Antenatal Care Flashcard

Submitted by : Dr Debilina Roy

Incidence of placenta previa at term-1in 200pregnancies

If placenta is thought to be low lying in routine anomaly scan-follow up ultrasound with TVS at 32weeks

Persistent low lying placenta or placenta previa at 32weeks who are asymptomatic-additional TVS at 36weeks recommended

TVS- will reclassify 26-60% placentas diagnosed as low lying in routine anomaly scan

TVS-PPV-93.3%, NPV-97.6%, FALSE NEGATIVE RATE-2.33%(in predicting placenta previa in women suspected of low lying placenta on TAS in second and early third trimester

Sensitivity-87.5%, specificity-98.8%

In third trimester -resolution of 90% before term(but less likely with previous cs)

In twin pregnancy-likelihood of persistence of placenta previa dependent on gestational age.

Majority resolve by third trimester.after 32weeks,50% of remaining placenta previa resolve but no change after 36weeks

Single course antenatal corticosteroid -recommended between 34+0-35+6weeks for women with low lying placenta or placenta previa

Appropriate prior to 34weeks of gestation in women with high risk of preterm birth

Tocolysis only useful for 48hrs for antenatal corticosteroid

If delivery urgently indicated(maternal/fetal concern)-no role of tocolysis

Late preterm delivery (34+0-36+6weeks)-should be considered for women with low lying placenta/placenta previa with h/o vaginal bleeding or risk factors for preterm birth

Uncomplicated placenta previa- delivery between 36+0to 37+0 weeks

Incidence of placenta accreta-1in 300to 1in 2000

More common in women over35yrs and IVF

Incidence of placenta accreta increases with number of caesarean sections.

Incidence of placenta accreta spectrum in women with placenta previa and no previous cs-3.3 to 4.0%

Incidence of placenta accreta spectrum in women with 3or more cs-50-67%

Risk of placenta accreta spectrum with number of cs-

1cs-3%

2cs-11%

3cs-40%

4cs-61%

5or more-67%

Placenta accreta spectrum remain undiagnosed before delivery in one half to two thirds of cases

Women with previous cs and anterior low lying placenta or placenta previa at routine fetal anomaly -should be specifically screened for placenta accreta spectrum

In absence of risk factors for preterm delivery in women with placenta accreta spectrum-planned delivery at 35+0-36+6weeks

MRI may be used to complement imaging to assess the depth of invasion and lateral extension of myometrial invasion, especially with posterior placentation and/or in women with ultrasound signs suggesting parametrial invasion

Sensitivity of MRI in diagnosing placenta accreta-75-100%

Specifity of MRI in diagnosing placenta accreta-65-100%

Uterus preserving surgery associated with-

Success-63.2%

Secondary hysterectomy-30%

Maternal mortality-3.7%

Subsequent menstruation-81.1%

Subsequent pregnancy-77.8%

Methotrexate and uterus preserving surgery associated with-16%unintentional urinary tract injury

Standard hysterectomy associated with 57%unintentional urinary tract injury

Emergency delivery (inspite of planned delivery between 34-35weeks in placenta accreta spectrum)-20%

Incidence of vasa previa-1in 1200 to 1in 5000

Upto 6in 10affected babies

Improved survival of 97% when vasa previa diagnosed antenatally with only 44% when diagnosis made during delivery

Planned cs at 34-36weeks (after a course of corticosteroid)

Placental pathological examination should be performed to confirm vasa previa ,in particular when stillbirth has occurred or there is acute fetal compromise during delivery

TAS AND TVS COLOR DOPPLER IMAGING (CDI)-highest accuracy with low false positive rate in diagnosing vasa pTvs CDI-sensitivity 100%,specificity-99-99.8%

Prophylactic hospitalisation from 30-32weeks in diagnosed vasa previa

Vasa previa-

Type 1-vessel connected to velamentous umbilical cord

Type 2-connected to succenturiate /accessory lobe

Classic presentation of vasa previa

Painless vaginal bleeding (benckiser’s haemorrhage)

(Total fetal blood volume at term 80-100ml/kg,loss of relatively small amount can have major implications)

Prenatal diagnosis most effective between 18-24weeks but needs to be confirmed during third trimester 30-32weeks)

