M ZEGHIDI 1 , Y MTAALAH 1 , F AMIRA 1 , C MBARK 2 , H OUESLATI 2 , S BOUSSETTA 1

1. ENCYSTED HEMATOCELE COMPLICATING CHRONIC ECTOPIC PREGNANCY: CONTRIBUTION OF MAGNETIC RESONANCE IMAGING (MRI) M ZEGHIDI1, Y MTAALAH1, F AMIRA1, C MBARK2, H OUESLATI2, S BOUSSETTA1 Department of Radiology1 and of gynecology2, Regional Hospital of Ben Arous OB1

2. Objectives Chronic ectopic pregnancy is an unusual situation in which the βhCG value can be low or negative. Sonography could not disclose final diagnosis. If in doubt, MRI is the investigation of choice for the assessment of pelvic masses, particularly for extra-ovarian masses as hematocele.

3. Materiels and methods We report the MRI features of five cases of chronic ectopic pregnancy with encysted hematocele. The mean overall age was 33 year-old.Their main complaints consisted in meno-metrorrhagia, subacute abdominal or pelvic pain. Pregnancy tests were positive but low in four cases and negative in one case.

4. Intrauterine pregnancy was denied with transvaginalsonography in all patients. Suprapubic and transvaginal ultrasound revealed a large heterogeneous adnexal mass in all the cases.

5. These patients underwent MRI in emergency. MRI was performed using 1.5 T superconductive system (GE system). Sagittal and axial + coronal T2-weighted images, axial T1-weighted images with and without fat saturation and axial T1 fat sat post contrast sequence were performed.

6. Results MRI, which was performed to better characterizing these adnexal masses, distinguished the different components of these lesions. MRI illustrated hematocele by assessing the location of this lesion, its anatomic relationships, its morphology and its signal characteristics.

7. We summarize our 5 cases in this table :

9. endometrial decidualization with an empty uterus A solid and cystic right adnexal mass A large adnexal complex cystic mass with several floating walls ranging near to the pouch of Douglas

10. Hematocele exhibited a global central low signal intensity on T1 and T2 weighted images associated with a peripheral high signal intensity on T1 image. These sequences demonstrated also a few pseudo-nodular foci with high signal intensity on T1 and low signal intensity on T2-weighted images suggesting hemorrhage with different age of blood products.

11. Axial T2-weighted MR image shows masses of high and medium signal intensity and axial T1-weighted MR image shows the same masses with medium signal intensity suggesting an encysted hematocele. Axial T1-weighted MR image shows also a cystic GS with a yolk-like structure surrounded by a thick wall. Post-contrast axial T1-weighted MR image shows a sausage like structure with an enhancing wall corresponding to the right fallopian tube that contains the GS surrounded by the trophoblast.

12. Adnexalmultilocular right mass corresponding to a lutealcyst+(central hyper T2, peripheral hypo T1) on coronal image, a hematocele (hyper T2, hyper T1) and a hematosalpix (heterogenous signal on T1 and T2 images) on sagittal sequences +

13. Discussion An ectopic pregnancy is a clinical condition in which a fertilized ovum implants in a area other than the uterine cavity. The most common site for ectopic pregnancy is the fallopian tube. The early diagnosis of ectopic pregnancy is based on the highly sensitive human chorionic gonadotrophin (β-hCG) and transvaginalsonography [1]. Chronic ectopic pregnancy is considered as a separate clinical entity in witch a blood collection is organized.

14. This bleeding is spontaneously stopped by blood clots or blocked by the omentum, the sigmoid colon and intestines making a real diaphragm. Indeed, when the bleeding is scarce (tubo-abdominal abortion, a cracked hematosalpinx), the blood is confined to the lowest point of the peritoneal cavity, namely the Douglas giving rise to a retro-uterine encysted hematocele but also it can give rise to a latero-uterine or peri-tubal one. The main strength of MR imaging is its ability to determine the exact organ of origin when this hematocele is not clearly determined by transvaginal US. This situation requires access to MRI in emergencies in such clinical settings.

15. MR study is proposed to provide additional information for a limited number of patients who need precise diagnosis. MR imaging is capable not only of identifying blood but also of determining the age of blood products as acute (intermediate signal intensity on T1 and marked low signal intensity on T2), subacute (peripheral high signal intensity with a distinct central area of low intensity signal on T1 and T2) or chronic (entirely high signal intensity on T1 and T2) [2].

16. MRI illustrates hematocele by assessing the location of the lesion, its anatomic relationships, its morphology and its signal characteristics (hypersignal T1/hypersignal T2/non cleared after fat saturation in sequence FATSAT) showing the hemorrhagic nature [3]. MRI also shows in some cases the abnormal gestational sac and allows locating it precisely [4].

17. Although these examples shows the superiority of MRI in comparison with ultrasound, specially in better characterization of blood elements and good anatomical definition), the sonographic appearance should be known by the junior radiologists. So they can suspect the diagnosis even if the clinical and biological context is misleading. In addition, MRI would be unnecessary if βhCG value is positive.

18. Conclusion MRI increased the diagnostic accuracy of chronic ectopic pregnancy owing to its excellent tissue contrast and spatial resolution.

19. References 1.Filhastre M, Dechaud H, Lesnik A, et al. Interstitial pregnancy : role of MRI. EurRadiol 2005; 15: 93-95. 2 . Kataoka ML, Togashi K, Kobayashi H, et al. Evaluation of ectopic pregnancy by magnetic resonance imaging. Hum Reprod 1999; 14: 2644-50. 3. Yoshigi J, Yashiro N, Kinoshita T, et al. Diagnosis of ectopicpregnancywith MRI: efficacy of T2*weightedimaging.MagnReson Med Sci 2006; 5: 25-32. 4. Kataoka ML, Togashi K, Kobayashi H, et al. Evaluation of ectopic pregnancy by magnetic resonance imaging.HumReprod 1999; 14: 2644-50.