SUMMARY OBJECTIVE: Fetal thymus involvement in prematurity has been studied, and this study aimed to evaluate its relationship with short cervix and amniotic fluid sludge in the second trimester of pregnancy. METHODS: In this prospective cross-sectional study, 79 pregnant women (19+0 to 24+6 weeks) were included, and cervical length and the presence or absence of amniotic fluid sludge were evaluated. In the three-vessel view of the fetal thorax, the thymus was identified, and its perimeter and transverse diameter were measured and transformed to a zeta score based on gestational age. RESULTS: Data from 22 women with short cervix (<25 mm) and 57 patients with normal cervix (≥25 mm) were analyzed. The transverse diameter of the fetal thymus was significantly greater in the short cervix group compared to that of the normal cervix group (z-score 2.708 vs. −0.043, p=0.003). There were no significant differences in the perimeter (z-score −0.039 vs. −0.071, p=0.890) or the transverse diameter (z-score 1.297 vs. −0.004, p=0.091) of the fetal thymus associated with the presence (n=21) or absence of sludge (n=58). CONCLUSION: A short cervix is associated with an increased transverse diameter of the fetal thymus during the second trimester of gestation.

Abstract Objective To describe a reference curve for cervical length (CL) in mid-trimester twin gestations using transvaginal ultrasound (TVU) and to investigate whether short CL increases spontaneous preterm birth (sPTB) in asymptomatic twin pregnancies. Methods This was a prospective cohort study performed at 17 outpatient antenatal facilities of Brazil with women at 18 0/7 to 22 6/7 weeks of gestation who participated in a randomized clinical trial screening phase (P5 trial) between July 2015 and March 2019. TVU was performed to provide CL measurement in all screened women. Almost all women with CL ≤ 30 mm received vaginal progesterone 200mg/day and they were also randomized to receive cervical pessary or not. We considered data from the CL distribution among asymptomatic twin pregnancies and analyzed CL and its association with PTB generating receiver operating characteristics (ROC) curves and Kaplan-Meier curves. Results A total of 253 pregnant women with twins were included in the distribution curve. The mean CL was 33.7 mm and median was 35.5mm. The 10th percentile was 17.8mm. We identified a PTB rate of 73.9% (187/253) with 33.6% of sPTB < 37 (85/253) and 15% (38/253) of sPTB < 34 weeks. The best cutoff point to predict sPTB < 37 was 24.15 mm. However, the ROC curve showed a poor performance (0.64). The Kaplan-Meier survival curves identified that only CL values ≤ 20mm were associated to sPTB < 34 weeks. Conclusion A cutoff point of CL ≤ 20 mm can be interesting point to identify short cervix in Brazilian twin pregnancies. However, in Brazilian asymptomatic twin pregnancies, CL does not show a good performance to predict PTB.

Resumo Objetivo Descrever uma curva de referência da medida do colo uterino no Segundo trimestre de gestações gemelares através de ultrassonografia transvaginal (TVU) e investigar a correlação entre a medida do colo uterino (CL) e o parto prematuro espontâneo (sPTB) em pacientes assintomáticas. Métodos Foi realizado uma coorte prospectiva multicêntrica em 17 centros de referência do Brasil com mulheres com gestação gemelar entre 18 0/7 a 22 6/7 semanas de gestação que participaram da primeira fase de um ensaio clínico randomizado (P5 trial) entre Julho/2015 a Março/2019. TVU foi realizada para obter a medida do colo uterino em todas as mulheres. A maioria das mulheres com CL ≤30 mm receberam progesterona por via vaginal 200mg/dia e estas foram randomizadas para receber ou não um pessário cervical. Este estudo considerou dados da medida do colo uterino entre mulheres assintomáticas, desenvolvendo uma curva de referência para gestantes gemelares e sua capacidade de predição do parto prematuro através de curva ROC (receiver operating characteristics) e curvas de sobrevida de Kaplan-Meyer. Resultados O total de 253 gestantes foram incluídos no estudo, A média do CL foi 33.7mm e a mediana 35.5mm. O Percentil 10 do CL foi 17.8mm. A taxa de parto prematuro foi de 73.9% (187/253) com 33.6% de sPTB < 37 (85/253) e 15% (38/253) de sPTB < 34 semanas. O melhor ponto de corte para predizer sPTB < 37 foi 24.15 mm, entretanto a curva ROC demonstrou baixa performance (0.64). A curva de Kaplan-Meier para sPTB identificou que apenas CL ≤ 20 mm estavam associados a sPTB < 34 semanas. Conclusão Colo uterino ≤20 mm pode ser um interessante ponto de corte para identificar colo curto entre gestações gemelares assintomáticas brasileiras. Entretanto, a medida do colo uterino não apresentou boa performance para predizer parto prematuro.

