Abnormal Uterine Bleeding: Pathogenesis and clinical findings
Authors: Joshua Yu, Karen Paik Reviewers: Ayaa Alkhaleefa, Parker Lieb,
Hypothyroidism
Hypothalamus senses ↓ serum thyroxine
↑Thyrotropin releasing hormone (TRH) release from hypothalamus
↑Prolactin (see Feedback Loop: Prolactin)
Exogenous estrogen (e.g. estrogen-only birth control)
↑ Peripheral adipose tissue
↑ Aromatase (enzyme present in adipose tissue)
↑ Conversion of androgens to estrogens (aromatization)
Excessive stress, exercise, low body mass (mechanism unclear)
↓ Hypothalamic gonadotropin releasing hormone secretion
↓Luteinizing hormone and follicle stimulating hormone release from pituitary
↑ Estrogen
Heavier bleeding
Angiogenesis in tumour tissue
Polycystic ovarian syndrome (see slide)
Pelvic inflammatory disease
Immature hypothalamic- pituitary-ovarian axis
(an immature axis is transient in most females)
↓ Positive feedback of estrogen in late follicular stage
No LH surge
Adenomyosis (endometrial tissue grows into uterus muscular wall)
Endometrial polyps
Retained products of contraception
Infection
Inflammation of endometrium
Endometrium is more fragile
Anovulatory Bleeding
Leiomyoma (benign tumour in myometrium)
Tara Shannon, Hannah Yaphe, Dr. Sarah Glaze* * MD at time of publication
Ovarian Scarring
Foreign bodies
Intrauterine device perforation
Physical trauma
Impaired follicle maturation
Anovulation
Corpus luteum does not form
No ovarian progesterone production
↑ Estrogen to progesterone ratio
Proliferative effect of estrogen unopposed
Endometrial proliferation
No progesterone to organize growing endometrium
Disorganized endometrium overgrows and sloughs off
Irregular bleeding
Menopause
Premature ovarian insufficiency
Intermittent congestion of polyp blood supply
Transient ischemia and slight polyp necrosis
Altered growth factor production
Vascular dysregulation and leakier vessels
Coagulopathies (e.g. von Willebrand disease)
Impaired hemostasis
Invasion of normal tissue
↓ Estrogen (hypoestrogenism)
Atrophy of endometrium and vulvovaginal tissue
Dry endometrial surfaces (↓ fluid to prevent friction)
Endometrial carcinoma
Micro- erosions of epithelium
Inflammation
Evidence unclear
Heavier and more irregular bleeding
Spotting
Heavier and more irregular bleeding
Light bleeding and spotting
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published May 2, 2022 on www.thecalgaryguide.com