The Menstrual Cycle
The typical menstrual cycle varies from woman to woman, as well as at various points in her life. By convention, the first day of menstrual bleeding is designated as day 1 of the menstrual cycle. The super absorbent pad absorbs about 10 ml of blood. A tampon usually holds about 4 ml of blood.
| Phase | Days |
|---|---|
| Follicular phase | 14 +/- 7 days |
| Luteal phase | 14 days |
| Menses | 4 +/- 2 days |
| Flow | 20 – 60 ml of blood |
Ovaries
The process of recruiting follicles usually takes 2-3 months and is driven by the number of FSH receptors on the follicle.
- Functions
- Generation of mature oocysts (folliculogensis)
- Production of steroid and peptide hormones
- Cell types
- Primary oogonia
- Granulosa cells
- Ovarian stroma
- Interstitial cells → theca cells
- Connective tissue cells
- Contractile cells
Menstrual cycle
| Follicle/ovary | Endometrium | Dominant hormone | |
|---|---|---|---|
| Day 1-14 (variable) | Follicular phase | Proliferative phases | Estrogen (Estradiol) |
| Day 15-28 | Luteal phase | Secretory phase | Progesterone |
Follicular Phase
Once estradiol passess 200pcg/L negative feedback turns into a positive
Luteal Phase
Folliculogenesis
Corpus Luteum
After ovulation the follicular remnant undergoes changes and becomes vascularized to become the corpus luteum. The primary function of the corpus luteum is to secrete progesterone, which maintains the endometrial lining. The corpus luteum lasts 10 days.
Menstruation
If there is no implantation by day 24 (in a 28 day cycle) the corpus luteum begins to involute and stops secreting progesterone. Progesterone withdrawal causes constriction of spiral arteries → endometrial necrosis. Prostaglandins released from necrosis cause pain and contraction of the uterus. The functionalis (superficial endometrial lining) separates from the basalis layer and exits through the vagina.
Steroidogenesis across the lifespan
- Childhood
- LH and FSH levels are high after birth but fall within a few months of life
- FSH > LH
- Puberty
- Gonadotropin levels gradually rise
- Sleep associated LH increase is one of the first signs of puberty
- Estradiol rises to give secondary sex characteristics, menarche
- LH > FSH
- Menopause
- Follicles decrease, amoung ot estrogen and inhibin decrease, and LH and FSH increase
- High incidence of twinning
- Short follicular phase (metorrhagia)
- FSH > LH
- LH stimulates thecal androstenedione production → estrone
- Follicles decrease, amoung ot estrogen and inhibin decrease, and LH and FSH increase
Dysmenorrhoea
“Painful menstrual flow to the point where it is debilitating”. Most common cause of cyclical pelvic pain in women of child-bearing age. It comes and goes in predictable intervals (known or unbeknownst to the patient. May be primary or secondary. Pregnancy must always be excluded in a woman with pelvic pain.
Primary dysmenorrhea: cyclical menstrual pain with no identifiable underlying cause. Diagnosis of exclusion.
Secondary dysmenorrhea: cyclical menstrual pain with an underlying cause. No. 1 cause is endometriosis.
| Primary dysmenorrhea | Secondary dysmenorrhea | |
|---|---|---|
| Age of onset | 16-25 yo | 30 – 45 yo |
| Onset of pain | Just prior to menses | Progresses through late luteal phase |
| Symptoms | Pain only | Other symptoms usually present |
| Response | Responds to NSAIDs and Combined oral contraceptive | Resistant to NSAIDs and COCs |
| Physical exam | Unremarkable | Depends on cause |
- OB/GYN differentials for chronic pelvic pain
- Dysmenorrhea
- Endometriosis
- Adenomyosis
- Leiomyoma
- Chronic PID
- Endometritis
- Ovarian or adnexal mass
- Reproductive tract cancer
- Pelvic organ prolapse
- Endometrial/endocervical polyps
- Intraabdominal adhesions
- Chronic ectopic pregnancy
- Ovarian retention syndrome
- Ovarian remnant syndrome
- Peritoneal cysts
- Outlfow tract obstruction
- Broad ligament syndrome
- Pelvic congestion syndrome
- Urologic differentials for chronic pelvic pain
- Chronic UTI
- Detrusor dyssynergia
- Interstitial cystitis
- Radiation cystitis
- Urinary tract cancer
- Urinary tract stone
- Urethral diverticulum
- Gastrointestinal differentials for chronic pelvic pain
- Irritable bowel syndrome
- Constipation
- Diverticular disease
- Colitis
- Inflammatory bowel disease
- GI tract cancer
- Celial disease
- Chronic intermittent bowel obstruction
- Musculoskeletal differentials for chronic pelvic pain
- Hernias
- Muscular strain
- Poor posture
- Myofascial pain
- Fibromyosis
- Degenerative joint disease (arthiti)
- Lumbar vertebrae compression
- Disk herniation or rupture
- Coccydynia
- Spondylosis
- Neurologic differentials for chronic pelvic pain
- Neurologic dysfunction
- Cutaneous nerve entrapment
- Neuralgia
- Piriformis syndrome
- Spinal cord or sacral nerve tumor
- Other differentials for chronic pelvic pain
- Psychiatric disorders
- Physical or sexual abuse
- Shingles
- Risk factors for chronic pelvic pain
- Early menarche
- Longer menstrual periods (more bleeding days)
- Higher BMI
- Smoking
- Parity is associated with dereased incidence of primary dysmenorrhea
- Pathophysiology
- Endometrial cells release prostaglandins during menstruation. Women with dysmenorrhea release higher levels of prostaglandins.
- When should you suspect secondary dysmenorrhea?
- Onset after 25 years old
- Abnormal pelvic exam findings
- Infertility or menstrual abnormalities
- Dyspareunia
- Does not respond to conventional therapy for primary dysmenorrhea
- Investigations
- Qualitative urine hCG
- Chalmydia and Gonococcal swabs
- UA w/cx: if CVA tenderness, dysuria
- TVS: if uterine/adnexal mass
- Treatment of primary dysmenorrhea
- NSAIDS: Ibruprofen, Naproxen, Melenamic acid, Ketoprofen
- COCs or progestin-only contraceptives in patients who do not respond to NSAIDs or as first line therapy in patients desiring contraception
Mittelschmerz
German for “Middle pain”. Classically one-sided lower abdominal pain coinciding with ovulation. Mechanism unknown. Possibly due to the release of fluid or blood from the follicle which irritates the lining of the abdomen. May last from minutes to up to 48 hours.Treatment is OTC analgesics.
