저자들은 5년간의 의무기록과 초음파 검사기록을 분석하여 정상임신에서 양수지수의 정상치 를 구하였으며, 태아의 태위에 따른 차이점에 대하여 알아보고자 하였다. 정상임신에서의 양 수지수는 임신 25~30주사이에 가장 높았으며, 그 이후 점차 감소하는 경향을 보였다. 임신 기간에 따라 미숙임신, 만삭임신, 과숙임신으로 나누어 비교한 결과, 과숙 임신으로 갈 수록 양수지수는 의의있게 감소하였다. 태아의 태위에 따른 분류에서 임신 37주이후에는 둔위임 신인 경우 두정위임신인 경우에 비하여 양수지수가 적은 경향을 보였으며, 양수지수 5.0cm은 두정위인 경우 1백분위, 둔위임신인 경우의 5백분위에 해당하는 수치였다. 따라서 향후 두 정위임신은 물론, 둔위임신인 경우에 적용할 수 있는 양수과소증의 진단기준에 관한 연구가 필요할 것으로 생각된다.

Objective: To evaluate the effect of fetal presentation to the measurement of amniotic fluid index(AFI) in singleton pregnancy after 20 weeks of gestation. Materials and Methods: Review of the medical and ultrasonographic records from 1992 to 1996 including AFI value and pregnancy outcomes was performed retrospectively. The inclusion criteria were (1) singleton pregnancy delivered after 37 weeks of gestation, (2) birth weight between 10th and 90th percentile, (3) no fetal anomaly, (4) 5 minute Apgar score≥7, (5) no maternal medical disease such as hypetensive disorders or diabetes, (6) and intact amniotic membranes at the time of ultrasonography. The results of 7,362 tests from 5,607 pregnancies were reviewed and analyzed. Results: In normal pregnancies after 20 weeks of gestation, the AFI value showed the peak during 25~30 week and decreased thereafter. The range of AFI during preterm pregnancy(30~36 weeks, N=2,836) were between 9.4 and 21.8 cm(5th to 95th percentile, mean value of 15.2±4.1cm). The range of AFI at term(37~40 weeks, N=1,245) were 7.7 and 21.9 cm(5th to 95th percentile, mean value of 14.2±4.5cm), which showed significant difference (p=0.000) from that of preterm. The range of AFI after 41 weeks(N=75) were within 4.3 and 26.7cm(5th to 95th percentile, mean value of 13.8±6.3cm), which showed gradual decrease. The AFI among the gravidas with breech presentation showed similar values between 20~36 weeks. At term pregnancies(after 37 weeks, N=84) with breech presentation, the AFI(range 5.2cm~22.3cm, mean value 13.5±4.8cm) was smaller than those with cephalic presentation, but statistically insignificant(p=0.103). The commonly used criteria for oligohydramnios, AFI 5.0cm, equated to 1st percentile in cephalic presentation and 5th percentile in breech pregnancies, respectively. Conclusion: In this study AFI throughout pregnancies after 20 week of gestation showed difference of distribution of AFI according to gestational age and fetal presentation in term pregnancy. Further studies would be required to establish the cutoff value of oligohydramnios in cephalic and breech presentation at term pregnancy to establish different criteria according to fetal presentation.