What is the most appropriate initial treatment for an 18-month-old with fecal impaction?

The most appropriate initial treatment for fecal impaction in an 18-month-old is the use of polyethylene glycol 3350. This osmotic laxative works effectively by drawing water into the stool, which helps to soften it and promote bowel movements. Polyethylene glycol is especially suitable for young children as it is generally well-tolerated and has a low risk of side effects.

Additionally, the gradual and gentle action of polyethylene glycol makes it a preferred choice for managing fecal impaction without causing discomfort or distress to the child. It's important to consider the age and delicate gastrointestinal system of young children when selecting a treatment option. Many healthcare providers recommend polyethylene glycol as a safe and effective first-line therapy for constipation and fecal impaction in pediatric patients.

In the context of the other treatment options: while manual disimpaction can be effective, it is often more invasive and can be uncomfortable for the patient. Enemas can also be effective but may pose risks of discomfort and are usually not the first-line treatment, especially in young children. Bisacodyl rectal suppositories may stimulate a bowel movement but are generally considered after first attempting gentler methods like polyethylene glycol.