Uterine artery pseudoaneurysm requiring embolization in pregnancy: a case report and review of the literature

Uterine artery pseudoaneurysm is a very rare cause of blood loss during pregnancy. It occurs after vascular damage when blood flows through the arterial wall layers, creating a pseudoaneurysm (Zimon et al. 1999). With improvements in imaging technology, uterine artery pseuoaneurysms are diagnosed with increasing frequency. Previously, the majority of uterine artery aneurysms were treated by laparotomy and internal iliac artery ligation (Descargues et al. 2001). In recent years, uterine artery embolization has become the accepted and reliable method to treat uterine artery pseudoaneurysm in haemodynamically stable patients (Kwon and Kim 2002). We present a case of pseudoaneurysm of the uterine artery presenting in pregnancy, diagnosed using duplex Doppler sonography which was successfully treated by uterine artery embolization and a review of the literature.

Pseudoaneurysms arise from vascular damage leading to a disruption and defect within the arterial wall. When the damaged artery does not seal properly, blood escapes, dissects the adjacent tissues around the damaged artery and forms a perfused sac that communicates with the arterial lumen (Zimon et al. 1999). Pseudoaneurysm of the uterine artery has been described as a consequence of Caesarean section (Descargues et al. 2001), dilatation and curettage (Kwon and Kim 2002), hysterectomy (Lee et al. 2001), myomectomy (Higon et al. 2007), and after an uncomplicated vaginal delivery (McGonegle et al. 2006). Our patient had no known risk factor for its occurrence and the aetiology remains unknown.

Although the effect of pregnancy on pseudoaneurysm is unknown, due to their rarity, pregnancy has been associated with an increased risk of rupture of true aneurysms, particularly during the third trimester and puerperium (Barrett et al. 1982). It is believed that the hormonal and haemodynamic environment of pregnancy causes changes in arterial content and organization that weaken arterial walls and predispose to aneurysmal rupture (Barrett et al. 1982). Pseudoaneurysms may be asymptomatic and detected only incidentally during radiologic investigation of other conditions or during surgery (McDermott et al. 1994). Symptomatic pseudoaneurysms manifest with severe vaginal bleeding or abdominal pain, with rupture the most serious cause of morbidity and mortality (Osol and Mandala 2009). Mortality has been described, after post-mortem, due to a case of ruptured pseudoaneurysm in pregnancy (Cardia et al. 2009). Non-invasive radiological imaging techniques such as ultrasound, CT and MR imaging facilitate the diagnosis of uterine artery pseudoaneurysm but ultrasound and MRI are safer in pregnancy (Belli et al. 2012). Smaller pseudoaneurysm of less than 10 mm may be difficult to identify on ultrasound and will require other forms of imaging such as MRI. There have been no documented teratogenic effects after the inadvertent administration of MR imaging contrast agents in pregnant women but it should only be used when additional information or treatment outweighs the potential risks (Tremblay et al. 2012).

Treatment options have evolved over the past few years from open surgical management to less invasive image guided interventions contributing to a dramatic decline in morbidity and mortality rates. Previously, the majority of uterine artery aneurysms were treated by laparotomy and internal iliac artery ligation (Descargues et al. 2001). In recent years, image guided catheter embolization has become the accepted and reliable method to treat uterine artery pseudoaneurysm in haemodynamically stable patients (Kwon and Kim 2002). There are other possible methods of treatment which could be considered such as US guided thrombin injection (Hong et al. 2012) or a covered stent (Jesinger et al. 2013) depending on the expertise of the operator and local experience.

Three cases of uterine artery aneurysms during pregnancy requiring selective embolization are reported in literature (Laubach et al. 2000; Cornette et al. 2014; Maignien et al. 2015) but this is the second case of successful diagnosis and treatment of uterine artery pseudo-aneurysm during pregnancy resulting in a term delivery.

These case reports suggest that fetuses can tolerate selective unilateral uterine artery embolization and though only two, were important pieces of literature in our decision making for active intervention. Uterine blood flow should not be sacrificed routinely but it can be done safely in a potentially life threatening condition as demonstrated by our case report and others in the literature. Blood supply from collaterals and the contralateral uterine artery allowed the pregnancy to continue safely. Additionally, there is evidence that the uterine artery frequently recanalises after embolisation (Das et al. 2013).

It is essential the fetus is monitored during and immediately after the procedure and regular fetal growth and placental perfusion assessments are maintained throughout the pregnancy. We were reassured by her assessments which showed the fetus was growing acceptably without compromise to placental perfusion. We considered a vaginal delivery but opted for an elective caesarean section, because of the uncertainty of the effects of uterine contractions on the thrombosed pseudoaneurysm and patient choice. The choice of timing of delivery was due to the difficult pregnancy, some continued pain and to minimise the chance of spontaneous labour.

In summary, uterine artery pseudoaneurysm should be considered in women with severe abdominal pain in pregnancy. It is a rare but potentially life threatening condition for the mother and fetus. Duplex Ultrasound is the most useful tool in its diagnosis in pregnancy. Management with selective unilateral uterine artery embolization appears to be safe, tolerated by the fetus and helpful in prolonging the pregnancy safely and reducing the morbidity associated with preterm birth.