This diagram shows the normal flow of blood in the major pelvic veins in the pelvis and abdomen. The blood from the legs is pumped up the iliac veins. Blood also returns from the kidneys, ovaries and other pelvic organs.
Diagram showing the normal venous blood flow up the right ovarian vein (right gonadal vein).
Diagram showing the normal venous blood flow up the left ovarian vein (right gonadal vein).
Diagram showing the normal venous blood flow up the internal iliac veins.
Diagram showing normal venous flow in the left renal vein (left kidney vein).
Diagram showing normal venous flow in the right renal vein (right kidney vein).
Diagram showing simple passive reflux in the left ovarian vein (gonadal vein) - the simplest cause of pelvic congestion. Often thought to be the main cause by doctors who do not use transvaginal duplex ultrasound check or treat the internal iliac veins.
Diagram showing the treatment for left ovarian vein reflux. Coil embolisation of the left ovarian vein stops the abnormal reflux and allows the normal flow to resume in all other veins.
Diagram showing venous reflux in the left ovarian vein and both internal iliac veins. This is the commonest pattern of reflux in pelvic congestion syndrome (PCS) - but is often missed as many doctors do not use transvaginal duplex ultrasound to find the internal iliac vein reflux.
Diagram showing embolisation by metal coils of the left ovarian vein and both internal iliac veins to treat the venous reflux. This is the commonest treatment pattern needed in pelvic congestion treatment.
Diagram showing the left renal vein being compressed by the superior mesenteric artery - the nutcracker syndrome. Venous blood flow is obstructed, increasing the pressure in the left kidney causing left flank pain and blood in the urine. This is actually VERY RARE.
Diagram showing the nutcracker compression of the left renal vein by the superior mesenteric artery and venous blood being diverted down the incompetent left ovarian vein. Many doctors misdiagnose this on MRI, CT, venography and IVUS; it is actually RARE. Most patients actually have pseudo-nutcracker (see below).
Diagram showing why embolisation of the incompetent left ovarian vein would worsen a true nutcracker compression. As the venous blood from the kidney is escaping down the ovarian vein, blocking the escape route would increase the pressure in the left renal vein, leading to left flank pain. However, this RARELY HAPPENS as most "nutcracker" compressions turn out to be pseudo-nutcracker (see later).
In the rare cases that prove to be a true nutcracker, a stent will open the obstruction. Occasionally a stent cannot be used and this needs to be done by open surgery.
Prize-winning research from The Whiteley Clinic showed that when a compression of the renal vein was found, and reflux in the left ovarian vein, embolisation of the ovarian vein did NOT worsen the condition, but actually cased the "compression" to open up again in most patients. It turns out that most patients with this appearance on MRI, CT, venography and even ultrasound actually have simple left ovarian vein reflux. The blood falling down the ovarian vein allows the renal vein to collapse, appearing to be compressed. When the reflux is cured by embolisation, the appearance of compression disappears and the renal vein opens up again. Hence the name "pseudo nutcracker".
Diagram showing the normal anatomy where the right common iliac vein passes in from of the left common iliac artery in the pelvis.
Diagram showing how the right common iliac artery can compress the left common iliac vein. causing venous blood to reflux down the left internal iliac vein. This is called the May-Thurner syndrome (MTS). However, just as with nutcracker syndrome, this is overdiagnosed by doctors who use MRI, CT, venography and IVUS. Looking at compression alone, without looking at the function, can lead to misdiagnosis (see "pseudo-May-Thurner syndrome").
Diagram showing the pseudo-May-Thurner syndrome. Although imaging might make the compression of the common iliac vein look significant, in reality most patient had simple reflux in their internal iliac veins. The "compression" is often caused by the position of the patient (lying flat" during MRI, CT, venography, IVUS and even ultrasound. Therefore a combination of duplex ultrasound and air plethysmography can be used to find out if the compression is significant. Most patients are cured by embolisation of the internal iliac vein reflux - hence the "pseudo-May-Thurner".