- Uterine AVMs are uncommon,
representing around 2 % of all causes of genital and intraperitoneal hemorrhages.
(1) However,
since they can lead to profuse and potentially life-threatening hemorrhage they cannot be ignored.
(2)
- Trans catheter embolization(TAE) of uterine AVM is being increasingly used as an alternate to surgery due to its minimally invasive nature and fertility sparing benefits.
(3)
- Uterine AVMs represent an abnormal communication between uterine arterial branches and myometrial venous plexus without intervening capillary network.
[Fig. 1]
Fig. 1: Image showing normal connection between arteries and veins via capillary bed, and AVM- abnormal connection between arteries and veins without intervening capillary bed via tangle of vessels.
References: Oliveri, Francesco, et al. "Arteriovenous Malformation Pulmonary (AVM) in a Post-Cesarean Woman: Intensive Care and Urgent Surgery Operation." European Journal of Molecular & Clinical Medicine 5.1 (2018).
♦ Pathophysiology and types:
Classification:
#Congenital Uterine AVMs: (3,4)
- Central nidus (tangle of vessels with characteristics of both arteries and veins) with multiple feeding arteries and draining veins.
- Extend beyond the uterus to involve the pelvic vasculature.
- Postulated cause: Failure of differentiatiation during embryological development.
#Acquired or traumatic uterine AVMs (3)
- Fistulous communication between intramural arteries and myometrial venous plexus without a characteristic nidus.
(5)
- Derive their blood supply from one or both uterine arteries.
- No extrauterine pelvic vascular supply.
(6)
- Postulated cause: arise as a result of incorporation of the venous sinuses within the myometrium after necrosis of the chorionic villi.
(7)
♦ Clinical presentation: (8) [Fig. 2]
Scenarios:
- Reproductive age group women with unexplained vaginal bleeding.
- Symptomatic multiparous women of child bearing age.
- Most common: menorrhagia and metrorrhagia.
Others:
- Anemia,
hypotension
- Vague pelvic discomfort,
urinary symptoms,
dyspareunia
- Congestive heart failure
- Recurrent spontaneous abortion
- Asymptomatic,
present post uterine trauma or due to hormonal changes related to pregnancy or menstrual cycle.
Fig. 2: Clinical presentation of patients with uterine AVM
References: Healthcare Global Hospital –Bangalore/IN
♦Associations/Risk factors for development of Acquired AVMs : (3,7,9)
- Multiple pregnancies
- Miscarriage
- Previous surgery - Dilatation and curettage(D&C) - Caesarean section (C-section) - Termination of pregnancy
♦ Diagnostic pitfalls: (9)
If serum beta HCG is elevated
- Retained products of conception (RPOC)
- Gestational trophoblastic disease (GTD)
♦ Diagnostic Modalities:(9,10,11) [Fig. 3]
Traditionally diagnosed by laparotomy.
- USG
- Color Doppler
- Pelvic MRI
- Contrast enhanced dynamic MR Angiography(MRA)
- Digital Subtraction Angiography
Fig. 3: Diagnostic modalities used for Uterine AVM diagnosis,findings, advantages and pitfalls. (10,11)
References: Healthcare Global Hospital –Bangalore/IN
♦ Therapeutic options: (3)
Management depends on hemodynamic status of the patient,
severity of hemorrhage,
patient's age and desire to preserve fertility.
# Medical management:
- Includes use of methylergonovine,
danazol,
hormonal treatments like OCPS,
GnRH agonists.
- Used in incidentally diagnosed asymptomatic patients or after control of initial heavy bleeding episode.
#Surgical management:
- Internal iliac artery ligation: Recurrence can result from development of collateral supply distal to ligation site.
- Hysterectomy: highly effective and permanent treatment,
currently reserved for women with failed embolization therapy or with no desire to preserve fertility.
# Endovascular management:
- Described first in the late 1980’s
- Indicated in hemodynamically unstable patients with repeated bleeding episodes requiring blood transfusions.
- TAE is a less invasive alternative for patients wishing to preserve their fertility.
♦ Anatomical considerations: (12,
13)
- Commonly ,the internal iliac artery bifurcates into anterior and posterior divisions.(77%)
- Variations include one stem (4%),
four or more stems (3%) and trifurcation (14%).
- The uterine artery commonly arises from anterior division of internal iliac artery as the first or second branch (51 %),
directly from the abdominal aorta or as a direct branch of internal iliac artery (6%).
[ Fig. 4,
Fig. 5]
Fig. 4: Diagram showing divisions and branches on internal iliac artery
References: Jaypeedigital.com, Basic sciences in Obstetrics and Gynaecology- Blood vessels of the pelvis.
Fig. 5: Pelvic angiogram demonstrating uterine artery originating from anterior division of Internal iliac artery.
References: A. Urquia et al. (2012) Arterial embolisation in postpartum hemorrhage. ECR C1397
- Uterine artery is a tortuous “U shaped vessel with descending,
transverse and ascending segments.
[Fig. 6]
- Cervicovaginal branches arise from transverse segment and should be spared during embolization.
Fig. 6: Internal iliac artery angiogram shows characteristic 'U' shaped course of the uterine artery with descending (1), transverse (2) and ascending (3) segments.
References: Pelage, J. P., et al. "Arterial anatomy of the female genital tract: variations and relevance to transcatheter embolization of the uterus." AJR. American journal of roentgenology 172.4 (1999): 989-994.
- Origin of uterine artery is usually not visible on AP view.
Contralateral anterior oblique is the best position to image both uterine arteries.[Fig. 7]
Fig. 7: Bilateral uterine artery angiogram, left uterine artery origin clearly identified in right anterior oblique (a) and right uterine artery origin in left anterior oblique (b) projections respectively.
References: Toh, Cheng-Hesion Wu Cheng-Hong, et al.(2004) Angiographic Features of Uterine artery Relevant to Uterine Artery Embolization for Uterine Fibroid and Adenomyosis. Chin J Radiol 29:163-169
- In congenital AVMs,
extrauterine arterial feeders from femoral,
lumbar and other branches of internal iliac artery should be checked and embolized.
- Pre-procedural MRA provides useful anatomic information prior to embolization.