• morbid obesity;
  • bladder pressure;
  • abdominal pressure;
  • sagittal abdominal diameter;
  • waist∶hip ratio;
  • Type II diabetes;
  • hypertension;
  • syndrome X

Objectives. To determine relationship of intraabdominal pressure to central obesity and the comorbidity of obesity.

Design. Non-randomized, prospective.

Setting. University hospital, operating room.

Subjects. Eighty-four anaesthetized consecutive patients prior to gastric bypass for morbid obesity and five non-obese patients before colectomy for ulcerative colitis.

Main outcome measures. Weight, body mass index (BMI), co-morbid history, sagittal abdominal diameter, waist:hip (W∶H) ratio and urinary bladder pressure, as an estimate of intra-abdominal pressure.

Results. Urinary bladder pressure was greater in the obese than the non-obese (18±0.7 vs. 7±1.6 cm H2O, P < 0.001), correlated with sagittal abdominal diameter (r = +0.67, P < 0.001) and was greater (P < 0.05) in patients with, than those without, morbidity probably (hypoventilation, gastroesophageal reflux, venous stasis, stress incontinence, incisional hernia) or possibly (hypertension, diabetes) due to increased abdominal pressure. W∶H ratio correlated with urinary bladder pressure in men (r = +0.6, P < 0.05) but not women (r = −0.3).

Conclusions. Increased sagittal abdominal diameter was associated with increased intraabdominal pressure which contributed to obesity-related comorbidity. W∶H ratio was not a reliable indicator of intraabdominal pressure for women who often have both peripheral and central obesity. Further studies are needed to evaluate the relationship between intraabdominal pressure and Type II diabetes and hypertension.