Which type of cleft has no visual oral manifestations and requires direct observation for diagnosis?

The type of cleft that has no visual oral manifestations and requires direct observation for diagnosis is indeed the occult submucous cleft palate. An occult submucous cleft palate is a subtle form of cleft that occurs beneath the mucosal surface, meaning that while the overlying tissue appears intact, the underlying muscle and structural support may be compromised. This condition typically doesn't present with visible clefts or obvious deformities in the oral cavity, making it difficult to diagnose through visual examination alone.

For diagnosis, direct observation through methods such as nasopharyngoscopy may be necessary to reveal the underlying structure of the palate. This condition can often go unnoticed until it leads to functional issues such as speech difficulties or a diagnosis is confirmed via imaging techniques.

In contrast, other types of clefts, such as overt clefts or submucous clefts, typically present with more apparent manifestations, making diagnosis simpler through visual examination. A bifid uvula may also be observed easily during an oral exam as it presents with a split or forked appearance of the uvula.