Question: Which CPT code should I use for nuchal translucency measurement in the second trimester? Code 76813 specifies first trimester. Arkansas Subscriber Answer: CPT specifically created 76813 (Ultrasound, pregnant uterus, real time with image documentation, first trimester fetal nuchal translucency measurement, transabdominal or transvaginal approach; single or first gestation) for the first trimester. Clinical literature indicates that this measurement only has value as a screening test between the 11th and 14th weeks.- After that time period, the ob-gyn will perform a quad screen instead. The reason is the fluid at the back of the neck normally disappears after the 14th week, even if the fetus has Down's syndrome.- You also need to be aware that because literature states that the ob-gyn should perform the nuchal translucency scan between the 11th and 14th weeks (some clinical articles recommend 11th-13th week), you may have a coverage issue with the payer. The exception is medical documentation showing that, at 17 weeks, the scan can detect a problem. If your physician is simply doing a scan to look for anomalies, bill the regular U/S codes.