Letter to the editor: spontaneous renal haemorrhage in end-stage renal disease

Dear Sir, We read with interest the comprehensive review of renal and extrarenal findings in haemodialysis patients by Degrassi et al., recently published in Insights into Imaging [1]. In this paper, the authors comprehensively describe acquired cystic kidney disease (ACKD) and renal tumours in end-stage renal disease (ESRD) plus musculoskeletal, cardiovascular and miscellaneous extrarenal complications of haemodialysis. After mentioning the common haemorrhagic diathesis in patients with chronic renal failure, the authors state that Bspontaneous non-traumatic bleeding may affect the perinephric and subcapsular spaces, renal parenchyma or collecting system^ [1]. Upon finishing reading the article, we thought that emphasizing the issue of spontaneous bleeding in ESRD could be useful for most general radiologists. In patients on chronic haemodialysis, acute abdominal pain is a common presentation which may herald a medical or surgical emergency and carries a high risk of morbidity and mortality. Knowledge of the aetiologic spectrum of abdominal complaints and prompt imaging investigation are crucial to providing a correct and timely diagnosis: according to a recent retrospective study, in the haemodialysis population, the main causes of acute abdomen pain are spontaneous intra-abdominal haemorrhage (21.2 % of patients) and non-occlusive mesenteric ischemia (18.1 %) in descending order of frequency. Non-traumatic bleeding involv ing the int ra-abdominal organs , retroperitoneum or muscles is significantly more common in ESRD than in the general population, invariably associated with haemodialysis rather than with peritoneal dialysis (PD), and is potentially fatal. Conversely, intestinal perforation and peritonitis largely predominate in patients on PD, and the incidence of acute pancreatitis in ESRD does not significantly differ from that in the general population [2–4]. Initially described by Wunderlich in 1856, spontaneous renal haemorrhage (SRH) with blood dissecting into the subcapsular and/or perinephric spaces is an uncommon but wellknown urological emergency. In the general population, the majority (two-thirds) of occurrences are secondary to ruptured benign (angiomyolipoma) or malignant kidney tumours. Another 20–30 % of cases are related to vascular lesions such as polyarteritis nodosa, renal aneurysms or arterio-venous malformations. Occasionally, SRH results from pyelonephritis, therapeutic anticoagulation or bleeding diathesis, and 5– 10 % of cases are considered idiopathic [5–8]. Conversely, in patients with chronic kidney failure, SRH is not exceptional and most usually associated with ACKD. At our hospital, where approximately 130 people receive regular haemodialysis, after excluding occurrences secondary to hereditary polycystic kidney and those attributed to excessive therapeutic anticoagulation, we collected seven such cases in ESRD (five out of seven patients were on haemodialysis) over the last 8 years. The multifactorial pathogenesis of SRH involves arterial intimal fibrosis and hypertension, causing the rupture of unsupported sclerotic arteries within cyst walls. Anticoagulation used for haemodialysis and uraemia* Massimo Tonolini [email protected]