Transvaginal ultrasound approach for diagnosing pelvic venous disorders.

Conception and design: FF, JS, FB, MS, NO, IT Analysis and interpretation: FF, JS, FB, MS, NO, IT Data collection: FF, JS, FB, MS, NO, IT Writing the article: FF, JS, FB, MS, NO, IT Critical revision of the article: FF, JS, FB, MS, NO, IT Final approval of the article: FF, JS, FB, MS, NO, IT Statistical analysis: Not applicable Obtained funding: Not applicable Overall responsibility: FF

The largest vein identifiable via the transvaginal route. To visualize it, the end of the transducer must be directed in an anterolateral direction, specifically towards the anterolateral wall of the pelvis. Anatomic landmarks include the psoas muscle and external iliac artery ( Fig 4 , A - F ). Fig 4 Right external iliac vein: B-mode, color Doppler, and spectral Doppler (A-C) . Anatomical landmarks of the external iliac vein. External iliac artery B-mode, Color Doppler (D and E) , and psoas muscle (F) . Right external iliac vein: B-mode, color Doppler, and spectral Doppler (A-C) . Anatomical landmarks of the external iliac vein. External iliac artery B-mode, Color Doppler (D and E) , and psoas muscle (F) . The internal iliac vein follows a vertical and oblique path, exhibiting a shorter length and smaller caliber than the external iliac vein. For accurate identification, it is essential to position the transducer towards the lateral pelvic wall, with the end facing downward toward the gluteal region. The main anatomical landmarks are the ovary, when located in its usual topography, and the internal iliac artery. The confluence of the external iliac vein can be identified, along with its anterior and posterior trunks (the anterior trunk drains the superior gluteal, ileolumbar, and lateral sacral regions; the other branches drain the posterior one) and its tributaries. 15 The ipsilateral ureter is an excellent structure for anatomical repair. It can be visualized in front of the internal iliac vessels and should be perceived as an anechoic tubular structure with no flow on color Doppler, exhibiting peristalsis (it fills and empties during the examination) ( Fig 5 , A - D ; Supplementary Video 1 , online only). Fig 5 Right internal iliac vein. B-mode, color Doppler, and spectral Doppler (A-C) . Anatomical landmark of the internal iliac vein. The ureter is positioned anterior to the internal iliac vessels (D) . Right internal iliac vein. B-mode, color Doppler, and spectral Doppler (A-C) . Anatomical landmark of the internal iliac vein. The ureter is positioned anterior to the internal iliac vessels (D) . The gonadal vein is formed by the convergence of two or three tributaries derived from the ovarian venous plexus. It typically follows a horizontal path between the uterus and the corresponding ovary, moving laterally and bypassing the ovary in an ascending direction. This pathway progresses from the pelvic region to the abdominal cavity, situated superficial to the external iliac vessels. The axial positioning of the cervix is critical for effective visualization of the adnexal venous plexus. The primary anatomical landmarks in this context are the external iliac vessels and the ovary. The myometrial veins are uterine veins that traverse the myometrium, communicating the adnexal venous plexuses horizontally. In the axial section of the uterus, veins are observed inside the external myometrium (arcuate veins), near the serosa. They become easily visible when dilated. The perivaginal, vesical, periurethral, and perianal veins are most clearly observed in pathological conditions. Insufficient veins in the pelvic area can drain the reflux to the lower limbs through the pelvic escape point, which is located in the perineal, inguinal, genital, and gluteal regions. This condition represents an important cause of vulvar and perineal varicose veins and MI and may be associated with pelvic discomfort, with or without pain. 2 , 14 , 15 , 16 , 17 , 18 Using the transvaginal route, we can identify the perineal point, gluteal point, and obturator scape point. The perineal point is identified as the most prevalent type of pelvic escape point, accounting for approximately 60% of treated cases in women. To accurately locate the perineal point, the transducer should be positioned at the vaginal introitus with the distal end directed anterior. The perineal point is located lateral to the urethra, on both the right and left sides, corresponding with the pudendal canal. It is where the perineal veins deepen after receiving the posterior labial tributaries 18 ( Fig 6 , A - C ). Fig 6 Transvaginal ultrasound (TVUS) study of pelvic escape points and anatomical landmarks. Perineal point: urethra (A-C) . Gluteal point: piriformis muscles and left gluteal vessels (D-F) . Obturator point: right obturator internus muscle and obturator vessels (G-I) . Transvaginal ultrasound (TVUS) study of pelvic escape points and anatomical landmarks. Perineal point: urethra (A-C) . Gluteal point: piriformis muscles and left gluteal vessels (D-F) . Obturator point: right obturator internus muscle and obturator vessels (G-I) . The gluteal point is located at the end of the transducer, which should be aimed posteriorly, specifically at the piriformis muscle located on the wing of the sacrum. In this region, it is possible to visualize the gluteal vessels along the roots of the sacral plexus. 