Pelvic pain of venous origin: diagnostic insights from transvaginal ultrasonography.

The pelvic venous system consists of two interconnected and highly variable networks: visceral and parietal. The internal iliac veins and gonadal veins are the principal components of these networks ( Fig. 1 ). Because these venous pathways are extensively interconnected, venous incompetence within the pelvis may involve a broader network rather than a single isolated vessel [ 10 ]. The internal iliac vein provides the main venous outflow pathway for the pelvis, draining the pelvic organs, gluteal region, perineum, and pelvic walls. Its major tributaries include the middle rectal, obturator, lateral sacral, and superior and inferior gluteal veins. When these tributaries are incompetent, varicosities may develop in multiple territories, including the uterus, vagina, bladder, rectum, vulva, perineum, and gluteal region ( Fig. 2 ) [ 11 – 13 ]. The right and left gonadal veins usually follow asymmetric drainage pathways. The left gonadal vein drains into the left renal vein, whereas the right gonadal vein drains directly into the inferior vena cava ( Supplementary Fig. 1 ) [ 13 ]. In the midabdomen, both veins course anterior to the psoas muscle and remain in direct contact with it. Their anatomy is highly variable, particularly in the number of trunks, interconnections, and drainage sites. In an anatomical study of 200 gonadal veins, Lechter et al. [ 14 ] reported one to six trunks arising from the distal third of the vein and gradually merging along the ascending course. The left gonadal vein is 6 times more likely than the right gonadal vein to develop insufficiency, primarily because of compression within the aortomesenteric space [ 15 , 16 ]. In addition, approximately 15% of left gonadal veins lack valves altogether [ 17 ]. Both gonadal veins drain the uterus, ovaries, mesosalpinx, parametrium, and pampiniform plexus. These drainage pathways form an important anastomotic network that helps regulate regional venous pressure [ 7 ]. When the gonadal veins are insufficient, they are classically associated with periovarian, periuterine, and vulvar varices. They may also be associated with varicosities of the extrapelvic round ligament, which can mimic inguinal hernias ( Fig. 3 ), and with atypical varices in the pudendal region and along the medial and posterior aspects of the thigh. Pelvic escape points are collateral venous pathways that connect the intrapelvic and extrapelvic venous systems [ 18 ]. The main routes include the following ( Fig. 4 ): Perineal points (60%–70%): clitoral, intermediate labial, and perineal veins [ 18 ]; Inguinal points (21%–36%): varices along the extrapelvic round ligament [ 18 ]; Gluteal points: superior and inferior gluteal veins, which may result in varices in the posterior thigh and sciatic nerve distribution [ 18 ]; Obturator points: pathways associated with varices of the perineum or medial thigh [ 19 ]. A detailed understanding of pelvic venous anatomy is essential for interpreting ultrasonographic findings in women with CPP of venous origin. Because the pelvic venous system is highly interconnected, abnormalities in one venous territory can influence both pelvic and extrapelvic hemodynamics ( Table 1 ) [ 20 , 21 ].

Imaging is central to the evaluation of PeVD. The main imaging modalities used in this setting are ultrasonography, CTV, MRV, and catheter-directed venography with IVUS [ 7 ]. Several ultrasound protocols have been described for assessing PeVD, and approaches vary according to institutional expertise and anatomical focus [ 9 , 11 , 29 , 30 ]. Doppler ultrasound is generally considered the preferred initial examination because it is dynamic, widely available, and free of ionizing radiation. By allowing assessment in different patient positions and through multiple acoustic windows, Doppler ultrasound provides real-time hemodynamic information that improves the detection of venous abnormalities. In clinical practice, the authors follow the protocol proposed by Barros et al. [ 30 ], which includes four complementary stages: transvaginal, transabdominal, transperineal, and lower-limb assessment. The TVUS stage is widely used in gynecological practice and is recognized as a first-line modality for investigating pelvic varices [ 11 ]. The examination is performed with a high-frequency endocavitary transducer (5–9 MHz), with the patient in the lithotomy position with the head of the bed elevated to at least 45° to promote venous filling. Close contact between the distal tip of the probe and the pelvic structures enables high-resolution B-mode and color Doppler imaging, allowing detailed assessment of venous plexus caliber, compressibility, and reflux. The examination is designed to identify periuterine and periovarian varices, evaluate the inferior segment of the gonadal veins, and assess the internal and external iliac veins. TVUS is also important for excluding alternative gynecological causes of CPP, particularly endometriosis. Transabdominal evaluation is performed with a low-frequency convex