Types of Abnormal Uterine Bleeding: Hormonal Mechanisms

Normal Endometrial Physiology (the baseline)

1. Estrogen (follicular phase) proliferates the endometrium - glands grow, stroma thickens, spiral arterioles develop.
2. After ovulation, the corpus luteum secretes progesterone, which "ripens" or stabilizes the proliferated endometrium into a secretory state.
3. When the corpus luteum degenerates, progesterone falls - this triggers orderly, synchronous shedding of the entire endometrium (menstruation).

1. Progesterone Withdrawal Bleeding

• The endometrium must first be exposed to adequate estrogen (to proliferate) AND then to progesterone (to differentiate into secretory endometrium).
• When progesterone is abruptly withdrawn, spiral arterioles vasoconstrict, tissue breakdown is orderly and progressive, and the entire endometrium sloughs simultaneously.
• Bleeding is self-limited in both amount and duration because of coordinated arteriolar vasoconstriction.

• Normal menstruation (corpus luteum regression)
• Stopping oral progesterone/progestin therapy after a course
• The "withdrawal bleed" seen in the pill-free interval of combined oral contraceptives (OCP)
• Progestin challenge test: administering medroxyprogesterone for 7-10 days then stopping - if withdrawal bleeding occurs, it confirms adequate estrogen priming and an intact outflow tract.

2. Progesterone Breakthrough Bleeding

• High progestin / low estrogen ratio causes endometrial atrophy - the glands become thin, the stroma becomes decidualized and fragile.
• The atrophic, poorly supported endometrium breaks down and bleeds erratically.
• There is no coordinated shedding; bleeding is unpredictable and often light but persistent (spotting).

• Progestin-only pills (mini-pill), especially with inconsistent use
• Depot medroxyprogesterone acetate (Depo-Provera) - well-known for irregular spotting
• Levonorgestrel IUD (Mirena) - causes endometrial atrophy leading to spotting, especially in the first 3-6 months
• Etonogestrel implant (Nexplanon)
• Long-term continuous combined OCP use

3. Estrogen Withdrawal Bleeding

• Estrogen alone stimulates endometrial proliferation.
• When estrogen drops sharply, the unstabilized (non-secretory) endometrium sheds.
• Because there is no progesterone-induced spiral arteriolar vasoconstriction, the bleeding may be more prolonged and less well-controlled than progesterone withdrawal bleeding - but it is still relatively organized if the estrogen fall is abrupt.

• Midcycle spotting (around ovulation), when the pre-ovulatory estrogen surge briefly drops before progesterone rises
• Bilateral oophorectomy
• Menopause-related bleeding if estrogen fluctuates
• Estrogen-only HRT therapy that is suddenly stopped
• Estrogen-only OCPs (rarely used): if estrogen is withdrawn, bleeding follows
• Bradley & Daroff's Neurology notes that perimenstrual estrogen withdrawal is also a well-established trigger for menstrual migraine

4. Estrogen Breakthrough Bleeding

• Without ovulation, no corpus luteum forms, so no progesterone is produced.
• Estrogen continues to stimulate endometrial proliferation unopposed.
• The endometrium becomes abnormally thick and fragile; different regions outgrow their blood supply at different times.
• Random portions of the endometrium shed at random times from random sites.
• No spiral arteriolar vasoconstriction occurs (no progesterone), so bleeding is NOT self-limited.

• Chronic anovulation (PCOS, hypothalamic dysfunction, hyperprolactinemia, perimenopause)
• This is the most common cause of anovulatory/dysfunctional uterine bleeding - Goldman-Cecil Medicine states: "Most anovulatory bleeding is due to either estrogen withdrawal or estrogen breakthrough bleeding."
• Obesity (peripheral aromatization of androgens to estrogen)
• Estrogen-secreting ovarian tumors (granulosa cell tumor)

Summary Comparison Table

Clinical Relevance

• Progestin challenge test exploits progesterone withdrawal: a positive result (bleeding after stopping progestin) confirms adequate endogenous estrogen and patent outflow tract.
• OCP breakthrough bleeding management: Early-cycle bleeding (before ovulation) = needs more estrogen; late-cycle bleeding = needs more progestin; continuous throughout cycle = endometrium needs more estrogen overall. (Textbook of Family Medicine)
• Chronic anovulatory estrogen breakthrough bleeding carries risk of endometrial hyperplasia and carcinoma from prolonged unopposed estrogen - endometrial biopsy is mandatory in women >35 years or with prolonged anovulatory bleeding.
• Progestin breakthrough bleeding from DMPA or implants is treated by short-course supplemental estrogen to "rescue" the atrophic endometrium.