9 According to our literature review, the identification of the gluteal point is documented only by Doppler ultrasound examination of the gluteal region with the patient in orthostasis or supine position, using a transducer positioned linearly or convexly in this region ( Fig 6 , D and F ). The obturator scape point leak point can also be assessed; however, its more anterolateral location on the pelvic wall makes it technically less accessible. Its anatomical reference point is the internal obturator muscle, which is located on the wing of the ischium. To our knowledge, this article is the first to propose the assessment of the obturator point via the transvaginal route ( Fig 6 , G - J ). The veins surrounding the uterus and ovaries are characterized as multiple dilated and tortuous structures, which present changes in the amplitude and/or direction of flow as observed on Doppler ultrasound examination. 4 In the pelvic region, a normal vein diameter is typically considered to be up to 5 mm. 1 , 4 However, there are divergent opinions among authors regarding this definition. Some consider veins larger than 5 mm as abnormal, whereas others use a limit of 7 mm. 1 , 11 Furthermore, it is critical to highlight that reflux can be detected in veins smaller than 5 mm, making it essential to assess the flow during the Valsalva maneuver 17 ( Supplementary Video 2 , online only). 1. Reflux in the internal iliac vein ( Fig 7 , A and B ); Fig 7 Atlas of pathological findings. Reflux in the internal iliac vein. (A) Right internal iliac vein at rest ( blue ). (B) Right internal iliac vein with reflux ( red ) during a Valsalva maneuver. Reflux in the left gonadal vein. (C) Color Doppler and (D) spectral Doppler ( Supplementary Video 3 , online only). Reflux at the perineal leak point/ Perineal leak points at rest ( blue ). (E) Perineal leak points with reflux ( red ) during a Valsalva maneuver: color Doppler and spectral Doppler (F and G) . 2. Reflux in the left gonadal vein ( Fig 7 , C and D ; Supplementary Video 3 , online only); 3. Reflux at the perineal leak point ( Fig 7 , E - G ); 4. Thrombosis of pelvic veins ( Fig 8 , A and B ); Fig 8 (A and B) Thrombosis of pelvic veins. (C) Internal iliac vein B-mode demonstrating an echogenic intraluminal web. (D) Spontaneous reflux. (E and F) Obliteration of gonadal veins with coil placement. (G-I) Patient with thrombosis of the vena cava and iliac veins, illustrating post-thrombotic changes and a dilated left gonadal vein with antegrade flow via the abdominal approach (anatomical landmark: psoas muscle via abdominal view). (J) Pelvic varicose veins owing to collateralization. Dilated and tortuous veins in the left adnexal region with spontaneous flow. (K and L) Flow reduction during the Valsalva maneuver, characteristic of collateral veins. 5. Post-thrombotic changes in the pelvic veins ( Fig 8 , C and D ; Supplementary video 4 , online only); 6. Obliteration of gonadal veins and the presence of coils ( Fig 8 , E and F ); and 7. Pelvic varicose veins due to collateralization ( Fig 8 , G - L ). Reflux in the internal iliac vein ( Fig 7 , A and B ); Fig 7 Atlas of pathological findings. Reflux in the internal iliac vein. (A) Right internal iliac vein at rest ( blue ). (B) Right internal iliac vein with reflux ( red ) during a Valsalva maneuver. Reflux in the left gonadal vein. (C) Color Doppler and (D) spectral Doppler ( Supplementary Video 3 , online only). Reflux at the perineal leak point/ Perineal leak points at rest ( blue ). (E) Perineal leak points with reflux ( red ) during a Valsalva maneuver: color Doppler and spectral Doppler (F and G) . Atlas of pathological findings. Reflux in the internal iliac vein. (A) Right internal iliac vein at rest ( blue ). (B) Right internal iliac vein with reflux ( red ) during a Valsalva maneuver. Reflux in the left gonadal vein. (C) Color Doppler and (D) spectral Doppler ( Supplementary Video 3 , online only). Reflux at the perineal leak point/ Perineal leak points at rest ( blue ). (E) Perineal leak points with reflux ( red ) during a Valsalva maneuver: color Doppler and spectral Doppler (F and G) . Reflux in the left gonadal vein ( Fig 7 , C and D ; Supplementary Video 3 , online only); Reflux at the perineal leak point ( Fig 7 , E - G ); Thrombosis of pelvic veins ( Fig 8 , A and B ); Fig 8 (A and B) Thrombosis of pelvic veins. (C) Internal iliac vein B-mode demonstrating an echogenic intraluminal web. (D) Spontaneous reflux. (E and F) Obliteration of gonadal