transducer (2–5 MHz). This stage focuses on the cava–iliac axis and is used to assess renal and iliac venous compression, post-thrombotic changes, congenital anomalies, and the mid-to-superior segments of the gonadal veins ( Supplementary Fig. 2 ). Transperineal and lower-limb assessments are performed with the patient standing and with a high-frequency linear transducer (7–12 MHz). The transperineal approach evaluates communication between the deep pelvic venous system and extrapelvic superficial veins through pelvic escape points ( Supplementary Fig. 3 ). Lower-limb imaging assesses the saphenous axis and identifies nonsaphenous varices of pelvic origin, which are typically located in the medial and posterior thigh, groin, gluteal region, or along the course of the sciatic nerve. The protocol stages can be performed in any sequence without compromising diagnostic accuracy. In patients referred from gynecological settings, particularly those with CPP or suspected endometriosis, evaluation often begins with the transvaginal approach. If no specific gynecological pathology is identified but pelvic varices are present, the additional stages are recommended to determine whether the etiology is primary, due to venous insufficiency ( Supplementary Fig. 4 ), or secondary, related to thrombotic or nonthrombotic obstruction. These stages also help assess downstream effects on the lower limbs. In patients initially evaluated in vascular surgery settings, suspicion of pelvic-origin reflux typically arises when atypically located lower-extremity varices are identified. In these cases, additional ultrasound stages are used to identify escape points, determine which venous trunks are involved, and assess how these abnormalities affect the pelvic cavity. The cervix is first located in the transverse plane. The transducer is then angled toward the right and left paracervical regions to visualize the periuterine venous plexuses ( Fig. 9 ). The gonadal veins are subsequently identified as they course laterally and superiorly toward the ovaries. The probe is then directed toward the lateral pelvic wall to identify the external and internal iliac veins. The external iliac vein is located anterolaterally, whereas the internal iliac vein lies posterolaterally. After the periuterine and paraovarian venous plexuses are identified, the examiner must distinguish physiological venous anatomy from patterns suggestive of venous insufficiency. A venous diameter up to 5.0 mm is generally considered within normal limits. However, thresholds for pathological dilation vary across studies, with reported cutoff values ranging from 6.0 mm to 8.0 mm. In clinical practice, the authors preferentially use a threshold of 7.0 mm, although reflux may be present even in veins measuring less than 5.0 mm in diameter [ 4 , 31 ]. Hemodynamic evaluation with color and spectral Doppler during the Valsalva maneuver is essential for improving diagnostic accuracy. Classic bidirectional flow, or markedly increased antegrade-flow amplitude even without complete flow reversal, should be considered suggestive of reflux ( Fig. 10 ) [ 4 ]. Although evidence remains limited, emerging data suggest that reflux lasting longer than 1 second in pelvic veins may be abnormal, similar to criteria used for the deep venous system, as proposed by Gavrilov et al. [ 32 ]. This criterion may also be applicable to the internal and external iliac veins. Gonadal plexus insufficiency is the most common ultrasonographic finding in patients with pelvic varices. TVUS allows assessment of both gonadal vein diameter and hemodynamics. Reflux can be clearly demonstrated on color and spectral Doppler imaging ( Fig. 11 , Video clip 1 ) [ 30 ]. When feasible, the internal iliac veins should also be evaluated with TVUS because this approach provides higher resolution than transabdominal imaging [ 33 ]. Although systematic data are lacking, the authors’ clinical experience suggests that TVUS is more precise than the transabdominal approach for detecting intraluminal webs, caliber reduction, and mural irregularities in patients with post-thrombotic changes involving the iliac veins ( Figs. 12 , 13 ). Pelvic vein dilation on TVUS does not always represent primary venous insufficiency. In some cases, dilated pelvic veins reflect collateralization due to caval or iliac vein thrombosis. In these situations, spectral Doppler typically shows no reflux during the Valsalva maneuver, which helps distinguish secondary varices caused by venous obstruction from primary insufficiency, in which reflux is expected ( Fig. 14 ). TVUS is also useful in the evaluation of acute pelvic pain. Although common causes include ovarian torsion and ruptured cysts, less common etiologies such as pelvic vein thrombosis should be considered after these conditions have been excluded ( Fig. 15 ). Thrombosis in atypical sites or small-caliber pelvic veins should prompt evaluation for vascular malformations and thrombophilic conditions, because these findings may affect management [ 34 ]. Parametrial vein thrombosis is less frequently observed but