Vasa previa in second trimester resolves in around 20%before delivery

For each additional millimetres-per week decrease in cervical length,odds of emergency cs increased by 6.50

Risk factor for vasa previa,(80% have one or more risk factors)

Velamentous cord insertion-62%

Low lying placenta-60%

ART

Bilobed placenta

Succenturiate lobe

Submitted by : Dr Jigyasa

PERCENTAGES
Obesity

• Obesity is becoming increasingly prevalent in the UK population and has become one of the most commonly occurring risk factors in obstetric practice, with 21.3% of the antenatal population being obese and fewer than onehalf of pregnant women (47.3%) having a body mass index (BMI) within the normal range.

• The prevalence of obesity in pregnancy has also been seen to increase, rising from 9–10% in the early 1990s to 16–19% in the 2000s.
• High prepregnancy BMI is associated with a small but statistically significant increase in severe maternal morbidity or mortality, with the adjusted rate difference per 10 000 women compared with normal BMI being 24.9 for women with class I obesity, 35.8 for women with class II obesity and 61.1 for women with class III obesity.
• 2015 MBRRACE-UK (Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the UK) review into maternal deaths, which reported that 30% of women who died were obese and 22% were overweight
• Confidential Enquiry on Maternal and Child Health (CEMACH 2003–5) recommended that women with a BMI 30 kg/m2 or more should be seen for prepregnancy counselling.
• Women with a raised BMI are at increased risk of NTDs, reporting an OR of 1.70 and 3.11 for women defined as obese and severely obese, respectively, compared with women of healthy weight.
• In the UK showed that approximately one-quarter of UK women aged between 19 and 24 years, and one-sixth of those aged between 25 and 34 years, are at risk of vitamin D deficiency.
• Recommended oral intake of 10 micrograms vitamin D daily for all pregnant and breastfeeding women cannot usually be met from diet alone.
• Specific recommendations include a requirement for all women with a BMI 30 kg/m2 or greater to have multidisciplinary care, a documented antenatal consultation about the intrapartum risks and to be advised to deliver in a consultant-led unit (CLU) for those with a BMI of 35 kg/m2 or greater.
• NICE CG62 Antenatal care for uncomplicated pregnancies58 recommends that maternal height and weight is measured at the booking appointment (ideally by 10 weeks of gestation) and the woman’s BMI is calculated
• Use of topiramate in pregnancy is linked to oral clefts. Topiramate and phentermine are also individually excreted in breast milk.
• Lorcaserin hydrochloride is a serotonin receptor agonist exposure in late pregnancy did result in lower birthweight of offspring, which persisted to adulthood. Lorcaserin is therefore contraindicated in pregnancy.
• Pregnant women with a booking BMI 40 kg/m2 or greater should be referred to an obstetric anaesthetist for consideration of antenatal assessment.
• One-quarter of maternal cardiac arrests were related to anaesthesia. Of this number, 75% of the women were obese. Epidural resite rate in the women with class III obesity (greater than 136 kg in weight) was 17% in a cohort study compared with 3% in the control group.
• A BMI greater than 40 kg/m2 is a risk factor for developing pressure sores.
• Obese women with gestational diabetes have a three-fold increased risk of congenital anomalies. Maternal gestational diabetes and obesity were independently associated with adverse pregnancy outcomes, with an even greater impact in combination.
• Clinicians should be aware that women with class II obesity and greater have an increased risk of pre-eclampsia compared with those with a normal BMI.
• Women with more than one moderate risk factor (BMI of 35 kg/m2 or greater, first pregnancy, maternal age of more than 40 years, family history of pre-eclampsia and multiple pregnancy) may benefit from taking 150 mg aspirin daily from 12 weeks of gestation until birth of the baby.
• The effects of three different cuff sizes (standard, 12 9 23 cm; large, 15 9 33 cm; and thigh, 18 9 36 cm) on blood pressure measurement .The differences in readings among the three cuffs were smallest in non-obese subjects and became progressively greater with increasing arm circumference in the obese population. Less error was introduced by using too large a cuff than by too small a cuff.
• When compared with women with a BMI of between 18.5 kg/m2 and 24.9 kg/m2 , risk ratios for pre-eclampsia of overweight, obese and severely obese women were 1.70, 2.93 and 4.14 respectively.
• Obesity is a risk factor for VTE with the risk of pulmonary emboli (adjusted OR [aOR] 14.9, being greater than for deep vein thrombosis (aOR 4.4)
• The RCOG recommends routine measurement of peak anti-Xa activity for women weighing 90 kg or more on therapeutic doses of low-molecular-weight heparin (LMWH)
• Obese and overweight women had a significantly higher prevalence of depression symptoms than women of normal weight and higher median prevalence estimates. This was found during pregnancy (obese, 33.0%; overweight, 28.6%; normal weight 22.6%) and postpartum (obese, 13.0%; overweight, 11.8%; normal weight, 9.9%).

