Transient hyperechogenicity of neonatal renal papillae - updating normal

• Design: This will be a retrospective observational study, rather than an assessment of individual patients over time. Objective will be to include only healthy infants based on clinical chart information.

• Hypotheses

  1. Premature infants show echogenic papillae more often than term infants;
  2. Healthy infants show echogenic papillae for several weeks

Sample size calculation

Prevalence of echogenic papillae in

• Term infants: \(\leq 10\%\)
• Premature infants: \(\sim 25\%\) (a range from 15% – 30% below)

Total number of subjects needed

EP in premature infants	N for 80% power	N for 90% power
0.15	1390	1861
0.16	1002	1342
0.17	764	1022
0.18	606	811
0.19	495	663
0.20	414	555
0.21	354	473
0.22	306	410
0.23	269	360
0.24	239	320
0.25	214	286
0.26	193	259
0.27	176	235
0.28	161	215
0.29	148	198
0.30	137	183