Caesarean scar pregnancy

Definition

Caesarean scar pregnancy

• Definition: implantation of the gestational sac in the caesarean scar of the lower uterine segment.
• Ultrasound: an empty cavity and empty cervical canal, the sac in the scar, thin myometrium towards the bladder.
• Danger: massive haemorrhage and uterine rupture as it grows, progression to placenta accreta spectrum.

• Caesarean scar pregnancy is an ectopic pregnancy in which the conceptus implants in the muscle or fibrous tissue of the scar after a previous caesarean section.

Classification

• Following Vial, two types are distinguished: in the first, the pregnancy implanted in the scar develops towards the isthmus and uterine cavity, with a high risk of massive bleeding from the implantation site; in the second, it implants deeply in a damaged scar and leads to uterine rupture and haemorrhage in the first trimester.

Occurrence & epidemiology

Epidemiology

• Its frequency is about 1 in 1,800 to 1 in 2,226 of all pregnancies; after caesarean section it is about 0.15% and accounts for 6.1% of ectopic pregnancies in women with at least one previous caesarean section.
• With rising caesarean section rates and better transvaginal ultrasound it is diagnosed increasingly often.

Clinical features

Clinical features and complications

• Initially it is often asymptomatic; the leading sign is vaginal bleeding without pain.
• Complications include uterine rupture, haemorrhage, coagulation disorders and even maternal death.

Diagnosis

• Typical findings are an empty uterine cavity and cervical canal, a gestational sac or placenta in the caesarean scar, a very thin myometrial layer towards the bladder (about 1–3 to 4.6 mm) and marked vascularity around the scar.
• Colour Doppler shows flow with a peak systolic velocity above 20 cm/s and a pulsatility index below 1; the sliding sign is negative.
• 3D ultrasound and MRI demonstrate the relationship of the sac to the bladder.

Keep learning in the app

Further reading (selection)

1. StatPearls: Ectopic Pregnancy (NCBI Bookshelf)
2. DocCheck Flexikon, Isthmozele

Cross-references