| Abstrakt: |
SUMMARY The normal upper urinary tract functions as a low-pressure, low-resistance urine propulsion system., During antidiuresis the pressure in the renal pelvis is zero to a few millimetres of mercury. Phasic contractions of the pelvis occur, but as there is no obstruction to outflow, intraluminal pressure is either unaffected or minimally raised. The contraction wave occludes the lumen of the pelvi-ureteral junction separating off a 'spindle' of urine. This 'spindle' is then conveyed along the ureter to the bladder by the complex contraction wave., During diuresis there is an increase in the renal tubular excretory pressure. This increase in pressure and the associated high flow rate produces a potential inflow-outflow imbalance resulting in a gradual increase in pelvic baseline pressure and volume, with a distal movement of the functional pelvi-ureteric junction. Pelvic contraction waves can be recorded as there is a relative outflow obstruction. As flow rate rises there is pooling of urine in the ureter, and ultimately a confluent column of urine in the upper urinary tract flowing continuously into the bladder. As the ureter increases in diameter with the rising baseline pressure the height of the contraction wave diminishes., If the high outflow resistance is sustained due either to polyuria or to organic obstruction, the continuous high baseline pressure leads to a permanent dilatation proximal to the obstruction with urinary stasis. In turn, because of a back pressure effect or secondary vascular occlusion, there is renal parenchymal atrophy with a fall in tubular secretory pressure and pelvic and ureteric intraluminal pressure. This results in the dilated urinary tract with low intraluminal pressure., Manometry has contributed to the understanding of the function of the renal pelvis and ureter. Although it is a useful research technique, in clinical practice it provides little information which cannot now be deduced from routine investigations such as infusion pyelography, micturating cystography, and radio-isotope renography. [ABSTRACT FROM AUTHOR] |
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