What causes parapelvic varices and a dilated left gonadal vein?

Causes of Parapelvic Varices and Dilated Left Gonadal Vein

Parapelvic varices and dilated left gonadal vein are primarily caused by venous outflow obstruction, most commonly due to Nutcracker Syndrome or Nonthrombotic Iliac Vein Lesions (NIVL). 1, 2

Primary Causes

Nutcracker Syndrome

• Compression of the left renal vein between the superior mesenteric artery and the aorta leads to increased pressure in the left renal vein 3, 4
• This increased pressure is transmitted retrograde into the left gonadal vein, causing dilation and pelvic varices 3, 5
• Typically presents with flank pain, hematuria, and pelvic pain 5, 6
• More common in women but can occur in both genders 4

Nonthrombotic Iliac Vein Lesions (NIVL)

• Compression of the left common iliac vein (May-Thurner Syndrome) can cause increased pressure in pelvic veins 1
• NIVL can result in increased pressure in the pelvic venous reservoir, leading to pelvic varices 1
• Often associated with chronic pelvic pain (CPP), which impacts up to 26% of women worldwide 1

Secondary Causes

Cirrhosis and Portal Hypertension

• Portal hypertension can lead to retrograde flow through collateral pathways including gonadal veins 4
• Results in pelvic varices and potentially anorectal varices 1, 4

Retroaortic Left Renal Vein

• Anatomical variant where the left renal vein passes behind the aorta instead of in front 4
• Can cause compression of the vein, leading to increased pressure and gonadal vein dilation 4

Venous Thrombosis

• Thrombosis of the inferior vena cava (IVC) or portal vein can cause venous hypertension 4
• Results in collateral formation and dilation of gonadal veins 4

Renal Cell Carcinoma

• Tumor thrombus in the left renal vein can cause obstruction 4
• Leads to increased pressure and retrograde flow into the gonadal vein 4

Diagnostic Approaches

Initial Imaging

• Duplex ultrasound is recommended as the first-line diagnostic tool 1
• Three sonographic criteria for pelvic venous insufficiency:
  • Dilated, tortuous pelvic vein >4 mm
  • Slow or reversed blood flow (3 cm/s)
  • Dilated arcuate vein in the myometrium communicating with pelvic varicosities 1

Advanced Imaging

• CT Venography (CTV) or MR Venography (MRV) of the abdomen and pelvis can identify:
  • Stenosis, occlusion, venous atresia, collaterals, and edema
  • Webs, trabeculations, and vein wall thickening
  • Diameters of pelvic and ovarian veins (varicose if >5 mm periuterine/periovarian veins and >6-8 mm ovarian veins) 1

Invasive Diagnostics

• Catheter venography is the next step after ultrasound if occlusion or stenosis is suspected 1
• Intravascular ultrasound (IVUS) is the most sensitive and specific imaging modality for detecting deep vein obstructive disease 1
• IVUS can detect significant lesions not initially seen with venography in up to 26.3% of patients 1

Treatment Considerations

For Nutcracker Syndrome

• Gonadal vein transposition is an effective surgical treatment with 61.1% of patients achieving complete symptom relief 7
• Left renal vein stenting is a less morbid alternative to open surgery 2
• Transperitoneal laparoscopic left gonadal vein ligation can be effective for pelvic congestion symptoms secondary to nutcracker syndrome 6

For NIVL and Pelvic Congestion

• Ovarian vein embolization is recommended as a first-line interventional treatment with 75% of patients experiencing significant symptomatic improvement 2
• Foam sclerotherapy is effective for leg, vulvar, and pudendal varicosities of pelvic origin 1, 2
• IVUS-guided stent placement for NIVL with >50% area reduction or >61% diameter stenosis can improve symptoms 1

Clinical Pitfalls and Caveats

• Pelvic varices can mimic cystic adnexal masses on gray-scale ultrasound; Doppler evaluation is essential 1
• The left ovarian vein diameter of 5 mm has a positive predictive value of 71%, and 6 mm has a positive predictive value of 83% for pelvic venous insufficiency 1
• Patients with both gonadal vein reflux and NIVL experience improved symptom relief with either simultaneous or staged iliac vein stent placement and ovarian vein embolization compared to ovarian vein embolization alone 1
• Comprehensive evaluation is necessary as multiple etiologies can coexist 4