A 32-year-old woman presents with heavy periods requiring pad changes every hour, describing clots "the size of golf balls." Meanwhile, in the emergency department, a 28-year-old with 6 weeks amenorrhoea reports unilateral pelvic pain and light vaginal bleeding. These scenarios represent two critical gynaecological presentations-abnormal uterine bleeding and ectopic pregnancy -that demand systematic evaluation and timely intervention. Understanding their classifications, epidemiology, and diagnostic frameworks forms the cornerstone of competent gynaecological practice.
Abnormal Uterine Bleeding (AUB) Classification:
Ectopic Pregnancy Essentials:
| Parameter | AUB | Ectopic Pregnancy |
|---|---|---|
| UK Prevalence | 25% reproductive-age women | 1.1% of all pregnancies |
| Peak Age | 40-50 years (HMB) | 30-34 years |
| Emergency Risk | Anaemia, rarely life-threatening | Life-threatening rupture |
| Mortality | <0.1% | 0.2-0.5% (if ruptured) |
📌 Mnemonic for Ectopic Risk Factors: PIPES
PID, IUD, Previous ectopic, Endometriosis, Surgery (tubal)


The mechanisms underlying abnormal bleeding diverge fundamentally between structural uterine pathology and ectopic implantation. In abnormal uterine bleeding , disrupted endometrial haemostasis results from either anatomical distortion (fibroids creating increased surface area, adenomyosis disrupting myometrial contractility) or molecular dysregulation (increased prostaglandin E2/prostacyclin ratio, impaired vasoconstriction). Anovulatory cycles-common in PCOS and perimenopause-produce unopposed oestrogen stimulation, causing irregular endometrial proliferation without progesterone-mediated stabilisation, leading to unpredictable breakthrough bleeding.
AUB Mechanistic Pathways:
Ectopic Pregnancy Pathophysiology:
In ectopic pregnancy , impaired tubal transport allows blastocyst implantation in the fallopian tube. Risk factors-previous PID causing tubal scarring, endometriosis creating inflammatory milieu, tubal surgery disrupting ciliary function-all compromise the tube's ability to propel the embryo uterine-ward. The trophoblast invades the tubal wall, eroding blood vessels and causing bleeding into the peritoneal cavity. Unlike the muscular uterus, the thin-walled tube cannot accommodate growing gestational tissue, leading to rupture typically at 6-8 weeks gestation when β-hCG reaches 3,000-5,000 IU/L.
| Mechanism | Clinical Consequence | Investigation Marker |
|---|---|---|
| Unopposed oestrogen | Irregular heavy bleeding | Anovulatory progesterone <3 nmol/L |
| Fibroid distortion | Predictable HMB | MRI shows submucosal location |
| Tubal trophoblast invasion | Unilateral pain + bleeding | β-hCG plateau or slow rise |
| Tubal rupture | Haemodynamic collapse | Free fluid on USS, falling Hb |
A 45-year-old presents with "flooding" periods lasting 9 days, passing clots, and requiring time off work. You quantify impact using a structured history, examine for structural causes, and order targeted investigations per NICE NG88 guidance. Meanwhile, a 26-year-old with positive pregnancy test and cramping requires urgent assessment for potential ectopic pregnancy , where clinical gestalt combined with serial β-hCG and transvaginal ultrasound determines management pathway.
History-Taking Priorities:
Examination Findings:
Investigation Algorithm (NICE NG88 & NG126):

| Investigation | Threshold | Sensitivity | Specificity |
|---|---|---|---|
| β-hCG rise >63% (48h) | Normal IUP | 99% | 93% |
| β-hCG plateau/fall | Failing pregnancy | 88% | 95% |
| USS gestational sac | β-hCG >1,500 IU/L | 90% | 100% |
| Endometrial thickness | >16mm (AUB) | 67% for pathology | 89% |
Separating benign from life-threatening bleeding requires systematic analysis. A 34-year-old with irregular bleeding and negative pregnancy test differs fundamentally from one with positive test and pain-the latter demands urgent ectopic exclusion . Similarly, distinguishing ovulatory HMB (regular cycles, structural causes) from anovulatory bleeding (irregular, endocrine dysfunction) guides targeted management for abnormal uterine bleeding .
