 Hi everyone, today I will be presenting retroavortic left renal vein with advanced renal cell carcinoma a case report with literature review. Demographically, the reported incidence of retroavortic left renal vein has been from 0.5 to 3.6% is retroavortic left renal vein is usually asymptomatic. It may sometimes present with hematuria, flank pain and vascular dilatation that is very costly. The most common type of retroavortic left renal vein is the type 1 and the frequency of urological symptom is highest in case of type 2 retroavortic left renal vein. The problem here is surgical approach on those patients is a challenge for the surgeons. Failure to recognize this anomalies may lead to severe hemorrhage and severe renal damage. Retroavortic left renal vein can be categorized into 4 types. Type 1 retroavortic left renal vein joins the inferior vena keva in the orthotopic position as in diagram A. Type 2 retroavortic left renal vein joins the inferior vena keva at lower level of L4, L5 vertebra as in diagram B. Type 3 retroavortic left renal vein, the circumavortic or collar left renal vein as in diagram C. Type 4 retroavortic left renal vein joins the left common iliac vein as in diagram D. With objectives of to document a case of retroavortic left renal vein presenting with advanced renal cell carcinoma, to understand the embryo physiology of retroavortic left renal vein, acquiring insight into other renal veins variations, their clinical implications with relevant literature. In case history, a 65-year-old male presented with complaint of hematuria since two months, left flank fullness associated with weight loss, who was having past history of right renal aprectomy 25 years back for obstructed non-functioning kidney. What we found on examination was no tenderness, normal vitals, surprisingly serum creatinine was 0.9 mg per deciliter. On urine microscopy, abundant RBCs were found per high-power field. On abdominal ultrasonography revealed irredefined large heterogeneously hypoechoic lesion arising from interpolar region of left kidney and casing left pelvic liceal system along with liver metastasis in right lobe of liver. Subsequently, patient was subjected to multi-slice triple-phase CT abdomen on the ground of ultrasonography findings for better evaluation. On multi-slice triple-phase contrast-enhanced CT abdomen exhaled view, we can appreciate markedly dilated retroavortic left renal vein coursing posterior to the aorta. On societal view, markedly dilated as well as elongated retroavortic left renal vein coursing posterior to the aorta. Rinal markedly engosed torso was left renal venous tributaries consequent on congestion due to retroavortic left renal vein. Rinal pelvic stone, significant pelvic ureteric obliteration at preserved function as we can appreciate on axial view onto the left as well as coronal view onto the right. Significantly encased, probably invaded and obliterated left pelvic liceal system to a greater extent at preserved renal excretory function as we can see here. Multiple hepatic left adrenal as well as left upper pole of kidney hypervascular metastasis. Pulmonary parenchymal hypervascular metastasis on left side through thorough review of literature other renal veins variations we can see here is circumavortic left renal vein onto the left is ventral course onto the left is dorsal course. Another renal vein variation on societal view is left renal vein with duplicated retroavortic course. This is duplicated retroavortic course and this is circumavortic left renal vein. Another variation is left sided inferior vena keva and a retroavortic right renal vein. To be discussed here is compression of the left renal vein between the abdominal aorta and vertebrae is called the posterior nut wrecker phenomenon. Embryologically the posterior cardinal veins, the sub cardinal veins and the supra cardinal veins are in the order of appearance. During the development of the inferior vena keva there are anastomatic communications between the sub cardinal and supra cardinal channels that form a collar of veins and circling the aorta. The ventral portion of the circumavortic collar persists as the normal left renal vein. If the dorsal portion of this collar persists then the left renal vein is posted to the aorta forming a retroavortic left renal vein. Proposed mechanism for clinical consequences. Compression of the left renal vein leads to hematuria because of elevated left renal vein pressure and congestion of the left kidney. It is well known that the gonadal, ascending lumbar, adrenal, ureteral and capsular veins are potential collateral venous pathway in case of renal vein compression or obstruction. These anomalous communication channels are responsible for hematuria. In addition vascular dilatation can result from increased drainage to pressure which can in men suffer from left sided varicoseal and boomer from pelvic congestion syndrome. Since the only surviving kidney now presents with advanced renal cell carcinoma rendering nephrectomy and visceral. Patient is being provided palliative treatment with multi-disciplinary treatment. What caution we need to apply is at nephrectomy a midline leprotomy or full roof tooth incision is recommended and any attempt to mobilize the kidney before dealing with the renal pedicle should be avoided. To be concluded with posterior nutcracker phenomenon is uncommon cause of urological problems such as hematuria, varicoseal and ureter pelvic junction obstruction. Failing to take care of it can lead to catastrophic surgical complications. These are the references we referred to. Thank you everyone.