Jaundice is considered one of the most common problems in neonates. About 60% of full term infants develop jaundice . Indirect hyperbilirubinemia is common and is related to a spread of physiologic and pathologic conditions. Neonates with UTI may present only with jaundice. UTI investigations have been included in routine workup of jaundice. Although investigating for UTI in neonates with significant unexplained indirect hyperbilirubinemia remains controversial . Hence the aim of this study was to evaluate UTI among neonates with significant unexplained indirect hyperbilirubinemia.
This study indicated the incidence of UTI in our studied cases was 11% of jaundiced neonates while no case in control group diagnosed with UTI with significant statistical difference between 2 groups (P value < 0.05). In previous studies, the incidence rate of UTI in jaundiced neonates has ranged from 5.8 to 21% . Ghaemi et al.  had a prospective study which reported UTI incidence of 5.8% in jaundiced neonates. The highest (21%) incidence of UTI was reported in a study done by omae et al. . The prevalence of UTI was 16.7% in a recent study performed by Ozcan et al. 
In our study there was no statistical difference between incidence of UTI between males and females as six out of 11 were females while five were males. Chen et al.  reported similar results as UTI incidence in males was 41.7% while in females was 58.3%. Another retrospective study done by Omar et al.  stated that UTI in males was 59.4% while in females was 40.6% with no statistical difference. On the other hand, Cleper et al.  reported that the percentage of UTI in females was 6 times less than in males and the percentage was also 3 times higher in males in the study of Bilgen et al.  Forty-five out of 100 in case group had irrelevant family history of jaundice with no statistical difference between 2 groups.
Blood culture in all cases confirmed to have UTI by urine culture was negative. This disagrees with study done by Bahat Ozdogan et al. who found that of UTI positive jaundiced neonates, 6.2% had documented bacteremia . The comparison between the positive & negative groups regarding history of maternal infections showed there was statistical significant difference between the two groups (p-value< 0.05).
As regards the most common isolated organisms, three out of 11 (36.4%) of positive cases were caused by Escherichia coli infection, 27.3% (3 out of 11) caused by acinetobacter bacilli. E. coli was the most common organism in studies of Chen et al.  and Bahat Ozdogan et al. showed that E. coli was the causative organism in 50% of cases  while Omar et al. found in their study that the most of isolated organisms were klebsiella (46.7%), and E. coli (37.5%) .
Our data showed that out of 11 cases, there were two cases diagnosed to have a posterior urethral valve (PUV) with mild hydronephrosis. The two cases had no signs of sepsis (e.g., fever, lethargy, or poor feeding), and all inflammatory markers were negative; this may attribute the bilateral hydronephrosis to mechanical obstruction by PUV rather than UTI. The guidelines of American Academy of Paediatrics (AAP) advocate doing US in all > 2-month-old infants with UTI accompanied by fever but there are no recommendations for neonates with UTI. Our study didn’t document a significant portion of USG abnormality neonates with UTI. However, in study done by Bahat Ozdogan et al., he found that there was abnormal finding in 28.1% in renal USG of jaundiced neonates confirmed to have UTI .
One limitation of the study is that not all the studied cases and controls have had urine culture; we performed screening for all neonates included in the study using urine analysis (including performing leukocyte esterase test (LE) and nitrite test) and microscopic examination for the presence of pyuria. This limitation was due to NICU and microbiology laboratory local policy, which restricts performing urine culture only to cases with sepsis (which was one of the exclusion criteria in the study) or cases with abnormal urine analysis or pyuria. However, obtaining urine samples using aseptic urinary catheterization technique increased the specificity of these investigations; also using aggregate urine analysis (the presence of any LE, nitrite, or pyuria > 5 WBCs/HPF) increases the sensitivity for UTI detection in infants less than 60 days of age to 99.4% as indicated in a study done by Tzimenatos L et al.  Also, the absence of pyuria can help in differentiation true UTI from asymptomatic bacteriuria .
UTI in neonatal period has many nonspecific symptoms like fever, lethargy, vomiting, anorexia, diarrhea, weight loss, changes in urine characters and jaundice. So, neonates with UTI could present early with jaundice . It remains unclear how UTI is related to jaundice in neonates but there are some explanations that need further evaluating studies. Of these explanations is hepatocellular injury that may be caused directly circulating microorganisms that caused UTI or by their circulating endotoxins. On the other hand, jaundice may be the cause of UTI through making neonates more prone to infections by decreasing the bactericidal activity of their serum as reported in study done by Cisowska et al. .