Normal Ovarian Vein Diameter on Ultrasound and CT
The ovarian veins are paired pelvic vessels that drain the ovaries and anastomose with the uterine venous plexus, playing a key role in pelvic venous circulation. Accurate measurement of ovarian vein diameter is important in the evaluation of pelvic congestion syndrome, ovarian vein thrombosis, and other causes of chronic pelvic pain. Recognizing normal caliber helps distinguish physiologic variation from pathologic dilatation.
Normal Reference Values
| Measurement |
|---|
| <7 mm |
Clinical Significance
An ovarian vein diameter of less than 7 mm is considered normal in the general population. Dilatation at or beyond this threshold—particularly when associated with reflux on Doppler or tortuous morphology—raises concern for pelvic venous insufficiency (pelvic congestion syndrome), a common but underdiagnosed cause of chronic pelvic pain in parous women.
It is important to note that mild ovarian vein dilatation can be an incidental finding in asymptomatic parous women, and clinical correlation is essential before attributing symptoms to this finding. Unilateral dilatation, especially on the right, may also warrant evaluation for extrinsic compression or thrombosis.
- Pelvic congestion syndrome
- Ovarian vein thrombosis (postpartum or spontaneous)
- Nutcracker syndrome with associated left ovarian vein hypertension
- May–Thurner variant with pelvic venous reflux
- Incidental dilatation in asymptomatic multiparous women
Reference: Rozenblit AM, Ricci ZJ, Tuvia J et al. Incompetent and dilated ovarian veins: a common CT finding in asymptomatic parous women. AJR Am J Roentgenol. 2001;176(1):119-22.
Imaging Notes
On ultrasound, the ovarian veins are best assessed with a combination of transabdominal and transvaginal approaches. The vein is measured in transverse cross-section at its widest visible point, and color Doppler or spectral waveform analysis should be used to assess for reflux (retrograde flow >1 second duration). Bowel gas and body habitus may limit visualization, particularly on the right side.
On CT, ovarian veins are readily identified on venous-phase contrast-enhanced acquisitions running from the ovarian hilum superiorly toward the inferior vena cava (right) or left renal vein (left). Diameter is measured perpendicular to the vessel long axis. Multiplanar reformats improve accuracy. CT also allows assessment of associated pelvic varices, venous tortuosity, and exclusion of thrombosis or extrinsic compression.