Radiological Diagnosis

Pelvic Arterio-Venous Malformation

The color Doppler findings show tortuous vessels in the adnexal region with markedly prominent vessels in the myometrium. On the basis of these findings, a diagnosis of pelvic arteriovenous malformation (AVM) was made. CT angiography was performed and revealed a soft tissue enhancing mass with enlarged tortuous vessels in both adnexal regions and in the uterine myometrium involving the uterus and vagina but without involvement of the bladder or rectum [Figure - 3]. The AVM was fed by branches of the internal iliac arteries on both sides and also by ovarian vessels [Figure - 4].

AVMs of the female pelvis are uncommon. The etiology may be congenital, traumatic, malignant or idiopathic [1] Congenital AVMs are considered to be undifferentiated vascular structures resulting from the arrest of embryonic development at various stages [2]. Acquired AVMs are usually caused by neoplasms or trauma and procedures such as curettage and uterine surgery have been implicated [3].

Symptoms include vaginal bleeding, throbbing discomfort in the lower abdomen, dyspareunic menorrhagia, shortness of breath, frequency of micturition and incontinence. Pelvic examination may reveal a poorly defined pulsatile adnexal mass. The uterus is occasionally soft and enlarged [5].

The gray scale ultrasound morphology of uterine AVMs includes prominent parametrial vessels, subtle myometrial inhomogeneity and multiple distinct anechoic spaces in the myometrium without mass effect. Other features include a focal mass effect within the myometrium or endometrial cavity that mimics a fibroid or polyp respectively and a cervical mass [8].

Color Doppler US features show intense color with extensive color aliasing and apparent flow reversal, while spectral Doppler shows slow resistance high velocity flow. While color Doppler and spectral Doppler interrogation of the uterus can strongly suggest the presence of an AVM, the ability of Doppler US to depict the precise extent of the lesion within the pelvis may be limited even with transvesical or endovaginal ultrasound. Doppler US however is the initial method of choice and the preferred method for following up patients after treatment [8].

Angiography is the current reference standard for the diagnosis of pelvic AVM. Although angiography can accurately define both the size of the AVM and vessel involvement it cannot accurately define adjacent organ involvement. The involvement of adjacent pelvic viscera is the major criterion in deciding between surgical extirpation and palliative embolotherapy. CT has been used to assess the size, extent and vascularity of AVMs and the degree of involvement of adjacent organs [5].

MR imaging may also be performed to confirm the diagnosis and delineate the extent of AVM.

Management of pelvic AVMs is either by transcatheter embolisation or surgery or both [8].