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Answer
C) Positive feedback
The reflex described is the Ferguson reflex - a classic example of positive feedback:
- Fetal head stretches the cervix
- Stretch receptors send signals to the hypothalamus
- Posterior pituitary releases oxytocin
- Oxytocin causes stronger uterine contractions
- Stronger contractions push the fetal head further into the cervix
- This causes more cervical stretch → more oxytocin release
- The cycle amplifies itself until delivery (the stimulus is removed)
This is positive feedback because the output (uterine contraction) enhances the original stimulus (cervical stretch), creating a self-amplifying loop - the opposite of negative feedback which would dampen the response.
The other options are wrong because:
- A) Negative feedback - would reduce oxytocin when contractions increase (e.g., how temperature regulation works)
- B) Feed-forward control - anticipates a disturbance before it occurs (e.g., insulin release in anticipation of a meal)
- D) Adaptive control - adjusts the set-point over time based on experience
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Answer
B) Stage III, high-risk
Let me work through the FIGO staging and WHO prognostic scoring for this Gestational Trophoblastic Neoplasia (GTN) case:
FIGO Staging
| Stage | Definition |
|---|---|
| I | Confined to uterus |
| II | Extends outside uterus but limited to genital structures |
| III | Lung metastases (with or without genital involvement) |
| IV | All other distant metastases (liver, brain, etc.) |
This patient has lung metastases only → Stage III
WHO Prognostic Scoring (to determine low vs high risk)
| Factor | Score 0 | Score 1 | Score 2 | Score 4 |
|---|---|---|---|---|
| Age | <40 | ≥40 | - | - |
| Antecedent pregnancy | Mole | Abortion | Term | - |
| Interval (months) | <4 | 4-6 | 7-12 | >12 |
| β-hCG (mIU/mL) | <1,000 | 1,000-10,000 | 10,000-100,000 | >100,000 |
| Largest tumor (cm) | <3 | 3-4 | ≥5 | - |
| Site of metastases | Lung | Spleen/kidney | GI | Brain/liver |
| Number of metastases | 0 | 1-4 | 5-8 | >8 |
| Prior chemotherapy | - | - | Single drug | ≥2 drugs |
Scoring this patient:
- Antecedent pregnancy: complete mole = 0
- Interval: 3 months = 0
- β-hCG: 150,000 mIU/mL = 4
- Largest lesion: 2.5 cm = 1
- Site: lung = 0
- Number of metastases: 5 = 2
Total = 0 + 0 + 4 + 1 + 0 + 2 = 7
- Score ≤6 = Low risk
- Score ≥7 = High risk
Answer: B) Stage III, high-risk (WHO score = 7, threshold for high-risk is ≥7)
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Answer
A) Apley's test
The image shows the patient lying prone with the knee flexed to 90°, and the examiner applying downward compression + rotation to the foot/heel - this is the classic Apley's Grind (Compression) Test.
Apley's Test
Position: Patient prone, knee flexed to 90°
Two components:
- Apley's Compression test - examiner presses down on the heel while rotating (grinds menisci between femur and tibia) → pain = meniscal tear
- Apley's Distraction test - examiner lifts the heel while rotating → pain = ligament injury
Positive test: Pain/clicking on compression = meniscal pathology
Why not the others?
| Test | Position | What it tests |
|---|---|---|
| Lachman | Supine, knee 30° flexed, anterior tibial pull | ACL integrity |
| McMurray | Supine, knee fully flexed, then extended with rotation | Meniscal tear (different position) |
| Thessaly | Standing on one leg, knee at 20° flexion, rotating body | Meniscal tear (weight-bearing) |
Clinical correlation: This young man's knee locking + pain after football is classic for a meniscal tear. Apley's test is specifically designed to identify meniscal pathology, making it the most appropriate test shown here.
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Answer
D) Suitable for the detection of neural tube defects
CVS cannot detect neural tube defects - that is the FALSE statement.
Chorionic Villous Sampling (CVS) - Key Facts
Timing: 10-13 weeks gestation (first trimester) ✅ - makes option A TRUE
What CVS CAN detect:
| Condition | Why |
|---|---|
| Chromosomal abnormalities (Down syndrome, trisomies) | Karyotyping from chorionic villi ✅ |
| Inborn errors of metabolism (thalassemia, PKU, Gaucher's) | Enzyme assays / DNA analysis ✅ |
| Single gene disorders | DNA analysis ✅ |
What CVS CANNOT detect:
- Neural tube defects (anencephaly, spina bifida) ❌
- These require AFP (alpha-fetoprotein) in maternal serum or amniocentesis (AFP in amniotic fluid) + detailed ultrasound
Why this patient needs CVS
- 6 weeks pregnant (first trimester - ideal timing for CVS)
- Family history of thalassemia (an inborn error of metabolism/hemoglobinopathy)
- CVS can diagnose thalassemia through DNA analysis of fetal cells
- It gives results earlier than amniocentesis (done at 15-20 weeks)
Neural tube defects = amniocentesis + maternal serum AFP, NOT CVS
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Answer
A) AST and ALT levels >400 IU/L
This is the finding least consistent with alcoholic hepatitis.
Why AST/ALT >400 IU/L is WRONG for Alcoholic Hepatitis
In alcoholic hepatitis, transaminases are characteristically mildly-to-moderately elevated, typically:
- AST: 50-300 IU/L (rarely exceeds 300-400)
- ALT: even lower than AST
Very high transaminases (>400 IU/L) suggest other causes of liver injury:
- Viral hepatitis (AST/ALT can reach thousands)
- Ischemic hepatitis ("shock liver")
- Drug-induced liver injury (acetaminophen toxicity)
- Autoimmune hepatitis
What IS consistent with Alcoholic Hepatitis:
| Finding | Consistent? | Explanation |
|---|---|---|
| AST:ALT ratio >1.5 (often >2:1) | ✅ YES | Classic hallmark - alcohol depletes pyridoxal phosphate more for ALT synthesis; also mitochondrial AST release |
| Total bilirubin >3 mg/dL | ✅ YES | Reflects cholestasis and hepatocellular damage |
| Heavy alcohol >6 months, abstinence <2 months | ✅ YES | Defining clinical criterion for the diagnosis |
Key Rule to Remember:
In alcoholic hepatitis: AST:ALT > 2:1, but AST is usually <300 IU/L and almost never exceeds 400 IU/L
Values >400 should make you question the diagnosis and look for another etiology.
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