Polymerase chain reaction for Group B Streptococci (GBS) at labor highly correlates with vaginal GBS load

OBJECTIVE

To explore factors associated with a high vaginal GBS load during labor considering (1) the recto-vaginal GBS load at 35-37 weeks' gestation determined by culture and (2) the vaginal GBS colonization determined by a polymerase chain reaction (PCR) assay during labor.

METHODS

From an unselected cohort of 902 pregnant women, we obtained (1) recto-vaginal swabs for culture of GBS at 35-37 weeks' gestation (GBS_rectovag-36), (2) vaginal swabs for GBS PCR detection at labor (PCR_vag-labor), and (3) vaginal swabs for culture of GBS at labor (GBS_vag-labor). The GBS load was classified semi quantitatively according to a culture protocol without prior broth enrichment of the swab samples: none (0), few (+), some (++), or many (+++) GBS colonies.

RESULTS

Among 902 unselected pregnant women, 859 (95%) had a vaginal swab culture taken at labor, which was classified semi quantitatively. High load GBS_vag-labor (+++) were found in 31 participants. GBS_rectovag-36 showed a sensitivity of 90% (28/31) and a PPV of 23% (28/121), whereas PCR_vag-labor had a sensitivity of 98% (30/31, non-significant difference) and a PPV of 42% (30/71, p < .01). PCR at labor had a lower sensitivity (78%) for detection of vaginal colonization with GBS at labor (any load) compared to recto/vaginal colonization with GBS at 36 weeks (92%). Vaginal colonization with GBS at 36 weeks seemed to have a lower sensitivity for detecting GBS in vagina at labor for high load (48%) and for any load (39%).

CONCLUSION

PCR at labor has higher detection rate (non-significant) and PPV in identification of laboring women with a high load of vaginal GBS compared with recto-vaginal culture at 36 weeks' gestation.

Urine dipstick for predicting intrapartum recto-vaginal colonisation by group B streptococci

INTRODUCTION

In pregnant women, bacteriuria with group B streptococci (GBS) may be associated with a high degree of recto-vaginal GBS colonisation and therefore an increased risk of early-onset GBS disease. The aim of this study was to assess the performance of routine use of dipstick urine analysis during pregnancy for prediction of recto-vaginal GBS colonisation at the time of labour.

METHODS

Among 902 unselected Danish pregnant women, we obtained results from 1) dipstick urine analysis, 2) urine culture carried out during pregnancy, if indicated, and 3) recto-vaginal culture at labour. The inclusion criteria were age > 18 years and gestational age ≥ 37 weeks.

RESULTS

Intrapartum recto-vaginal GBS colonisation was predicted by a positive urine dipstick with 5% sensitivity only.

CONCLUSION

Dipstick urine analysis had a low sensitivity for predicting intrapartum recto-vaginal colonisation with GBS.

FUNDING

none.

TRIAL REGISTRATION

not relevant.

Using virtual-reality simulation to ensure basic competence in hysteroscopy

BACKGROUND

Hysteroscopy is a technically challenging procedure. Specialty curricula of obstetrics and gynaecology appraise hysteroscopy for trainees but there is no present evidence-based training program that certifies the fundamental technical skills before performance on patients. The objectives of this study were to develop and gather validity evidence for a simulation-based test that can ensure basic competence in hysteroscopy.

METHODS

We used the virtual-reality simulator HystMentor™. Six experts evaluated the feasibility and clinical relevance of the simulator modules. Six modules were selected for the test and a pilot study was carried out. Subsequently, medical students, residents, and experienced gynaecologists were enrolled for testing. Outcomes were based on generated simulator metrics. Validity evidence was explored for all five sources of evidence (content, response process, internal structure, relations to other variables, consequences of testing).

RESULTS

Inter-case reliability was high for four out of five metrics (Cronbach's alpha ≥ 0.80). Significant differences were identified when comparing the three groups' performances (p values < 0.05). Participants' clinical experience was significantly correlated to their simulator test score (Pearson's r = 0.49, p < 0.001). A single medical student managed to achieve the established pass/fail score (6.7% false positive) and three experienced gynaecologists failed the test (27.3% false negative).

CONCLUSIONS

We developed a virtual-reality simulation-based test in hysteroscopy with supporting validity evidence. The test is intended to ensure competency in a mastery learning program where trainees practise on the simulator until they are able to pass before they proceed to supervised training on patients.