ANATOMY

Detailed explanation-1: -Hydronephrosis is swelling of one or both kidneys. Kidney swelling happens when urine can’t drain from a kidney and builds up in the kidney as a result. This can occur from a blockage in the tubes that drain urine from the kidneys (ureters) or from an anatomical defect that doesn’t allow urine to drain properly.

Detailed explanation-2: -Hydronephrosis or urinary tract dilation refers to dilation of the pelvis and calyces of the kidney where urine is collected.

Detailed explanation-3: -Hydronephrosis is defined as dilatation and distension of the renal collecting system of one or both kidneys due to obstruction of urine outflow distal to the renal pelvis (i.e., ureter, urinary bladder, and urethra).

Detailed explanation-4: -Hydronephrosis occurs when there is either a blockage of the outflow of urine, or reverse flow of urine already in the bladder (called reflux) that can cause the renal pelvis to become enlarged.

Detailed explanation-5: -The most common renal abnormality is hydronephrosis (also known as renal pelvic dilatation) with an incidence estimated between 0.5 and 1% [3, 4]. Two grading systems exist for fetal hydronephrosis – the anterior posterior diameter (APD) and the Society for Fetal Urology (SFU) grade.