Pregnancy subsequent to uterine artery embolization

Abstract

We read with interest the article by Ravina et al. (1Ravina J.H. Vigneron N.C. Aymard A. Le Dref O. Merland J.J. Pregnancy after embolization of uterine myoma report of 12 cases.Fertil Steril. 2000; 73: 1241-1243Abstract Full Text Full Text PDF PubMed Scopus (205) Google Scholar). We were keen to add our own case to the literature on embolization and pregnancy. SMC, a 29-year-old married woman, originally presented in February 1997, with a 6-month history of heavy periods, urinary frequency, and abdominal distension. An ultrasound and subsequent MRI confirmed the presence of a 7.0 × 6.7 × 7.9 cm fundal fibroid. The patient decided to proceed with uterine artery embolization to treat her symptomatic fibroid. The procedure took place in June, and post-operative recovery was routine. Six months following the procedure, a repeat MRI revealed the fibroid had shrunk to 4 × 5 × 5.5 cm (volume reduction of 63%). A pregnancy test 11 months after the embolization was positive. The patient had an uncomplicated antenatal course. Nuchal assessment was reassuring and in addition to the 20-week anomaly scan, serial growth scans were performed at 26 and 34 weeks. Fetal growth was normal as was umbilical artery blood flow. Uterine artery blood flow was normal bilaterally, although the right uterine artery was noted to be of smaller calibre at 26 and 34 weeks. The mode of delivery was discussed with the patient. She did not wish a trial of labor, and at 38 weeks, she had an uneventful elective caesarean section. Easy delivery was achieved of a live male infant weighing 3.38 kg with Apgars of 9 and 10 (after 1 and 5 minutes, respectively). Whilst complete occlusion of the uterine arteries may lead to successful regression of symptoms in many women, there remains a theoretical risk of coincidental uterine infarction and necrosis. The abundant pelvic collateral circulation seems to prevent this. How the uterus responds when its functional capacity is stretched, for example in pregnancy, is uncertain. Indeed the normal uterine artery appearances seen in our case reinforce the view that either collateral supply is able to supersede the occluded uterine vessels or that there is a process of recanalization of the embolized vessels. This may have implications for the long-term results of embolization. It has been postulated that by decreasing the uterine vasculature, placental function and fetal growth will be detrimentally affected. Animal studies in monkeys have shown that by chronically reducing uterine artery blood flow, there is a substantial reduction in the number of spiral artery entries into the intervillous space at term (2Misenhimer H. Ramsey E. Martin C. Donner M. Margulies S. Chronically impaired uterine artery blood flow. Effect on uteroplacental circulation and pregnancy outcome.Obstet Gynecol. 1970; 36: 415-419PubMed Google Scholar). These are the resistance vessels resistance to blood flow. Rats with uterine artery ligation of the relevant horn have been shown to experience intra-uterine growth restriction or even intra-uterine death (3Wigglesworth J. Fetal growth retardation. Animal model uterine vessel ligation in the pregnant rat.Am J Path. 1974; 72: 347-350Google Scholar). These findings however have not been borne out clinically in humans. There are reports of the maintenance of reproductive capacity in women who have undergone bilateral ligation of internal iliac and ovarian arteries, demonstrating the extensive collateral supply to the gravid uterus (4Mengert W. Burchell C. Blumstein R. Daskal J. Pregnancy after bilateral ligation of the internal iliac and ovarian arteries.Obstet Gynecol. 1969; 34: 664-666PubMed Google Scholar). Uterine artery ligation has been shown to permit a viable pregnancy with no evidence of IUGR or pre-eclampsia (5Mitchell G, Mellor S, Burslem R. Pregnancy following bilateral uterine artery ligation. Br J Obstet Gynecol 1977;84:551–4.Google Scholar). Several studies report subsequent pregnancy following bilateral uterine artery embolization for post-partum hemorrhage, cervical ectopic pregnancy, and arterio-venous malformation. Our case, as well as the series of Ravina et al. demonstrate that full-term pregnancy is possible following uterine artery embolization for fibroids, with the presence of normal color flow Doppler in uterine and umbilical vessels, and the absence of any evidence of fetal growth restriction or maternal pre-eclampsia.