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Unilateral Hand Oligodactyly: Prenatal Diagnosis With 3‐Dimensional Sonography

We describe a case of unilateral hand oligodactyly diagnosed in a fetus at 20 weeks’ gestation. The functional diagnosis of the anomaly was substantially facilitated by the application of 3-dimensional (3D) sonography. A 34-year-old woman in her third pregnancy who had a child with trisomy 18 and an ordinary follow-up, including first-trimester screening for aneuploidies, attended our unit for a routine 20-week scan. A 2-dimensional sonographic examination showed a male fetus with primarily normal biometric characteristics and anatomy; however, only 4 fingers and metacarpals were seen in the left hand. A 3D sonographic examination (surface mode) confirmed the 2-dimensional findings and showed a left hand with normal movements and grasping (Figure 1A). Apparently, there was a gap between the thumb and the middle finger, but no stumps or rudimentary structures were seen (Figure 1B). Amniocentesis was subsequently performed, resulting in a normal male karyotype, and the pregnancy was followed uneventfully until labor started spontaneously. At 37 weeks, a 3120-g healthy neonate was vaginally delivered, and the left hand was examined. It showed a normal bone structure with only 4 fingers (Figure 1C); the thumb was normal, and the other 3 fingers, contrary to what we thought, had replaced the 4 regular ones, so it was difficult to precisely determine which finger was actually missing. No signs of amputation or finger hypoplasia were seen, and the hand had normal functional movements. Hand radiography confirmed the examination findings, showing a 4-fingered hand with normal structure and no specific finger missing (Figure 1D). The 20-week scan includes screening for hand and finger anomalies. However, the fingers are frequently difficult to visualize, and malformations cannot always be ruled out accurately.1 The use of 3D sonography improves the detection rate for those defects, enabling imaging of the hand and finger surfaces and favoring assessment of hand functionality; however, 3D sonography is still not a part of the routine anomaly scan, and its use is reserved for situations with a previous suspicion of malformations. To the best of our knowledge, the 3D sonographic finding of isolated and unilateral hand oligodactyly diagCLINICAL LETTERS