The standard antenatal check provides the basis for routine biophysical screening, assessment, referral and education for women attending the antenatal clinic.
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These guidelines are not exhaustive. They are designed to work alongside the newly developed Hand Held Pregnancy Record (HHPR). Please also refer to the Antenatal Care Schedule-Routine Low Risk CPG.
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Gestation and estimated due date (EDD)
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If the LNMP is unreliable, women are to be offered a dating ultrasound.
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Dating scans are offered during the Royal Women's Hospital Pregnancy Booking Clinic (PBC) or by the Pregnancy Day Care Centre (PDCC).
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If arranging a dating ultrasound through the PDCC:
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- give the woman a completed ultrasound form requesting a dating ultrasound (signed by midwife or doctor)
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- you or the woman can book an appointment directly by contacting the PDCC on Tel: (03) 9344 2092
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Gestation is recorded at each visit.
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Calculate the EDD according to the following:
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The EDD according to the LNMP is used if:
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- the LNMP is reliable (the woman is certain of the first day of LNMP and she has a regular 28 or 35* day cycle)
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- the early dating scan calculates the EDD to be within 5 days of a reliable LNMP due date
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The EDD according to the Early Dating Ultrasound is used if:
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- the LNMP is unreliable and/or
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- the early dating scan calculates the EDD outside 5 days of a reliable LNMP due date
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- ultrasound performed prior to 14 weeks is more accurate for estimating gestation
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The 18-20 week scan should be used if:
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- There was no dating scan performed and
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- The LNMP is unreliable and/or
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- The 18-20 week scan calculates the EDD outside 10 days of a reliable LNMP due date.*
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*Add 7 days to the EDD when a woman has a regular 35 day cycle.
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Urinalysis
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Urine testing for chronic renal disease (CRD)
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At booking
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1. A clean catch MSU is to be collected at the Pregnancy Booking Clinic which will be used for dipstick urinalysis to be performed by the Core Laboratory as an initial screen for CRD. Centralised dipstick urinalysis gives more reliable results.
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2. Urine testing positive for protein or red cells will have formal microscopy performed as an initial screening for CRD.
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3. Chemistry and microscopy results will be reported in Medipath and available from CLARA.
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4. If the laboratory report indicates blood or protein on urinalysis but the Dipslide (see below) was negative for bacteriuria, a referral may need to be made to the physician for further investigation of CRD.
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Urine testing for asymptomatic bacteriuria (AB)
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At booking
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1. Innoculate a dipslide with part of the MSU (see above) and send to the core laboratory for identification of any culture.
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2. All booking pathology results will be reviewed by medical officers at the next week's PBC.
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- If at any visit a woman reports symptoms of a urinary tract infection, or screening for bacteriuria is indicated, then an MSU for MC&S should be sent to pathology. Also contact the obstetric resident on call, as they may decide to commence antimicrobial agents and/or review the woman before awaiting results. If left untreated, UTIs can lead to pre-term births and low birth weight infants.
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Urine testing for proteinuria
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The Women's will no longer routinely test low-risk women for proteinuria at each antenatal visit (Level IV Evidence).
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Please refer to the section headed Blood Pressure for further clarification on testing for proteinuria when indicated.
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Urine testing for glycosuria
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Glycosuria is common in pregnant women with normal blood glucose levels and whose Glucose Tolerance Test (GTT) is within normal limits.
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The Women's has abandoned screening women routinely for glycosuria at each antenatal visit. If a woman is suspected of having a problem with carbohydrate metabolism, then a Glucose Tolerance Test (GTT) is indicated.
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All women will continue to be offered routine screening for gestational diabetes with a Glucose Challenge Test (GCT) at 26 weeks via venepuncture, followed by a GTT if indicated by the results.
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Any woman with a history of GDM or immediate family history of diabetes requires a GTT by 16 weeks or as soon as feasible, and referred to the diabetic educator for counselling if GTT is abnormal.
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- If the GTT is negative, repeat GTT at 26-28 weeks.
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Blood pressure
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The normal physiological effects of pregnancy on blood pressure should be discussed with each woman early in pregnancy.
