P-456 First trimester sonographic diagnosis and management of abdominal ectopic pregnancy (AEP)

Abstract

Study question What are clinical and ultrasound characteristics of first trimester abdominal ectopic pregnancies? Summary answer A significant proportion of AEPs occur after assisted conception. Patients are asymptomatic or have mild symptoms. Ultrasound morphology is varied and early detection is vital. What is known already AEP is rare, accounting for approximately 1% of ectopic pregnancies with a prevalence of 1/10,000 pregnancies. Early detection is critical to initiate timely treatment and decrease the risk of severe maternal morbidity. Although assisted reproductive technology (ART) has been associated with increased risk of ectopic pregnancy, risk factors specific to abdominal ectopic pregnancy are unknown. The aim of this study was to describe ultrasound features of AEP and propose sonographic criteria which could be utilised to aid diagnosis during the first trimester. Study design, size, duration This was a retrospective single-centre study of consecutive patients with a sonographic diagnosis of AEP between 2008 – 2024 at a tertiary referral centre. Participants/materials, setting, methods All patients presenting to our centre with a positive urine pregnancy test are assessed clinically followed by a transvaginal and/or transabdominal ultrasound scan using high resolution equipment. We performed a retrospective review of our database to identify all cases of AEP during the study period. We report clinical and ultrasound characteristics, management and clinical outcomes. In addition, we suggest novel criteria to assist sonographic diagnosis of AEP. Main results and the role of chance Thirteen patients were diagnosed with an abdominal ectopic pregnancy during the study period. Their median age was 35 years and median gestational age at diagnosis was 7 + 1 (range 5 + 4 to 14 + 4) weeks. 5/13 (38%) patients conceived using ART. 5/13 (38%) were asymptomatic, whilst the remaining 8/13 (62%) presented with mild vaginal bleeding and/or abdominal pain. 8/13 (62%) pregnancies were implanted within the pouch of Douglas, 3/13 (23%) within the uterovesical fold and 2/13 (15%) at the pelvic sidewall. Morphology varied from an inhomogeneous swelling in 5/13 (38%) cases to a gestational scan with live embryo in 2/13 (15%) cases. 5/13 (38%) patients opted for expectant management, which was successful in 4/5 (80%) of cases, 7/13 (54%) had laparoscopic excision and the remaining patient had transvaginal ultrasound-guided methotrexate injection because the pregnancy was inaccessible at laparoscopy. Based on our findings, we propose novel sonographic criteria for the diagnosis of AEP: 1) presence of a gestational sac or trophoblastic tissue which is separate from the uterus and ovaries and adherent to the peritoneum, 2) absence of a tissue layer overlying the pregnancy, 3) negative ‘sliding organs’ sign; 4) evidence of blood supply derived from the peritoneal surface on colour Doppler examination. Limitations, reasons for caution The main limitation of this study is the small number of cases, despite a lengthy study period at a busy tertiary referral centre. This reflects the rarity of AEP. Wider implications of the findings The diagnosis of AEP should be considered by all clinicians performing early pregnancy scans. Our development of new sonographic criteria for AEP should help to facilitate earlier detection of AEP amongst patients having routine scans after assisted conception. Trial registration number No