Key Discriminators:
45 years: Endometrial cancer (2% of PMB)-requires urgent investigation
Common Diagnostic Pitfalls:
| Feature | Ectopic Pregnancy | Miscarriage | Ovulatory HMB | Anovulatory Bleeding |
|---|---|---|---|---|
| Cycle Pattern | Amenorrhoea then bleeding | Amenorrhoea then bleeding | Regular heavy cycles | Irregular unpredictable |
| Pain | Unilateral, severe | Midline cramping | Dysmenorrhoea | Minimal |
| β-hCG Pattern | Slow rise (<50% in 48h) | Falling | N/A | N/A |
| USS Findings | Adnexal mass, no IUP | Products in uterus | Structural pathology | Thickened endometrium |
| Urgency | EMERGENCY | Urgent | Routine | Routine |
NICE NG88 advocates a stepwise approach to abnormal uterine bleeding , prioritising medical management unless structural pathology mandates surgery. First-line treatment-levonorgestrel intrauterine system (LNG-IUS)-reduces menstrual blood loss by 94% at 12 months, superior to all oral therapies. For ectopic pregnancy , NICE NG126 stratifies management by haemodynamic stability, β-hCG level, and patient preference, balancing tubal preservation against treatment success.
AUB Medical Management:
AUB Surgical Options:
Ectopic Pregnancy Management:
| Treatment | Indication | Success Rate | Key Monitoring |
|---|---|---|---|
| LNG-IUS | First-line HMB | 94% reduction MBL | Review 3-6 months |
| Methotrexate | Ectopic β-hCG <1,500 | 88% single dose | β-hCG days 4, 7 |
| Salpingotomy | Ectopic + fertility desire | 93% success | 7% persistent trophoblast |
| Hysterectomy | Failed medical Rx | 100% cure | Surgical complications |
Real-world patients present nuanced challenges. A 38-year-old with HMB and concurrent anticoagulation for prosthetic heart valve requires coordinated cardiology input before considering surgical management . Similarly, a woman with recurrent ectopic pregnancy and single remaining tube faces difficult decisions balancing fertility preservation against treatment success . These scenarios demand synthesis of clinical evidence, patient values, and multidisciplinary expertise.
Challenging AUB Cases:
Complex Ectopic Scenarios:
| Scenario | Key Consideration | Management Modification |
|---|---|---|
| Anticoagulation + HMB | Bleeding risk vs thrombosis | Tranexamic acid safe, avoid NSAIDs |
| Single tube + ectopic | Fertility preservation | Salpingotomy if feasible, counsel re: IVF |
| β-hCG >5,000 + ectopic | High rupture risk | Surgery preferred over methotrexate |
| Perimenopausal IMB | Malignancy risk | Mandatory endometrial sampling |
Key Take-Aways:
Essential Gynaecology Numbers:
| Parameter | Threshold | Clinical Significance |
|---|---|---|
| β-hCG discriminatory zone | 1,500 IU/L | USS should show IUP if present |
| Normal IUP β-hCG rise | >63% in 48h | <50% suggests ectopic/failing |
| Methotrexate β-hCG limit | <1,500 IU/L | Higher levels = surgery preferred |
| LNG-IUS MBL reduction | 94% at 12 months | Superior to all oral therapies |
| Endometrial thickness (AUB) | >16mm abnormal | Warrants further investigation |
| Ectopic recurrence risk | 10-15% | After one previous ectopic |
Key Principles:
Quick Reference:
| Condition | First Investigation | First-Line Management | Red Flag |
|---|---|---|---|
| HMB (regular cycles) | FBC, ferritin, pelvic USS | LNG-IUS 52mg | Postmenopausal bleeding |
| HMB (irregular cycles) | Add TSH, prolactin | Combined OCP or LNG-IUS | Age >45 + IMB (cancer risk) |
| Suspected ectopic | β-hCG + transvaginal USS | Depends on stability/β-hCG | Shoulder tip pain, syncope |
| Pregnancy unknown location | Serial β-hCG (48h) | Expectant if falling | β-hCG plateau or slow rise |
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