<scp>ISUOG</scp>Practice Guidelines: role of ultrasound in the prediction of spontaneous preterm birth

Abstract

The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) is a scientific organization that encourages sound clinical practice and high-quality teaching and research related to diagnostic imaging in women's healthcare. The ISUOG Clinical Standards Committee (CSC) has a remit to develop Practice Guidelines and Consensus Statements as educational recommendations that provide healthcare practitioners with a consensus-based approach, from experts, for diagnostic imaging. They are intended to reflect what is considered by ISUOG to be the best practice at the time at which they are issued. Although ISUOG has made every effort to ensure that Guidelines are accurate when issued, neither the Society nor any of its employees or members accepts liability for the consequences of any inaccurate or misleading data, opinions or statements issued by the CSC. The ISUOG CSC documents are not intended to establish a legal standard of care, because interpretation of the evidence that underpins the Guidelines may be influenced by individual circumstances, local protocol and available resources. Approved Guidelines can be distributed freely with the permission of ISUOG ([e-mail]). According to the World Health Organization, a preterm birth (PTB) or delivery is defined as occurring between 20 + 0 and 36 + 6 gestational weeks1. In 75–80% of cases, it occurs spontaneously, following either preterm labor (PTL) or preterm prelabor rupture of membranes (PPROM), while, in the remaining 20–25% of cases, it results from the health provider's intervention (iatrogenic or medically indicated)2, 3. The estimated global PTB rate increased from 9.8% to 10.6% between 2000 and 2014, accounting for almost 15 million live PTBs in 20144 and over one million deaths in 20105; PTB is the leading cause of neonatal mortality worldwide and in survivors may be responsible for lifelong morbidities5. In addition to neonatal death, there are several short-term consequences of prematurity, including respiratory distress syndrome (RDS), bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, retinopathy of prematurity and sepsis, while the long-term sequelae include cerebral palsy, cognitive impairment and behavioral/social deficits6. Apart from the health consequences for the individual and the family, the burden of prematurity on society and the economic impact of long-term stay in a neonatal intensive care unit (NICU), recurrent hospital admissions and specialized follow-up needs can also be devastating. The annual societal economic burden of PTB in the USA was estimated by the Institute of Medicine to be at least $26.2 billion in 20077. In 2014, the annual expenditure for the Canadian population was reported, corresponding to the gestational-age distribution, to be: $123.3 million for early preterm infants, $255.6 million for moderately preterm infants, $208.2 million for late preterm infants and $587.1 million for all infants8. In contrast to PTB, defining PTL is not straightforward. Different criteria have been reported in different publications, contributing to a lack of consistency in the response to symptomatic patients presenting at maternity units. The physiologic pathways involved in spontaneous term labor are fundamentally different from the pathological ones involved in PTL. Spontaneous PTL is considered to be a syndrome rather than a single condition, in part because it may be induced by one or more of several distinct mechanisms9. Infection and inflammation were among the first mechanisms to be studied as potential causes of PTB, possibly because the detection of pathogens in the amniotic cavity can be achieved relatively easily. Other important causal factors were described subsequently; these included cervical insufficiency, a decline in progesterone action, uterine overdistention and malformations, vascular disorders, breakdown of maternal–fetal tolerance and allergy-induced mechanisms10. The heterogeneity of causality explains the difficulty in developing universally effective diagnostic, preventive and therapeutic measures for PTB. Nevertheless, cervical effacement (shortening) is one of the common pathways to PTB, preceding delivery by or and it is to and by has been to be and in the of PTB in and also a in the and the of for spontaneous PTB in is there are preventive that can be to patients at of The preventive that have been include progesterone or cervical and The and potential with to neonatal be with and is also considered the has been in with in spontaneous PTB and the practice is by and In a different clinical the of has been in the of PTL to the at for PTB in to The difficulty in the for PTB not be there is heterogeneity among the for prematurity or gestational at birth is not for the of preventive or therapeutic measures PTB, because it be to a in as in the of or and are there has been on the of which long-term health and that be in on PTB. The of is to the of in the of PTB in and with of with the of prematurity and the and long-term of the was for in the following The and of The for Health and The and on the of and imaging in the and The was for the and the was on 20 recommendations are on the evidence that practice for in which evidence is of the of and of evidence in ISUOG Guidelines are in Although a of spontaneous PTB is the important for PTB, it is in of of clinical have been with the of patients at for PTB. they from in and different has been the common for the uterine in the of and the and the when to intervention or to imaging not the detection of potential include the of the and the to cervical which with of the and to the The to to of a to which was as a to which patients not from of these be best to to The of has been as part of for PTB. The between by and the of spontaneous PTB was first described more than the of and as a is for any to and be following a and and for have been reported to be more than for the for The Medicine of in cervical