• Proportion of pregnant women who completed first trimester screening is inversely proportional to their BMI (64% of women with BMI 18–24.9 kg/m2 versus 61% of women with BMI greater than 30 kg/m2 and 47% if BMI greater than 40 kg/m2 .
• women with a BMI between 30 and 40 kg/m2 do not have increased risk of fetal loss associated with chorionic villus sampling or amniocentesis. Higher loss rates were observed for women with class III obesity following amniocentesis (aOR 2.2)
• Approximately 60% of obese primiparous women and 90% of obese multiparous women achieved vaginal birth following induction of labour.
• NICE CG190127 recommends that women with a booking BMI greater than 35 kg/m2 have planned labour and birth in an obstetric unit. Those who have a BMI of between 30 kg/m2 and 35 kg/m2 at booking should have individualised assessment of place of birth.
• Risk of caesarean section increased by 50% in overweight women and more than doubled in obese women.(OR in class III obesity 3.38)
• Additionally, elective induction of labour at 38, 39 and 40 weeks of gestation was associated with lower odds of macrosomia and caesarean sections. There were no differences in the odds of operative vaginal birth, lacerations, brachial plexus injury or respiratory distress syndrome. However, induction of labour results in lower mean birthweight, and fewer fractures and cases of shoulder dystocia.
• In order to prevent one fracture, it would be necessary to induce 60 women.
• Fetuses from the induction of labour group were at increased risk of raised bilirubin of more than 250 mmol/l (9% in induction group versus 3% in expectant group;) and phototherapy (11% in induction group versus 7% in expectant group;)
• Only 54.6% of obese pregnant women had successful VBAC compared with 70.5% of those with a normal BMI.
• Class III obesity is associated with increased rates of uterine rupture during trial of labour143–145 and neonatal injury.
• In addition, babies born to mothers with obesity are up to 1.5 times more likely to be admitted to a neonatal intensive care unit than babies born to mothers of a healthy weight.
• A minimum waiting period of 12–18 months after bariatric surgery is recommended before attempting pregnancy to allow stabilisation of body weight and to allow the correct identification and treatment of any possible nutritional deficiencies that may not be evident during the first months.
• Obese women who had bariatric surgery had a lower incidence of pre-eclampsia (OR 0.45,), gestational diabetes (OR 0.47) and large-forgestational-age neonates (OR 0.46,), while a higher incidence of small-for gestational-age neonates (OR 1.93), preterm birth (OR 1.31), admission for neonatal intensive care (OR 1.33) and maternal anaemia (OR 3.41) was identified.
• All pregnant women with a booking BMI 30 kg/m2 or greater should be screened for gestational diabetes.
• Women with more than one moderate risk factor (BMI of 35 kg/m2 or greater)
• Clinicians should be aware that women with a BMI 30 kg/m2 or greater, prepregnancy or at booking, have a pre-existing risk factor for developing VTE during pregnancy.
• Women with BMI 30 kg/m2 or greater are at increased risk of mental health problems and should therefore be screened for these in pregnancy.
• Obese pregnant women (BMI 30 kg/m2 or greater) are at increased risk of a range of structural anomalies.
• Women with a BMI greater than 35 kg/m2 are more likely to have inaccurate SFH measurements and should be referred for serial assessment of fetal size using ultrasound.
• NICE CG190127 recommends that women with a booking BMI greater than 35 kg/m2 have planned labour and birth in an obstetric unit. Those who have a BMI of between 30 kg/m2 and 35 kg/m2 at booking should have individualised assessment of place of birth.
• Women with a booking BMI 30 kg/m2 or greater should have an individualised decision for VBAC following informed discussion and consideration of all relevant clinical factors.
• Women with a BMI 40 kg/m2 or greater should have venous access established early in labour and consideration should be given to the siting of a second cannula.
• Women with a booking BMI 30 kg/m2 or greater should receive appropriate specialist advice and support antenatally and postnatally regarding the benefits, initiation and maintenance of breastfeeding.

