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PBL Analysis - Day 1 (Trigger 1)

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STEP 1: SCENARIO SUMMARY

• Lower abdominal pain (crampy, intermittent, suprapubic) - 1 day
• Vaginal bleeding - started as spotting, gradually increasing
• Dizziness + generalized weakness
• No fever, no rash, no medications

• Irregular menstrual cycles
• LMP: ~2-3 months ago (uncertain)
• Obstetric history: G2P1 (1 living child, age 3, normal delivery; no prior miscarriages)

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STEP 2: CUES (What stands out?)

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STEP 3: PROBLEM IDENTIFICATION

1. Bleeding in early pregnancy (amenorrhoea ~2-3 months + vaginal bleeding)
2. Acute lower abdominal/pelvic pain
3. Dizziness and weakness - suggesting haemodynamic instability or anaemia

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STEP 4: HYPOTHESES / DIFFERENTIAL DIAGNOSES

Primary Hypothesis: Ectopic Pregnancy

"Ectopic pregnancy accounts for up to 20% of diagnoses among women presenting with vaginal bleeding or abdominal pain in the first trimester of pregnancy."

• Rosen's Emergency Medicine

Differential Diagnoses (ranked by likelihood):

• Dizziness and weakness suggest haemodynamic compromise
• This is a life-threatening emergency

"Ectopic pregnancy is the most common obstetric cause of maternal death in the first trimester."

• Roberts & Hedges' Clinical Procedures in Emergency Medicine

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STEP 5: LEARNING OBJECTIVES (What do we need to know?)

1. What is ectopic pregnancy? Where does it implant?
2. What are the risk factors?
3. What is the pathophysiology of ectopic pregnancy?
4. How do you diagnose ectopic pregnancy?
5. What investigations are needed?
6. How do you manage ectopic pregnancy?
7. How do we classify spontaneous abortions?

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STEP 6: APPLYING KNOWLEDGE

A. What is Ectopic Pregnancy?

B. Risk Factors

C. Pathophysiology

• The tube stretches and eventually ruptures
• Bleeding into the peritoneal cavity (haemoperitoneum) occurs
• This causes peritoneal irritation, pain, and haemodynamic shock

D. Classic Triad (Ectopic Pregnancy)

• Present in ~50% of patients
• Pain can be unilateral, bilateral, sharp, dull, or crampy
• Bleeding is usually scanty/dark (unlike normal menstruation)
• Shoulder-tip pain = diaphragmatic irritation from haemoperitoneum

E. Spontaneous Abortion Classification (differential)

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STEP 7: INVESTIGATIONS NEEDED

Immediate (Emergency)

Interpretation of β-hCG

• Single β-hCG is of limited use alone (overlap between normal and abnormal pregnancies)
• Serial β-hCG (48 hours apart): A rise of ≥63% suggests viable IUP; <53% rise or a fall suggests ectopic or failing pregnancy
• Discriminatory zone (~1,500-2,000 mIU/mL): At this level, an IUP should be visible on TVUS; absence of IUP = suspect ectopic

Ultrasound Findings Suggesting Ectopic

• Absence of intrauterine gestational sac with positive β-hCG
• Adnexal mass (may or may not contain a gestational sac)
• Free fluid in the Pouch of Douglas = haemoperitoneum (ruptured ectopic)
• A "tubal ring" sign on TVUS

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STEP 8: MANAGEMENT

Immediate Priorities (ABC)

1. IV access + fluid resuscitation
2. Vital signs monitoring
3. Blood tests + crossmatch (prepare for surgery)
4. Confirm pregnancy with β-hCG

Definitive Management Options

1. Surgical (most common)

• Laparoscopy (preferred) - shorter hospital stay, less blood loss, shorter recovery
• Laparotomy - if haemodynamically unstable/ruptured ectopic
• Salpingectomy (tube removal) vs. Salpingostomy (tube-conserving) - depends on contralateral tube status and future fertility desires

"Laparoscopy is superior to laparotomy for management of ectopic pregnancy in most cases."

• Berek & Novak's Gynecology

2. Medical (Methotrexate)

• Indications: haemodynamically STABLE, unruptured, small (<3.5 cm) ectopic, β-hCG <5000 mIU/mL, no fetal cardiac activity, patient compliant for follow-up
• Mechanism: Folate antagonist - inhibits rapidly dividing trophoblast cells
• Contraindications: haemodynamic instability, ruptured ectopic, liver/renal disease, breastfeeding, immunocompromise

3. Expectant Management

• Only for selected stable patients with low/falling β-hCG and no cardiac activity

Rh Status

• If the patient is Rh-negative, administer anti-D immunoglobulin (RhoGAM) to prevent isoimmunisation

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STEP 9: DIAGNOSTIC ALGORITHM (Summary Flowchart Logic)

Positive β-hCG + Pain/Bleeding
        ↓
   Transvaginal Ultrasound
        ↓
IUP seen? → YES → Manage as threatened/incomplete abortion
        ↓ NO
Adnexal mass / free fluid? → YES → Ectopic pregnancy (likely)
        ↓ NO (indeterminate)
Serial β-hCG 48h later
        ↓
Rise ≥63% → Likely viable IUP, repeat USS
Fall or <53% rise → Ectopic or failed IUP → Manage accordingly

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STEP 10: KEY LEARNING POINTS (PBL Take-Home)

1. Any woman of reproductive age with pain + bleeding + amenorrhoea = rule out ectopic pregnancy first
2. Ectopic pregnancy is the leading cause of maternal death in the 1st trimester - treat as emergency
3. The classic triad (pain, amenorrhoea, bleeding) is present in only ~50% - high index of suspicion needed
4. β-hCG + TVUS are the diagnostic cornerstones
5. Dizziness and weakness in this patient = haemodynamic compromise = possible rupture
6. Rh status must always be checked in early pregnancy bleeding
7. Irregular cycles make LMP unreliable - always consider pregnancy even with vague history

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• Berek & Novak's Gynecology (Ectopic Pregnancy chapter, pp. 1757-1768)
• Roberts & Hedges' Clinical Procedures in Emergency Medicine (ectopic pregnancy, p. 4543-4589)
• Bailey & Love's Short Practice of Surgery 28th Edition (Chapter 87)
• Rosen's Emergency Medicine (Epidemiology, ectopic pregnancy)
• Textbook of Family Medicine 9e (Management of ectopic pregnancy)