THE PROMISING POTENTIAL OF DIMETHYLMETHYLENE BLUE (DMMB) IN PREDICTING DEEP VEIN THROMBOSIS (DVT) AMONG PREGNANT WOMEN ATTENDING ANTENATAL CLINIC IN RURAL NIGERIA

Abstract

Background: Deep Vein Thrombosis (DVT) is a significant health concern for pregnant women, as pregnancy-related physiological changes elevate the risk of thrombotic events. In rural areas with poor infrastructures, like Nigeria, Dimethyl methylene blue is being tested as a method to detect DVT earlier in pregnancy for improved maternal health. 

Methods: 254 pregnant women attending antenatal clinic in a private hospital in Wasimi, in Ogun State, Nigeria, were included into the cross-sectional study. Pregnant women in the second and third trimester were recruited. Compressed ultrasonography (CUS), the definitive diagnostic test for DVT, supported the findings of Dimethyl methylene blue tests that were run on potential DVT patients. Data on true positive, false positive, true negative and false negative in both trimesters were the main subjects. 

Results: Dimethyl methylene blue testing identified 7 positive DVT cases that were confirmed by compressed ultrasonography images. All three false positives (two in the third trimester and one in the second trimester) were also verified as negative by CUS. However, true negatives did not undergo CUS, so negative predictive value (NPV), cannot be calculated. The positive predictive value (PPV) among verified positives was 70% (7/10; 95% CI: 39-89%). However, putting an assumption that all DVT cases were captured by DMMB assay, the sensitivity will be 100% (95% CI: 59-100%). Trimester-specific PPV was 75% (3/4; 95% CI: 30–95%) in the second trimester and 66.7% (4/6; 95% CI: 30-90%) in the third trimester.

Conclusion: The use of DMMB in detecting DVT in women during pregnancy was sensitive and specific. The use of CUS confirm all TP cases. The presence of FP makes it important to have confirmation tests to confirm diagnosis, especially in the third trimester. Dimethyl methylene blue can be a good first-line screening test for DVT at antenatal clinics, particularly in rural communities.