Anti-D prophylaxis is required for partial but not complete molar pregnancies. Confirmation of the diagnosis of complete molar pregnancy may not occur for some time after removal, which could delay administration of anti-D. Therefore, If the diagnosis of complete molar pregnancy cannot be established within 72 hours, anti-D prophylaxis can be administered for practical reasons.
In suspected molar pregnancies, anti D should be given unless histopathology ( to confirm the type of molar pregnancy) result comes before the 72 hour window.