Dilation and Curettage (D&C) - Complete Procedural Guide

Indications

• Evaluation of abnormal uterine bleeding (AUB)
• Endometrial biopsy / screening for endometrial carcinoma
• Combined with hysteroscopy for global endometrial sampling

• Removal of retained products of conception (incomplete/missed abortion, postpartum)
• Removal of endometrial polyps
• Treatment of excessive uterine hemorrhage
• Elective termination of pregnancy (first trimester)

Note: Performing a D&C solely to resolve hormonally related AUB (anovulatory bleeding) has been found to be ineffective as a primary treatment.

Contraindications

Equipment

• Sterile gloves, gown, drapes
• Antiseptic solution (e.g., povidone-iodine)
• Graves or Auvard (weighted) speculum
• Single-tooth tenaculum
• Uterine sound
• Cervical dilators (Hegar or Pratt series)
• Kevorkian endocervical curette
• Sharp uterine curette
• Suction curette (8-12 mm) + suction machine with tissue trap
• Stone (polyp) forceps
• Ring forceps
• Formalin specimen bottles + Telfa pads / lens paper
• Local anesthetic: lidocaine 2% with epinephrine (paracervical/submucosal block)
• IV access, fluids, pulse oximeter (if IV sedation used)

Anesthesia & Analgesia

• NSAID (e.g., ibuprofen) 1 hour before the procedure reduces cramping
• Paracervical block (most common for office setting): injected at the cervicovaginal junction before tenaculum placement and dilation
• Submucosal cervical block: simpler alternative, generally sufficient
• Oral diazepam 10 mg 1 hour pre-procedure can be combined with local anesthesia
• IV sedation if needed (with monitoring and resuscitation equipment available)
• General or regional anesthesia if performed in the operating room

Pre-Procedure

1. Obtain informed consent; answer all questions about procedure, risks, and alternatives.
2. If pregnancy related: check hemoglobin/hematocrit, blood type, Rh, coagulation studies; obtain pregnancy test if status uncertain.
3. Prophylactic antibiotics are not routinely indicated.
4. Establish IV access if sedation will be used or if hemodynamic risk is present.
5. Optional: misoprostol (prostaglandin) the night before or laminaria placed in the os the night before for cervical priming/dilation (especially useful in postmenopausal women with cervical stenosis).

Step-by-Step Technique

Step 1 - Patient Positioning

Step 2 - Bimanual Examination

Step 3 - Expose the Cervix

Step 4 - Empty Bladder

Step 5 - Paracervical Block

Step 6 - Apply Tenaculum

Step 7 - Endocervical Curettage (Fractional D&C)

Skip this step if the problem is pregnancy-related or if an endocervical curettage was recently done during colposcopy.

Step 8 - Uterine Sounding

• Confirm the axis/direction of the uterine cavity
• Measure the depth of the uterus
• Normal depth: < 10 cm in premenopausal; < 8 cm postmenopausal
• Depth > 10 cm in a postmenopausal woman is abnormal; consider perforation if the sound passes unexpectedly deep

Step 9 - Cervical Dilation

Step 10 - Suction Curettage

• Insert the largest suction curette that passes easily through the dilated os.
• Connect to suction tubing (with tissue trap in-line).
• Position the curette at the uterine fundus.
• Turn on the suction machine (60 mmHg pressure minimum).
• Close the suction valve on the curette handle.
• Use a rotary, slightly in-and-out motion to sample the endometrium systematically on all walls.
• Do not withdraw the curette past the internal os (suction will be lost).
• Continue until no further tissue returns and increased resistance to rotation is felt (gritty sensation = bare myometrium).
• Turn off suction, then remove the curette.
• Use a curved curette for anteflexed/retroflexed uterus; straight curette for midposition.

Step 11 - Sharp Curettage (Additional Sampling)

Step 12 - Polyp Search

Step 13 - Final Suction Pass (Optional)

Step 14 - Remove Instruments

Complications

Post-Procedure Management

• Monitor vital signs until stable.
• Mild cramping and spotting are expected for 1-2 weeks.
• Advise patient to report: fever, increasing pelvic pain, heavy bleeding, or abnormal discharge.
• Send all specimens in clearly labeled, separate formalin containers.
• Rh-negative patients receiving a D&C for pregnancy-related indications should receive Rh immunoglobulin.

