VACTERL Renal anomalies

Text created in association with Dr David Milford, consultant nephrologist at Birmingham Children’s Hospital.

Renal problems in VACTERL vary greatly – from those which will have no effects on health to abnormalities which are incompatible with life. It is therefore not possible to make blanket statements about the importance of renal anomalies to the child, and this leaflet therefore describes the various possibilities in turn.

All of the problems described also occur in children who do not have VACTERL as they are abnormalities of very early kidney development that may occur in children without any other problems.

Some kidney defects may be detected during antenatal scans – however this is usually only the case if detailed scanning is performed (e.g. if there is some suspicion that the unborn baby is likely to have problems and additional scans are carried out). Routine scans are relatively unlikely to pick up kidney anomalies.

The normal kidneys

A normal, healthy individual has two kidneys; one on each side of the body. These organs continuously filter the blood, removing some substances and balancing the concentration of others. The kidneys also have key roles related to control of water balance and blood pressure.

The fluid produced by the kidneys is known as urine. Urine travels from the kidneys to the bladder through a muscular tube called a ureter and is stored until the bladder is emptied through the single urethra.

Bilateral renal agenesis

This condition describes the situation where neither kidney is present (‘bilateral’ relates to ‘both sides’ and ‘agenesis’ means ‘failure to form’). Because urine produced by the baby in the womb contributes to the amniotic fluid (‘waters’) which surround it, and adequate quantities of amniotic fluid are essential for lung and limb development, a lack of kidneys can result in a marked underdevelopment of the lungs and abnormalities of limb position. These babies usually die soon after birth because of breathing difficulties or severe kidney failure.

Unilateral renal agenesis

‘Unilateral’ means ‘one sided’ – so in this condition one kidney has failed to form. So long as the remaining kidney functions and remains healthy, this will cause no problems – we don’t really need two at all.

If a newborn baby is found to have only one kidney, the ultrasound scans of the remaining kidney are examined closely. If problems are found, then further tests may be required. Even if the kidney appears healthy there may be an abnormality of the junction between the bladder and the ureter allowing urine to flow back towards the kidney (‘vesicoureteric reflux’). Because this can lead to kidney damage if there is a urine infection it is important to exclude this problem at an early stage to prevent infections damaging the one remaining kidney (see separate entry).

It is useful to know if a person only has one kidney, and on which side of the body it is ... if an injury is sustained, this information may be useful to doctors. A medical identity bracelet/necklace should be worn, such as those from ‘Medicalert.’

Hypoplastic or dysplastic kidneys

‘Hypoplasia’ refers to inadequate develop- ment i.e. ‘small in size’. Kidneys which are small in size at birth are frequently referred to as ‘hypoplastic’ but the term ‘dysplastic’ (related to disordered or faulty development) is frequently more accurate.

If only one kidney is affected, there is no problem – the remaining one can cope. If both are affected, the consequences will depend on the amount of functioning tissue remaining. This may be determined by an isotope scan (DMSA scan) which indicates the distribution and amount of functioning kidney tissue. If kidney function is inadequate, the child may be suitable for dialysis and a kidney transplant.

Horseshoe kidney

An individual with a horseshoe kidney has two kidneys which have fused their lower poles while the upper part remains separate. This does not usually cause any problems although it can occasionally be associated with vesicoureteric reflux (see separate entry) or obstruction to urinary flow. Sometimes there may be dilatation of the ureter suggesting obstruction to flow; this is usually caused by the abnormal route the ureter has to take with a consequent delay in emptying the ureter.

Diagram showing various kidney problems

Crossed renal ectopia

In this condition both kidneys lie on the same side of the body, one kidney located beneath the other ... the ureter belonging to the abnormally located kidney crosses back to join the bladder in its normal location. Sometimes there is fusion between the two kidneys.

Crossed renal ectopia is not usually associated with any clinical problems although the abnormally placed kidney may be felt as a lump in the abdomen.

Duplex kidney

A duplex kidney is one which is split into two separate units, each with its own ureter (ureteric duplication). Duplex kidneys can be present on one or both sides.

Sometimes only one unit is functional; the ureter from the non-functioning unit may show gross vesicoureteric reflux (see separate entry). Another possibility is that a ureterocoele forms. This is a thin layer of tissue over the opening of the ureter that can obstruct it completely or, more commonly, allow urine out through a small hole in the tissue layer causing a balloon- like structure to appear in the bladder. Surgery is often required to allow free drainage of urine and to reduce obstruction to urine flow out of the ureter.

Cystic dysplastic kidney

This is sometime wrongly called a polycystic kidney (a term which should be reserved only for a specific, genetic condition which develops with age). It refers to a kidney which has developed wrongly (is ‘dysplastic’) and contains multiple cystic structures and abnormal tissue types e.g. cartilage, reflecting the underlying developmental abnormality.

The consequences depend on how much functioning renal tissue remains. Sometimes a badly cystic kidney will shrivel and even disappear; if this happens before birth it may appear to be a case of unilateral renal agenesis. Some surgeons remove ‘shrivelled’ kidney remnants, however others believe this unnecessary.

Vesicoureteric reflux

This is a condition where urine flows back up the ureters, from the bladder towards the kidneys. It is associated with a high incidence of urine infections – which is its importance, for in a young baby this can lead to kidney scarring. Scarring has two consequences: firstly, it represents a loss of functional kidney tissue; secondly, the remaining kidney tissue is required to undertake extra work and this may cause damage through over-work, resulting in a further loss of kidney tissue. The latter can lead to kidney failure. High blood pressure commonly accompanies kidney scarring because the damaged kidney tissue produces a hormone which increases blood pressure.

Children of up to three or four years who have reflux are given low dose antibiotics to reduce the incidence of urine infections as this is the most vulnerable age for developing kidney scars. Reflux can be found in the presence or absence of pre-existing kidney abnormalities.

Ureteric obstruction

Pelviureteric obstruction may be present as a developmental anomaly; this restricts the flow of urine from the kidney. If severe, the narrowed section of the ureter that joins the pelvis must be surgically removed. Any obstruction to urine flow may damage the kidneys and must be dealt with effectively.

Follow up

Long term monitoring of children is only really necessary in five circumstances:

  • if impaired kidney function is present.
  • If kidney scarring is extensive.
  • if high blood pressure is present.
  • if there is vesicoureteric reflux.
  • if there is obstruction.
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