[Diagnosis of gastroenterologic diseases with sonography. Part 4: Interventional sonography, endoscopic sonography].

Ultrasonography permits targeted aspiration under constant vision. The aspiration needle may be passed independently of the transducer head, may be attached laterally to the transducer, or centrally integrated within a special aspiration transducer. The complication rate, which depends upon the size of the needle, is low, so that the indication for this procedure can be "liberal". The development of every smaller probes with increasing resolution has resulted in an increase in the range of applications of endosonography, and there is already a whole spectrum of accepted indications for endosonographic inspection.