SBA — Single Best Answer · Review
Question 174
Delivery suite → Haemorrhage
Classification
Question
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A woman at 34 weeks has painful APH and uterine tenderness. Ultrasound demonstrates a retroplacental collection. In another woman with an almost identical presentation, ultrasound is normal. Which statement best explains how these results should alter diagnostic reasoning?
Question Stem
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Options
A
A normal ultrasound excludes abruption more reliably than an abnormal ultrasound supports it
B
Because ultrasound has poor sensitivity but high specificity, demonstration of a retroplacental clot supports abruption, whereas its absence does not reliably exclude it
C
Ultrasound findings should be disregarded in both women because abruption is exclusively a histological diagnosis
D
Both women require repeat ultrasound before a clinical diagnosis can be made
E
The normal scan excludes clinically significant abruption provided CTG is reassuring
Explanation
This question requires application of diagnostic-test characteristics. Ultrasound has poor sensitivity for detecting retroplacental clot in placental abruption, meaning false-negative scans are common. Its specificity is considerably higher, so a positive finding can support the clinical diagnosis. The asymmetry is crucial: positive imaging may strengthen suspicion, but negative imaging cannot safely rule out abruption. Clinical assessment remains central in both women.
Option Validity
A) Poor sensitivity makes a negative ultrasound relatively weak evidence against abruption.
C) Ultrasound findings can contribute useful evidence even though abruption remains primarily a clinical diagnosis.
D) Repeat imaging is not required before acting on a convincing clinical presentation.
E) Neither a normal scan nor initially reassuring fetal assessment reliably excludes abruption.
Further Reading
RCOG Green-top Guideline No. 63. Antepartum Haemorrhage. Royal College of Obstetricians and Gynaecologists; 2011.