Guideline for Ultrasound procedures performed in Family Health by the midwife sonographer services: Operational Guideline.

Transcription

1 Title Guideline for Ultrasound procedures performed in Family Health by the midwife sonographer services: Operational Guideline Implementation date June 2015 Version One Supersedes N/A Contact Name and Job Title (author) Louise Doody Joint Lead Fetal Medicine Services Nia Wyn Jones, Associate Professor in Obstetrics and Gynaecology Date of submission March 2015 Date on which guideline must be reviewed (this should be one to three years) March 2020 Explicit definition of patient group to which it applies (e.g. inclusion and exclusion criteria, diagnosis) Abstract Out-patient referrals for obstetric ultrasound (after completion of detailed scan) to the midwifery sonography service This guideline covers the role of the midwifery sonography scan service, eligibility, the indication, pathway and timing of ultrasound scans with the midwifery sonography service Key Words Statement of the evidence base of the guideline has the guideline been peer reviewed by colleagues? Midwifery sonography service Ultrasound Fetal growth and wellbeing 4 & 5 Evidence base state highest level from (1-5) 1a meta analysis of randomised controlled trials 1b at least one randomised controlled trial 2a at least one well-designed controlled study without randomisation 2b at least one other type of well-designed quasi-experimental study 3 well designed non-experimental descriptive studies (i.e. comparative / correlation and case studies) 4 expert committee reports or opinions and / or clinical experiences of respected authorities 5 recommended best practise based on the clinical experience of the guideline developer 1

2 INTRODUCTION The aim of this protocol is to define the overall objectives for the routine ultrasound (USS) scanning by midwife sonographers of patients (this guideline is for use alongside the Guideline for ultrasound procedures performed in Family Health by the midwife sonographer services: Technical Guideline) It is recognized that there will be occasions when even the minimum requirements may be unattainable, i.e. high maternal BMI, and in these circumstances it is the responsibility of the midwife sonographer to determine when the examination is complete. Any technical limitations are to be recorded on the ultrasound report for the examination. Abnormal findings may require additional scanning and imaging to clearly demonstrate the abnormality and other associated pathology. Appropriate follow up care by using the recommended pathways should be sought and documented on the patients report. Ultrasound request forms including electronic requests on Medway For the request to be accepted, the indication and requested examination must be documented on Medway and in Part 1 hand held records. Reporting Midwife sonographers will be responsible for issuing a written report direct to the requesting clinician. Any unusual findings and/or pathology should be discussed with senior obstetrician in the clinic. Where a discussion with a clinician has taken place regarding a patient in relation to pathology or management, this should be documented in the report stating who the case has been discussed with and the outcomes of the discussion. The midwife sonographer may give a verbal explanation to the patient when appropriate. A report should be placed into the patients hand held notes and hospital notes where available.. 2

3 Radiology is responsible for USS for the following indications (see Obstetric radiology protocols): Dating and viability scans before 20 weeks Nuchal translucency scan fetal anomaly scan All in-patient USS requests Multiple pregnancy Placental site USS All trans-vaginal USS requests including cervical length Non-obstetric pathology (e.g. suspected ovarian pathology) Any post-natal USS Role of midwifery sonography service The role of this service is: Assessment of fetal growth and wellbeing (with Doppler and amniotic fluid index) After a completed detailed scan Routine growth scans should be no more frequently than 4 weeks unless there is a change in the clinical situation JUSTIFIED: History Maternal age > 40 years Maternal vascular disease / renal impairment / antiphospholipid antibody syndrome or hypertension Maternal diabetes Previous fetal growth restriction Previous stillbirth Maternal substance use (excluding cannabis only) Teenage pregnancy if the pregnant woman is still growing (consultant request) Low body mass index (BMI: <18 kg/m 2 ) Increased BMI: > 40 kg/m 2 USS every 4 weeks starting between weeks Single USS at 34 weeks USS at approx.. 28 & 36 weeks only unless other indication 3

4 Previous big baby: >4.5 kg JUSTIFIED: Current pregnancy Small for dates uterus Ante-partum haemorrhage: follow-up outpatient scans Pregnancy induced hypertension requiring treatment Pre-eclampsia Pre-term rupture of membranes PAPP-A <0.4 multiples of the median (MoM) Reduced fetal movements (second episode) Large for dates uterus only if polyhydramnios suspected (tense abdomen and difficulty palpating fetal parts) Assessment of fetal lie or presentation 36 weeks gestation Single USS after 36 weeks Following clinically indicated normal scan repeat scan indicated no more often than 2-4 week interval Single clinically indicate USS. New guidance on scanning at risk pregnancies for monitoring fetal growth is under development. Until this is completed please consider the appropriateness of scanning at 28 and 36 weeks for these women. 4

