Macrosomatia and ultrasonography: what is the problem?

It has been claimed that sonographic techniques offer no advantages over palpation of the maternal abdomen for detection of macrosomatia. We studied a group of 498 pregnant patients, 36 (7.2%) of whom gave birth to infants having macrosomatia. A sensitivity of 67%, specificity of 97%, and positive predictive value of 67% was obtained using our method without significant systematic error. Three problems that could reduce the value of ultrasonography in the detection of macrosomatia were detected: (1) use of equations with systematic errors; (2) human bias; and (3) use of ultrasonography machines/transducers with insufficient capacity.