What is the primary cause of pelvic congestion syndrome?

Primary Causes of Pelvic Congestion Syndrome

Pelvic congestion syndrome (PCS) is primarily caused by venous insufficiency and reflux in the pelvic venous circulation, with the most common etiology being valvular incompetence in the ovarian veins, particularly the left ovarian vein. 1

Pathophysiological Mechanisms

The etiology of PCS is multifactorial, involving several key mechanisms:

1. Venous Valvular Insufficiency

   • Primary cause in most cases
   • Results in retrograde (caudal) flow in the ovarian veins
   • More common in the left ovarian vein due to anatomical factors 1

2. Venous Obstruction

   • Mechanical compression of veins, particularly:
     • Left common iliac vein compression (May-Thurner syndrome)
     • Left renal vein compression (Nutcracker syndrome) 1
   • These obstructions can lead to increased pressure in the pelvic venous reservoir

3. Combined Mechanisms

   • Many patients have both reflux and obstruction contributing to symptoms
   • A single-center retrospective review found that patients with both gonadal vein reflux and nonthrombotic iliac vein lesions (NIVL) had better symptom relief with combined treatment than with ovarian vein embolization alone 1

Risk Factors and Contributing Elements

• Hormonal Factors

  • Estrogen has vasodilatory effects on veins
  • Multiple pregnancies increase risk (multiparous women are most affected) 2, 3
  • Symptoms often improve after menopause 1

• Anatomical Considerations

  • Left ovarian vein drains into the left renal vein at a right angle (versus right ovarian vein draining directly into IVC)
  • This anatomical difference makes the left side more susceptible to reflux 4

• Pregnancy-Related Changes

  • Increased pelvic venous capacity (up to 60% during pregnancy)
  • Progesterone-mediated venous relaxation
  • Mechanical compression from the gravid uterus 3

Diagnostic Findings

Imaging studies typically reveal:

• Ultrasound findings: Dilated pelvic veins (>8mm), altered flow with Valsalva maneuver, retrograde flow in ovarian veins 1

• MRI/CT findings: Engorged periuterine and periovarian veins, venous anatomic variants, and possible compression of left renal vein 1

• Venography/IVUS: Gold standard for diagnosis, showing reflux and measuring degree of venous stenosis (>50% area reduction or >61% diameter stenosis is considered significant) 1

Clinical Pearls and Pitfalls

• Common misdiagnosis: PCS is frequently misdiagnosed or overlooked, with average time to diagnosis reported as up to four years after initial presentation 3

• Asymptomatic findings: Incompetent and dilated pelvic veins can be found in asymptomatic women, making it important to correlate imaging findings with clinical symptoms 4

• Associated conditions: Many women with PCS have morphologic findings of polycystic ovarian syndrome, but without the typical clinical features of hirsutism and amenorrhea 1

• Recurrence mechanism: Recurrence of PCS after ovarian vein embolization can occur through other tributaries in the venous network, such as the median sacral vein 5

Understanding these multiple contributing factors is essential for proper diagnosis and management of PCS, as treatment approaches may need to address both reflux and obstruction components for optimal symptom relief.