Thrombocytopenia is characterized by reduced platelet count <150000/mm3 causing impaired primary hemostasis. Bone marrow suppression, petechiae, mucosal bleeding, and prolonged bleeding time occur, increasing hemorrhage risk with minor trauma including invasive procedures like rectal instrumentation. Rationale: A. Rectal temperature is not specifically contraindicated after an ileostomy because the rectum is typically bypassed but not traumatized. Risk is lower unless active inflammation or surgical complications exist. Focus is on stoma care and preventing infection and skin breakdown. B. Rectal temperature is contraindicated in thrombocytopenia due to high risk of mucosal trauma and bleeding. Fragile rectal mucosa can easily hemorrhage with minor insertion. Avoid all rectal procedures to prevent hemorrhage and worsening platelet deficiency complications. C. A productive cough with oxygen therapy does not contraindicate rectal temperature measurement. There is no direct bleeding or mucosal integrity issue. Priority is maintaining airway clearance and adequate oxygenation while monitoring respiratory status, not avoiding rectal routes. D. Hypothermia does not inherently contraindicate rectal temperature measurement; in fact, rectal temperature may provide accurate core readings. Care focuses on gradual rewarming and preventing complications like arrhythmias and metabolic acidosis, not bleeding risk.