Diagnosing caesarean scar pregnancy with transvaginal ultrasound

Alex Rourke, Radiology Nottingham University Hospitals


Caesarean scar pregnancy (CSP) is the implantation of a pregnancy in a hysterotomy scar. The prevalence is low and the diagnosis is challenging, with 13% of reported cases misdiagnosed (Timor-Tritsch et al, 2016). Misdiagnosis is significant as untreated CSPs can result in serious complications.

In 2016 the RCOG published criteria for diagnosing CSP using transvaginal ultrasound. However, these criteria were derived from descriptive studies. A literature review will therefore be conducted to identify the evidence base for diagnosing CSP and evaluate the RCOG’s guidelines.


A literature review was conducted with a carefully considered search strategy. Key words from the title were enhanced and used as search terms in high quality healthcare databases. The results were assessed against inclusion and exclusion criteria, leaving three articles for critical appraisal.


  1. Timor-Tritsch et al’s (2012) study described seven imaging features for diagnosing CSP with TVUS. These support the RCOG’s diagnostic criteria. However, a small number of cases (n=26) were used. Also, the study’s conclusions came from practical experience rather than tested evidence.
  2. Buresch et al (2014) described six ultrasound markers that also support the RCOG’s criteria. However, again these recommendations are based on the experience of the authors and not a trial.
  3. Timor-Tritsch et al (2016) found an accurate method for diagnosing CSP by assessing the location of the gestation sac relative to the midpoint of the uterus. This was not described by the RCOG.


The literature review showed that the RCOG’s diagnostic criteria are supported by current research evidence and can be used in local practice.

However, research based on large scale studies of accuracy was not found. This means that while the results of the literature review agree with the RCOG, validated evidence to support the diagnosis of CSP with TVUS is still lacking.

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