[Deterioration of clinical findings in hip joint follow-ups in neonatal screening].

6 per cent out of 4290 hips checked by neonatal ultrasound screening could be reexamined later on. 7 of 200 hips (i.e. 4 per cent), primarily categorized as type IIa, showed an unexpected severe deterioration to type D (n = 3) or even to type IIIa (n = 4) after a mean-time of 9 weeks. Additional 5 cases with similar unfavourable courses from IIa to IIc, D or IIIa, and even 3 initially normal hips, changing to type IIa, were seen in another screening material (not yet systematically analyzed). Reasons for possible initial misinterpretation (purely visual evaluation in most cases, uncertainties in measuring suboptimal sonographic cuts, deficiencies in technical equipment and documentation), equivocal classification of border-line sonograms as well as possible influence of additional risk factors are discussed. Routine sonographic re-examinations after 6 (to 12) weeks are recommended as obligatory for all hips.