Department of Obstetrics and Gynaecology, Kwong Wah Hospital, 25 Waterloo Road, Kowloon, Hong Kong SAR, China.

Case report

This is a case of a 35-year-old woman, G5 P0 A4 , who was admitted to our gynaecological emergency unit with vaginal bleeding and 6 weeks amenorrhoea.

Her personal history included 2 spontaneus abortions in the 1 st trimester and 2 ectopic tubal pregnancies. Both tubal pregnancies were surgically treated via laparoscopy.

On admission, vaginal examination revealed a closed cervical os with no vaginal bleeding. The uterus was anteverted and bulky in size. Conventional transvaginal 2D-ultrasound on admission showed a 0.5 cm gestation sac-like structure at the isthmic portion of the uterus. Inside the sac was a small fetal pole without detected heart rate. The admission diagnosis was missed abortion.

Patient was rescanned in 2 weeks and ultrasound exam revealed a gestation sac with the fetus, CRL corresponded with 7 weeks of gestation. The gestational sac was located in the cervical portion of the uterus. 3D-ultrasound (multi-planar and render mode) was employed to demonstrate the cervical pregnancy for better patient counseling.

The patient was treated with a single dose of intramuscular injection of methotrexate (50mg/m²). The pre-treatment plasma beta-hCG level was 5344 IU/ml and was decreased to 3 IU/ml 8 weeks after treatment. Patient had her period 16 weeks after treatment. There were no maternal complications.

Images 1-4: 7 weeks, images show gestational sac with the fetus located in the cervix.

Videos 1,2: Video 1 shows the sagittal view of the uterus with the cervical pregnancy, uterine cavity has high endometrium but no sign of pregnancy within the cavity. Video 2 is using power Doppler to demonstrate the vascularization around the gestational sac, peri-trophoblastic flow.

Discussion

This article presents a case of cervical pregnancy diagnosed by transvaginal 2D and 3D ultrasound. Cervical pregnancy is a rare condition characterized by implantation of a fertilized ovum in the endocervical canal below the internal cervical os. It's incidence is less than 0.1% of all ectopic pregnancies [1]. It is a crucial to differentiate between cervical pregnancy and isthmic pregnancy for prognostic reasons. Cervical pregnancy is not compatible with viable pregnancy but an isthmic pregnancy can reach viability and term. Diagnosis of cervical pregnancy is based on clinical and ultrasonographic findings, but it's differentiation from the isthmic pregnancy remains a challenge. The main sonographic criteria for diagnosis of cervical pregnancy are as follows [2]: 

• Gestational sac within the cervix
• Empty uterine cavity
• Dilated cervix
• Normal uterine size 

Three-dimensional ultrasound with or without power Doppler imaging has been described as an useful tool in confirming the diagnosis of the cervical pregnancy [5,6].

References:

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2. Ushakov FB, Elchalal U, Aceman PJ, Schenker JG. Cervical pregnancy: past and future. Obstet Gynecol Surv. 1997;52:45-59.

3. Jurkovic D, Hacket E, Campbell S. Diagnosis and treatment of early cervical pregnancy: a review and a report of two cases treated conservatively. Ultrasound Obstet Gynecol 1996; 8: 373-80.

4. Timor-Tritsch IE, Monteagudo A, Mandeville EO et al. Successful management of viable cervical pregnancy by local injection of methotrexate guided by transvaginal ultrasonography. Am J Obstet Gynecol 1994; 170: 737–739.

5. Su YN, Shih JC, Chiu WH, Lee CN, Cheng WF, Hsieh FJ. Cervical pregnancy: assessment with three dimensional power Doppler imaging and successful management with selective uterine artery embolization. Ultrasound Obstet Gynecol. 1999; 14:284-7.

6. Ruano R, Reya, F, Picone O, Chopin N, Pereira PP, Benachi A, Zugaib M. Three-dimensional ultrasonographic diagnosis of a cervical pregnancy. Clinics 2006;61 (4):355-8.