In simple words: Macrostomia is a birth defect where a baby's mouth is unusually wide. This happens because parts of the face that normally join together during pregnancy don't fuse properly.The size of the opening can range from a slightly wider mouth to a large split that goes towards the ear.

Macrostomia is a congenital physical anomaly characterized by an abnormally large mouth opening. It results from the incomplete or failed fusion of the maxillary and mandibular processes during embryonic development, leading to a cleft at one or both corners of the mouth. The cleft may vary in severity, ranging from a minor widening of the mouth to a significant fissure extending towards the ear. It can occur in isolation or as part of a syndrome, such as craniofacial microsomia or Treacher Collins syndrome.

Example 1: A newborn is diagnosed with isolated macrostomia, presenting with a wide mouth opening extending 1 cm laterally from the commissure on the right side, without other facial anomalies., A child with craniofacial microsomia presents with unilateral macrostomia on the left side, along with ear deformities and mandibular hypoplasia. , An infant with bilateral macrostomia has an abnormally large mouth opening on both sides, along with additional deformities of the first and second branchial arches, affecting the oral cavity's aesthetics and function.

Documentation should include detailed descriptions of the cleft, including laterality (right, left, bilateral), extent of the cleft, associated facial and other anomalies, and family history of similar conditions. Imaging studies like CT or MRI scans may be necessary. Genetic testing results may also be relevant for documentation.