UTERINE ARTERIOVENOUS MALFORMATION: A CASE SERIES AND REVIEW OF THE LITERATURE
Siddhi Mathur, Sophie Bussiere-Cote, and Eva Mocarski
A uterine arteriovenous malformation (AVM) is a rare lesion, but one with catastrophic consequences (Kelly et al, 2003). AVMs, when unrecognized can result in life threatening bleeding. The literature describes uterine AVMSs as either congenital or acquired. Acquired AVMs are more common and have been reported after caesarian sections, Dilatation &Curettage, Dilatation & Evacuation, gestational trophoblastic disease, and exposure to DES. Congenital AVMs, are often seen in patients with congenital AVMs elsewhere. Given the paucity of cases, the true incidence remains largely unknown. In a previous series, included 464 women with abnormal uterine bleeding, uterine AVMs were found in 4.6% of study subjects (O’Brien et al, 2006).
Previous cases have described young women of childbearing age with a history of instrumentation, presenting with abnormal bleeding. The majority of acquired AVMs stem from a single artery joining a single vein (Delotte et al, 2006). Contrastingly, congenital AVMs have been described as a connection of multiple arteries and veins, as a result of abnormal embryological development of primitive vascular structures (Molvi et al, 2011).
There are multiple modalities that can be used to help diagnose AVMs, such as ultrasound, CT, and MRI. At this time, the gold standard method is pelvic angiography. On gray-scale ultrasound, an AVM appears as a localized tortuous anechoic spaces in the myometrium (Molvi et al, 2011). With Doppler spectral ultrasound, AVMs show high flow velocity that is different from normal myometrial vessels with low resistance mixing of arterial and venous waveform (Timmerman et al, 2003).
Based on previous literature, ultrasound is not diagnostic of an AVM, and the false positives from ultrasound can delay management of conditions such as RPOC and spontaneous abortions. The diagnosis can be challenging and at this time there is no definitive ultrasound criterion that is sensitive for determining which patients require MRIs.
With these two cases, we would like to illustrate the diversity in presentation, and considerations for immediate and future management.
A 21 year old G3P1A1 presented to the Emergency department at 10 weeks gestation with a twin pregnancypresenting with vaginal bleeding. She was initially managed expectantly. She returned to the emergency room with persistent bleeding approximately 3 weeks later. Her obstetrical history was significant for a dilatation & curettage and a C-section.
At this time a repeat ultrasound was done and was found to be suspicious for an AVM, the other differential being retained products of conception. She was managed as an inpatient with misoprostol and did not pass any retained products. An MRI was done and showed that there was a tubular enhancing structure within the endometrial cavity, measuring approximately 5.9 x 4.8 x 5.5 cm that was in keeping with a large arteriovenous malformation .
She underwent embolization without any complication, and was followed up as an outpatient until B-HCG levels decreased to zero.
A 23 year old G1A1P0 presented to the emergency department with a 6 week history of persistent vaginal spotting and cramping after a therapeutic abortion. Her obstetrical history was significant for one D&C. The first ultrasound was done in the emergency room and noted some heterogeneous hypoechoic areas that could either be retained products of conception or an AVM.
Since her B-HCG was zero, there was concern that this was more in keeping with an AVM. Serial ultrasounds were done which continued to show the heterogeneous hyperechoic area. She was diagnosed with an AVM. Her cramping had resolved; she continued to have some light spotting. Given that her symptoms had improved and size of the AVM was stable, she was managed as an outpatient in clinic, where contraception was strongly recommended to prevent any further pregnancy related bleeding.
After a discussion with the radiology team, they did not recommend serial ultrasounds. If she experienced any heavy bleeding, uterine artery embolization would be considered.
We have presented two cases, where AVMs presented with similar symptoms and were managed differently given size of the lesion and resolution of bleeding. Our second case provides an example where an AVM can be managed conservatively if symptoms resolve. Both these cases demonstrate a need for development of diagnostic guidelines on ultrasound, and long term management in patients who do not present with severe bleeding.