摘要：o.jective: Precise determinatio. o. fetal head po.itio. in labo. is a prerequisite fo. safe instrumental deliveries, and essential fo. the assessment o. labo. pro.ress. Recent studies have cast serio.s do.bts o. the accuracy o. the time-ho.o.ed digital vaginal examinatio. (DVE) in co.pariso. to.transabdo.inal ultraso.nd scans (TUS). Ho.ever, transabdo.inal imaging is technically difficult with a deeply engaged fetal head in the seco.d stage o. labo.. We examined the accuracy and time requirements o. transvaginal scans (TVS) in the seco.d stage o. labo. fo. determinatio. o. fetal head po.itio.. Study design: Sixty labo.ing wo.en in the seco.d stage o. labo. with a deeply engaged fetal head were examined by experienced nurse midwives and senio. residents. Fetal head po.itio. was reco.ded as “ time o. a 12- ho.r clo.k.&quo.; Subsequently, TUS and TVS were independently perfo.med by a skilled so.o.rapher. Accuracy and time requirements fo. all 3 examinatio.s were reco.ded. Results: Fetal head po.itio. co.ld be determined in all cases by TVS, but no. in 7 cases and 9 cases by DVE and TUS, respectively (P < .03; P < .008). A discrepancy o. 60° o. mo.e between the DVE and TUS o. TVS was fo.nd in 13/60 cases (21.7% ) and 14/60 cases (23.3% ), respectively. A ≥ 90° discrepancy was fo.nd in 9/60 cases (15% ) and 12/60 cases (20% ), respectively (P <.02 fo. co.pariso. o. TUS and TVS). In 5 cases, the digital examinatio. erro.eo.sly perceived an o.ciput po.terio. po.itio. as o.ciput anterio.. No.significant differences in fetal head po.itio. were detected between TUS and TVS, when the examinatio. was technically feasible. The mean time (± SD) required fo. determining fetal head po.itio. was sho.test fo. TVS (8.7 ± 5.8 seco.ds) in co.pariso. to.DVE (22.7 ± 14.6 se-co.ds; P < .0001) o. TAS (31.7 ± 19.1 seco.ds; P < .0001). Co.clusio.: Transvaginal so.o.raphy was the mo.t successful and accurate metho. fo. determinatio. o. fetal head po.itio. in the seco.d stage o. labo., and required