Placental infections with histologically confirmed Plasmodium falciparum are associated with adverse birth outcomes in India: a cross-sectional study

Table 1 Scoring system used to evaluate presence and severity of placental pathologic changes and parasitaemia

	Histopathologic severity
	Mild	Moderate	Severe
Perivillous or intervillous fibrin	Present in <20% IVS	Present in 20-50% IVS	Present in >50% IVS
Fibrinoid necrosis	Focal: localised to few fibrin areas		Diffuse: >50% fibrin affected
Calcification	Focal: localised to few areas of fields viewed		Diffuse: >50% affected in total fields viewed
Syncytial knots	Normal: <1/3 villi affected		>1/3 villi affected in total fields viewed
Pigment deposition	Focal presence in small amounts	Small spots or larger de- posits in many locations	Large amount present widely
Polymorphonuclear cells	<10 cells/HPF	10-25 cells/HPF	>25cells /HPF
Mononuclear cells	<10 cells/HPF	10-25 cells/HPF	>25 cells/HPF
Parasite presence*	Scanty: 1-5/in any HPF	5-10 in 2 or more HPF	>10 in any 2 or more HPF
Parasitaemia**	1%	1-10%	>10%

Note: Intervillous spaces and villous structures were examined for the presence of parasitized cells and inflammatory cells. The intervillous and perivillous fibrin, inflammatory cells, villous stroma, the syncytium and Hofbauer cells were examined for the presence of pigment deposition. Morphological changes were evaluated in syncytial knots, Hofbauer cells, foetal red blood cells, villous stroma and fibrinoid necrosis and calcification. Pigment was identified as brownish granular looking material that shows birefringence under polarized light. Calcifications were identified as dark bluish purple spots that did not show birefringence on polarized light.
*Plasmodium species can not be identified on histology slides, and is based on the standard microscopy and RDT results. **Percent parasitaemia is calculated against 500 erythrocytes per HPF.
Abbreviations: IVS intervillous space, HPF High power field (100x), (total fields viewed = 50), RDT rapid diagnostic tests.

ISSN: 1475-2875