veins with coil placement. (G-I) Patient with thrombosis of the vena cava and iliac veins, illustrating post-thrombotic changes and a dilated left gonadal vein with antegrade flow via the abdominal approach (anatomical landmark: psoas muscle via abdominal view). (J) Pelvic varicose veins owing to collateralization. Dilated and tortuous veins in the left adnexal region with spontaneous flow. (K and L) Flow reduction during the Valsalva maneuver, characteristic of collateral veins. (A and B) Thrombosis of pelvic veins. (C) Internal iliac vein B-mode demonstrating an echogenic intraluminal web. (D) Spontaneous reflux. (E and F) Obliteration of gonadal veins with coil placement. (G-I) Patient with thrombosis of the vena cava and iliac veins, illustrating post-thrombotic changes and a dilated left gonadal vein with antegrade flow via the abdominal approach (anatomical landmark: psoas muscle via abdominal view). (J) Pelvic varicose veins owing to collateralization. Dilated and tortuous veins in the left adnexal region with spontaneous flow. (K and L) Flow reduction during the Valsalva maneuver, characteristic of collateral veins. Post-thrombotic changes in the pelvic veins ( Fig 8 , C and D ; Supplementary video 4 , online only); Obliteration of gonadal veins and the presence of coils ( Fig 8 , E and F ); and Pelvic varicose veins due to collateralization ( Fig 8 , G - L ). Although different authors recommend different criteria for the diagnosis of pelvic varicose veins, our thorough review of the relevant literature, along with our professional experience, led us to the following conclusions. - Venous diameter: Parauterine veins with a diameter of up to 5 mm are considered normal. 1 , 2 , 3 , 4 However, diameter alone should not be the only factor used to assess these veins, because smaller veins may indicate reflux and larger veins may not indicate any signs of reflux. 2 - Definition of reflux: Reflux in pelvic varicose veins is defined differently than in peripheral veins. It can be characterized by the inversion of flow or increased flow during the Valsalva maneuver, 4 considering that it is already reversed. - Reflux time: There are few studies on reflux time in pelvic varicose veins. A recent publication by Gavrilov et al 15 suggests that a reflux time of greater than 1 second indicates reflux in pelvic veins, comparable with findings in deep veins. For both the internal and external iliac veins, we consider a reflux time of greater than 1 second, because these veins are part of the deep venous system. - Leak points: Leak points are assessed when there is an insufficiency caused by the pelvic reflux connection that breaks the pelvic floor and drains into the perineal region or lower limbs. This assessment is not performed routinely, but rather when we detect this connection through venous mapping of the lower limbs ( Fig 9 ). Fig 9 Detailed schematic representation of the pelvic escape points: clitoris point ( CP ), intermediate perineal point ( IPP ), posterior perineal point ( PP ), inguinal point ( IP ), obturator point ( OP ), inferior gluteal point ( IGP ), and superior gluteal point ( SGP ). Venous diameter: Parauterine veins with a diameter of up to 5 mm are considered normal. 1 , 2 , 3 , 4 However, diameter alone should not be the only factor used to assess these veins, because smaller veins may indicate reflux and larger veins may not indicate any signs of reflux. 2 Definition of reflux: Reflux in pelvic varicose veins is defined differently than in peripheral veins. It can be characterized by the inversion of flow or increased flow during the Valsalva maneuver, 4 considering that it is already reversed. Reflux time: There are few studies on reflux time in pelvic varicose veins. A recent publication by Gavrilov et al 15 suggests that a reflux time of greater than 1 second indicates reflux in pelvic veins, comparable with findings in deep veins. For both the internal and external iliac veins, we consider a reflux time of greater than 1 second, because these veins are part of the deep venous system. Leak points: Leak points are assessed when there is an insufficiency caused by the pelvic reflux connection that breaks the pelvic floor and drains into the perineal region or lower limbs. This assessment is not performed routinely, but rather when we detect this connection through venous mapping of the lower limbs ( Fig 9 ). Fig 9 Detailed schematic representation of the pelvic escape points: clitoris point ( CP ), intermediate perineal point ( IPP ), posterior perineal point ( PP ), inguinal point ( IP ), obturator point ( OP ), inferior gluteal point ( IGP ), and superior gluteal point ( SGP ). Detailed schematic representation of the pelvic escape points: clitoris point ( CP ), intermediate perineal point ( IPP ), posterior perineal point ( PP ), inguinal point ( IP ), obturator point ( OP ), inferior gluteal point ( IGP ), and superior gluteal point ( SGP ).

