Cesarean scar pregnancy is a precursor of morbidly adherent placenta.

Objective: To provide further sonographic, clinical and histological evidence that Cesarean scar pregnancy (CSP) is a precursor to and an early form of second- and third-trimester morbidly adherent placenta (MAP).

Methods: This is a report of 10 cases of CSP identified early, in which the patients decided to continue the pregnancy, following counseling that emphasized the possibility of both significant pregnancy complications and a need for hysterectomy. Pregnancies were followed at 2-4-week intervals with ultrasound scans and customary monitoring. The aim was for patients to reach near term or term and then undergo elective Cesarean delivery and, if necessary, hysterectomy. Charts, ultrasound images, operative reports and histopathological examinations of the placentae were reviewed.

Results: The ultrasound diagnosis of CSP was made before 10 weeks. By the second trimester, all patients exhibited sonographic signs of MAP. Nine of the 10 patients delivered liveborn neonates between 32 and 37 weeks. In the tenth pregnancy, progressive shortening of the cervix and intractable vaginal bleeding prompted termination, with hysterectomy, at 20 weeks. Two other patients in the cohort had antepartum complications (bleeding at 33 weeks in one case and contractions at 32 weeks in the other). All patients underwent hysterectomy at the time of Cesarean delivery, with total blood loss ranging from 300 to 6000 mL. Placenta percreta was the histopathological diagnosis in all 10 cases.

Conclusion: The cases in this series validate the hypothesis that CSP is a precursor of MAP, both sharing the same histopathology. Our findings provide evidence that can be used to counsel patients with CSP, to enable them to make an informed choice between first-trimester termination and continuation of the pregnancy, with its risk of premature delivery and loss of uterus and fertility.