A 14-day-old male neonate was admitted with history of lump abdomen and excessive cry for 4 days and progressively enlarging lump in left side of abdomen for 2 days. There was no history of fever, lethargy, poor feeding, vomiting, seizure or any respiratory symptom. There was no bowel or urinary complaints. Perinatal period was uneventful.

The infant was irritable with normal general physical examination and stable vitals. There was a hard, non-mobile, 4×3 cm lump present in left hypochondrium and lumbar regions. Rest of the systemic examination was normal.

Investigations revealed neutrophilia and deranged renal function (urea 177 mg/dL; creatinine 1.4 mg/dL). Urine examination showed plenty of red blood cells, leukocytes and proteinuria. USG abdomen showed enlarged left kidney with altered echotexture. After 2 days of admission, the child developed lethargy, poor feeding and shock. Sepsis was suspected; investigations showed neutrophilia with toxic granules, positive CRP and Staphylococcus aureus in blood culture.

Fig. 1 RLRV with multiple left renal abscesses (RLRV, retroaortic left renal vein; IVC, inferior vena cava).

The infant responded to antibiotics and inotropes but had feeble bilateral femoral and distal lower limb pulses. CT abdomen (Fig.1 and 2) showed retroaortic left renal vein (type 1) with bulky, poorly functioning left kidney. Multiple interparenchymal non-enhancing hypodense areas were seen suggestive of multiple renal abscesses with extension into lower perirenal space; thrombus was present in lower abdominal aorta. Doppler study showed monophasic flow in femoral arteries suggestive of proximal partial obstruction. Coagulation profile of the patient was normal.

Fig. 2 Partial thrombosis of lower abdominal aorta.

The child improved on antibiotics, low molecular weight (LMW) heparin and supportive measures with gradual disappearance of lump and improved pulse volume. Follow-up CT angiography done after 18 days showed 20% luminal narrowing of distal abdominal aorta with small residual abscess in left kidney at lower pole. On follow-up after 3 months of treatment with LMW heparin, Doppler USG showed small left kidney with residual scarring of lower pole with normal blood flow in renal artery and abdominal aorta; injection heparin was stopped.

RLRV is a malformation characterized by presence of a vessel that drains the left renal blood up to the inferior vena cava crossing behind the aorta [1]. The incidence of RLRV has been reported from 0.5% to 2.3% [4,5]. RLRV is classified into four types according to their drainage site and the most common is type I [1]. Nutcracker phenomenon refers to compression of the left renal vein, most commonly between the aorta and the superior mesenteric artery, and posteriorly between aorta and vertebrae [2]. Symptoms commonly include hematuria, flank pain, varicocele and proteinuria [6]. Hematuria is the most common symptom and is due to rupture of thin-wall varices into the collecting system, secondary to elevated venous pressure [6]. This patient with RLRV type1 presented with acute onset left renal lump, excessive cry, hematuria and proteinuria suggestive of posterior nutcracker phenomenon. These focal renal bleeds and infarcts are potential sources of bacterial localization that may result in septicaemia, as was seen in our patient. Thrombosis of aorta in our patient was secondary to septicemia and renal abscesses extending into perirenal space of left kidney.

We conclude that RLRV can lead to a cascade of complications due to its compression, and should be suspected in an infant presenting with renal lump and hematuria.

Contributors: All the authors were involved in the diagnosis and management of the patient. All authors approved the final manuscript.

Funding: None; Competing interests: None stated.

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