
Ulipristal acetate (SPRM)	5-10 mg/day x 13 weeks - reduces fibroid size
GnRH agonists (leuprorelin)	Downregulate HPO axis - shrink fibroids pre-operatively (short-term, bone loss risk)
GnRH antagonists (elagolix 300 mg BD, relugolix 40 mg OD)	Combined with estradiol 1 mg + norethindrone 0.5 mg to reduce HMB and preserve bone density

Surgical - Uterus-Preserving

Hysteroscopic myomectomy - submucosal fibroids; preserves fertility; better outcomes vs. uterine artery embolization
Open/laparoscopic myomectomy - intramural/subserosal; preserves uterus; vasopressin injection aids haemostasis
Uterine artery embolization (UAE) - minimally invasive; less effective than myomectomy
Focused ultrasound surgery / Radiofrequency ablation - newer ablative options
Endometrial ablation - if AUB without desire for fertility (not for large fibroids)

Note: Power morcellation has fallen out of favour because of the risk of disseminating occult malignant tissue that can appear like fibroids on imaging.

Surgical - Non-Uterus-Preserving

Hysterectomy - definitive treatment; options: abdominal, vaginal, laparoscopic

Emergency surgery is only required for uncontrollable menstrual bleeding or severe uncontrollable pain - these are rare.

(Source: Bailey and Love's Short Practice of Surgery; Goldman-Cecil Medicine; Sabiston Textbook of Surgery)

Clinical Summary Table: AUB vs. Fibroid

Feature	AUB (functional/medical)	Fibroid (structural/mass)
Age	Any (most common perimenopausal)	Reproductive age (peak 40-49)
Presentation	Irregular/heavy bleeding	Heavy bleeding + pelvic mass
Examination	Normal or enlarged uterus	Enlarged, irregular, firm uterus
Key investigation	Pelvic USS + endometrial biopsy	Pelvic USS / MRI
Treatment	Medical (hormones, NSAIDs)	Conservative / Medical / Surgical
Definitive surgery	Endometrial ablation / Hysterectomy	Myomectomy / Hysterectomy

Sources: Sabiston Textbook of Surgery; Bailey and Love's Short Practice of Surgery (28th Ed.); ROSEN's Emergency Medicine; Robbins & Kumar Basic Pathology; Goldman-Cecil Medicine; Berek & Novak's Gynecology.

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