and the and are the educational that for the and for they are with the which is on these be with the a of the with the of the and the cervical and on the be for at least be between the and the with the a of the that can be on cervical and with to the are in the of can be a or Although the may be with of and for the the is as it is more and and to The on between the and the the of the by a or by the on the in patients with and from or are for the of has that be for by 36 with and be in more than of all that have of intervention in patients with a the and there are society the of for of can be effective is as by the rate described in a of of the is in of when is in of when is between and and in when is in with cervical the may be it is or the cervical with a between as a to be it is that of a can be of the The is between and of and to its from at to at 36 The in the is on in of or in 20 and in with a The of a the for PTB in factors or In the the and the the gestational at the the rate of spontaneous the of to PTB on as the population its PTB the for defining and PTB, the gestational at which the is and the of healthcare and patients with the preventive that is a it is to by between and of as part of the to gestational to to the difficulty in the and of the uterine gestational of is the for because is a common for preventive as progesterone and as as a for therapeutic as of and for of are not for PTB in a The first in the the for was the was to and the was to a of 15 the rate of PTB was and that at a of was a that included more than reported that not have a and on and between and 36 gestational with any the of a is a between and that a of 20 a of for PTB for a rate of the to increased the to at the of the rate to The of is by the that can be part of a in which factors may the of In for more than a of has been in the of as the best to PTB to is the of the amniotic the cervical and is to the of cervical The the in of from a with and of the cervical and of the of has been to as accurate for is its not be included in the or is as the or in the amniotic cavity and may as or and has been with and increased for PTB, in the of a and spontaneous there is the for diagnostic or Although of the amniotic membranes from the was with increased of PTB, was not for and cervical by nor of the cervical in to the uterine is considered to be a of PTB when to The of in is to a of the patients with a and a of PTB, in to preventive intervention in a Different preventive have been of have a of the evidence is or for Although by and in with a have been with increased of and and with of In in with and a for 20 has been with a in rather than in the for patients be to The of in the of PTB is to be related to the of and of cervical by of the of and by its on the in the of the scientific in the of for of PTB, the of and of in the has been for the of PTB in patients with spontaneous preterm almost a reported when with not recurrent PTB or neonatal in a population with a of spontaneous In the of in the of or was to PTB and neonatal and has been as the of PTB in patients with and a In the first of individual a in the of PTB to and in neonatal with the of the of the preterm which reported neither nor with the of progesterone in a of patients at for PTB, including with was including from the the in the of PTB to 36 as as in the of neonatal and in with a with any on In the for birth International including at for PTB, with spontaneous PTB or a results that progesterone the of PTB in and the of neonatal including and birth and for respiratory The of was also with a of PTB The considered that there were to the and of progesterone In reported among progesterone be considered the best for at of PTB because of or a of spontaneous PTB. with or there was of evidence for a in PTB and for of of progesterone progesterone every is for with with spontaneous PTB and a from detection of the 36 gestational one or as as to the as a to the and PTB. The reported in are the and with or there are to of one over the of with reported in PTB in with and a and of as recurrent with cervical or spontaneous a of patients from a in PTB for patients with with is also by the in of patients with progesterone in the of a and neonatal and mortality with between and these of progesterone and every the to cervical can be of a for are not as has been to are and the They as cervical and of the have been with The studied patients with and reported a in PTB in the of patients with a while the of patients with a not a in the of PTB between and and of cervical with standard care or in at for PTB also to in the of PTB and and the of The to also to of cervical in addition to progesterone in of neonatal or mortality in with the evidence not the of cervical to PTB in patients with research of or be a of Although a of million in healthcare expenditure has been for the of in the several the of the of a in the of progesterone results in a of PTB with its and to patients with at least one for PTB, of with a are at for the of in PTB. on with and PTB and and of in was that of the was by of with a rate of of and a in the of spontaneous PTB and In the with of PTB, the of was with a in the of PTL to and in the hospital of these patients to in the of a PTB which included for between and 20 of its there was a in the rate of PTB, for the and gestational-age and was in in for patients as at for PTB and in in which progesterone was be that there has been the and of of be by as the local of PTB, and of gestational at of preventive and by patients and healthcare also potential as and the of that it is not to which be by to in with the ISUOG Practice Guidelines on the of the when a local with of preventive measures that there are and for PTB for between and and of progesterone for patients as The a of rather than 20 or 15 a to a of than with which are with PTB and to the as for PTB. factors can be or of factors include to care and or and for or of these or factors are the of to that as of and are with health to which include in PTB The for