Resumo Objetivo Este estudo tem como objetivo determinar se o uso de pessário cervical associado a progesterona em gestações de gêmeos dicoriônicos-diamnióticos (DC-DAs) com colo do útero curto (≤ 25 mm) apresenta taxa de parto prematuro (PP) equivalente à de gestações gemelares DC-DA sem nenhuma intervenção/não selecionadas. Métodos Um estudo de coorte histórica foi realizado entre 2010 e 2018, incluindo um total de 57 mulheres grávidas com gestações gemelares DC-DA. As mulheres admitidas de 2010 a 2012 (n = 32) não receberam tratamento, e não foram selecionadas pelo comprimento cervical (grupo Não Tratado, GNT), enquanto as admitidas de 2013 a 2018 (n = 25) receberam pessário cervical rotineiramente associado a progesterona após o diagnóstico de colo curto entre a 18a e a 27ª semanas de gestação (grupo Pessário-Progesterona, GPP). O desfecho primário analisado foi a taxa de PP antes de 34 semanas. Resultados Não houve diferenças estatísticas entre o GNT e o GPP em relação ao PP < 34 semanas (respectivamente, 18,8%; versus 40,0%;; p = 0,07) e ao peso médio ao nascer do gêmeo menor (2.037 ± 425 g versus 2.195 ± 665 g; p = 0,327). A análise de Kaplan-Meyer foi realizada, e não houve diferenças entre os grupos antes de 31,5 semanas. A regressão logística demonstrou que o nascimento prematuro anterior (< 37 semanas) apresentou razão de probabilidades (odds ratio, OR) de 15,951 (intervalo de confiança de 95%; [IC95%;]: 1,294-196,557; p = 0,031*) para o nascimento prematuro < 34 semanas no GPP. Conclusão Em gêmeos DC-DA com colo uterino curto (o que significa maior risco de nascimento prematuro), o tratamento com pessário cervical associado a progesterona pode ser considerado equivalente em diversos aspectos relacionados à prematuridade no GNT, apesar da grande diferença entre os grupos.

Abstract Objective The present study aims to determine if the use of cervical pessary plus progesterone in short-cervix (≤ 25 mm) dichorionic-diamniotic (DC-DA) twin pregnancies is equivalent to the rate of preterm births (PBs) with no intervention in unselected DC-DA twin pregnancies. Methods A historical cohort study was performed between 2010 and 2018, including a total of 57 pregnant women with DC-DA twin pregnancies. The women admitted from 2010 to 2012 (n = 32) received no treatment, and were not selected by cervical length (Non-Treated group, NTG), whereas those admitted from 2013 to 2018 (n = 25), were routinely submitted to cervical pessary plus progesterone after the diagnosis of short cervix from the 18th to the 27th weeks of gestation (Pessary-Progesterone group, PPG). The primary outcome analyzed was the rate of PBs before 34 weeks. Results There were no statistical differences between the NTG and the PPG regarding PB < 34 weeks (18.8%; versus 40.0%; respectively; p = 0.07) and the mean birthweight of the smallest twin (2,037 ± 425 g versus 2,195 ± 665 g; p = 0.327). The Kaplan-Meyer Survival analysis was performed, and there were no differences between the groups before 31.5 weeks. Logistic regression showed that a previous PB (< 37 weeks) presented an odds ratio (OR) of 15.951 (95%; confidence interval [95%;CI]: 1.294-196.557; p = 0.031*) for PB < 34 weeks in the PPG. Conclusion In DC-DA twin pregnancies with a short cervix, (which means a higher risk of PB), the treatment with cervical pessary plus progesterone could be considered equivalent in several aspects related to PB in the NTG, despite the big difference between these groups.