Rationale: Micrognathia is a subtle facial malformation characterized by a small mandible and receding chin. Fetal micrognathia is often associated with chromosomal abnormalities, skeletal dysplasia, and various syndromes. Once it is dignosised, detailed fetal malformation screening and chromosome examination should be carried out.
Patient concern: One pregnant woman with suspicion of fetal micrognathia was referred from her local hospital to our hospital for detailed fetal malformation screening and fetal echocardiography. Examination of the fetus was performed using a two-dimensional and three-dimensional ultrasound probe in multiple planes. The fetus showed micrognathia without glossoptosis with features of the inferior facial angle (IFA) ≤50° and his tongue reached anterior mandibular border box during normal movement.
Diagnoses: The fetus was diagnosed as isolated micrognathia prenatally without multisystem abnormalities.
Interventions: Amniocentesis was performed and the fetus was found to carry 46XN with 6q14.1 duplication, the significance of which was unclear.
Outcomes: The fetus was labored through vagina at 38 weeks gestation. A small soft cleft palate was diagnosed after delivery.
Lessons: This case suggests that once prenatal diagnosis of the fetal micrognathia has been made, we should carefully examine the presence of fetus's multisystem developmental abnormalities and due consideration should be given for associated soft cleft palate.