Duplicated ureter or Duplex Collecting System is a

congenital condition A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can r ...

in which the

ureteric bud The ureteric bud, also known as the metanephric diverticulum, is a protrusion from the mesonephric duct during the development of the urinary and reproductive organs. It later develops into a conduit for urine drainage from the kidneys, which, in ...

, the embryological origin of the

ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...

, splits (or arises twice), resulting in two ureters draining a single

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

. It is the most common renal abnormality, occurring in approximately 1% of the population.Siomou E. et al
Duplex collecting system diagnosed during the first 6 years of life after a first urinary tract infection: a study of 63 children
Journal of Urology, 2006; 175(2):678-81; discussion 681-2J. Gatti, J. Murphy, J. Williams, H. Koo, emedicine overview
Ureteral Duplication, Ureteral Ectopia, and Ureterocele
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Pathophysiology

Ureteral development begins in the human fetus around the 4th week of embryonic development. A ureteric bud, arising from the mesonephric (or Wolffian) duct, gives rise to the ureter, as well as other parts of the collective system. In the case of a duplicated ureter, the ureteric bud either splits or arises twice. In most cases, the kidney is divided into two parts, an upper and lower lobe, with some overlap due to intermingling of collecting tubules. However, in some cases the division is so complete as to give rise to two separate parts, each with its own renal pelvis and ureter.

Diagnosis

Prenatally diagnosed

hydronephrosis Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of t ...

(fluid-filled kidneys) suggest post-natal follow-up examination. The strongest neo-natal presentation is

urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...

. A hydronephrotic kidney may present as a palpable abdominal mass in the newborn, and may suggest an ectopic ureter or ureterocele. In older children, ureteral duplication may present as: * Urinary tract infection - most commonly due to

vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directio ...

(flow of urine from the bladder into the ureter, rather than vice versa). *

Urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...

in females occurs in cases of ectopic ureter entering the vagina, urethra or vestibule.

Classification

Ureteral duplication is either of: ; Partial: I.e., the two ureters drain into the

bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

via a single common ureter. Partial, or incomplete, ureteral duplication is rarely clinically significant. ; Complete: In which the two ureters drain separately. Complete ureteral duplication may result in one ureter opening normally into the bladder, and the other being ectopic, ending in the

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

, the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...

or the

vulval vestibule The vulval vestibule (or vulvar vestibule or vestibule of vagina) is a part of the vulva between the labia minora into which the urinary meatus (urethral opening) and the vaginal opening open. Its edge is marked by Hart's line. It represents the ...

. These cases occur when the ureteric bud arises twice (rather than splitting).Sadler, T. W., Langman's medical embryology - 11th ed. p. 240, .

Prevalence

Duplicated ureter is the most common renal abnormality, occurring in approximately 1% of the population. It occurs in about 0.7% of healthy adults and in 2% to 4% of people with urinary tract issues. Reviewed: 12/04/2020 ; Race: Duplicated ureter is more common in

White Americans White Americans are Americans who identify as and are perceived to be white people. This group constitutes the majority of the people in the United States. As of the 2020 Census, 61.6%, or 204,277,273 people, were white alone. This represented ...

than in

African-Americans African Americans (also referred to as Black Americans and Afro-Americans) are an ethnic group consisting of Americans with partial or total ancestry from sub-Saharan Africa. The term "African American" generally denotes descendants of enslav ...

. ; Sex: Duplicated ureter is more common in females. However, this may be due to the higher frequency of

s in females, leading to a higher rate of diagnosis of duplicated ureter.

Complications

A duplicated ureter increased the risk of: *

Hydronephrosis Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of t ...

Urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...

(UTI) *

Vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directio ...

* Incontinence

References