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The objective of this article was to describe the TVUS technique used for examining pelvic veins. A detailed overview of the ultrasound anatomy of this region is provided. In addition to presenting the changes detected by this approach concerning PeVD, the advantages and limitations of the method are discussed. Furthermore, specific aspects of image acquisition and interpretation will also be reviewed. 10 , 11 , 12 , 13 , 14

Ultrasound examination is widely recognized as the first-line imaging modality for investigating PeVDs, using approaches such as transabdominal (TA), transvaginal (TVUS), transperineal, and venous mapping of the lower limbs. 1 , 4 , 11 A TA approach is crucial for studying the iliocaval axis, focusing on issues such as venous compressions, post-thrombotic changes, and the search for tumor masses that may compress the vessels. It is also used, although less frequently, to detect congenital or acquired vascular abnormalities. However, for a more targeted examination of the pelvic veins, a transvaginal approach is preferred. This method provides superior visualization of the pelvic venous plexuses and internal iliac vein tributaries compared with a TA approach. 4 , 19 Therefore, we propose performing TVUS examination to study PVDs, focusing on the periuterine, perivaginal venous plexuses and gonadal and iliac veins. This imaging modality has high sensitivity and specificity for the diagnosis of pelvic varicose veins and the detection of reflux and post-thrombotic changes in the gonadal and iliac plexuses. 10 , 18 , 20 The transvaginal transducer is characterized by its shorter wavelength and higher frequency compared with the convex (abdominal) transducer. Its proximity to the pelvic structures ensures greater resolution of images of organs and venous plexuses. This technique is also less affected by factors such as gases or body habitus. There is also an increase in the sensitivity of images obtained with color Doppler imaging, which allows better visualization of blood vessels, including veins that normally exhibit low velocity flow. 21 Although it may be uncomfortable for some patients, it is superior to the TA, MR venography (MRV), or CT venography (CTV) for evaluating changes in flow direction during the Valsalva maneuver, using color and spectral Doppler examinations compared with the TA route, because with the latter modality, during the maneuver of effort, in most cases, the vein to be studied moves from its initial position and leaves the operator's field of vision, losing the ability to analyze and predict the presence of reflux. 4 , 11 A previous study conducted by our group demonstrated a sensitivity of 96% and a specificity of 100% in the detection of pelvic varicose veins using TVUS examination compared with phlebography. 10 Although the TA approach is useful for evaluating gonadal veins in the proximal segment, it does not provide an adequate analysis of venous reflux in the pelvic region. Additionally, it presents limitations in the visualization of the internal iliac veins and their tributaries, both at rest and during the Valsalva maneuver. 1 Furthermore, based on our experience, when a dilated gonadal vein with reflux is identified during the Valsalva maneuver using TVUS examination with Doppler, it is unusual not to find a corresponding abnormality detected via the abdominal route. 19 In a comparative study of TA ultrasound and TVUS examination, 72 internal iliac veins were assessed. The results revealed that all 72 veins (100%) were successfully visualized using TVUS examination, whereas only 15 (21%) were identified by TA ultrasound examination. Of the 72 veins examined, 12 (17%) exhibited valve incompetence by TVUS examination, compared with only 2 (3%) identified by TA, both of which were detected by TVUS examination. The limitations of TA imaging are generally attributed to the presence of intestinal gas. The results indicate that TVUS examination has a higher success rate in detecting internal iliac vein reflux, suggesting that the TVUS method may be more sensitive and accurate than the TA approach. 19 , 20 Based on similar reasoning, we began incorporating TVUS examinations into the monitoring of patients with post-thrombotic changes involving the iliac venous system. Chronic post-thrombotic changes in the veins such as a reduction in caliber, irregularities in the walls, the presence of echogenic intraluminal webs, and reflux can be identified via the transvaginal route in the internal and external iliac veins. 