Submitted by : Dr Surbhi Sinha

• Small for gestational age (SGA) – Infant born with birthweight < 10th centile  SGA birth - EFW or AC < 10th centile  Severe SGA - EFW or AC < 3rd centile • LBW (Low birth weight ) - Infant with birth wt <2500 gm • 50-70 % SGA foetuses - Constitutionally small (with appropriate fetal growth for maternal size and ethnicity ) • Women with 1 Major risk factor (Odd’s ratio OR >2.0 ) -> Referred for :
– Serial USG measurement of fetal size (Biometry) &
– Umbilical Artery Doppler from 26-28 wks

• 3 or more Minor R.F – Referred for Uterine Artery Doppler at 20-24 wks

• Previous SGA – 2 Fold increased risk of subsequent SGA

• 1st trimester PAPP-A value < 0.415 MoM -> Major R.F for SGA

• Using 5th centile cut off ( 0.415 MoM) -> OR for SGA = 2.7 OR for Severe SGA =3.66

• Unexplained low 1st trimester PAPP-A +/or a low hcg (0.5 MoM) -> a/w increased frequency of adv obstetric outcome including SGA infant.

• In High risk population, Uterine art Doppler @ 20-24 wks -> Moderate predictive value

• 1st trimester ut artery Doppler -> High specificity 91-96% High NPV 91-99% Low Sensitivity (12-25%)

• Serial SFH measurement Recommended at each ANC visit -> from 24 wks onwards (Improves prediction)

• SFH plotted on customised Chart >>> population-based chart (May improve prediction)

• Using AC or EFW (2 measurements )for estimating growth velocity -> AT LEAST 3 weeks apart to minimise FP rates for diagnosing FGR

• High Risk Population :

Fetal AC < 10th centile Sn 72.9- 94.5% Sp 50.6- 83.8% EFW <10th centile Sn 33.3-89.2% Sp 53.7-90.9% • A customised EFW <10th centile -> Predictive of SGA neonate Sn 68% Sp 89%

• OR of adverse outcomes for SGA vs Not SGA -> 1.59 (Non customised fetal weight reference)
-> 2.84 (Customised reference)

• Change in AC suggestive of FGR -> <5mm change over 14 days • Severe SGA -- Incidence of Chrm. Anomalies 19% • Mc chrom defect < 26 weeks -> Triploidy

• Mc chrm defect > 26 weeks -> Trisomy 18
• Fetal infections responsible for -> 5% of SGA foetuses (MC -> CMV, Toxopl, Malaria & Syphilis )

• Risk reduction in SGA -> when aspirin started < 16 wks • Stop smoking by 15 wks -> reduce the risk back to that of non smokers

• When defined by Customised fetal wt standards -> 81% SGA foetuses have Normal UA Doppler

• SGA foetuses with Normal UA artery Doppler -> Increased risk of Neonatal morbidity (OR 2.26 95% CI 1.04-4.39) & adverse Neurodevelopmental outcome

• Incidence of AFI <= 5 cm in low risk pop. -> 1.5%

• AFI <= 5 cm A/w with -> increased risk of C .S for fetal distress (RR 2.2 , 95% CI 1.5-3.4) and APGAR score < 7 at 5 mins (RR 5.2, 95% CI 2.4-11.3) BUT NOT ACIDEMIA • In Preterm SGA • Increased rate of C.S in BPP group (biophysical profile ) with NO improvement in perinatal outcome • BPP has High false negative for fetal academia -> 11%
• BPP- Not recommended for fetal surveillance in Preterm SGA fetus
• PNMR with UA AREDV -> 12%
• Increased DV PIV -> 39%
• Absence or reversal of DV a-wave -> 41%

Submitted by : Dr Jigyasa

Red cell antibodies were detected in 1.2% of pregnancies, while the prevalence of clinically significant antibodies was placed at 0.4%.