may have clinically significant implications when detected on TVUS. Its identification can alter therapeutic planning, particularly in high-risk patients. Routine parametrial evaluation is therefore recommended as part of the TVUS examination, especially in patients with cancer ( Fig. 16 ) [ 35 ]. Despite its advantages, TVUS has inherent limitations. Its restricted field of view prevents adequate evaluation of extrinsic compression affecting the left common iliac or left renal veins, which requires complementary transabdominal imaging. Diagnostic accuracy also depends heavily on the examiner’s familiarity with the technique and with the hemodynamic criteria used to assess pelvic venous insufficiency. CTV provides excellent anatomical detail and is particularly useful for identifying abdominal venous compression ( Fig. 17 , Supplementary Fig. 5 ). However, it has important limitations, including exposure to ionizing radiation, which is especially relevant in younger women, and dependence on appropriate timing of image acquisition relative to contrast bolus administration. Physiological variation in pelvic venous return may also limit opacification of key venous segments [ 36 ]. MRV provides high-quality anatomical characterization of pelvic venous structures without radiation exposure. Dynamic magnetic resonance imaging with time-resolved magnetic resonance angiography/venography, typically performed with 3-second temporal resolution, can depict gonadal vein reflux [ 37 ]. However, both CTV and MRV are usually performed with the patient in the supine position, which limits functional assessment [ 38 ]. In this position, venous reflux may be inadequately demonstrated, whereas vascular compression may be overestimated because gravitational loading on the vessels is reduced ( Fig. 18 , Supplementary Fig. 6 ) [ 39 ]. Catheter-directed venography, particularly when combined with IVUS, is valuable for evaluating the abdominal and pelvic venous systems. It enables detailed visualization of the venous lumen, identification of iliac or renal vein compression, and precise pressure-gradient measurement. In complex cases, it also provides direct information for therapeutic decision-making [ 38 ]. CTV, MRV, and catheter-directed venography with IVUS should therefore be considered when ultrasound findings are inconclusive, technical limitations are present, or complex anatomical abnormalities are suspected. These modalities complement ultrasound by refining anatomical characterization, improving diagnostic confidence, and informing therapeutic planning ( Fig. 19 ).

Pelvic pain of venous origin has variable clinical manifestations and often presents with nonspecific symptoms, which contributes to underdiagnosis. Recognizing risk factors and characteristic symptom patterns is therefore essential for guiding imaging evaluation and improving diagnostic accuracy [ 1 , 9 ]. Table 2 summarizes the main predisposing factors reported in the literature, including hormonal, obstetric, and familial factors commonly associated with primary forms of PeVD [ 1 ]. The most common manifestation is chronic noncyclic pelvic pain that worsens during menstruation, prolonged standing, or physical exertion. Deep dyspareunia is also common and often worsens after intercourse. Other frequent symptoms include perineal heaviness, low back pain, and urinary symptoms such as urgency. Table 3 summarizes the most commonly reported symptoms. These findings should be distinguished from the cyclic pain typical of endometriosis, which is highly prevalent and remains an important differential diagnosis [ 1 , 24 , 28 ]. Fig. 8 illustrates the anatomical-functional correlation between venous territories and predominant clinical manifestations. This integrated approach can help clinicians relate clinical signs and symptoms to hemodynamic abnormalities detected on imaging studies [ 4 , 22 ]. In a retrospective study of 132 patients, Herrera-Betancourt et al. [ 24 ] found that dysmenorrhea, visible vulvar varices, and tenderness over the ovarian points each had more than 80% sensitivity for diagnosing pelvic pain of venous origin. The combination of postcoital pain and ovarian point tenderness increased diagnostic sensitivity to 94%, with a specificity of 77%. However, pelvic varices alone do not establish a pathological diagnosis. Clinical symptoms must therefore be correlated with functional imaging findings to distinguish clinically relevant venous disease from incidental venous dilation [ 15 ].

Pelvic pain of venous origin is common but remains underrecognized in conventional ultrasound protocols. This review emphasizes the need to incorporate evaluation of PeVD into routine ultrasonographic practice, particularly through transvaginal imaging. Failure to identify a venous etiology, either as an independent cause or in association with other estrogen-dependent conditions, contributes to diagnostic delay and inappropriate therapeutic decision-making. Coordinated care among radiology, gynecology, and vascular surgery is essential for effective, patient-centered management.

