TABLE 8

Diagnostic Performance of AF PCR According to the Time of Acute Maternal Primary Infection

First Author, YearCT Cases/AF Tested (Prevalence)Sensitivity (Positive Test Results/CT Cases) (95% CI)Specificity (Negative Test Results/Non-CT Cases) (95% CI)PPVa (CT Cases/Positive Test Results) (95% CI)NPVb (No CT Cases/Negative Test Results) (95% CI)
First-trimester seroconversion
 Sterkers, 201217011/154 (7%)91% (10/11) (59%–100%)100% (143/143) (97%–100%)100% (10/10) (69%–100%)99% (143/144) (96%–100%)
 Wallon, 20101124/127 (3%)75% (3/4) (19%–99%)100% (NR) (97%–100%)100% (NR) (29%–100%)99% (NR) (96%–100%)
 Rabilloud, 2010168,c7/234 (3%)57% (4/7) (14%–86%)100% (226/227) (99%–100%)80% (4/5) (NR)99% (226/229) (NR)
 Thalib, 20051699/357 (3%)33% (3/9) (7%–70%)99% (347/348) (98%–100%)75% (3/4) (22%–98%)98% (347/353) (96%–99%)
Second-trimester seroconversion
 Sterkers, 201227/114 (24%)78% (21/27) (62%–94%)100% (87/87) (96%–100%)100% (21/21) (84%–100%)94% (87/93) (89%–99%)
 Wallon, 201030/108 (28%)97% (29/30) (83%–100%)100% (NR) (95%–100%)100% (NR) (88%–100%)99% (NR) (93%–100%)
 Rabilloud, 2010c39/182 (21%)67% (26/39) (51%–82%)99% (141/143) (97%–100%)93% (26/28) (NR)92% (141/154) (NR)
 Thalib, 200546/200 (23%)80% (37/46) (47%–85%)97% (149/154) (92%–99%)88% (37/42) (74%–96%)94% (149/158) (89%–97%)
Third-trimester seroconversion
 Sterkers, 201212/23 (52%)100% (12/12) (74%–100%)100% (11/11) (72%–100%)100% (12/12) (74%–100%)100% (11/11) (72%–100%)
 Wallon, 201017/26 (65%)88% (15/17) (67%–99%)100% (NR) (66.4%–100%)100% (NR) (78.2%–100%)82% (NR) (48%–98%)
 Rabilloud, 2010c34/65 (52%)74% (25/34) (59%–88%)100% (31/31) (89%–100%)100% (25/25) (NR)78% (31/40) (NR)
 Thalib, 200525/36 (69%)68% (17/25) (66%–81%)91% (10/11) (57%–99%)94% (17/18) (71%–99%)56% (10/18) (31%–78%)
Overall diagnostic performance
 Sterkers, 2012d51/295 (17%)86% (43/50) (77%–96%)100% (241/241) (99%–100%)100% (43/43) (92%–100%)97% (241/248) (95%–99%)
 Wallon, 2010e51/261 (20%)92% (47/51) (81%–98%)100% (NR) (98%–100%)100% (NR) (93%–100%)98% (NR) (95%–99.5%)
 Rabilloud, 2010c80/481 (17%)69% (55/80) (59%–79%)99% (398/401) (98%–100%)95% (55/58) (NR)94% (398/423) (NR)
 Thalib, 200580/593 (13%)71% (57/80) (61%–81%)98% (506/513) (97%–99%)89% (57/64) (78%–95%)96% (506/529) (93%–97%)
  • Note that, in these studies, the majority of the women had continued treatment throughout pregnancy once the diagnosis of acute T gondii infection was made. Differences in the percentages of women on treatment and the duration of treatment before amniocentesis could explain differences in the reported sensitivity of the AF PCR across these studies. NR, not reported.

  • a NPV is the probability that the fetus would not be infected if the AF PCR result is negative.

  • b PPV is the probability that the fetus would be infected if the AF PCR result is positive.

  • c For the Rabilloud et al study, the PPV and NPV values listed represent the PPV and NPV at 6, 18, and 30 wk of gestation, respectively.

  • d In the Sterkers et al study, 7 of 50 infants with CT had a negative AF PCR, giving an overall sensitivity for the AF PCR of 86% (all the 7 cases that were not detected in utero were subclinical cases).

  • e In the Wallon et al study, 4 of 51 infants with CT had a negative AF PCR (all 4 infants were asymptomatic up to 1 y of age, likely suggesting a milder infection with a lower parasite load). Factors contributing to the increased sensitivity of the AF PCR method in this study included (1) larger volumes of AF (10 mL), (2) use of a real-time PCR method, (3) 529 gene targets, and (4) fluorescent probes.