Caesarean scar pregnancy: time to explore indications of the caesarean sections?

A retrospective study was conducted in women with history of a caesarean scar pregnancy (CSP) to explore the possible causative mechanisms. Over a period of 40 months, a total of 16,926 deliveries and 3554 caesarean sections (CS) occurred in our hospital. Nine cases of CSP were identified at an incidence of 1:1880 births and 0.25% of all CS. Analysis of the indications of the previous CS revealed that 88.8% of women with known indication had undergone CS without labour. Out of them, 75% underwent CS at preterm gestation and 25% had term elective procedure for breech presentation. Of the patients, 77.7% had multiple CS. Conservation of the uterus was possible in 77.7% of patients utilising non-radical forms of treatment. As most of the women underwent CS with a non-contractile uterus without labour, we believe that the risk of CSP may be related to the indications of the previous CS as the number of CS alone could not explain the occurrence of CSP. It is time to explore this area so that screening strategies can be developed to detect CSP at the earliest possible gestation and to prevent life-threatening complications such as uterine rupture and severe hemorrhage. Impact statement What is already known on this subject? A caesarean scar pregnancy (CSP) is a life-threatening condition that can result in uterine rupture and in severe haemorrhage. Although the diagnostic criteria for the CSP have been established, the risk factors that favour the condition are not well understood. We know that the incomplete healing of the lower uterine segment (LUS) from poor vascularisation can create a microscopic dehiscent tract through which the blastocyst enters the myometrium. Some have postulated that the healing processes following the elective procedures, such as for breech deliveries performed in a non-developed LUS, might facilitate this process. What do the results of this study add? In this study, analysis of the indications of the previous CS revealed that majority of women with a known indication had undergone CS without labour, either at preterm gestation or term elective procedure for breech presentation. We have postulated the possible causative mechanisms in relation to the physiology of LUS development. To the best of our knowledge, this is the first study that has looked specifically at the relationship between the indications of previous CS and CSP. What are the implications of these findings for clinical practice and/or further research? Further studies exploring the indications of the previous CS are recommended so that early first-trimester screening strategies can be generated towards this subgroup of patients to detect CSP at the earliest possible gestation.