title: Recognition and application of the rectangular sonographic appearance of the urinary bladder.
abstract: OBJECTIVE
  The purpose of this study was to investigate the rectangular sonographic appearance of the urinary bladder and its application.
  
  
  METHODS
  A prospective study was conducted from May 2007 to December 2010. Fifty of 53 healthy women and 31 female patients who had large pelvic fluid-filled cystic lesions but were otherwise healthy in workup were selected. The mean ages ± SDs of the healthy participants and patients were 27.4 ± 13.5 and 30.4 ± 15.2 years, respectively. Both the healthy participants and patients underwent abdominopelvic sonographic evaluations of the pelvic cavity, including the uterus, adnexa, and bladder. The appearance of the bladder was assessed when moderately filled, overfilled, and after voiding, and the volume, presence or absence of the rectangular appearance of the bladder, and presence or absence of large pelvic cystic lesions were observed and compared.
  
  
  RESULTS
  The bladders of the 50 healthy participants and 31 patients with pelvic fluid-filled lesions could show the rectangular appearance, but all of the pelvic cystic lesions did not show this finding; the difference between the bladders and cystic lesions was significant (P < .001). The volumes between the moderately filled bladders of the patients (322.7 ± 93.3 mL) and the cystic lesions (320.4 ± 78.9 mL) showed no significant difference (P = .07), and neither did the volumes between the moderately filled bladders of the healthy participants (322.4 ± 75.6 mL) and the cystic lesions (320.4 ± 78.9 mL; P = .38).
  
  
  CONCLUSIONS
  The bladder can show a rectangular appearance on sonography. The rectangular appearance is unique and can be used for identification of the bladder. Definitive recognition of the bladder is useful for avoiding errors in situations likely to be associated with bladder-related pitfalls.
authors.affiliation: Department of Ultrasound, Affiliated Hospital of Hainan Medical College, 31 Longhua Rd, 570102 Haikou, China. wsz074@yahoo.com.cn
authors.forename: Size
authors.initials: S
authors.lastname: Wu
authors.forename: Rong
authors.initials: R
authors.lastname: Tu
authors.forename: Guangqing
authors.initials: G
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003560:Cysts / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011446:Prospective Studies; D014463:Ultrasonography; D001743:Urinary Bladder / Q000000981:diagnostic imaging*