Complications

Complications are secondary problems or events that arise during the course of a disease, its treatment, or a medical procedure, and that worsen the overall outcome or add new challenges. They are not part of the disease’s natural history by itself, but rather occur as a consequence of the illness, the intervention, or patient factors such as age and comorbidities.

In clinical practice, complications are categorized by timing (acute vs late), cause (directly related to disease or treatment vs incidental), and preventability. Some complications are predictable and preventable with measures such as aseptic technique, prophylactic medications, careful monitoring, and early mobilization; others may be less predictable or unavoidable.

Common postoperative complications include surgical site infection, bleeding, deep vein thrombosis, pulmonary embolism, pneumonia, and organ dysfunction such as acute kidney injury. Medical complications can include arrhythmias, sepsis, electrolyte disturbances, and delirium, depending on the condition and therapy. Obstetric, pediatric, and chronic disease contexts each have specific commonly observed complications.

Prevention focuses on risk assessment, adherence to guidelines, vaccination, monitoring, and rapid response to warning signs. Early detection enables timely treatment that can limit severity, reduce length of stay, and improve prognosis. Documentation of complications is important for quality assessment and informs future care decisions.

Outside medicine, the term complications can describe difficulties that arise when pursuing plans or processes, indicating additional problems alongside the intended outcomes.