19 The presence of continuous flow in the pelvic veins may indicate an obstruction in either the iliac or renal veins. Such obstructions are typically not the result of previous thrombotic events; however, the consequences of embolizing pelvic outflow pathways may be just as severe as embolizing outflow pathways for post-thrombotic obstruction. Another point worth highlighting is the use of TVUS examination with Doppler imaging to investigate thrombosis of the pelvic venous plexuses when diagnosing pelvic pain. In our experience, this diagnosis is often underestimated by ultrasound operators and radiologists who specialize in imaging the female pelvis. This oversight also extends to cases of pulmonary thromboembolism of uncertain origin that are encountered by clinicians. 19 In addition to the established accuracy of TVUS in the diagnosis of pelvic venous insufficiency, we also suggest its widespread use as a follow-up examination after embolization of gonadal and/or iliac veins, as well as pelvic varicose veins. The images obtained serve as evidence for both the physician and the patient, demonstrating the procedure and materials used. They allow the observation of the obliteration or reduction of the veins and the presence of coils within them. 19 A critical aspect that requires our attention is the different causes of pelvic varicose veins. They may arise from insufficiency, which can be identified transvaginally by the presence of reflux during the Valsalva maneuver, or they may result from collateralization owing to a secondary proximal obstruction (thrombotic or congenital). It is important to demonstrate valve closure during the Valsalva maneuver in cases of post-thrombotic sequelae of the cavoiliac system, especially when there is dilation and anterograde flow in the left gonadal vein. Doppler ultrasound examination may not always provide adequate information for certain clinical presentations related to PVD. In these cases, it may be necessary to use multiplanar imaging methods, such as MRV or CTV to assess the abdominal and pelvic veins. In addition, if TVUS examination is not possible, produces inconclusive results, or reveals (complex) anatomical variations, MRV and CTV can provide a more complete evaluation for patients with PVDs. However, these methods have limitations, such as the need for intravenous contrast, the lack of information on venous hemodynamics, and the possibility of overestimation of venous compressions owing to the supine position required for imaging. 1 , 4 Conventional catheter phlebography was previously considered the gold standard for diagnosing pelvic venous pathologies 4 and remains relevant in cases where there is high clinical suspicion but inconclusive results from noninvasive diagnostic tests. When combined with intravascular ultrasound examination, this approach provides detailed visualization of abdominal and pelvic veins, facilitates the identification of compressions in the iliac or renal veins, offers high-resolution intraluminal imaging, and enables precise pressure measurements. These capabilities make it a valuable tool for confirming hemodynamically significant obstructions and informing therapeutic decisions. However, with advances in TVUS diagnostics, as discussed in this article, we aim to provide clinicians a less invasive alternative that can optimize pelvic vascular studies and improve the overall diagnostic approach. Despite its broad applicability, TVUS examination presents some limitations. It is an operator-dependent technique and does not provide an adequate assessment of more cranial venous structures, such as the gonadal veins in their abdominal course, iliac vein compressions, or in patients with anatomical variations. The examination is significantly more sensitive when appropriate provocative maneuvers are applied; their absence may lead to false-negative results, particularly in cases of intermittent reflux. Moreover, TVUS examination cannot be performed in patients for whom transvaginal access is contraindicated.

TVUS is a valuable tool for the assessment of PeVDs; however, its importance is often underestimated in the literature owing to the interdisciplinary nature of this condition. Although not widely explored in vascular surgery, TVUS examination has significant potential and should be integrated into PeVD investigations. The lack of awareness among imaging specialists and gynecologists regarding its use contributes to many cases going undiagnosed, because venous pelvic pain is often mistaken for other conditions. Therefore, disseminating knowledge about TVUS is critical to improving the interdisciplinary management of PeVD.

