Early resolution of increased nuchal translucency in a fetus with trisomy 18 Claudio Celentano, MD, a Nicola G. Di Donato, MD, a Federico Prefumo, MD, b and Sigi Rotmensch, MD c Penne, Genova, Italy, and Tel Aviv, Israel The normal timing for first-trimester nuchal translucency screening of aneuploidies is 10 to 14 weeksÕ gestation. We describe a fetus with trisomy 18 that presented at 11 weeks with increased nuchal thickness. Reevaluation at 12 and 13 weeks showed early return to normal of the increased nuchal measurement. (Am J Obstet Gynecol 2003;189:880-1.) Key words: Nuchal translucency, trisomy 18 screening The normal timing for first-trimester nuchal trans- lucency screening of aneuploides is 10 to 14 weeks. We describe a fetus with trisomy 18 that presented at 11 weeks with increased nuchal thickness. Reevaluation at 12 and 13 weeks showed early return to normal of the increased nuchal measurement. Case report A 34-year-old woman, gravida 3, para 2, was referred for ultrasound assessment. The two previous pregnancies had been uneventful. The last menstrual period was con- firmed by early transvaginal scan at 7 weeksÕ gestation. Ultrasound examination at 11 weeksÕ gestation demon- strated a fetus with a crown-rump length (CRL) consistent with the dates and a nuchal translucency of 4.1 mm (>95th percentile, Fig 1). The excessive nuchal fluid accumula- tion appeared as a large, swelling, fluid-filled cavity at the neck region and it extended to the skin covering the head, chest, and abdomen. The nuchal translucency--adjusted risk for Down syndrome was above the cutoff value for offering fetal karyotyping at our institution (1:300). The patient underwent repeat ultrasound examinations at 12 and 13 weeksÕ gestation, revealing a nuchal translucency thickness of 2.3 mm (Fig 2) and 1.6 mm, respectively. The adjusted risk recalculated on these two occasions was below the screening cutoff value. The subcutaneous tissue swelling was no longer present at the second and third scan (Fig 3). All three ultrasound assessments were performed by the same operator. After extensive coun- seling, the couple decided on invasive testing. Am- niocentesis performed at 15 weeks’ gestation demon- strated a 47,XX+18 karyotype. Detailed ultrasound examination at 18 weeksÕ gestation revealed no fetal abnormalities or growth restriction. Termination of preg- nancy was requested by the parents, and fetal autopsy did not highlight any major fetal abnormalities. Furthermore, major fetal heart anomalies were excluded. The karyotype was confirmed postnatally. Comment Increased nuchal translucency measurement is a tran- sient ultrasonographic finding whose pathogenesis is unknown. Lymphatic system abnormalities, congen- ital heart diseases, and early cardiac failure have been identified as possible causes. Increases in nuchal trans- lucency are usually observed between 10 and 14 weeks of gestation but often disappear after this period. Spontaneous resolution of increased nuchal translucency thickness in the second trimester of pregnancy (ie, after the gestational age at which screening takes place) has been well described in cases with both normal and abnormal karyotypes. First-trimester nuchal translucency screening for chromosomal abnormalities has been reported to have a sensitivity greater than 80% not only for trisomy 21, but also for other aneuplodies such as trisomy 13 and trisomy 18. 1 The case described here provides for the first time evidence of the return to normal values of an increased nuchal translucency measurement well within the gesta- tional interval of 10 to 14 weeks. This quick spontaneous resolution supports the hypothesis that some transient functional phenomenon, such as a temporary cardiac strain abnormality, may be one of the underlying mechanisms in the development of increased nuchal From the Department of Obstetrics and Gynecology, San Massimo Hospital, a the Department of Obstetrics and Gynecology, G. Gaslini Institute, University of Genova, b and the Department of Obstetrics and Gynecology, Edith Wolfson Medical Center. c Received for publication February 4, 2003; revised April 2, 2003; accepted May 19, 2003. Reprint requests: C. Celentano, MD, Department of Obstetrics and Gynecology, 5 Umbria St, 65016 Montesilvano (PE), Italy. E-mail: ccelen@tin.it Ó 2003, Mosby, Inc. All rights reserved. 0002-9378/2003 $30.00 + 0 doi:10.1067/S0002-9378(03)00660-4 880