Active disease on intestinal ultrasound in pregnancy is associated with an increased risk of adverse obstetric and neonatal outcomes: an international multi-centre prospective cohort study.

Abstract

Background: Clinically active inflammatory bowel disease (IBD) impacts 30-50% of women antenatally1,2. Such clinically active disease is associated with an increased risk of adverse pregnancy outcomes, including preterm delivery2. However, the validity of clinical scores to assess antenatal disease activity has been questioned, whilst both faecal calprotectin (FCP) and intestinal ultrasound (IUS) are feasible and accurate in pregnancy3,4. We aimed to assess whether active disease defined by IUS may predict adverse obstetric outcomes in pregnant women with IBD. Method(s): This international multi-centre prospective cohort study recruited both preconception and pregnant individuals with IBD in Australia and the USA from 2017-2023. Participants underwent clinical assessments and FCP testing six months before conception, in each trimester (T1, T2, and T3), and, when feasible, six weeks postpartum. IUS was performed preconception and in T1 and T2. Clinically active disease in pregnancy was defined by a PGA>1, or a HBI>5 or SCCAI >3. A FCP>100mug/g was considered elevated, and IUS remission was defined as a bowel wall thickness of <3mm in all bowel segments, with normal bowel wall stratification, a lack of extra-mural complications, and an absence of mesenteric fat hypertrophy or hyperaemia. Univariable and multivariable binary logistic regression analyses including relevant confounders were used to determine the independent impact of IUS disease activity on obstetric outcomes. Cohen coefficients were used to determine agreement between FCP, IUS and clinical disease activity. Result(s): 379 participants, 200 with Crohn's Disease (CD), were recruited. Overall, rates of adverse obstetric outcomes were comparable to the general population (Figure 1). Maximal bowel wall thickness (BWT) >6mm in T1 was associated with a three-fold increased risk of neonatal intensive or special care unit admission (RR 3.10;1.27-7.54, p=0.013) and in T2 was associated with a four-fold increased risk of prematurity (4.51; 1.45-14.04, p=0.009). IUS hyperaemia in T2 was associated with a three-fold increase in preeclampsia risk (3.61; 1.07-12.15, p=0.038). FCP >100mug/g in T2 was associated with an increased risk of preterm delivery after adjusting for clinical disease activity (RR 2.90; 1.22-7.50, p=0.028). Agreement between clinical (HBI or SCCAI) and IUS/FCP activity during pregnancy was weak (Figure 2). Conclusion(s): Sub-clinical disease activity identified on IUS in pregnancy is associated with an increased risk of pre-term delivery, with poor agreement between clinical symptoms and objective biomarkers of disease activity during pregnancy. IUS monitoring should be performed as part of routine antenatal IBD care and IUS remission targeted.