INTRODUCTION

Pseudoaneurysms result from arterial wall laceration or puncture, allowing blood to dissect into the periarterial tissues and to create a perfused  sac that communicates with the parent artery lumen.1
Colour Doppler US is the primary imaging modality  with definitive diagnostic features1.
The main stay for successful  treatment for the pseudoaneurysms is transcatheter arterial embolization, although many other  therapeutic options have been described in sporadic isolated case reports.
We report  the diagnosis and management of uterine artery pseudoaneurysm presenting as a large cystic SOL in the fundus in post abortal  setting.

CASE REPORT

A 27 year old   woman  came to our department with intermittent vaginal bleeding after D&C for   therapeutic abortion 60 days earlier. Serum BHCG was negative. Transvaginal pelvic sonography showed an empty endometrial cavity, EE- 4mm Fig 1. Additionally, there was a rounded thick walled structure filled with  internal low level mobile echoes  at the endometrial-myometrial interface  in fundus measuring 4.1 x4.2  cm Figure 1.

Figure 1

 Transvaginal real-time gray scale and color Doppler images with spectral analysis. Longitudinal grayscale sonograms show empty  uterine cavity  .Additionally, there is a round anechoic structure with increased through-transmission at the endometrial-myometrial interface  in the fundus .

A transverse color Doppler image Fig 2 showed  that the cystic structure is filled with blood and has varying colors  with   turbulent arterial flow within the sac Fig.3 and  a swirling blood flow pattern at the base of this structure  (not shown). Based on the constellation of above findings, pseudo aneurysm was diagnosed.
A communicating neck to an adjacent artery could not be identified. Myometrium beyond the fundus was present all around. No dilated veins were detected around the lesion on Doppler sonography.

Figure 2

A communicating neck to an adjacent artery could not be identified. Myometrium beyond the fundus was present all around. No dilated veins were detected around the lesion on Doppler sonography.
 

Figure 3

A transverse color Doppler image  shows  that the cystic structure is filled with blood and has varying colorswith  turbulent arterial flow within the sac

A transverse color Doppler image shows  that the cystic structure is filled with blood and has varying colors (arrows) with  turbulent arterial flow within the sac and  shows a swirling blood flow pattern at the base of this structure  (figure not shown ).

There was also a small amount of   fluid within the pelvis. The ovaries appeared normal.
 
The patient was admitted for planned transcatheter uterine artery embolization on the basis of the sono-graphic findings.   Angiography was performed using the Seldinger technique through the common femoral artery. Initial pelvic angiography was performed, followed by selective internal iliac angiography and uterine angiography.   Right Fig.4  and left Fig. 5 uterine arteriograms showed  a pseudoaneurysm  supplied by bilateral uterine arteries  approximately 4-cm  in the region of the fundus, corresponding to the sonographic images. Subsequently, the embolisation was performed  using Gelfoam which was carefully introduced into the uterine artery   until stasis of flow was confirmed angiographically. Embolization of the contralateral uterine artery was  performed in the same manner . Complete stasis  of flow was achieved following embolisation. A postembolization right Fig.6 and Left Fig.7 uterine arteriograms showed  occlusion of flow to the region of the pseudoaneurysm. There were no procedural complications.
Selective right Fig 4 and left Fig 5 uterine arteriograms show a pseudoaneurysm   supplied by bilateral uterinearteries.

Figure 4

Selective right  uterine arteriograms show a pseudoaneurysm supplied by bilateral uterine arteries.

Figure 5

Selective left uterine arteriograms show a pseudoaneurysm supplied by bilateral uterine arteries.

A postembolization right Fig 6 and left Fig 7 uterine arteriograms shows occlusion of flow to the region of the pseudoaneurysm.

Figure 6

A postembolization right uterine arteriograms shows occlusion of flow to the region of the pseudoaneurysm.

Figure 7

A postembolization  left uterine arteriograms shows occlusion of flow to the region of the pseudoaneurysm.

After transcatheter embolization, The PV bleeding stopped within  3 days and  follow-up pelvic sonography performed 6 weeks after discharge showed thrombosis with  resolution in the  size  of the pseudo aneurysm(figures not shown).

DISCUSSION

Pseudo aneurysm of uterus has been recognized very long ago and the first description of the similar lesion was given by a Polish surgeon Franz Konig in1955 2.   Uterine Pseudoaneurysms  have been reported to occur with a history of  wide range of uterine trauma  in both obstetric and gynecology practice (3-12).
Non traumatic etiologies have also been reported although rare   after uncomplicated spontaneous vaginal deliveries 13 in association with pregnancy14, abnormal placentation15 , gestational trophoblastic neoplasia16  and leiomyoma without prior surgery or pregnancy17 .
Other uterine  vascular injuries include AVM, pseudoaneurysm with AVM, AVF, Direct arterial branch rupture1.
A patient who presents with extensive vaginal bleeding with a normal B-HCG level in post abortal setting , especially after any instrumentation, should be suspected to have an Iatrogenic vascular injury18. The diagnosis can be made on transvaginal color Doppler US, which should be performed prior to any further instrumentation as further curettage can make the bleeding worse.
Pseudoaneurysms result from   inadequate sealing of a laceration or puncture of the arterial wall during surgery or penetrating trauma.Under the influence of sustained arterial pressure, blood dissects into the tissues around the damaged artery and forms a perfused sac that communicates with the arterial lumen.

