Development of the utero-placental circulation in cesarean scar pregnancies: a case-control study

Cesarean scar pregnancy with expectant management

“…Jauniaux et al believed that during the first trimester of pregnancy, the tip of the spiral arteries could be blocked by the extravillous trophoblast plugs in normal intrauterine pregnancies, which could prevent the free and continuous flow of maternal blood throughout the villi space of the ultimate placenta. However, for CSP patients, the permanent loss of the MT in the scar area, coupled with a reduction in spiral arteries, may result in direct contact between the anchoring villi of the primitive placenta in CSP and large‐diameter arteries of the outer uterine wall, which leads to a rapid increase in blood flow around the gestational sac in the first trimester 22 . Therefore, it is believed that the thinner myometrial in the scar area is associated with more significant changes in the structure of the uterine wall.…”

“…However, for CSP patients, the permanent loss of the MT in the scar area, coupled with a reduction in spiral arteries, may result in direct contact between the anchoring villi of the primitive placenta in CSP and largediameter arteries of the outer uterine wall, which leads to a rapid increase in blood flow around the gestational sac in the first trimester. 22 Therefore, it is believed that the thinner myometrial in the scar area is associated with more significant changes in the structure of the uterine wall. Moreover, the rapid increase in blood flow around the gestational sac is more significant, which may increase the occurrence of intraoperative hemorrhage.…”

Debunking 20th century myths and legends about the diagnosis of placenta accreta spectrum

“…In addition, the definition of what constitutes subplacental or uterovesical 'hypervacularity' in the second half of pregnancy remains elusive and there is currently no vascularity score to assess relative degrees in uteroplacental vasculature changes associated with PAS. Placental lacunae have been reported from 11-14 weeks in pregnancies with confirmed PAS at birth [36][37][38][39] . However, differences between placental lacunae and placental lakes are not always clear (Figure 4) and not all cases of PAS present with lacunae.…”

A Cesarean scar pregnancy is not an ectopic pregnancy

“…It is true that most such pregnancies carry a serious risk and the obstetric performance of patients with CSP is poor. In a fairly representative observational study by Jauniaux et al 20 , nearly 50% of CSPs presented as a missed miscarriage and, in women who decided to continue the CSP, around half (55%) who carried it into the third trimester developed placenta accreta spectrum, a now well-described outcome of CSP 21,22 . Increasingly, lately, CSPs are studied, treated and their statistics reported not as a gynecological entity, in the category of 'ectopic pregnancy', but rather as an obstetric one.…”