1. Transducer insertion: The endocavitary transducer, covered with a nonlubricated condom and gel, is gently introduced through the vaginal introitus. 2. Initial pelvic scan: Perform a B-mode scan in longitudinal and transverse planes to obtain an anatomical overview. Avoid excessive pressure to prevent compression or distortion of venous structures. 3. Cervix and venous plexus evaluation: Identify the uterine cervix in longitudinal and transverse views. Adjust the transducer laterally to visualize the periuterine and perivaginal venous plexuses bilaterally ( Fig 1 , A - C ). Fig 1 (A) Uterine cervix: transverse view. (B) Uterine cervix, right paracervical scan. (C) Uterine cervix, left paracervical scan. 4. Ovaries and gonadal veins: Locate the ovaries to assist in identifying gonadal veins, which course laterally and superiorly. Note the variability in ovarian position owing to uterine ligament asymmetry ( Fig 2 , A - C ). Fig 2 Left gonadal vein. The left gonadal vein runs laterally and ascends relative to the left ovary B-mode (A) , Color Doppler (B) , spectral (C) . 5. Iliac veins: Angle the transducer toward the lateral pelvic wall to identify the external iliac vein (anterolateral) and the internal iliac vein (posterolateral), including its anterior and posterior trunks. 6. Perivaginal veins: If needed, apply vaginal ultrasound gel to distend the fornices and enhance visualization of perivaginal veins ( Fig 3 , A ). Fig 3 (A) Anterior and posterior vaginal fornices. (B) Urethra. (C) Anus-axial view. 7. Periurethral and perianal veins: Recoil the transducer to the vaginal introitus to assess periurethral veins ( Fig 3 , B ), then angle posteriorly to evaluate perianal veins ( Fig 3 , C ). 8. Doppler evaluation: Use grayscale, color, and spectral Doppler to assess venous patency, diameter, flow characteristics, reflux, and signs of thrombosis or post-thrombotic changes. 9. Provocative maneuvers: During Doppler assessment, all veins should be evaluated both with and without the Valsalva maneuver (forced expiration against a closed glottis for 4-5 seconds), voluntary coughing, or pelvic floor contraction. These maneuvers increase intra-abdominal pressure and help to reveal pathological reflux or alterations in pelvic venous flow. Transducer insertion: The endocavitary transducer, covered with a nonlubricated condom and gel, is gently introduced through the vaginal introitus. Initial pelvic scan: Perform a B-mode scan in longitudinal and transverse planes to obtain an anatomical overview. Avoid excessive pressure to prevent compression or distortion of venous structures. Cervix and venous plexus evaluation: Identify the uterine cervix in longitudinal and transverse views. Adjust the transducer laterally to visualize the periuterine and perivaginal venous plexuses bilaterally ( Fig 1 , A - C ). Fig 1 (A) Uterine cervix: transverse view. (B) Uterine cervix, right paracervical scan. (C) Uterine cervix, left paracervical scan. (A) Uterine cervix: transverse view. (B) Uterine cervix, right paracervical scan. (C) Uterine cervix, left paracervical scan. Ovaries and gonadal veins: Locate the ovaries to assist in identifying gonadal veins, which course laterally and superiorly. Note the variability in ovarian position owing to uterine ligament asymmetry ( Fig 2 , A - C ). Fig 2 Left gonadal vein. The left gonadal vein runs laterally and ascends relative to the left ovary B-mode (A) , Color Doppler (B) , spectral (C) . Left gonadal vein. The left gonadal vein runs laterally and ascends relative to the left ovary B-mode (A) , Color Doppler (B) , spectral (C) . Iliac veins: Angle the transducer toward the lateral pelvic wall to identify the external iliac vein (anterolateral) and the internal iliac vein (posterolateral), including its anterior and posterior trunks. Perivaginal veins: If needed, apply vaginal ultrasound gel to distend the fornices and enhance visualization of perivaginal veins ( Fig 3 , A ). Fig 3 (A) Anterior and posterior vaginal fornices. (B) Urethra. (C) Anus-axial view. (A) Anterior and posterior vaginal fornices. (B) Urethra. (C) Anus-axial view. Periurethral and perianal veins: Recoil the transducer to the vaginal introitus to assess periurethral veins ( Fig 3 , B ), then angle posteriorly to evaluate perianal veins ( Fig 3 , C ). Doppler evaluation: Use grayscale, color, and spectral Doppler to assess venous patency, diameter, flow characteristics, reflux, and signs of thrombosis or post-thrombotic changes. Provocative maneuvers: During Doppler assessment, all veins should be evaluated both with and without the Valsalva maneuver (forced expiration against a closed glottis for 4-5 seconds), voluntary coughing, or pelvic floor contraction. These maneuvers increase intra-abdominal pressure and help to reveal pathological reflux or alterations in pelvic venous flow.

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