A retrospective, observational multicentre trial on the nephrological outcome and associated congenital anomalies in children with Horseshoe Kidney.

Congenital abnormalities of the kidney and urinary tract (CAKUT) represent the main cause of CKD in children. Among them, the horseshoe kidney (HSK) represents one of the most frequent and is characterised by the presence of two distinct, functioning kidneys positioned on each side of the spine, fused together at one of the poles. The incidence of this condition is approximately 1 case every 400-600 new births with a prevalence in the male sex with a ratio of 2:1. Even though these children aregenerally asymptomatic and the diagnosis is often incidental , some may develop symptoms due to complications, such as infections, nephrolithiasis and urinary tract obstruction. More rarely risks of neoplastic degeneration and renal damage are described following trauma to the abdomen and lumbosacral spine. This condition is also associated in up to a third of cases with other abnormalities: the most frequent affect the urinary tract and genitals; however, abnormalities affecting other organs or systems as well as well-defined syndromic pictures. Due to its frequent asymptomatic nature, horseshoe kidney is historically considered a condition with a good prognosis and rarely as a risk factor capable of reducing survival or predisposing the kidney to long-term damage.

The primary objective of the study is:

To assess the 'nephrological outcome' understood as 'prevalence of patients who developed' and 'survival time free from": chronic renal failure, proteinuria, hypertension nephrolithiasis, UTI, renal neoplasms and renal trauma.

The secondary objectives of the study are:

1. Prevalence of congenital and associated genito-urinary and systemic abnormalities;
2. Description of renal anatomical features;
3. Assessment of the usefulness of second level radiological investigations (VCUG, static renal scintigraphy, ddynamic renal scintigraphy).

Inclusion Criteria:

• Patients with confirmed ultrasound and/or scintigraphic diagnosis of horseshoe kidney;
• Patients with an age at first assessment of between 0 and 18 years;
• Obtaining written Informed consent.

Exclusion Criteria:

• Patients with a definitive diagnosis of another form of CAKUT during the diagnostic pathway.

Patients followed at the participating centres from 01/01/2012 to 31/12/2021 for a nephro-urological pathology will be enrolled in the study.