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Strategies to avoid and treat light-headedness and fainting should be discussed with all pregnant women.
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Blood Pressure1 is monitored at every antenatal visit to detect the following hypertensive disorders:
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- gestational hypertension2
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- pre-eclampsia / eclampsia
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A woman is hypertensive when:
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- systolic BP is =/> 140mmHg and/or
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- diastolic BP is =/> 90mmHg for two or more consecutive occasions over several hours
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If upper arm circumference >33cm, use large cuff
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1. If hypertensive, wait 15 minutes before repeating BP, following rest.
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2. If hypertension persists, perform a dipstick urinalysis as an initial screen for proteinuria.
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3. Inquire about fetal movements, general wellbeing, headaches, visual disturbances, epigastric pain and assess for oedema. Record these details in the Pregnancy Record. Note: 50-80% of normotensive pregnant women experience moderate oedema, usually in the lower limbs but also fingers, face or generalised. (Enkin et al., 2000:p71)
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4. Refer all hypertensive women (BP =/> 140/90 and <170/110), with or without other symptoms, to the Pregnancy Day Care Centre before 5 pm. After hours refer to the Emergency Department assessment clinic or consider admission.
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5. The woman's assessment in the PDCC may include (over a few hours) a CTG, AFI, Dopplers, FBE, LFT, creatinine, urea, urates, repeated BPs, 24 hr urine collection.
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6. Depending on outcomes, the staff of the PDCC, Emergency Department assessment clinic and/or the reviewing medical officer will decide with the woman her subsequent care path.
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7. It is envisaged that it is a shared responsibility between the PDCC, Emergency Department assessment clinic, team doctors and midwives to communicate and follow up the woman's subsequent care path.
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- if BP =/>170/110mmHg, refer immediately to the obstetric registrar on call for admission to Birth Suite for intensive care
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- provide a calm environment and do not leave the woman unattended
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- do not ask the woman to provide a specimen for urinalysis
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Fundal height - symphyseal fundal (S-F) height measurement
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Fundal height is used to indirectly measure fetal growth in relation to gestational age. Fundal height, measured in centimetres, should equal the number of weeks gestation plus or minus 2 cm.
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A discrepancy between fundal height and gestation may indicate a fetus small or large for gestational age and should be investigated, usually by ultrasound for macrosomia or intra-uterine growth restriction (IUGR).
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Polyhydramnios, oligohydramnios, malpresentation and uterine anomalies are also possible reasons for a discrepancy in fundal height and may be diagnosed with ultrasound.
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1. Fundal height is measured and recorded at each visit on an empty bladder. Measurement should start at the variable point (the fundus) and continue to the fixed point (the symphysis pubis) using a non-elastic tape measure. The centremetre side of the tape should be face down to avoid a biased measurement.
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2. After 20 weeks, a S-F Height measurement equal to the number of weeks gestation plus or minus 2 cm can be considered normal.
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3. A discrepancy of more than two cms, i.e. 3cms or more after 20 weeks should be referred ASAP to the obstetric registrar or clinic consultant for further investigation. This includes increased fundal height or reduced fundal height.
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4. A reduced fundal height is likely to require an assessment involving CTG, AFI, Dopplers and growth ultrasound.
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- If a senior medical officer is unavailable AND the woman is >26-27* weeks, a midwife may request CTG/AFI/Dopplers through the PDCC, using the CTG request form. If any of the above tests are non-reassuring, she will be reviewed by medical staff in the PDCC. Arrange next clinic appointment to be in consultation with the team's obstetrition.
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*Interpretation of CTG assessment prior to 30 weeks requires specialist obstetric advice.
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Fetal movements
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We can expect primigravidae women to begin feeling fetal movements from around 20-22 weeks and multigravidae women from around 18-20 weeks. Each woman will experience fetal movements at an amount that is normal for her.
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In clinic
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1. All women are to be asked about fetal movements at each visit from around 20 weeks and encouraged to report any perceived reduction in fetal movements as soon as possible.
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2. Any woman with a perceived reduction in fetal movements after 26-27 weeks, including women approaching term, should be referred immediately to the PDCC (or Emergency Department Assessment Clinic if after 5 pm) for CTG assessment. All being well, the woman will return to you to complete her antenatal consultation with notification of results from the PDCC.
