Congenital ureter anomalies

Definition

The ureter drains urine from the kidney into the bladder. Not simply a tube, the ureter is an active organ that propels urine forward by muscular action. It has a valve at its bottom end that prevents urine from flowing backward into the kidney. Normally there is one ureter on each side of the body for each kidney. However, among the many abnormalities of ureteral development, duplication is quite common. Ureters may also be malformed in a variety of ways—some harmful, others not.

Description

There are many different types of ureter anomalies. Ureters can be duplicated completely or partially, they can be in the wrong place, they can be deformed, and they can end in the wrong place. The trouble these abnormalities bring is directly related to their effect on the flow of urine. As long as urine flows normally through them, and only in one direction, no harm is done. A description of ureter anomalies follows.

• Duplication of ureters is quite common, either in part or completely. Kidneys are sometimes duplicated as well. Someone may have four kidneys and four ureters or two kidneys, half of each drained by a separate ureter, or a single kidney with two, three, or four ureters attached. As long as urine can flow easily in the correct direction, such malformations may never be detected. If, however, one of the ureters has a dead end, a stricture or stenosis (narrowing), or a leaky ureterovesical valve (between the ureter and bladder), infection is the likely result.

• Stricture or stenosis of a ureter prevents urine from flowing freely. Whenever flow is obstructed in the body—urine, bile, mucus, or any other liquid—infection follows. Ureters can be obstructed anywhere along their course, though the ureterovesical valve is the most common place.

• A ureter may have an ectopic (out-of-place) orifice (opening): it may enter the bladder, or even another structure, where it does not belong and therefore lack an adequate valve to control reflux.

• The primary ureter, or a duplicate, may not even reach the bladder, but rather terminate in a dead end. Urine will stagnate there and eventually cause infection.

• A ureter can be perfectly normal but in the wrong place, such as behind the vena cava (retrocaval ureter), the large vein in the middle of the abdomen. In this case the ureter may be pinched by the vena cava so that flow is hindered. Other abnormal locations may also lead to compression and impaired flow.

• Besides infection, urine that backs up causes the ureter and the kidney to expand or dilate. Eventually, the kidney stops functioning because of the back pressure. This condition is called hydronephrosis (a kidney swollen with urine).

Demographics

The urogenital system is more likely than any other organ system to have birth defects, and they can occur in endless variety. Congenital ureter anomalies affect as many as one in every 160 individuals.

Causes and symptoms

Practically the only symptom generated by ureteral abnormalities is urinary tract infection. A lower tract infection, in the bladder, is called cystitis. In children it may cause fever and systemic symptoms, but in adults it causes only cloudy, burning, and frequent urine. Upper tract infections, by contrast, can be serious for adults and children, causing high fevers, back pain, severe generalized discomfort, and even leading to kidney failure or septicemia (infection spreading throughout the body by way of the blood stream).

In rare cases, urine from an ectopic ureter will bypass the bladder and dribble out of the bottom somewhere, through a natural orifice like the vagina or a completely separate unnatural opening.

Diagnosis

For children experiencing serious or recurrent urinary tract infections, the pediatrician will search for underlying abnormalities. Cystoscopy (looking into the bladder with a thin telescope-like instrument) and x rays with a contrast agent to illuminate the urinary system will usually identify the defect. Computed tomography scans (CT) and magnetic resonance imaging (MRI) may provide additional information. Urine cultures to identify the infecting germs will be repeated frequently until the problem is corrected.

Treatment

Sometimes the recurring infections caused by flow abnormalities can be treated with repeated and changing courses of antibiotics. Over time, the infecting germs develop resistance to most treatments, especially the safer ones. If it can be done safely, it is better to repair the defect surgically. Urologists have various approaches to urine drainage that range from simply reimplanting a ureter into the bladder, in such a way that an effective valve is created, to building a new bladder out of a piece of bowel.

Category: Nephrology Notes