The hallmark feature is the formation of polyclonal IgG autoantibody against the P antigen, which is a polysaccharide surface antigen on red cells in most humans. As a weak, biphasic antibody, it absorbs to the P antigen in the cold temperature as in the periphery in the primary phase, and fixes complement on recirculation to the core temperature in the secondary phase, resulting in intravascular hemolysis. Diagnosis
The purposes of laboratory investigations are to: 

Confirm the presence of intravascular hemolysis in terms of metabolic products of red cells and hematopoietic response. Establish the diagnosis of autoimmune hemolytic anemia and differentiate from other AIHA. Identify other supporting features as in hematopathological findings.For intravascular hemolysis, the laboratory parameters include increased serum free hemoglobin, lactate dehydrogenase, unconjugated bilirubin, and reduced haptoglobin. Urine tests may show elevated hemoglobinuria and hemosiderinuria in chronic cases. Reticulocytosis may not be apparent in the acute phase or when there is viral-induced myelosuppression.Once the clinical suspicion of autoimmune hemolytic anemia is made, direct antiglobulin test (DAT) or direct Coombs test is the first line of investigation to confirm the presence of warm autoantibodies. Testing with polyspecific and IgG-specific antiglobulin agents is usually negative, and that with C3-specific agent may be positive. On excluding warm autoimmune hemolytic anemia (WAIHA), the cold agglutinin titer should be examined for cold agglutinin disease (CAD). The diagnosis of PCH is suspected when both WAIHA and CAD are excluded. The complement level is usually low. Donath-Landsteiner test is the confirmatory test for PCH.
More commonly, open reduction and rigid internal fixation is placed.When the width of the mandible is less than 1 cm, the jaw loses its endosteal blood supply. Instead, the blood supply comes largely from the periosteum. Open reduction (which normally strips the periosteum during the dissection) can lead to avascular necrosis. In these cases, oral surgeons sometimes opt for external fixation, closed reduction, supraperiosteal dissection or other techniques to maintain the periosteal blood flow. High velocity injuries
In high velocity injuries, the soft tissue can be severely damaged far from the bullet wound itself due to hydrostatic shock. Because of this the airway must be carefully managed and vessels well examined. Because the jaw can be highly comminuted, MMF and rigid internal fixation can be difficult. Instead, external fixation is often used,. Pathologic fracture
Fractures where large cysts or tumours are in the area (and weaken the jaw), where there is an area of osteomyelitis or where osteonecrosis exist cause special challenges to fixation and healing. Cysts and tumours can limit effective bone to bone contact and osteomyelitis or osteonecrosis compromise blood supply to the bone. In all of the situations, healing will be delayed and sometimes, resection is the only alternative to treatment. Prognosis
The healing time for a routine mandible fractures is 4–6 weeks whether MMF or rigid internal fixation (RIF) is used.