Anti-D is the most commonly encountered antibody during pregnancy.

Before routine antenatal anti-D prophylaxis, late immunisation during a first pregnancy was responsible for 18–27% of cases.

The prevalence of positive antibody screens was 1:80, with a 1:300 prevalence of clinically significant alloantibodies other than anti-D.

All women should have their blood group and antibody status determined at booking and at 28 weeks of gestation

The overall perinatal survival in pregnancies complicated by red cell antibodies causing fetal anaemia following treatment was reported to be 84%, with nonhydropic fetuses having better survival (94%) than hydropic fetuses (74%).

Genotyping can be undertaken from 16 weeks of gestation for all except K which can be undertaken from 20 weeks, due to the risk of a falsenegative result if performed earlier in pregnancy.

Of note, in dizygotic twins, a maternal blood test for fetal genotyping will not differentiate between the twins: just that at least one has the corresponding gene.

An anti-D level of > 4 iu/ml but < 15 iu/ml correlates with a moderate risk of HDFN and an anti-D level of > 15 iu/ml can cause severe HDFN. Referral for a fetal medicine opinion should therefore be made once anti-D levels are > 4 iu/ml.

An anti-c level of > 7.5 iu/ml but < 20 iu/ml correlates with a moderate risk of HDFN, whereas an antic level of > 20 iu/ml correlates with a high risk of HDFN. Referral for a fetal medicine opinion should therefore be made once anti-c levels are > 7.5 iu/ml.

For anti-K antibodies, referral should take place once detected, as severe fetal anaemia can occur even with low titres.

The presence of anti-E potentiates the severity of fetal anaemia due to anti-c antibodies so that referral at lower levels/titres is indicated (unless the fetus has only one of these antigens).

An anti-D level < 4 iu/ml or an anti-c level of < 7.5 iu/ml correlates with a low risk of fetal anaemia and therefore referral to a fetal medicine specialist is not immediately indicated Anti-D and anti-c levels should be measured every 4 weeks up to 28 weeks of gestation and then every 2 weeks until delivery. Referral to a fetal medicine specialist for consideration of invasive treatment should take place if the MCA PSV rises above the 1.5 multiples of the median (MoM) threshold or if there are other signs of fetal anaemia. MCA PSV monitoring is predictive of moderate or severe fetal anaemia with 100% sensitivity and a false positive rate of 12% Monitoring with MCA PSV should be used with caution after 36 weeks as its sensitivity for the detection of fetal anaemia decreases. The risk of fetal loss following an FBS is 1–3%, but is higher if the fetus is hydropic. Red cell preparations for IUT should be group O (low titre haemolysin) or ABO identical with the fetus (if known) and negative for the antigen(s) corresponding to maternal red cell antibodies.

It should also be less than 5 days old and in citrate phosphate dextrose (CPD) anticoagulant, cytomegalovirus (CMV) seronegative, irradiated and transfused within 24 hours of irradiation. Blood packs should have a haematocrit (packed cell volume, PCV) of 0.70–0.85.

In exceptional cases, it will be necessary to give O RhD-positive, c-negative blood, for example in HDFN because of anti-c alloimmunisation, where giving RhD-negative blood would be harmful

Pregnant women with red cell antibodies, who are assessed as being at high risk of requiring a blood transfusion, should have a cross-match sample taken at least every week.

Current BCSH guidelines require a sample no more than 72 hours old for providing compatible blood in pregnancy,24 but do allow a deviation to the 3-day rule for individual cases such as high-risk women with placenta praevia without red cell antibodies where weekly samples can be taken

Blood for intrauterine transfusion (IUT)– blood for IUT has the same requirements as blood for neonatal exchange, except that plasma is removed by the blood centre to increase the haematocrit to 0.70–0.85 and it is always irradiated. Blood for IUT should never be transfused straight from 4ºC storage.

Blood for IUT is processed to order as it only has 24 hours’ shelf life after processing and normally requires a minimum of 1 working day’s notice, unless an emergency.

