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Antepartum haemorrhage (APH) is defined as genital tract bleeding from 24+0 weeks’ gestation and complicates 3-5% of pregnancies.1
The three most important causes of APH are placenta praevia, placental abruption and vasa praevia, these result in high morbidity and mortality for both mother and baby.
Other causes of APH include lower genital tract sources such as cervical polyps, vaginitis and cervicitis.
Placenta praevia occurs when the placenta lies in the lower uterine segment. It can lead to the complete or partial covering of the internal cervical os.
Placenta praevia increases the likelihood of APH due to poor attachment of the placenta to the uterine wall.
Figure 1 shows the classical grading of placenta praevia.
Placenta praevia can also be grouped into two subtypes:
Minor placenta praevia (grade 1 and 2): the placenta is low but does not cover the internal cervical os
Major placenta praevia (grade 3 and 4): placenta lies over the internal cervical os
Risk factors for placenta praevia include:2
Previous caesarean section
Previous termination of pregnancy
Advanced maternal age (over 40)
Deficient endometrium (e.g. due to manual removal of the placenta)
Typical symptoms of placenta praevia include:1
Painless vaginal bleeding
Light contractions may be present
Typical clinical findings in placenta praevia include:
Lie and presentation may be abnormal
Low lying placenta on 20-week anomaly scan
Relevant bedside investigations include:
Vital signs: respiratory rate, BP, oxygen saturations, pulse and temperature
Relevant laboratory investigations include:
Full blood count, urea and electrolytes and LFTs: helps to exclude hypertensive conditions such as HELLP or pre-eclampsia