Threatened Miscarriage

Vaginal bleeding before 24 weeks with a closed cervical os and a confirmed viable intrauterine pregnancy (cardiac activity present) on ultrasound.

Occurs in up to 20 to 25% of pregnancies, and the majority continue successfully.

Light to moderate vaginal bleeding, with or without mild cramping. The cervix is closed on examination and uterine size is appropriate for gestational age.

Transvaginal ultrasound confirming an intrauterine pregnancy with fetal cardiac activity.

Any woman presenting with bleeding and pain should have ectopic pregnancy actively excluded as part of the same assessment (see that entry).

• Reassurance; bed rest has no proven benefit and is not routinely recommended
• Vaginal micronized progesterone 400 mg PO/PV bd is considered specifically in women with a threatened miscarriage AND a history of one or more previous miscarriages (subgroup benefit shown in the PRISM trial), continued until around 16 weeks if used
• Anti-D prophylaxis considered for Rh negative women with heavy bleeding or pain after 12 weeks
• Safety net advice: return if bleeding worsens, pain increases significantly, or tissue is passed; repeat scan if bleeding persists

Referral: early pregnancy unit; obstetric review for recurrent or persistent bleeding.