About

CSP is a rare form of ectopic pregnancy where the gestational sac, villi, and placenta are wholly or partially implanted in the myometrium of a previous scar. The incidence of CSP has been reported as approximately 1:2,000 of all pregnancies.

CSP is likely a precursor to, and shares common histology with, placenta accreta spectrum (PAS). The two conditions may represent a continuum of the same disease, with CSP being a diagnosis of the first (and early second) trimester, and PAS being diagnosed later in pregnancy (second trimester and beyond). Like PAS, the rate of CSP parallels that of cesarean birth and is expected to rise as the rate of cesarean birth increases and as the diagnostic accuracy of imaging for CSP improves.

By contrast, CSP is distinct from ectopic pregnancy as CSP occurs within uterine cavity and can result in a live born infant, which rarely, if ever, occurs in an ectopic pregnancy. Thus, treatments appropriate for ectopic pregnancy should not be used indiscriminately to treat or manage CSP.

Cesarean Scar Pregnancy (CSP)—Up todate

What type of CSP patients is particularly well suited for HIFU?

Patients with short gestational age and small gestational sac.

How does HIFU work for cesarean scar pregnancy (the advantages)? 

HIFU is a non-invasive technique that has properties of safety, effectiveness, precision, no radioactive damage, and less pain. These properties have allowed HIFU to obtain increasing attention from obstetrics and gynecology, which have requirements of retaining the organ and function integrity. It was deduced that HIFU causes a sufficient local rise in temperature that causes necrosis (60°C) of the gestational sac without damaging the surrounding or overlying tissues, achieving the goal of non-invasive treatment, and avoiding surgical damage. 

Clinical evidence

According to A Retrospective Analysis of the Treatment of Cesarean Scar Pregnancy by High-Intensity Focused Ultrasound, Uterine Artery Embolization and Surgery, CSP patients with short days of gestational age and a small gestational sac can be treated with HIFU. HIFU can be considered as an adjuvant therapy before laparoscopy, hysteroscopy, or hysteroscopy–laparoscopic in order to reduce intraoperative bleeding and increase the safety of the surgery.

Cases for CSP treatment

Fig.1 Real-time monitoring ultrasound images obtained from a patient with CSP before and after HIFU.

Notes: (A): Pre-HIFU ultrasound image showed a gestational sac (red arrow) embedding in the CSP scar; (B): Real-time ultrasound image showed the significant gray scale change (red arrow) in the embedding area of the CSP scar immediately after HIFU treatment.

Fig.2 Contrast-enhanced ultrasound obtained from a patient treated with HIFU. 

Notes: (A): abundant blood supply in myometrium of CSP scar (white arrow) around gestational sac before HIFU ablation; (B): significantly reduced blood supply in myometrium of CSP scar (white arrow) around gestational sac after HIFU ablation.