Intramural pregnancy represents a rare form of ectopic pregnancy [1]. It is characterized by the presence of trophoblastic tissue beyond the endometrial/myometrial junction and the conceptus is partially or completely located within the myometrium [2, 3]. Some women with early intramural pregnancies are asymptomatic, but the condition may also present with a variety of symptoms, ranging from mild vaginal bleeding and pain [4] to maternal collapse due to uterine rupture and intra-abdominal hemorrhage [5]. The etiology is unknown; however, it has been suggested that previous surgical trauma to the uterine body may lead to the formation of myometrial defects that enable intramural implantation [5, 6]. Intramural pregnancies have also been described within foci of adenomyosis [7].

Intramural pregnancy is difficult to diagnose due to its variable location within the uterus and different degrees of myometrial involvement. The diagnosis was made on ultrasound scan; magnetic resonance imaging (MRI) was not used to confirm the diagnosis, as experienced ultrasound operators are usually able to reach the diagnosis without additional imaging [4]. Three-dimensional ultrasound provides clear views of the endometrial–myometrial junction which may be helpful in difficult cases [8].

The following set of criteria [4] has been proposed in order to make the ultrasonographic diagnosis of intramural pregnancy:

Intramural pregnancy should be differentiated from cervical and caesarean scar pregnancies, which are also characterized by trophoblastic invasion of the myometrium [9]. These types of ectopic pregnancy represent a distinct subgroup of ectopic pregnancies since they are located at or below the internal os, caused by iatrogenic trauma to the uterine body and they follow a similar clinical course [10]. Intramural pregnancies should not be confused with interstitial pregnancies either, which are implanted in the interstitial portion of the Fallopian tube. It is essential to visualize the proximal segment of the interstitial tube adjoining the uterine cavity and the gestational sac in order to reach the correct diagnosis of interstitial ectopic pregnancy [11]. The differential diagnosis of intramural pregnancy includes invasive gestational trophoblastic disease, which may present with vascular foci deep inside the myometrium [12].

The clinical course and management of intramural pregnancy depends on the location of the pregnancy, the degree of myometrial invasion, gestational age at the time of diagnosis, viability and whether it is a wanted pregnancy [4]. Partial intramural pregnancies can be accessed vaginally via dilatation and curettage; however, the procedure should be performed under ultrasound guidance to ensure complete evacuation of the tissue as well as to minimize the risk of uterine perforation [4]. In cases of complete intramural pregnancies, when the sac is not accessible transcervically, local or systemic treatment with methotrexate can be used [11]. Uterine artery embolization has also been described in successfully treating intramural pregnancy [13]. Intramural pregnancies may progress into the third trimester and result in a live birth [5]; however, asymptomatic women who present with a viable ongoing wanted pregnancy need to be informed of the risk of uterine rupture and hysterectomy due to abnormally adherent placenta [1, 4].