PTB in is a of spontaneous PTB. individual in reported for PTB from to in with spontaneous PTB with term spontaneous PTB, term birth and have also been described as factors for recurrent has been for the of PTB in for The first from in the was the of with a spontaneous PTB progesterone with has been with of mortality and and long-term as as and its has been the has on the and of of progesterone with reported a increased to delivery with the while there was a of PTB in with progesterone the was with including also that progesterone was to in PTB a for the was The which included with spontaneous PTB or a a in PTB in these for patients with of the was not for patients with spontaneous PTB and there was the was In a including and at for spontaneous PTB because of a of spontaneous PTB or also that progesterone be considered the preventive intervention of for a of on with a of PTB and a in the to a of and a of on with a of spontaneous PTB that there is evidence to the of progesterone for of PTB. Although the a of PTB and and of these results for and of to with of The of progesterone in with a of spontaneous PTB, or with a The be to follow-up PTB in with a of spontaneous PTB, it to progesterone or 36 of in the following the of on with a of spontaneous PTB, its is with a in PTB and a potential in neonatal and birth a there to be a of with its the for patients with a spontaneous PTB and has been that at of have included of Although studied the of progesterone between and gestational there was a for to be with of recurrent PTB in a progesterone be for patients to there is recommendations for the of and for of cervical insufficiency, as cervical or with spontaneous of are factors for recurrent or PTB at for with PTB of cervical was with a in the rate of PTB to the in a is by the on for PTB in which reported a in PTB heterogeneity high-quality and was with the the of patients with spontaneous PTB not clinical criteria for cervical for with and spontaneous PTB, with PTB from to and and from to with The of progesterone to and as as a of that progesterone and have in PTB and and mortality in patients with spontaneous PTB and on that cervical is with spontaneous PTB, of the the to progesterone has been a follow-up is for patients at for recurrent spontaneous PTB and for of cervical of and with has been effective and in Ultrasound follow-up can in of when potential can provide a for with a on a in patients progesterone with to the of a the rate of spontaneous PTB at and with a in rate of for PTB and of for PTB and the rate of with progesterone are for patients on progesterone with spontaneous PTB, from the early and as is not gestational According to is for as is at gestational the of be every the when the is patients with the and of cervical be and may be protocol with is in have been of to PTB of a as of the the of the cervical and of or amniotic has not been as has been to According to a and evidence not of cervical to PTB in with and of of progesterone or of with cervical as and are at increased for PTB. of cervical than is with increased of factors than the may be in with cervical and as to the of PTB in following The of by is also in the of with was when to a it to with a of to either with one or by progesterone and in of of spontaneous PTB. with a uterine or that the cervical are at increased of spontaneous PTB, with or these related more to late than to early for by is moderately of PTB at in patients with a of also from the and preventive as with a of have a term at cervical with a rate of recurrent spontaneous late or is to the or by the uterine the in the of Although by in patients with term at cervical and were in PTB in the of patients a spontaneous The is diagnostic and therapeutic for the of of Although for with factors for PTB have been as intervention to for these and infants, to the of these in the rate of was the of on in practice that were not in and in of and the and of among different The that specialized are as part of care in it that be in the of PTB on and global consistency in practice are for the of specialized of spontaneous PTBs are by spontaneous with presenting with of a also as PTB, are in clinical accounting for of the of The of PTL is and cervical for the of and and or of uterine in of patients with PTL and cervical there is spontaneous and of these patients at has impact on the of the of in of and have been as to in which symptomatic patients are at increased for PTB and have the of in the of PTB in symptomatic more than with PTL and cervical reported that was with the of PTB in patients with and with in the impact of of at in PTB in symptomatic to the with a in the rate of PTB and increased to delivery of with the the of the on of PTB in symptomatic not a on of delivery reported that evidence that of to the of these to by to with Although to in the of PTL care, different and for have been may a between hospital or and the of for and with these are the of of 20 for and for from as a in with between 20 and a of 15 to the between and while to as the which a be of reported for birth from of 15 20 the was was was and was In contrast to the a of with PTL that the of for the of clinical be for the gestational at According to the to the for delivery be 36 for presenting at + 0 to + 6 for presenting at + 0 to + 6 for presenting at + 0 to + 6 and for presenting at + 0 to + 6 the heterogeneity it to for the of symptomatic of 15 or 20 and may be as for and of PTB have also been for the of PTB in symptomatic in with is the of these is in the and amniotic The detection of in the cervical or at of has been with increased of spontaneous a was it the of a increased of PTB the with the it not to the of with and as as a clinical to a of with care in the of PTB. that the of in with to in for PTB in patients with 20 there are to its clinical as its is of the by and in the of amniotic and have been for the of PTB in symptomatic and of patients that have to spontaneous PTB in symptomatic for 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