When should a hip ultrasound be performed in breech infants?

Hip Ultrasound Screening in Breech Infants

Hip ultrasound should be performed at 4 to 6 weeks of age (not in the newborn period) for breech infants with normal hip examinations, with the American Academy of Pediatrics specifically recommending selective screening for all girls born breech and considering it optional for boys born breech. 1

Timing: Why 4-6 Weeks?

The critical window of 4 to 6 weeks balances two competing concerns:

• Too early (newborn period): Ultrasound has excessively high sensitivity for physiologic hip laxity and acetabular immaturity that spontaneously resolves, leading to false-positives and unnecessary treatment 1. Studies show 84-95% of Graf type II hips normalize by 3 months, and 99.6% of infants screened at 1 month remain normal 1

• Delayed screening allows: Time for neonatal physiologic immaturity to resolve while still enabling early intervention if true dysplasia exists, with no negative impact on outcomes from this short delay 1

The AAOS recommends pediatric orthopedic referral before 4 weeks of age, but actual imaging is typically deferred to the 4-6 week window 1

Risk-Stratified Approach

Highest Priority (Mandatory Screening):

• Girls with breech presentation - This is the single highest risk group per AAP guidelines 1

Consider Screening:

• Boys with breech presentation - Optional per AAP 1
• Girls with positive family history 1
• Any infant with equivocal physical examination findings 1

Immediate Imaging (Any Age):

• Positive Barlow or Ortolani test (unstable/dislocatable hip) - These infants need imaging regardless of age, though ultrasound confirmation can reduce unnecessary treatment as 41-58% of abnormal physical exams are false-positives 1

Critical Caveats

The 8-week ultrasound is NOT the endpoint. Recent evidence shows that 9% of breech infants with normal 6-week ultrasounds developed late DDH by 6 months, with female sex conferring 5-fold increased odds 2. This supports:

• Follow-up imaging at approximately 6 months (AP pelvis radiograph) even after normal ultrasound, particularly for female breech infants 2
• Recognition that DDH is truly "developmental" - it can develop after birth, not just be present congenitally 2

Premature breech infants <29 weeks gestational age may not require routine ultrasound screening if physical examination remains normal, as one study found 0% incidence of DDH in this specific subgroup 3. However, this represents emerging evidence and should be applied cautiously.

Practical Algorithm

1. At birth: Perform Barlow/Ortolani maneuvers on all breech infants

   • If positive → immediate imaging and orthopedic referral
   • If negative → proceed to step 2

2. At 4-6 weeks:

   • All breech girls → hip ultrasound
   • Breech boys → consider ultrasound (discuss with family)
   • Any equivocal exam → ultrasound

3. At 6 months:

   • All breech infants with normal prior ultrasound → AP pelvis radiograph (especially females)
   • This catches late-developing dysplasia 2

4. After 4 months of age: Radiography becomes more useful than ultrasound as the femoral head ossific nucleus appears (typically 4-6 months) 1

Do not screen in the immediate newborn period - the false-positive rate is unacceptably high and leads to overtreatment 1. The 4-6 week window is evidence-based and intentional.