Truth or Myth: Intra-abdominal Pressure Increases in the Lithotomy Position

Study Objective: To determine if there were differences in intra-abdominal pressure (IAP) in the supine, low lithotomy, and high lithotomy positions. Design: Prospective cohort study. Setting: University medical center. Patients: Twenty-nine women undergoing surgery for prolapse or stress incontinence. Interventions: Relevant medical history, including the pelvic organ prolapse quantification stage, body mass index, and airway grade (Mallampati score), was abstracted from patients’ medical charts. IAP was measured in centimeters of water (cmH₂O) on the day of their surgery before induction of general or intravenous anesthesia using a T-doc air charged urodynamic catheter (Laborie Aquarius; Ontario, Canada) placed in a patient's vagina (for patients with incontinence) or rectum (for patients with prolapse). Measurements and Main Results: IAP was measured in 3 positions: supine (legs at 0°), low lithotomy (legs in Yellowfin stirrups at 45°; Allen Medical, Acton, MA), and high lithotomy (legs at 90°). The means ± SDs IAP for the groups were as follows: in the supine position, 18.6 cmH₂O ± 7.6; low lithotomy, 17.7 cmH₂O ± 6.6; and high lithotomy, 17.1 cmH₂O ± 6.3. In the same women, there was a significant decrease in IAP from the supine to high lithotomy positions, with a mean difference of 1.4 cmH₂O ± 3.7, p = .05. Similarly, there was a significant, though smaller, decrease in mean IAP when moving from the supine to low lithotomy positions in these same women (mean decrease of 0.9 cmH₂O ± 1.5, p = .004). Neither change is clinically significant based on previous research that suggests 5 cmH₂O is a clinically significant change. Conclusion: Placing patients’ legs in a low or high lithotomy position does not result in a clinically significant increase in IAP. Therefore, surgeons and anesthesiologists can consider positioning patients’ lower extremities in stirrups while patients are awake to minimize discomfort and possibly reduce the risk of nerve injuries.