•        No true mass present

 

·         Mass resolved spontaneously

 

•        Mass hidden by bowel loops

 

·         Bowel loops or soft tissues mistaken for mass

 

•        Mass displaced into the abdomen (the position of a mass may vary depending upon the degree of bladder distension)

 

•        Large ovarian masses may mimic bladder/ascots

 

•        A dermoid or calcified mass giving rise to an echoenic anterior surface with distal shadowing may not give the appearance of a mass (need plain abdominal radiograph) — the ‘tip of the iceberg’ sign.