D&C  may cause a pseudoaneurysm, an AVM, or both. The vessels of an AVM are apt to be injured even by minute trauma, with a resulting concomitant pseudoaneurysm1.
The location of the pseudoaneurysm is dependent on the clinical setting and mode of trauma .The most common location reported in the literature  is the isthmic region at the junction of uterine body and cervix in the  setting of cesarean section. Post abortal pseudoaneurysms  after dilataion and curettage can occur anywhere in the uterine body and  fundus . To our knowledge, fundal location of the pseudoaneurysm as a large cystic lesion in post abortal setting has not been reported.

Gray-scale US shows  an   pulsating anechoic or hypoechoic structure    anywhere in the uterine body and fundus. Doppler US helps establish the diagnosis. Blood-filled cystic structure with varying colors   in and around the uterus  characterized by a typical swirling motion called the “yin-yang sign” is diagnostic 1.
  Within the pseudoaneurysm sac, swirling arterial flow with different directions and velocities is seen, with varying colors according to the variable degree of turbulence at color Doppler US as demonstrated in our case .In the neck of the pseudoaneurysm, the to-and-fro pattern may be potentially identified at duplex Doppler US because the arterial blood flows like a jet (forward flow) into the aneurysm cavity during systole, then reverses (backward flow) into the original artery during diastole 19 This pattern is explained by the pressure gradient between a distended, high-pressure pseudoaneurysm and a low-pressure artery during diastole 20  However, in the case of a uterine artery pseudoaneurysm, demonstration of the neck of the pseudoaneurysm at US may be difficult because of the small size of the parent artery 19 within the uterine myometrium , as may have been the case with   our  patient where the location  was in the fundus.
Radiologic techniques with  greater sensitivity  has an important role not only in the diagnosis but also  management. A complete work-up will help in determining the cause, location, morphologic features, rupture risk, and clinical setting of the pseudoaneurysm; identifying any patient comorbidities; and evaluating surrounding structures and relevant vascular anatomy, information that is essential for treatment planning.
   Differential diagnoses of large cystic uterine lesions reported in literature  include cystic degeneration of uterine leiomyoma, cystic adenomyosis (adenomyotic cysts), congenital uterine cysts such as mesonephric and paramesonephric cysts, cervical nabothian cysts, intramyometrial hydrosalpinx, and echinococcal cysts 21.The characteristic Doppler findings  permits confident diagnosis and differentiation between various cystic lesions of uterine myometrium .
Transcatheter arterial embolization has emerged as a highly effective technique for controlling obstetric and gynecologic hemorrhage1.Absorbable gelatin sponge pledgets are usually the material of choice for embolization of acquired AVMs, pseudoaneurysms arising from small branches, cases of combined AVM and pseudoaneurysm, and direct arterial rupture because of the ease of delivery and the duration of effect. The 3–5-week duration of occlusion by absorbable gelatin sponge pledgets is sufficient to stop hemorrhage while still permitting slow development of collateral vessels1.  

After embolization of both uterine arteries, preservation of fertility and the resumption of menstruation are possible because of the temporary occlusion by absorbable gelatin sponge pledgets and the extensive collateral circulation from pelvic arteries 14. In our  case ,  after embolization of both uterine arteries  ,  the bleeding stopped indicating the success of embolisation with resumption of normal menstrual cycles .
Steinauer et al 22 in his study  summarized the efficacy of post abortion uterine artery embolization in cases of refractory hemorrhage. Embolization was successful in 90%  of cases. All failures  were in patients who had confirmed abnormal placentation.  When retained villi are abundantly present within a pseudoaneurysm, rapid recruitment of collateral vessels following arterial embolization may occur from pelvic arteries, recanalizing the pseudoaneurysm23 This can occur in the setting of abnormal placentation (placenta accreta) and gestation trophoblastic neoplasia. Embolisation with  chemotherapy is recommended in such setting.
Another important  cause   of embolization failure   is inadequate embolization of a pseudoaneurysm supplied by extrauterine feeding arteries, such as the internal pudendal artery  , ovarian artery, inferior epigastric artery, or contralateral uterine artery23 .Thus,  the serum β-HCG test and a meticulous search for possible feeding arteries during angiography are recommended to avoid  embolisation failure. In our case the serum beta HCG was negative and there were no extrauterine feeders at  angiography.
The reported  mean radiation dose to the ovaries is  586 mGy (range 204-729 mGy)24
Patients who are hemodynamically stable can undergo conservative management with observation as there are reports of spontaneous complete resolution of aneurysm19 .Other less invasive Therapeutic options  include radiologic procedures such as US-guided  bimanual compression25, US-guided percutaneous thrombin injection26.The use of noninvasive treatment has led to a marked decrease in the morbidity and mortality rates for pseudoaneurysms.

CONCLUSION

Pseudoaneurysm of uterus   in the post abortal setting can present as a cystic lesion in the myometrium  with a characteristic diagnostic features on ultrasound and colour doppler . Placing the imaging findings in the clinical context (ie, the history of the cause of the pseudoaneurysm) allows the diagnosis of a pseudoaneurysm. Uterine artery embolization is an alternative to hysterectomy in patients with postabortion hemorrhage refractory to conservative measures, with  no major short- or long-term side effects.