title: Does body mass index influence the degree of pelvic tilt produced by a Crawford wedge?
abstract: BACKGROUND
  A pelvic tilt of 15° is standard practice when positioning a woman for caesarean section, and is commonly produced by tilting the operating table or placing a wedge under the right hip. This study investigated whether body mass index affects the degree of pelvic tilt produced when a wedge is used.
  
  
  METHODS
  Women undergoing category 3 and 4 caesarean sections were stratified into three groups according to their body mass index at antenatal booking: ≤ 25kg/m(2), 25.1-35kg/m(2) and >35kg/m(2). Twenty women were recruited into each group. Lateral tilt at caesarean section was provided with a Crawford wedge under the right hip and the degree of pelvic tilt was measured using a protractor device.
  
  
  RESULTS
  The median [range] pelvic tilt angle for the groups in order of ascending body mass index were 15° [12-22°], 19° [11-29°] and 17° [2-28°]. There was a significant increase in the variability of pelvic tilt with increasing body mass index (P=0.001). The proportion of patients with pelvic tilt <15° was observed to be 20%, 15% and 30% for women of body mass index ≤ 25kg/m(2), 25.1-35kg/m(2) and >35kg/m(2), respectively.
  
  
  CONCLUSIONS
  Variability in pelvic tilt increased with body mass index and was greatest with a booking body mass index >35kg/m(2).
authors: Department of Anaesthesia, St Michaels Hospital, Bristol, UK. nicola.harvey@uhbristol.nhs.uk
authors: N L
authors: NL
authors: Harvey
authors: R L
authors: RL
authors: Hodgson
authors: S M
authors: SM
authors: Kinsella
mesh_terms: D000328:Adult; D000773:Anesthesia, Obstetrical; D015992:Body Mass Index; D002585:Cesarean Section / Q000379:methods*; D005260:Female; D006801:Humans; D009765:Obesity; D056888:Patient Positioning; D010388:Pelvis / Q000033:anatomy & histology*; D011247:Pregnancy