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A 35-year-old woman (G3P2, 2 previous C-sections) at 32 weeks gestation presents with painless bright red vaginal bleeding. The bleeding was spontaneous, stopped after 20 minutes, and soaked 2 pads. On examination: uterus soft and non-tender, fetal heart 145 bpm, fetus in transverse lie.
Questions
a) What is the most likely diagnosis? (1 mark)
Placenta praevia: painless, causeless, bright red bleeding + soft non-tender uterus + normal fetal heart + abnormal lie (transverse) + risk factors (2 previous C-sections, age 35).
b) What investigation confirms the diagnosis? (1 mark)
Transvaginal ultrasound (TVS) — gold standard for placental localisation. Also assess for placenta accreta (previous C-section + praevia = high risk).
c) Why must you NOT perform a digital vaginal examination? (2 marks)
Digital vaginal examination can trigger catastrophic bleeding from the placental edge vessels by physically disrupting the placenta at or near the cervical os. It should only be performed in a "double setup" (theatre, anaesthetised, crossmatched blood, surgical team ready).
d) Outline your management plan for this patient. (4 marks)
- Admit to hospital (risk of recurrent heavier bleeding).
- Assess: ABC, IV access, FBC, Group and Save.
- Corticosteroids (betamethasone 12mg IM x2 doses 24h apart) for fetal lung maturation (32 weeks).
- Avoid strenuous activity, sexual intercourse, digital vaginal exam.
- Anti-D 250 IU IM if Rh-negative.
- Plan elective C-section at 37 to 38 weeks (major praevia with previous C-section scars).
- Assess for accreta: MRI/colour Doppler (2 previous C-sections = approximately 40% accreta risk).
e) What is the risk of placenta accreta in this patient and why? (2 marks)
Risk is approximately 40% (2 previous C-sections + praevia). Previous C-section scars cause defective decidualisation in the lower segment → trophoblast invades deeply into the myometrium (accreta/increta/percreta) → placenta cannot separate after delivery → may require hysterectomy. Plan multidisciplinary delivery (senior obstetrician, interventional radiology, blood bank).