Limited Obstetric Ultrasound

Definition: A limited obstetric ultrasound examination is performed to answer a specific, acute clinical question, when an immediate impact on management is anticipated, and when time or other constraints make performance of a standard sonogram impractical or unnecessary. See the AIUM Practice Parameter for the Performance of Obstetric Ultrasound Examinations.


If a limited obstetric ultrasound is performed on a woman who has not previously had a standard or detailed ultrasound examination, a subsequent standard sonogram should be obtained, where appropriate. In patients who require serial sonograms and have already had a standard or detailed scan, some will only need limited scans, whereas others will require standard or detailed follow-up scans. Clinical judgment should be used to determine the proper type of ultrasound examination to perform and the appropriate frequency for follow-up examinations.


Background: Professional groups with interests in obstetric sonography, including the American Institute of Ultrasound in Medicine (AIUM), the American College of Obstetricians and Gynecologists (ACOG), and the American College of Radiology (ACR), have proposed guidelines for standard obstetric sonography. More advanced detailed sonograms are also common for patients with identified risk factors for fetal anomalies or other complications. The term standard sonogram is used here according to the AIUM Practice Parameter for the Performance of Obstetric Ultrasound Examinations. The terms level I and level II are obsolete, and their usage is discouraged.


When possible, a standard sonogram is more desirable than a limited sonogram. However, in current obstetric practice, a standard sonogram may be either impractical or unnecessary in certain clinical situations, and a limited obstetric ultrasound examination may be more appropriate. In addressing "limited sonograms," this document assumes that obstetric ultrasound is only obtained when clinically important information is required. If a standard sonogram has not previously been obtained, it should be obtained if the clinical situation permits.


Obstetric ultrasound examinations are not performed for entertainment or for sex determination in the absence of an accepted clinical indication. Obstetric ultrasound examinations are not performed solely for billing purposes.


Lack of qualification or inexperience of the sonographer/sonologist does not justify performance of a limited ultrasound examination when a standard examination is indicated. Sonographer/sonologist qualifications are described in the Training Guidelines for Physicians Who Evaluate and Interpret Diagnostic Obstetric Ultrasound Examinations and the Standards and Guidelines for the Accreditation of Ultrasound Practice.


Documentation: Limited sonograms require documentation as described in the AIUM Practice Parameter for Documentation of an Ultrasound Examination. Whenever feasible, images should be stored as part of the medical record. Whether images are obtained, a full description of the findings is required. When a patient undergoes a limited ultrasound examination, it is important that she understands why a limited scan is being done and that she has appropriate expectations regarding the information sought.


This document is not intended to provide a formal definition of a limited sonogram for coding and billing purposes.


Approved: 10/07/1997; Reapproved: 11/14/2009, 04/02/2014

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