Prospective observational pilot study evaluating the frequency of cow's milk protein allergic prococolitis in newborns hospitalized in neontal medicine at the university hospital of Nice who presented rectal bleeding.

Inclusion of all newborns in the neonatal medicine department at Nice University Hospital with isolated rectal bleeding.

A note of information and non-opposition will be presented and given to the biological mother. She has the right to object to this study, on her own initiative, at any time.

Collection of data relating to the newborn during hospitalization, the results of the clinical examination and the systematic check-up carried out in accordance with standard practice, and data at discharge.

Follow-up of the newborn to determine the cause of rectal bleeding and therefore the frequency of procolitis allergic to cow's milk proteins.

Prospective observational study of current practices without any intervention.

Inclusion Criteria:

1. All newborns ≤ 28 days corrected age or ≤ 44 amenorrhea weeks corrected age hospitalized in neonatal medicine with isolated rectorrhagia;
2. Affiliated to social security ;
3. Presenting isolated rectorrhagia defined as rectorrhagia without hematemesis/ repeated vomiting/ tense or distended abdomen/ apathy/ apnea/ bradycardia or signs of severity (tachycardia, desaturation, poor coloration);
4. After obtaining the biological mother's non-objection;

Exclusion Criteria:

1. All newborns with ulcerative enterocolitis, congenital digestive malformations or rectorrhagia following digestive surgery;
2. Opposition to participation in research involving the human person.

All newborns ≤ 28 days corrected age or ≤ 44 amenorrhea weeks corrected age hospitalized in neonatal medicine with isolated rectorrhagia.