Chronic pelvic pain (CPP) is defined as noncyclic pain lasting longer than 6 months and arising from pelvic organs or structures [ 1 ]. It is a common complaint among women, accounting for approximately 10%–15% of outpatient gynecological consultations [ 2 ]. Because gynecological, urological, gastrointestinal, and musculoskeletal disorders can all contribute to CPP, the diagnostic process is often prolonged and frustrating for patients [ 3 ]. Among gynecological causes, pelvic pain of venous origin is the second most frequent etiology and accounts for approximately 16%–31% of cases [ 4 ]. This condition is second only to endometriosis and has an estimated prevalence of 10% among women of reproductive age [ 5 ]. Pelvic pain of venous origin typically presents as chronic noncyclic discomfort that worsens during menstruation and after prolonged standing or sitting. Deep dyspareunia is also frequent and often worsens after intercourse [ 6 ]. Richet first described pelvic varices in 1857 [ 6 ]. However, the association between pelvic varicosities and CPP in women was not established until 1949, when Taylor introduced the concept of pelvic congestion syndrome (PCS) [ 6 ]. More than half a century of isolated observations followed before advances in imaging enabled the development of formal diagnostic criteria and standardized classifications. In 2021, the American Vein and Lymphatic Society recommended replacing traditional terms such as PCS, May–Thurner syndrome, and nutcracker syndrome with the broader term pelvic venous disorders (PeVD). This revised nomenclature was intended to better reflect the clinical spectrum of these disorders by encompassing multiple hemodynamic mechanisms, including reflux, thrombotic and nonthrombotic obstruction, and congenital anomalies, while recognizing that these mechanisms frequently overlap [ 7 ]. The Symptoms-Varices-Pathophysiology (SVP) classification system was introduced as part of this initiative. This system categorizes cases according to clinical symptoms, the presence of varices, and anatomical, hemodynamic, and etiological findings. By linking symptoms with venous anatomy and pathophysiology, the SVP framework supports clearer communication among specialists and may help generate more consistent clinical evidence [ 7 ]. Despite this conceptual restructuring and the marked increase in scientific output over the past decade, pelvic pain of venous origin remains underdiagnosed in clinical practice. Delayed recognition can substantially impair quality of life, and affected women may wait up to 7 years before receiving a definitive diagnosis and appropriate treatment [ 8 ]. Several imaging modalities are available for assessing PeVD, including ultrasonography, computed tomography venography (CTV), magnetic resonance venography (MRV), and catheter-directed venography with intravascular ultrasonography (IVUS). Among these modalities, ultrasonography is distinctive because it combines high spatial resolution with real-time hemodynamic evaluation [ 6 , 7 , 9 ]. Its ability to directly visualize the pelvic veins makes it particularly useful for identifying varices, reflux, and morphological abnormalities. Because PeVD remains underrecognized, radiologists, gynecologists, vascular surgeons, and other specialists involved in the care of patients with CPP should be familiar with its venous anatomy, pathophysiological mechanisms, clinical manifestations, risk factors, and imaging findings. This article reviews these topics and focuses on the role of ultrasonography, particularly transvaginal ultrasound (TVUS), in identifying pelvic venous abnormalities.

The etiopathogenesis of pelvic pain of venous origin is multifactorial and involves anatomical, hormonal, genetic, and environmental factors. This complexity likely contributes to the heterogeneity of clinical presentations and to the variability in therapeutic response [ 1 ]. Pelvic venous reflux is one of the principal pathophysiological mechanisms underlying PeVD. It is characterized by dilation and incompetence of the ovarian veins, internal iliac veins, or other venous trunks ( Fig. 5 ) [ 22 ]. Congenital abnormalities of the venous wall may contribute to abnormal vessel dilation, which can compromise valvular function and promote reflux [ 23 ]. This reflux mechanism is most common in multiparous women of reproductive age, particularly those between 35 and 45 years of age, in whom hormonal influences have a central role. Estradiol promotes vasodilation by stimulating nitric oxide production, whereas progesterone reduces venous tone and weakens valvular function. Together, these effects may increase susceptibility to reflux in pelvic veins, especially during pregnancy or after prolonged hormonal exposure [ 22 , 24 , 25 ]. Venous obstruction is the second major pathophysiological mechanism and is associated with extrinsic compression of central venous trunks. The most frequent causes are compression of the left renal vein between the aorta and superior mesenteric artery ( Fig. 6 ) and compression of the left common iliac vein by the overlying right common iliac artery ( Fig. 7 ) [ 25 ]. The reservoir model proposed by Meissner et al. [ 7 ] conceptualizes symptoms in terms of pressure redistribution across four main venous compartments: the left renal hilum, the pelvis, extrapelvic superficial veins, including the vulva, perineum, and medial/posterior thigh, and the superficial and deep veins of the lower extremities. For example, compression of the left renal vein may cause flank pain and hematuria when collateral compensation is insufficient. Alternatively, if decompression occurs through the left ovarian vein, the same upstream obstruction may present as CPP. Similarly, reflux or obstruction in any venous compartment may be partially offset by collateral development, which redirects venous pressure to more caudal territories. As a result, different anatomical and hemodynamic abnormalities may produce similar symptoms, whereas similar lesions may produce different clinical manifestations depending on the extent and distribution of collateralization [ 7 ]. Psychosomatic dimensions should also be considered when evaluating patients with pelvic pain of venous origin. Studies have shown that up to 60% of affected patients have associated emotional disturbances, which may modulate pain perception and influence response to treatment [ 26 , 27 ]. These findings support a multidisciplinary approach that includes psychological assessment and care as part of the clinical management of PeVD.