Pregnancies located below the internal os cervical and Caesarean scar ectopics

Cervical pregnancy is defined as the implantation of the conceptus within the cervix, below the level of the internal os. Caesarean scar pregnancy is a novel entity, which refers to a pregnancy implanted into a deficient uterine scar following previous lower segment Caesarean section [48]. Prior to the introduction of high resolution transvaginal scanning, the distinction between cervical and Caesarean section scar pregnancies was not possible. In older literature 33% of 'cervical' pregnancies occurred in women with a history of previous Caesarean section, which indicates that scar pregnancies probably account for a significant number of ectopics below the level of the internal os [49].

The common characteristic of both cervical and Cae-sarean scar pregnancies is their implantation into myome-trial defects following previous intrauterine surgery (Fig. 14.8). In case of cervical pregnancy the implantation

Caesarean Scar Pregnancy
Fig. 14.8 A 7 weeks' Caesarean scar pregnancy with the gestational sac herniating into the myometrial defect.

is usually into the false passage which occurred during previous attempts at cervical dilatation. As a result of myometrial involvement surgical evacuation of cervical or Caesarean ectopics often results in serious haemorrhage. The bleeding tends to be more severe with increasing gestation. Pregnancies below the internal os are often viable and it is not unusual for Caesarean ectopics to progress to full term. In these cases women usually develop placenta praevia/accreta, which is often complicated by severe post-partum haemorrhage and peri-partum hysterectomy [50].

An attempt to remove cervical or Caesarean section pregnancy is likely to cause severe vaginal bleeding and hysterectomy rates of 40% have been described when a D&C was attempted without pre-operative diagnosis of cervical pregnancy [51]. Various additional methods directed at reducing the bleeding from the implantation site have been used in conjunction with D&C. They include: insertion of a Foley catheter into the cervix, intrac-ervical vasopressin injection, cervical Shirodkar cerclage, transvaginal ligation of the cervical branches of uterine arteries or angiographic uterine artery embolization. The use of any of these methods in adjunction with D&C reduces the risk of hysterectomy to <5% (Fig. 14.9).

Similar to other types of ectopic pregnancy medical treatment with methotrexate or expectant management can be used in smaller non-viable cervical pregnancies. Although conservative management is successful in some cases, it is associated with prolonged vaginal bleeding which may last for many months and there is also a risk of infection and sepsis. For these reasons surgery should be used in preference for cervical/Caesarean scar ectopic except in very small cases on non-viable pregnancies which can be managed expectantly [52].

Types Uterine Caesarean
Fig. 14.9 An anterior myometrial defect is clearly visible following evacuation of a Caesarean pregnancy.

The risk of recurrence of cervical/Caesarean ectopic is low, and provided the next pregnancy is located normally within the uterine cavity, it is likely to be uncomplicated.

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