5 NOT JUSTIFIED Abdominal pain Fetal sexing Social reasons Repeat USS for growth within 2 weeks of previous scan Repeat USS within 2 weeks of normal scan for reduced fetal movements (in context of IUGR repeat USS in less than one week if persistent reduced fetal movements) BMI >19 kg/m 2 up to 39 kg/ m 2 Possible rupture of membranes Previous caesarean section Polycystic ovarian syndrome Previous gestational diabetes Previous breech presentation Non-recurrent miscarriage Cannabis smoking Indications for UA Doppler: Abdominal circumference below 10 th percentile Fetal biometry, particularly abdominal circumference crossing (to or below lower) percentile lines Oligohydramnios only if associated with growth restriction Women with reduced fetal movements Women diagnosed with maternal vascular disease/pre-eclampsia or hypertension Women with established diabetes (type 1 or 2) Women with gestational diabetes if growth below 10 th centile or maternal hypertension Consultant request provided relevant clinical history 5

6 Pathways for Women Attending for Midwife Scan Referred for Midwife Scan Normal findings Fetal abnormality suspected Abnormal findings e.g. SGA, absent or reversed UA Doppler Breech presentation Planned pathway e.g. home / ANC Confirm by Obstetric Sonographer Review in ABC (if not scheduled for ANC) Give ECV leaflet and refer for discussion re: options Refer to Fetal Medicine/ Fetal Care if appropriate weeks >ANC 38+ weeks >ABC Organise ECV Please Note: All ECV s at QMC are booked via FMM 6

7 APPENDIX : EXPLANATORY NOTES FOR REFERRAL CRITERIA A. Symphysis-fundal height (SFH) should be plotted on the chart in the hand held notes and the referral for USS is indicated if the SFH plots less than the 5 th centile or is crossing centiles. The most common causes are small baby and/or reduced liquor volume. A further scan 2-4 weeks later may be needed to ensure that the growth velocity is normal, particularly if there is discrepancy between the abdominal (AC) and head circumference (HC) centiles or if the fetal biometry is below the 10 th centile. If the follow up scan shows normal progression of HC and AC measurements above the 10 th centile with normal AFI, no further scans are needed in the absence of other risk factors. Where consistent growth along the 3-10 th centiles is demonstrated then further scans at 2-4 weekly intervals are reasonable. Remember though that most symmetrically small babies with normal liquor and UA Doppler are normal. Consider referral to Fetal Maternal Medicine (FMM) / Fetal Care Unit (FCU), or SGA Clinic at City, if measurements fall below the 3 rd centile, although note that measuring the bi-parietal diameter (BPD) and HC at term can be difficult and falsely low readings are common. A previous baby should not be considered small for dates unless the birth weight was below the 10 th centile at delivery. Women delivering babies previously below the 3 rd centile who were structurally and chromosomally normal are suitable for antenatal scan surveillance in subsequent pregnancies. Women with a birth weight less than 2.5 kg after 37 weeks should also be offered serial USS scans. Unless the problem started early (i.e. in the 2 nd trimester) it is sensible to scan from 28 weeks. At the City Hospital campus this can be performed through the Small Baby Clinic. 4-6 weekly scan should suffice whilst growth is normal however the absolute frequency will need to be individualised. Measurements of growth, liquor volume and UA Doppler should be documented. B. Risk factors for macrosomia include diabetes (pre-existing and gestational), previous macrosomia, maternal obesity, excessive weight gain during pregnancy, multiparity, male fetus, gestational age more than 41 weeks, white race, high maternal birth weight, maternal 7

8 height, and maternal age years. The prediction of birth weight based on antenatal US scanning is extremely imprecise in normally grown and macrosomic fetuses (with a typical mean error range of g). Serial estimations of SFH measurement customised for maternal physiological variables significantly increase the detection rate of the large for gestation (LGA) fetus. If the SFH is above the 90 th centile on serial measurement prior to 34 weeks a glucose tolerance test (GTT) is recommended if this has not already been done at 28 weeks. Ultrasound estimation of fetal weight adds little additional useful information (ACOG) and is therefore not recommended in women in the absence of diabetes. If the SFH is above the 90 th centile after 34 weeks on serial (not single) measurement, with no previous GTT at 28 weeks, exclusion of diabetes should be considered although there are no reference ranges for a GTT at this gestation. Care should be individualised a blood sugar series should be considered. USS can be performed if the uterus is measuring large for dates and there is clinical suspicion of polyhydramnios (tense abdomen and difficulty palpating fetal parts) to confirm or refute this diagnosis. If an USS has demonstrated EFW above the 90 th centile in the third trimester further serial US scans (in the absence of diabetes) are not necessary. It remains unclear how scans should influence the management of women with previous difficult deliveries (e.g. shoulder dystocia / caesarean section) and the decision for scanning needs to be individualised and following counselling be a senior obstetrician. Decisions regarding the frequency of scanning in a diabetic pregnancy should be made by the multidisciplinary team in the diabetic ante-natal clinic. C. The risk of a repeated poor outcome following a previous stillbirth is clearly related to the aetiology. Previous growth restriction or hypertension should be managed as described in sections A and E and are likely to warrant scanning every 2-4 weeks in subsequent pregnancies. Even if the previous loss was caused by a non-recurring problem serial USS (albeit less frequently) may be offered to provide 8

