Is bigger better? A comparison of growth restriction rates using the crown-rump length derived due date from the smaller versus larger twin.

BACKGROUND: Although the smaller twin's crown-rump length is most accurate in establishing the estimated due date in dichorionic gestations, societal guidelines favor the use of the larger twin measurements based on concern for missing a diagnosis of fetal growth restriction. OBJECTIVE: This study aimed to compare the accuracy of the diagnosis of early- and late-onset fetal growth restriction in dichorionic twin gestations conceived by assisted reproductive technology using the estimated due date as established by the crown-rump length of the smaller vs larger twin. STUDY DESIGN: This was a 10-year retrospective cohort study of nonanomalous, dichorionic gestations conceived with assisted reproductive technology at 2 institutions. The incidence of early-onset (<32 weeks of gestation) and late-onset (≥32 weeks of gestation) growth restriction derived from the Hadlock formula using the smaller and larger crown-rump length estimated due date was compared with the true estimated due date by assisted reproductive technology. Statistical significance was determined using the Fisher exact test. The incidence of missed fetal growth restriction cases, false-positive rate, and error were calculated along with the relative risk for a missed diagnosis using the smaller crown-rump length. RESULTS: A total of 176 subjects were screened: 81 had a fetal growth ultrasound at 24 to <32 weeks of gestation, and 58 had a fetal growth ultrasound at ≥32 weeks of gestation. There was a significant difference in the incidence of fetal growth restriction using the 3 dating strategies in both gestational age ranges (P<.001) with the smaller crown-rump length estimated due date more closely approximating the true rate. Before 32 weeks of gestation, the smaller crown-rump length estimated due date missed 2.5% of fetal growth restriction cases, whereas the larger crown-rump length estimated due date missed 0.6% of fetal growth restriction cases, with false-positive and error rates of 1.2% and 3.7% and 5.5% and 6.2%, respectively. After 32 weeks of gestation, the smaller crown-rump length estimated due date missed 1.8% of cases, whereas the larger crown-rump length estimated due date missed 0% of cases, with false-positive and error rates of 2.6% and 4.4% and 5.3% and 5.3%, respectively. The relative risk for a missed diagnosis of fetal growth restriction using the smaller crown-rump length estimated due date was 1.77 for early-onset growth restriction and 1.22 for late-onset growth restriction. CONCLUSION: Using the estimated due date derived from the smaller twin led to a more accurate detection of fetal growth restriction at a cost of a higher missed diagnosis rate.

Establishing the Most Accurate Due Date in Dichorionic Twin Gestations by First and Second Trimester Ultrasound.

OBJECTIVE: To determine the optimal sonographic dating of dichorionic gestations. MATERIALS AND METHODS: We reviewed dichorionic pregnancies conceived with assisted reproductive technologies (ART) at 2 institutions between 2006-2016, excluding fetuses with major anomalies. Gestational age was calculated with smaller, larger, and mean of the crown-rump lengths (CRL) and biometry midgestation and compared to the ART age. The mean and mean absolute deviation of the observed gestational age from the ART age was calculated to assess accuracy, precision, and presence of bias. The incidence of small for gestational age using the smaller and larger CRLs was compared to the ART age via McNemar's test. RESULTS: Based on 140 ultrasounds, the CRL from the smaller twin best approximates the true gestational age with least bias compared to the larger twin or average (mean absolute deviation: 2.8, mean deviation: -0.1 [95% CI: -0.4, 0.2] versus 2.7, -0.9 [-1.1, -0.6] and 2.9, -1.5 [-1.8, -1.3], in days, respectively). Based on 165 ultrasounds, biometry from the smaller fetus is least accurate compared to the larger or mean (11.8, 2.5 [1.5, 3.6] versus 11.7, 0.8 [-0.3, 1.8] and 11.9, -1.0 [-2.0, 0.04], respectively). The incidence of small for gestational age neonates did not differ from the true rate using either the CRL from the larger or smaller twin (p > .05). CONCLUSION: In ART dichorionic gestations, ultrasound of the smaller fetus is most accurate in establishing gestational age in the first trimester but least accurate in the second, though all methods performed well with little clinical difference.

Pyelonephritis in Pregnancy: Relationship of Fever and Maternal Morbidity.

Objective To evaluate the relationship between maternal fever at the time of hospital admission and subsequent maternal morbidity in pregnant patients with pyelonephritis. Study Design In this retrospective cohort study, inpatient records were reviewed for all obstetric patients discharged from a single tertiary care hospital between June 1, 2011, and May 30, 2017, with the diagnosis of pyelonephritis. Patients were stratified into two groups, those with and without fever at the time of admission. Descriptive statistics were utilized to evaluate the association of fever at the time of presentation with subsequent morbidity. Using admission vital signs, maternal early warning criteria (MEWC) were applied and odds ratios calculated to predict intensive care unit (ICU) admission. Results A total of 110 patients were admitted with pyelonephritis in pregnancy; 24 patients were febrile and 86 patients were afebrile on admission. There was no difference in rates of maternal ICU admission between both groups. Positive MEWC was predictive of ICU admission with an adjusted odds ratio of 16.54 (95% confidence interval: 1.29-212.5; p = 0.03). Conclusion Afebrile pregnant patients with pyelonephritis remain at risk of significant maternal morbidity. Application of the MEWC on admission identifies patients at higher risk of ICU admission.