A pathological study of five cases of pyelonephritis in the newborn.

It is increasingly recognized that many problems concerning the aetiology, recognition and natural history of urinary tract infections are still unresolved, and this is particularly true of such infections in infancy. There is, for example, no general agreement about their incidence in the first months of life: Stansfeld (1954) has pointed out that pyelonephritis occurs more frequently in the first year than at any other age, and most frequently of all in the first month, but this distribution pattem has not been universally recognized. The divergence of opinion may derive from a failure to consider pyelonephritis as a possible cause of such symptoms as vomiting, anorexia, constipation, diarrhoea and poor weight gain, or from uncertainty in assessing the significance of those minor abnormalities in the urine which may be the only diagnostic feature of chronic pyelonephritis. The situation is further confused by disagreement over the interpretation of various lesions which may be found in the kidneys of small infants dying of renal disease so that even necropsy may not resolve clinical uncertainty. Among the few existing reports of the morbid anatomical findings in cases of neonatal pyelonephritis are those of Chown (1927) who could find only nine cases in the earlier literature. To these he added detailed reports of 30 cases of 'pyelitis' in infancy. Most of his cases showed the changes of acute suppurative pyelonephritis but four with chronic pyuria showed in addition 'inflammatory lesions in various stages of healing'. Craig (1935) gave the post-mortem findings in six cases of acute pyelonephritis and Hunt (1936) described one case with unilateral acute suppurative pyelonephritis fatal 13 days after birth. More recently Claireaux and Pearson (1955) have recorded chronic pyelonephritis in a newborn infant. The histological picture of acute pyelonephritis in early infancy is indistinguishable from that found at any other age; in the chronic stage, however, differences may appear which have hitherto been insufficiently recognized and it is the purpose of this paper to discuss them.