Discussion
postpartum hemorrhage (PPH) is considered to be the leading cause (25%) of maternal death, especially in developing countries,1 that requires multidisciplinary management, including gynecologists, anesthesiologists, and interventional radiologists. Knowledge of the obstetrical and surgical history of patients with PPH is required to anticipate the most probable cause of PPH. In fact, visual estimation of blood loss (VEBL) was described as the most common and practical way.2 Some researchers noted that in spite of the relative accuracy of the weighing method, it could not prevent the process of severe PPH. The key actions to successful management of PPH are early recognition and prompt treatment.3
AVF results from an abnormal connection between an artery and a vein have been described in the pelvic vasculature and, more rarely, in the uterus.4 A UAVF is a rare cause of congenital or acquired-in-nature PPHs that represent 1% to 2% of all genital and intraperitoneal hemorrhages and, as such, should be considered in any postpartum female complaining of vaginal bleeding, particularly if the patient has undergone instrumentation of the uterus.5-8 Acquired UAVF has been attributed to various causes, including malignancies, pregnancy-related, previous uterine trauma from repeated D&E, surgery, infection, and diethylstilbestrol exposure.5,6,9-14 Most reported cases are acquired secondary to D&E but rarely to vaginal delivery.15 A UAVF is most commonly identified when it causes complications during pregnancy, typically in women between 20 and 40 years old, suggesting that hormonal changes during pregnancy and the menstrual period may play a role in its pathogenesis.16 The primary clinical manifestation of a UAVF is paroxysmal massive vaginal bleeding that it potentially life-threatening. The characteristics of vaginal bleeding in our case were a massive gush of vaginal blood that suddenly stopped, possibly due to the opening and closing of the blood sinus. The amount of vaginal bleeding was difficult to estimate, but it was enough to cause severe anemia, syncope, and unstable vital signs. This bleeding requires blood transfusion in 30% of cases.17 While the true incidence of a UAVF is unknown, and fewer than 150 cases have been reported.18 O’Brien et al.19proposed a rough incidence of 4.5%, which would make its diagnosis an even more critical issue for women with unexplained vaginal bleeding.
A UAVF is easily diagnosed now using color-Doppler ultrasonography (CDUS).20 Other imaging modalities of importance include pelvic magnetic resonance imaging (MRI) , hysteroscopy, and DSA.21 While DSA is considered the gold standard modality for diagnosing a UAVF,5 many authors have found transvaginal ultrasound (TVUS) and CDUS more preferable diagnostic methods in the last two decades because they are less invasive.22 Grey scale imaging can reveal subtle myometrial heterogeneities or anechoic spaces.19 CDUS provides a more specific image and presents a color mosaic with thickened vessels and flow reversals. Color-Doppler allows for the identification and localization of increased vascularity, whereas spectral flow Doppler generates a waveform from which systolic and diastolic velocities may be measured. The spectral analysis of AVF lesions reveals a tangle of vessels with a high-velocity flow; spectral Doppler shows high-velocity and low-resistance flow, with low RI values ranging from 0.25 to 0.55 and high PSV values in the range of 40-100 cm/s.19 In our case, a 78.5 cm/s PSV was recorded in the mid-range, and the patient’s continued symptomatic status necessitated a more aggressive approach.
The differential diagnosis of a UAVF comprises several conditions, including hemangiomata, sarcoma of the uterus, trophoblastic disease, and pelvic varicose veins. In the latter condition, the vessels do not pulsate, and they are situated in the outer half of the myometrium.21,22 In contrast to a real AVF with a fistula, a non-AVF should be considered subinvolution of the placental bed, which is defined as failure to obliterate the placental bed vessels in the absence of retained placental tissues after cessation of pregnancy or after abortion.22 A correct sonographic diagnosis is, thus, very crucal.23 However, relying only on Doppler measurements could result in the overdiagnosis of an AVF, as increased vascularity in the endometrium, which resolves spontaneously in 1-2 weeks, can also be noted immediately post D&C.24 With DSA, hypertrophied uterine arteries contributing to a large area of hypervascularity and rapid outflow into pelvic venous channels indicate the presence of a UAVF.25 Although contrast medium-enhanced DSA has been the conventional criterion for standard diagnostic tests, its current use is rare; it is now predominantly used during embolization therapy. Failure to recognize a UAVF could lead to an improper treatment, a life-threatening hemorrhage, and hysterectomy procedures. However while a rapid, prompt, and precise recognition of a UAVF as the cause of bleeding is critical because fistulas are life-threatening and uterine instrumentation may aggravate the condition, the entity in the postpartum must not be overdiagnosed, for many so-called UAVFs have spontaneously resolved at follow-up imaging.15,23
A UAVF treatment is individualized based on clinical manifestations and fertility requirements. Five main factors must be considered in the planning and treatment of patients with a UAVF: these include hemodynamic state, size and location of the lesions, degree of bleeding, age, and the desire for future fertility.15Intervention options from conservative management to definitive surgical hysterectomy are available to patients.8,11,26-28 DSA is the gold standard for diagnosing an AVF and also an interventional treatment technique. Because retaining fertility function and relieving clinical symptoms are most important for these women,29 bilateral UAE is regarded as a method that effectively provides adequate symptomatic relief and retains fertility with minimal side effects, lower complication rates, and major surgical risks.12 Selective uterine artery embolization (UAE) , which has replaced surgery as the optimal treatment modality for symptomatic UAVFs, has advantages that include a >95% success rate, with a 4% complication rate in retrospective review articles.30,31 UAE complications include post-embolization syndrome in the form of severe pelvic pain and radiation exposure, infection, embolization of nontarget organs, impairment of ovarian function, intrauterine adhesions, and rebleeding after blood recanalization. Several successful intrauterine pregnancies after the UAE of UAVFs have been reported including a successful twin pregnancy, which suggests that adequate collateral blood supply can develop to support a full-term pregnancy.32 Peitsidis et al. reported a 27 % pregnancy rate following bilateral UAE.13 Women who become pregnant after UAE are at risk of malpresentation, cesarean delivery, preterm birth, and PPH.33 While the impact of UAE on future fertility and pregnancy outcomes has been studied extensively, the subject remains somewhat controversial.
Herein, we present a woman who suffered from secondary PPH following vaginal delivery; her condition was diagnosed using DSA. This report stresses the fact that the clinical suspicion of an acquired UAVF is crucial to promptly diagnosing and treating secondary PPH. Still, diagnosing and treating this condition is remains challenging for physicians. By sharing this case report, we hope our experience will add to what data exist already on UAVFs.