Objective: To evaluate the performance of abdominal palpation as a screening test for intrauterine growth retardation (IUGR) in a low risk population, under standard practice conditions.
Study design: Population based observational study of 6318 consecutive low risk singleton pregnancies. The Dutch obstetric system distinguishes low from high risk pregnancies. In the low risk group abdominal palpation as a screening test is performed by midwives. If a complication, like IUGR, during prenatal care is assessed, the women is referred to a consulted obstetrician. Ultrasound is performed by the consulted obstetrician. In case of sustained suspicion the women is selected as high risk.
Outcome parameters: severe small for gestational age (SGA) birthweight below 2.3rd centile, all SGA birthweight below 10th centile, operative delivery, neonatal morbidity and perinatal mortality. Screening value of abdominal palpation, abdominal palpation combined with ultrasound, and the performance of high risk selection was assessed by conventional performance measures.
Results: Abdominal palpation as a screening test for IUGR is of limited value: the observed sensitivities were 28% for severe SGA and 21% for SGA p < or = 10, respectively. After ultrasound in case of sustained suspicion, the sensitivity in detection of severe SGA was 25% and positive predictive value (PPV) 16%. In detection of SGA p < or = 10 sensitivity was 15% and PPV 55%, which means 45% were false positives. The sensitivity of the Dutch obstetric system in selection of high risk pregnancies in detection of severe SGA was 53%, in detection of SGA p < or = 10 was 37%. Perinatal mortality was 0.9% (57/6318) and 32% of these cases were SGA. Six cases of fetal death were unrecognised during prenatal care (0.09%) and seem preventable. The prevalence of a 5 min Apgar Score < or = 7 was significantly higher in the SGA infants if SGA was defined as p < or = 10.
Conclusions: The diagnostic performance of abdominal palpation as a screening test for IUGR detection in a low risk population is disappointing. However, various stratagems such as routine ultrasound do not improve detection rate or perinatal morbidity and mortality.