9 reassurance. Women should be informed that USS in this circumstance is to provide reassurance. D. All women beyond 24 weeks who report a change in the pattern or reduced fetal movements (RFM) should be assessed using the following: detailed history, clinical examination (SFH, blood pressure and urinalysis), fetal heart auscultation and CTG (beyond 26 weeks). Ultrasound scan assessment (growth, amniotic fluid index (AFI), Doppler) should additionally be undertaken if: second episode of RFM one episode of RFM with decreased SFH any episode of RFM with CTG abnormalities not requiring immediate delivery continued perception of reduced fetal movements despite a normal CTG one episode of RFM if there are any additional risk factors for stillbirth or growth restriction. If scanning is considered necessary then it should be performed when the service is next available, preferably within 24 hours. If an ultrasound scan has been performed in the preceding two weeks a further scan is not necessary. (NUH Guideline: Reduced Fetal Movements After 24 Weeks Gestation; 2013). E. Hypertension, preeclampsia, maternal vascular disease and antiphospholipid syndrome are all strong indications for antenatal scanning: Current gestational mild to moderate hypertension (BP<160/110 with no proteinuria): If the diagnosis is before 34 weeks arrange an USS for growth, liquor volume and UA Doppler. If the USS is normal then do not repeat after 34 weeks. If the diagnosis is after 34 weeks, arrange an USS if fetal movements or SFH abnormal. Current gestational severe hypertension (BP>160/110): USS for growth, liquor volume and UA Doppler. Do not repeat more frequently than every 2 weeks if the results normal. 9

10 Current pre-eclampsia (hypertension and proteinuria): at diagnosis arrange USS for growth, liquor volume and UA Doppler. If normal, repeat every 2 weeks. Previous history of mild and late onset pre-eclampsia does not mandate routine scanning. If routine scans are planned these should be restricted to the third trimester if the blood pressure remains normal earlier on. Previous history of early onset (<34 weeks) severe preeclampsia does require surveillance from an earlier gestation in subsequent pregnancies. The frequency of scanning in these cases should be determined individually based on previous disease severity and underlying risk factors, although 2-4 weekly scans are likely to be sufficient. Uterine artery Doppler recordings at 23 weeks (Small baby clinic or Fetal-Maternal Medicine unit) can be considered if the result is going to increase the US scan intervals. Maternal vascular disease, renal impairment and antiphospholipid syndrome also need serial USS for growth and well-being. The onset and frequency of scanning will be decided by their named consultant and based on disease severity, previous obstetric history and any additional risk factors. 2-4 weekly scans are likely to be sufficient, at least initially. F. Antepartum haemorrhage (APH) is an indication for antenatal scanning. Placenta praevia can be diagnosed or excluded and poor placental function may be detected, as evidenced by fetal growth restriction, oligohydraminos and raised UA Doppler. (If growth is normal then there is no indication for UA Doppler.) Abruption however cannot be diagnosed by USS and a normal scan does not exclude this diagnosis. In-patient scanning for APH will be performed in radiology and follow-up scanning should be arranged through the midwife sonography service (with the exception of women with placentae praevia who need a placental site USS). Repeat scanning within 2 weeks is not justified for repeated APHs unless the UA Doppler recordings are abnormal. 2-4 weekly scans are warranted if bleeding is frequent and recurrent, or if fetal growth 10

11 restriction is demonstrated on scan. Vaginal bleeding before 20 weeks gestation does not mandate regular scans throughout the rest of the pregnancy, unless other risk factors are present. In the case of an anterior placenta reaching the os in a patient with a previous caesarean section a rescan is advised in FMM / FCU at 32 weeks to examine for placental accreta. G. If there is uncertainty regarding fetal lie or presentation after 36 weeks then a scan is reasonable, at which time the placental localisation should also be documented if the lie is non-longitudinal or the presentation is anything other than cephalic. However, women who have had a breech presentation at term in a previous pregnancy or those with a breech noted earlier in the pregnancy should not be scanned routinely. The presentation should be determined clinically beyond 36 weeks gestation. Scan can be organised at that point if there is doubt with regard to presentation. Women referred for a presentation scan will not have fetal biometry measured unless there is a clinical indication for biometry to be performed. H. Scanning should be performed in preterm pregnancies with confirmed rupture of membranes as it is associated with placental dysfunction, malpresentation and subsequent preterm delivery. AFI may help to predict outcome in cases of very early (<28 weeks) prolonged preterm rupture of membranes (PROM). However, the diagnosis of PROM should be made by speculum examination +/- ACTIM PROM test. Seeing liquor is the diagnostic test. A scan should not be used to help determine if PROM has occurred; liquor volumes are frequently normal in this situation and borderline/low values may in fact be normal for that pregnancy or caused by other pathology. This is even more the case at term gestations. It is reasonable to request a scan if there is clinical evidence of oligohydraminos (e.g. small for dates uterus with easily palpable fetal parts) or polyhydraminos (large for dates uterus with impalpable fetal parts). I. Although a reduced BMI (<18 kg/m 2 ) has been noted as a risk factor for fetal growth restriction, the association is not a strong one. In most 11

