Bilateral persistent sciatic artery: a potential risk in pelvic arterial embolization for primary postpartum hemorrhage

Abstract

Emergency transcatheter embolization of the uterine arteries is an effective method to control primary postpartum hemorrhage (1,2). Persistence of the sciatic artery is a rare congenital abnormality in which this artery originates from the anterior division of the internal iliac artery and provides the major part of the arterial blood flow to the ipsilateral inferior limb (3,4). Therefore, correct identification of this rare abnormality is crucial to prevent irreversible ischemic damage of the lower limbs in case of embolization of the uterine arteries for postpartum hemorrhage. We report a case of bilateral persistent sciatic arteries detected before attempted uterine artery embolization for postpartum hemorrhage. A 19-year-old woman was referred to our Institution because of uncontrollable primary postpartum hemorrhage after cesarean section with a hemoglobin level of 6.1 g/dL and an estimated blood loss of 2000 mL. Manual exploration of the uterus did not reveal any retained portion of the placenta. Disseminated intravascular coagulopathy was confirmed in the presence of thrombocytopenia (platelet count 39 000 × 109/L), elevated prothrombin time and hypofibrinogenemia (fibrinogen level 0.45 g/L). The patient had had a blood transfusion (5 units) and received fresh-frozen plasma. Uterine atony was treated with intravenous prostaglandin-E2 analog (sulprostone, Nalador®, Laboratoire Schering, Lys-lez-Lannoy, France) at a dose of 1000 µg and manual external uterine massage. Because of persistent bleeding, the decision to perform embolization was made in consensus by the obstetrician, the anesthetist and the interventional radiologist. Digital subtraction angiography of the pelvis showed a high aortic bifurcation with bilateral short common iliac arteries and almost immediate bifurcation into small-caliber external iliac arteries and large-caliber internal iliac arteries. Selective angiography of the anterior division of the left iliac artery was then performed to localize the origin of the left uterine artery (2). The left internal iliac artery was large and continued into the left lower limb as a persistent sciatic artery (Fig. 1). The left uterine artery originated at the anterior aspect of the internal iliac artery, below the origin of the superior gluteal artery (Fig. 2). The left uterine artery was tiny and tortuous and despite several attempts could not be selectively catheterized, even with the use of a 3-F microcatheter. The same anatomy and catheterization problems were found on the right side. Further angiographic analysis showed that both sciatic arteries coursed through the posterior aspect of the thighs and continued as the popliteal arteries. Because of persisting bleeding and the presence of sciatic arteries preventing embolization of the anterior division of the internal iliac artery, hysterectomy was subsequently performed. After hysterectomy, the patient was referred to the intensive care unit and discharged at postoperative day 14. Digital subtraction angiogram over the left hip shows enlarged left internal iliac artery and persistent sciatic artery (arrow) and hypoplastic left external iliac artery (arrowhead). Digital subtraction angiogram obtained during selective catheterization of the left internal iliac artery shows tiny uterine artery (arrowheads) originating 1 cm below the origin of the superior gluteal artery. Persistent sciatic artery is clearly seen (arrow). Selective arterial embolization is widely considered as the treatment of choice for severe postpartum hemorrhage in case of failure with conservative therapy. This technique has a high success rate with minimal morbidity (1). Although no complications were encountered in our experience involving more than 150 cases so far, arterial embolization may not be free of side-effects. The location of the injection, the particle size, and the amount of the material used for proper embolization may influence the safety of the procedure (1). When superselective catheterization of the uterine artery is not feasible because of spasm or a too small caliber, it is possible to embolize more proximally in the anterior division of the internal iliac artery (5). We found this situation in about 20% of our cases and this was not correlated with higher degrees of morbidity (1,2). Conversely, in our current case with persisting sciatic artery in which the uterine artery could not be catheterized, the embolization of the anterior division of the internal iliac artery was not attempted because of the high potential risk of irreversible ischemic damage of the lower limbs. To our knowledge, this condition as a cause of failure of uterine embolization has never been reported so far. In conclusion, persistent sciatic artery is rare. However, because of the widespread use of pelvic embolization to treat a variety of diseases, such as postpartum hemorrhage, uterine leiomyomata and bleeding from pelvic tumors, the correct identification of this uncommon vessel in due time is crucial. This case highlights the importance of understanding the arterial anatomy of the pelvis, its potential variations and their potential impact on the outcome of the procedure.