Cervical ectopic pregnancy

Clinical History

A 31-year-old woman of oriental origin presented to the casualty ward with a two-week history of pelvic pain and vaginal bleeding.

Imaging Findings

The patient had a termination of pregnancy 6 years ago and was known to have subfertility. She had received no treatment for this and had an unremarkable past medical history. According to her last menstrual period, she was six weeks pregnant, and this was confirmed on doing a serum human chorionic gonadotrophin assay. A transvaginal sonography done showed an empty uterus with an irregular gestational sac containing a yolk sac and foetal pole, adjacent to the uterus. A foetal heartbeat was identified, and the crown rump length of the embryo was 6 mm, consistent with a 7-week gestation. The patient’s plasma HCG was over 41,000 at this time, but later rose to over 130,000. Due to the uncertainty of the location of the ectopic pregnancy, an MRI was performed which demarcated a heterogeneous mass that appeared to be lying low within the anterior wall of the cervical canal. The patient had by this time become anaemic, requiring a 4-unit blood transfusion, as the haemoglobin was just 6.2 g/dl. The transvaginal sonography was repeated, which confirmed the cervical location. Using sonographic guidance, 2 mls of amniotic fluid was aspirated from the sac, and then 2mls (50mg) of methotrexate injected intra-amniotically. No complication occurred, and termination was later confirmed on doing a sequential HCG analysis and a follow-up ultrasound scan.

Discussion

The clinical findings of an empty uterus with an irregular gestational sac containing a yolk sac and a foetal pole seen on transvaginal sonography, and confirmed on MRI to be within the cervical canal, is consistent with a cervical ectopic pregnancy. This was treated by sonographic-guided methotrexate instillation. It is known that cervical ectopic pregnancy, although consisting of less than 1% of all ectopic pregnancies, can be life threatening. The incidence is now as low as 1 in 2400 in the USA, but has a substantial geographical variation. It has an increasing incidence in certain parts of the world, largely due to the increased use of assisted fertility techniques but also due to the growing incidence of pelvic inflammatory disease. The exact aetiology has yet to be determined, although previous cervical instrumentation is a predisposing factor (1, 2). Clinically, the presentation is with painless vaginal bleeding following secondary amenorrhoea, but abdominal pain, dysuria and fever are commonly present. On examination, a hyperaemic cervix with a partially open external os may be seen, with products of conception being present within the cervical canal. The uterus and adnexae are usually found to be normal. On developing abortion, early placenta previa and cervical neoplasia may all be difficult to exclude clinically. Cervical pregnancy is defined as an embryo implanting below the level of the internal os, and is traditionally diagnosed by an elevated human chorionic gonadotrophin level and by using transvaginal ultrasound. A gestational sac is identified within the cervix and is seen to have a well-formed spherical or ovoid shape, which is especially prominent if it contains a yolk sac or embryo. This needs to be distinguished from a cervical abortion that is in progress, which would appear as a flattened sac with no recognisable contents (3). However, this distinction can be difficult and a follow-up sonography at an interval of at least 24 hours may be useful. Some cases may still remain equivocal and will need a prompt diagnosis to be made to reduce the risk of a catastrophic haemorrhage, and an MRI may show characteristic findings. MR may also be useful in distinguishing a cervical ectopic pregnancy from certain cases of gestational trophoblastic disease, cervical carcinoma and placenta previa. Typical MR findings are a heterogeneous haemorrhagic mass with an irregular border. Internally, there is variable signal intensity representing different stages of haemorrhage, with a low signal seen peripherally on T2-weighted images. Following contrast administration, there is an intense enhancement of internal solid components and possibly also the edge. The latter is more variable as this low signal region may just represent haemosiderin from a previous haemorrhage (4). Parametrial vascularity, pelvic-free fluid and ovarian abnormalities if seen are not specific. An absence of pelvic-free fluid would not be surprising in a lesion entirely confined to the cervix. The major goal of conservative management is to preserve the uterus and hence fertility, though there is no universally accepted therapeutic approach. Transvaginal sonographic-guided treatments avoid the deficiencies of systemic methotrexate administration and also the risks associated with surgical intervention. These involve intra-amniotic or intrafoetal injection of usually KCl or methotrexate, though there is no accepted standard (3, 5). Prognostically, however, all conservative treatments are more efficacious the earlier the diagnosisis made.

Differential Diagnosis List

Final Diagnosis

Cervical ectopic pregnancy.

URL:	https://www.eurorad.org/case/3234
DOI:	10.1594/EURORAD/CASE.3234
ISSN:	1563-4086