12 women clinical assessment is sufficient in order to assess fetal growth. If poor fetal growth is suspected or the woman is at high risk of growth problems due to other reasons, then an ultrasound scan may be considered. The indications for USS at 28 weeks are: Weight gain less than 1.6 kg between 20 and 28 weeks (0.2 kg/week) SFH plots on or below the 10 th centile Static or restricted growth as suggested by plotted SFH measurements (NUH Guideline: Low BMI in Antenatal Women; 2013). J. It is recognised that assisted conception, advanced maternal age and cigarette smoking are all associated with a greater risk of preterm birth and fetal growth restriction (RCOG guideline number 31). However, this heightened concern should be met by an increase in the frequency of clinical reviews if necessary. Scanning should only be performed if additional clinical concerns arise. Assisted conception, per se, is not an indication for routine scanning. Primiparous women over 40 years of age may warrant increased surveillance but this should initially be addressed clinically. K. Substance misuse is a marker for poor obstetric outcomes, particularly IV drug use. Cocaine, in particular, is directly toxic to the placenta. Furthermore, scanning often proves to be an incentive for attendance at clinics in a group of women who otherwise show poor compliance. Routine scanning is indicated, with 4-6 weekly scans being adequate in the absence of other risks. Cannabis smoking in isolation has not been implicated in fetal growth restriction and does not warrant routine growth scans. It may be a marker of poly-drug use, however, and may indicate a need for clinical surveillance. L. There are many causes of abdominal pain in pregnancy but very few are detectable by obstetric scanning. The midwife sonographer service will not scan women with abdominal pain. 12

13 M. There is no indication for booking a growth scan at 36 weeks gestation to assist in the decision of mode of delivery for women with a previous caesarean section. Although the size of the fetus may have an impact on success rates, scanning is no more sensitive at predicting outcomes than clinical palpitation in this context. N. 23% of Nottingham women are obese (BMI >30 kg/m 2 ) at the start of pregnancy (Nottingham Public Health 2011). Women should understand that ultrasound scans are less accurate both at assessment of fetal anatomy and fetal growth. The SFH chart should be completed at every visit after 24 weeks. Attention to the velocity of growth is important as is enquiry about fetal movements. When growth appears to be less good early recourse to USS should be arranged. In the absence of gestational diabetes, fetal macrosomia should be noted but does not require additional intervention or repeated scanning. If, beyond 36 weeks, there is doubt with regard to presentation a presentation scan can be arranged directly with the Midwife Scan Service. (NUH Guideline: Care of pregnant women with a BMI of 30 or more; 2012). O. Raised body mass index (BMI), history of PCOS and previous big baby are all markers for increased risk of gestational DM in the current pregnancy. However, this should be investigated by performing a GTT rather than routinely booking a growth scan (at 28 or 36 weeks). If the GTT is normal, then clinical palpation should suffice. Indeed, the evidence does not support changing management in women with a big baby in the absence of diabetes. Women with a previous history of gestational diabetes are best managed through the joint diabetic/obstetric clinic. P. History of non-recurrent miscarriage: in the absence of underlying causes for miscarriage, such as antiphospholipid syndrome and maternal inherited thrombophilia routine scanning in the second and third trimester is not indicated. Parental reassurance, if required, should be provided clinically. Women with a repeatedly ( 3) unexplained miscarriage and poor obstetric history do warrant 13

14 scanning as underlying problems may not have been uncovered by current tests. Q. PAPP-A (which is a component of the first trimester combined test) less than the 5 th centile (0.4 multiples of the median) is associated with a 3-fold increased risk of adverse fetal outcomes including miscarriage, stillbirth, infant death, intrauterine growth restriction (IUGR), preterm birth and pre-eclampsia. Although the test has poor sensitivity and high false positive rates women with a PAPP-A result <0.4 MoM will be offered serial USS every 4 weeks starting between weeks gestation. For list of references please see Technical Guideline 14