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3. You may or may not detect fetal movements during your palpation, but if so, record it in the Pregnancy Record as FMF (fetal movements felt).
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NOTE: CTGs are not performed under 26-27 weeks. However, if a woman is <26-27 weeks and reports reduced/no fetal movements, refer her to the obstetric registrar on call, clinic consultant or the PDCC, even if the FH is audible via a sonicaid. Perceived reduced fetal movements under 26 weeks in the presence of an audible fetal heart may still require further obstetric assessment, e.g. ultrasound (AFI) or Dopplers.
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Via phone
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With regard to fetal movements exclusively, women who experience a perceived reduction in movements should be advised to come in to the hospital for CTG monitoring immediately, either in PDCC (before 5 pm) or the emergency department after hours.
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Women in late pregnancy (or those who are unsure of the amount of movements) may be asked to sit quietly for 1-2 hours, and call back if movements remain reduced. If so, women should then be advised to come in for a CTG assessment as above.
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Auscultation of the fetal heart (FH)
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- a growing uterus and normal fetal movements indicate a fetus that is alive and well
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- however, women benefit emotionally and psychologically from listening to the FH
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- therefore, offer auscultation of the FH at each visit from the time a FH can be detected using a Sonicaid
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- as a guide, auscultation of the fetal heart from 16-20 weeks is recommended
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- in practice, early detection of the FH is more successful on slimmer women than heavier women
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- failure to detect the FH at any gestation requires immediate referral to the obstetric registrar on call, PDCC or emergency department for viability scanning to exclude fetal demise
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NOTE: With regard to early auscultation, each clinician must explore the benefits and disadvantages in the light of his/her experience in conjunction with each woman's wishes and informed choice. Many experienced doctors and midwives successfully auscultate the FH with a Sonicaid from around 14 weeks. However, flexibility is encouraged for those practitioners who, given the above considerations, wish to wait longer than 16-20 weeks or choose to provide auscultation a little earlier. What is important is that women are informed reassuringly of the issues regarding early auscultation.
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Abdominal palpation
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It is expected all clinicians are skilled in performing abdominal inspection and palpation.
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1. The lie is recorded from 30 weeks. Any deviations from a longitudinal lie should be referred to the next available clinic where the woman can be seen by her Team's obstetrician. She should be seen within 7-10 days if she cannot be seen on the day. Refer any woman found with an unstable lie from 37 weeks to the on call obstetric registrar.
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2. The presentation is recorded from 33-34 weeks. A woman with breech presentation found or persisting at 36 weeks may have External Cephalic Version (ECV) discussed, offered and organised for 37 weeks in the PDCC by the obstetric Registrar or clinic Consultant. The obstetrician performing the ECV is required to confirm the booking of the ECV.
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3. Abdominal station is recorded from 36 weeks. Its record is useful in terms of revealing a trend that may be useful for management of labour / induction.
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Thrombo-embolic disease
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It is expected clinicians will inquire about / examine women's legs to assess for signs and symptoms of thrombo-embolic disease6.
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Antenatal risk factors for thrombo-embolic disease:
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- presence of lupus anticoagulant
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- Thrombophilia (inherited)
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Superficial thrombo-phlebitis
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May appear as a tender, inflamed linear area with or without varicose veins.
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If you suspect superficial Thrombophlebitis, the woman will require referral to the obstetric registrar on call or clinic consultant for assessment.
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Treatment may require any, or a combination of:
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- short-term aspirin (unless close to term)
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- ointments containing anticoagulant compounds
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Deep Venous Thrombosis (DVT)
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During pregnancy - more common in left limb by a ratio of 9:1
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Classical signs (of which any may be absent):
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Any suspicion of a DVT requires immediate referral to the obstetric registrar or clinic consultant for further investigation.
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Clinical assessment alone will be wrong in 30-50% of cases.
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DVT can only be confirmed by Doppler Ultrasound or Venography.
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Doppler Ultrasound is less invasive but is limited in assessing the pelvic veins.