Assessing Tubal Patency via Fluid in the Pouch of Douglas (POD)

The Core Concept

Methods That Use This Principle

1. Hysterosalpingography (HSG) - Primary Radiological Method

• Performed during the follicular phase (Days 7-10 of cycle) to avoid disrupting an early pregnancy and to benefit from natural cervical mucus favorability.
• A radio-opaque contrast medium (water-based or oil-based) is injected transcervically through a cannula into the uterine cavity.
• X-ray / fluoroscopy images are taken sequentially.
• Patent tube: Contrast fills the uterine cavity, opacifies the fallopian tube along its entire length, and then spills freely from the fimbriated end into the peritoneal cavity (peritoneal spill sign). This contrast pools in the POD and is seen as a diffuse haziness around the tube ends on X-ray.
• Blocked tube: No peritoneal spill; contrast stops at the point of obstruction.
  • Proximal occlusion (cornual block): contrast does not enter the tube at all.
  • Distal occlusion / hydrosalpinx: tube fills and dilates but no spill from the ampullary end.
• Grainger & Allison's Diagnostic Radiology: "HSG is primarily involved in assessing tubal patency. A dilated fallopian tube with absence of spill of contrast agent from the ampulla is suggestive of a hydrosalpinx."
• The negative predictive value for tubal occlusion is high (if spill is seen, the tube is very likely truly patent). However, the positive predictive value is relatively low (apparent block may be due to tubal spasm, mucous plug, or technical factors).

Therapeutic benefit: Pregnancy rates are actually higher after HSG compared to no testing, and higher still when oil-based contrast is used (likely due to mechanical flushing of mucus plugs from the tube).

2. Sonosalpingography / Saline Infusion Sonography (SIS) - Ultrasound-Based Method

• Saline (plain or agitated/air-saline) is injected transcervically into the uterine cavity while performing transvaginal ultrasonography (TVS).
• Patent tube: Free fluid accumulates and can be seen in the POD on ultrasound - this is the direct sign of tubal patency.
• Harrison's Principles of Internal Medicine (2025): "Tubal patency is assessed by demonstrating passage of agitated saline contrast through the tubes or accumulation in the cul-de-sac as visualized by ultrasonography."
• Berek & Novak's Gynecology: "The use of agitated saline (air-saline) during sonohysterography provides good negative predictive value when compared to HSG or laparoscopy."
• Advantages over HSG: no ionizing radiation, can be done in a clinic, also evaluates the uterine cavity for polyps and fibroids, and simultaneously assesses ovarian morphology.
• Limitation: Standard 2D sonohysterography cannot define tubal architecture as well as HSG.
• Contrast-enhanced sonosalpingography (e.g., ExEm foam, SonoVue) gives better accuracy but contrast agents for this use are not available in all countries.

3. Laparoscopy with Chromopertubation - Gold Standard

• Considered the gold standard for diagnosing tubal and peritoneal disease.
• Under laparoscopic vision, indigo carmine or methylene blue dye is injected transcervically into the uterus.
• Patent tube: Dye is seen flowing through the tube and spilling from the fimbriated ends into the POD/peritoneal cavity (visible blue staining of the cul-de-sac fluid).
• Blocked tube: No dye exits the fimbriae; the dye may even distend the tube (hydrosalpinx pattern) without exit.
• Additional benefit: direct visualization of the external surfaces of the tubes, ovaries, and peritoneum - can simultaneously diagnose and treat endometriosis, adhesions, and peritubal/periovarian disease.
• Berek & Novak's: "Even laparoscopy has been reported to have a false positive rate of 11% for proximal tubal occlusion" when examined histologically (due to transient tubal spasm at the time of the procedure).

4. Falloscopy (Intratubal Endoscopy)

• A fiberoptic microendoscope is passed transcervically via hysteroscopy into the tubal ostia.
• Allows direct visualization of intratubal mucosa, identifying mucosal damage, debris, agglutination, or spasm.
• Limited by instrument availability and risk of tubal perforation; not in routine use.

Summary: How Fluid in the POD Confirms Tubal Patency

Clinical Notes

• Apparent obstruction on HSG or SIS may be due to tubal spasm (not true blockage) - laparoscopic chromopertubation is used to confirm equivocal findings.
• Textbook of Family Medicine: "Assessment of fallopian tube patency is accomplished by HSG (first choice) or laparoscopy (if history strongly suggests prior tubal damage)."
• In cases of suspected prior damage (PID, previous ectopic, endometriosis), even a normal HSG showing POD spill may miss peritubal adhesions - positive Chlamydia serology with a normal HSG should prompt laparoscopy.
• Proximal tubal catheterization (guided by HSG or hysteroscopy) can restore patency in up to 85% of proximal obstructions identified on HSG.