Intra-abdominal thrombosis is a complication of paroxysmal nocturnal 
hemoglobinuria (PNH). There is scarcity of data on cases presenting with 
thrombosis in whom PNH is the predisposing factor. We assessed the role of PNH 
defect in 81 patients with intra-abdominal thrombosis, 44 patients of Budd 
Chiari syndrome and 37 patients of extra hepatic venous obstruction. 
Flowcytometry with glycosylphosphatidyl inositol-anchored proteins 
(GPI-AP)-CD55, -CD59, and -CD16 was performed on all patients and controls to 
assess the prevalence of deficiencies and PNH-type phenotype clone size. 
Deficiencies of individual GPI-AP were seen in 17.3% cases versus 3.4% controls. 
This was due to CD55 deficiency on red blood cells and CD16 deficiency on the 
granulocytes. Deficiency of multiple GPI-APs was less frequent (3.7% cases). 
Data of this study indicate that the PNH defect as detected with CD55, CD59, and 
CD16 is not an important cause of intra-abdominal thrombosis in northwestern 
India.