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Pulmonary embolism
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Requires high index of suspicion towards:
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- SOB, tachypnoea, dyspnoea
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Any suspicion requires urgent medical attention.
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Referral guidelines
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If at any time you are unsure in your assessment, it is perfectly acceptable to ask another colleague to perform the assessment with a woman's permission. If you are both unsure of a decisive finding, e.g. unsure of presentation at 38 weeks, it will be necessary to ask for the on-call obstetric registrar or clinic consultant to review the assessment.
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- women with obstetric related complaints, which require same day medical attention, can be referred to the obstetric registrar or Urgent Care (emergency)
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- women with obstetric related complaints, which do not require same day medical attention, can be referred to the team obstetrician at his/her next clinic day
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- women with minor non-obstetric medical complaints can be referred to their local GP
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- the Women's Pregnancy Day Care centre (before 5 pm) and Urgent Care assessment centre (after hours) are also available for CTGs and hypertension assessment
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Notes
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The following instructions for antenatal blood pressure measurement are given by the Three Centres Consensus Guidelines on Antenatal Care, 2001, in order to standardise BP measurement methods:
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- To be measured, women should sit down with feet supported. Measurements should be taken after two to three minutes resting in this position. (Level III-2 evidence).
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- A standard size cuff should be used for women with an arm circumference 33 cm and a large cuff used for arm circumference >33 cm (Level IV evidence).
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- Systolic blood pressure should be palpated at the brachial artery and the cuff inflated to 20mmHg above this level. The cuff should be deflated slowly, at approximately 2mmHg per second (Level IV evidence).
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- Diastolic blood pressure readings should be recorded using the Korotkoff V sound. If phase V is not present, phase IV should be recorded (Level II evidence).
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- Hypertension is defined when systolic blood pressure is 140mmHg and/or diastolic blood pressure (Korotkoff V) is 90mmHg or there is an incremental rise of 30mmHg systolic or 15mmHg diastolic (Level IV evidence).
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- Evidence supports the use of a mercury sphygmomanometer to measure blood pressure but only an anaeroid sphygmomanometer complies with the Occupational Health and Safety Recommendations (1999). It is necessary to recalibrate anaeroid machines regularly, especially in high use situations (Level III evidence).
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- Automated devices and ambulatory blood pressure monitoring devices should not be used in routine clinical practice until more detailed information is available about their accuracy and effectiveness (Level III evidence) (Three Centres Collaboration, 2001:p41).
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- Please note that phase V is the disappearance of the Korotkoff sounds. Phase IV is the muffling of the sounds (Enkin et al, 2000:p71).
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1. Pregnancy-induced hypertension may occur at any time in the second half of pregnancy. It rarely occurs before 28 weeks of pregnancy, but when it does occur this early it frequently leads to pre-eclampsia with its associated high rate of perinatal morbidity and mortality. On the other hand, when pregnancy induced hypertension occurs late in the third trimester, a much more frequent occurrence, the maternal and fetal risks are much smaller. Therefore, although routine antenatal screening for hypertensive disorders before 28 weeks gestation may have a low productivity in terms of the number of positive diagnoses per visit, it has a high potential to prevent maternal and fetal morbidity and mortality (Enkin et al., 2000:p73).
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2. The reduction in velocity of lower-limb venous flow (due to increased venous distensibility and to flow obstruction related to pressure from the gravid uterus) and the hypercoagulable state of pregnancy (due to increased concentrations of vitamin K dependent factors and to decreased fibrinolytic activity) provide an increased risk of thrombo-embolic disease. Consequently, pulmonary embolism joins pregnancy-induced hypertension and maternal cardiac disease as the most important non-traumatic causes of maternal death. Between 10% and 15% of women with deep venous thrombosis in their leg or pelvic veins will have a pulmonary embolus (Humphrey, 1999:p85).
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Royal Women's Hospital Clinical Practice Guidelines (CPGs) are intended to provide guidance to health care professionals, based on a thorough evaluation of research evidence, on the practical assessment and management of specific clinical issues or situations. The guidelines allow some flexibility on the part of the health care professional based on the needs of the specific patient for whom they are caring.
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