Ectopic Pregnancy: A Clinical Casebook

16. Intramural Pregnancy

Maria Memtsa  and Davor Jurkovic1, 2  

(1)

Department of Obstetrics and Gynecology, University College Hospital, London, UK

(2)

Gynaecology Diagnostic and Outpatient Treatment Unit,, University College Hospital, Lower Ground Floor, Elizabeth Garrett Anderson Wing, 235 Euston Road, NW1 2BU London, UK

Maria Memtsa

Email: davor.jurkovic@nhs.net

Davor Jurkovic (Corresponding author)

Email: davor.jurkovic@nhs.net

Keywords

Ectopic pregnancyIntramural pregnancyUltrasoundMethotrexate

Case Study

A 41-year-old woman, gravida 3 para 0, presented to our early pregnancy assessment unit at 7 weeks’ gestation. She had two early miscarriages in the past. One of them resolved spontaneously while the second one required surgical management. Three years prior to this pregnancy, she had undergone a laparoscopic myomectomy for a right fundal Type II submucous fibroid. There was nothing else of note in her past medical and surgical history.

She was asymptomatic at presentation and she was generally well. On transvaginal ultrasound scan, the uterus appeared grossly normal, but the uterine cavity was severely distorted and the endometrium could only be clearly seen in the central and in the left upper aspects of the cavity. A gestational sac containing a 6.2-mm live embryo was seen in the right upper aspect of the uterus (Fig. 16.1a). The gestational sac was completely separated from the endometrial cavity by a thick layer of myometrium. There was no evidence of decidual reaction in the vicinity of the gestational sac. Although both interstitial segments of the Fallopian tubes were clearly seen, the endometrium in the right upper aspect of the cavity was impossible to delineate. These findings were suggestive of a complete intramural pregnancy .

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Fig. 16.1

a A transverse section of the uterus showing an empty uterine cavity (UC) on the left. The gestational sac containing an embryo (E) is seen on the right. Note the absence of decidual reaction in the vicinity of the sac (arrow). b A three-dimensional scan image after the completion of the treatment showing the uterus in the coronal plane. Note the absence of the endometrium in the right aspect of the uterus between the remaining functional cavity (UC) and the right interstitial tube (arrow)

The crown–rump length was small for her gestational dates and the embryo was bradycardic. Although these findings indicated that the pregnancy was likely to fail, she was advised that it would be best to start treatment without any delay. In view of the location of pregnancy, surgical treatment would have been very difficult as the gestational sac was not accessible transcervically. Transabdominal approach would have carried a risk of additional injury to the uterine muscle and incomplete removal of the pregnancy. After discussion, she opted for medical treatment with methotrexate . Her full blood count, clotting screen, liver, and renal function tests were all normal. Her serum β-human chorionic gonadotropin (β-hCG) was 35,119 IU/l.

My Management

A.

B.

C.

D.

E.

F.

Diagnosis and Assessment

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 [23]. 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 [56]. 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:

·               Gestational sac/products of conception located above the internal os and medial to the interstitial portion of the Fallopian tube

·               Evidence of trophoblast breaching the endometrial/myometrial junction (for partial intramural pregnancy) or completely surrounded by myometrium (in complete intramural pregnancy)

·               Lack of decidual reaction adjacent to the trophoblast

·               Evidence of increased peri-trophoblastic blood flow on colour Doppler examination

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 [14].

The decision to terminate the pregnancy was made easier in this case by the findings which were highly suggestive of an abnormal pregnancy. If the pregnancy was normal, the patient could have considered expectant management. This would, however, almost certainly result in the placenta being abnormally adherent and the patient would probably require a hysterectomy at the time of delivery. As discussed previously, there would have also been a risk of uterine rupture and massive hemorrhage.

Conservative and medical management was considered, since the pregnancy was not amenable to transcervical resection. Local injection of methotrexate under ultrasound guidance was offered and accepted, given the fact that the pregnancy was not developing normally. Methotrexate arrests the development of pregnancy and facilitates recovery. Intramural pregnancy occasionally presents as a life-threatening condition, which requires immediate surgical treatment. Our patient was asymptomatic and we were able to offer her a choice of different management options. Treatment was proved to be successful and the uterus was preserved. However, the right side of the uterine cavity remained obliterated as the result of her previous uterine surgery.

Management

The patient was booked for transvaginal local injection of methotrexate . The procedure was carried out in the outpatient setting. She was given ibuprofen 400 mg and co-amoxiclav 625 mg orally 30 min prior to the procedure. The gestational sac was punctured transvaginally under continuous ultrasound guidance using a 33-cm 18 G needle. The tip of the needle was placed inside the chest of the embryo and negative pressure was applied until the cardiac activity ceased. The needle was then withdrawn into the coelomic cavity and 1.5 ml of coelomic fluid was aspirated. Following that 25 mg of methotrexate was injected into the gestational sac. The patient experienced only minimal discomfort during the injection and she was allowed to go home an hour after the procedure had been completed.

Following the procedure, the patient remained well and she was attending regular follow-up visits. Her serum β-hCG declined steadily and it became undetectable 6 weeks after the initiation of treatment. The gestational sac initially decreased in size, but then it became larger due to the extensive degenerative changes to reach the peak diameter at 7 weeks after the injection. Subsequently, the sac started to decrease again and after 8 months it was completely resolved (Fig. 16.2).

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Fig. 16.2

A graph showing changes in the size of the intramural pregnancy and serum β-hCG levels following the local injection with methotrexate. β-human chorionic gonadotropin (β-hCG)

Outcome

She experienced irregular vaginal bleeding initially, but her normal menstrual cycle had resumed after 2 months the injection of methotrexate. At her 12th month follow-up visit, the right side of the endometrial cavity remained obliterated with adhesions. The interstitial portion of the right tube, however, appeared normal (Fig. 16.1b). She was planning another pregnancy and she was offered a laparoscopic right salpingectomy to prevent a recurrent intramural ectopic pregnancy.

Clinical Pearls/Pitfalls

·               Women with intramural pregnancies can present with a variety of symptoms from asymptomatic to shock due to uterine rupture and intra-abdominal hemorrhage.

·               The diagnosis is difficult due to its variable location within the uterus and different degrees of myometrial involvement.

·               The diagnosis is usually made on ultrasound scan. Three-dimensional ultrasound provides clear views of the endometrial–myometrial junction which may be helpful in difficult cases.

·               Intramural pregnancy should be differentiated from cervical and caesarean scar pregnancies.

·               Treatment options include dilatation and curettage under ultrasound guidance, local or systemic treatment with uterine artery embolization.

·               Intramural pregnancies may progress into the third trimester and result in a live birth; however, there is a risk of uterine rupture and hysterectomy due to abnormally adherent placenta.

·               Intramural pregnancy occasionally presents as a life-threatening condition which requires immediate surgical treatment.

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