A 2-year Audit of a Midwife-based Obstetric Ultrasound Service

Abstract

This was an audit of a midwife-based obstetric ultrasound service over a 2-year period from 1998 to 1999. The service only covered requests for gestational assessment, evaluation of fetal growth, placental site and liquor volume. During that period, request for complete fetal mophological assessment was not entertained. However, survey for fetal structural abnormalities were performed whenever possible. A total of 6400 examinations were performed for 5358 pregnancies, representing 65.7% of all ultrasound examinations in the antenatal clinic. All procedures were performed by 6 midwives with varying degree of experience. Intra-uterine fetal death or missed abortion was detected in 1.1% of cases, abnormal fetal growth in 15.8%, abnormal liquor volume in 2.4% and 7 cases of newly diagnosed multiple pregnancies. Only 1902 (29.7%) examinations were performed between 16 to 20 weeks, the optimal period for morphological assessment, while 1894 (29.6%) were at or before 15 weeks. Over 60% of examinations were referred for dating, while fetal growth assessment account for another 28.2%. Thirty cases were referred out for further assessment because of suspected fetal abnormalities which were confirmed in 21 (70%). Of the 28 cases of fetal abnormalities which were not diagnosed at the time of ultrasound examinations, prenatal diagnosis was considered to be possible in 16, which included 6 cases who had an examination before 13 weeks of gestation, 7 cases of predominantly cardiac anomalies, 2 cases of isolated polydactyly and 1 case of unilateral club foot. (HKJGOM 2001; 2: 73-79)