Blood for neonatal exchange– Blood should be less than 5 days old (to ensure low supernatant potassium levels), CMV negative and irradiated unless the risk to the baby of delaying exchange transfusion while obtaining irradiated blood outweighs this. It should be plasma reduced (rather than in saline-adenine-glucose-mannitol [SAGM] additive solution), with a haematocrit of 0.50–0.60.
Blood for neonatal small volume (‘top-up’) transfusion-Blood should be CMV negative but does not need to be irradiated unless the neonate has had a previous IUT and blood can be stored in SAGM (rather than plasma reduced) and be up to 35 days old (as a topup transfusion is a much smaller volume than an exchange transfusion).

In general, for red cell antibodies that could cause fetal anaemia but which have been stable throughout pregnancy, delivery should take place between 37 and 38 weeks of gestation.

The risk of long-term neurodevelopmental delay is no different in the antenatally treated cohort compared with unaffected pregnancies, with normal outcome expected in more than 90% of cases.

Sensorineural hearing loss is more common in infants affected by haemolytic disease of the newborn because of the toxic effect of prolonged exposure of bilirubin on the developing eighth cranial nerve.

USE OF ANTI D Ig Percentage Flashcard

Prior to the availability of anti-D immunoglobulin (anti-D Ig), the incidence of Rh D alloimmunisation in D negative women following two deliveries of D positive, ABO-compatible, infants was approximately 16%

. Following routine post-partum administration of anti-D Ig, the rate of alloimmunisation dropped to approximately 2%.

A further reduction in the sensitisation rate ranging from 0•17 to 0•28% was achieved by introducing routine antenatal prophylaxis during the third trimester of pregnancy

A reduction in mortality associated with HDN, from 46/100 000 births to 1•6/100 000 births.

SUMMARY OF KEY RECOMMENDATIONS

1. Following potentially sensitising events, anti-D Ig should be administered as soon as possible and always within 72 h of the event. If, exceptionally, this deadline has not been met some protection may be offered if anti-D Ig is given up to 10 days after the sensitising event
2. In pregnancies < 12 weeks gestation, anti-D Ig prophylaxis is only indicated following ectopic pregnancy, molar pregnancy, therapeutic termination of pregnancy and in cases of uterine bleeding where this is repeated, heavy or associated with abdominal pain. The minimum dose should be 250 IU. A test for fetomaternal haemorrhage (FMH) is not required 3. For potentially sensitising events between 12 and 20 weeks gestation, a minimum dose of 250 IU should be administered within 72 h of the event. A test for FMH is not required 4. Appropriate tests for FMH should be carried out for all D negative, previously non-sensitised, pregnant women who have had a potentially sensitising event after 20 weeks of gestation, and additional dose(s) of anti-D Ig should be administered as necessary 5. All D negative pregnant women who have not been previously sensitised should be offered routine antenatal prophylaxis with anti-D Ig (RAADP) either with a single dose regimen at around 28 weeks, or two-dose regimen given at 28 and 34 weeks 6. It is important that the 28-week sample for blood group and antibody screen is taken prior to the first routine prophylactic anti-D Ig injection being given. This forms the second screen required in pregnancy 7. Routine Antenatal Anti-D Ig Prophylaxis (RAADP) should be regarded as a separate entity and administered regardless of, and in addition to, any anti-D Ig that may have been given for a potentially sensitising event 8. Following birth, ABO and Rh D typing should be performed on cord blood and if the baby is confirmed to be D positive, all D negative, previously non-sensitised, women should be offered at least 500 IU of anti-D Ig within 72 h following delivery. Maternal samples should be tested for FMH and additional dose(s) given as guided by FMH tests 9. In the event of an intrauterine death (IUD), where no sample can be obtained from the baby, an appropriate dose of prophylactic anti-D Ig should be administered to D negative, previously non-sensitised women within 72 h of the diagnosis of IUD, irrespective of the time of subsequent delivery 10. Where intra-operative cell salvage (ICS) is used during Caesarean section in D negative, previously nonsensitised women, and where cord blood group is confirmed as D positive (or unknown), a minimum dose of 1500 IU anti-D Ig should be administered following the re-infusion of salvaged red cells, and a maternal sample should be taken for estimation of FMH 30–45 min after reinfusion in case more anti-D Ig is indicated

POTENTIALLY SENSITISING EVENTS IN PREGNANCIES OF LESS THAN 12 WEEKS OF GESTATION

In pregnancies <12 weeks gestation, Anti-D Ig prophylaxis (minimum dose 250 IU) is only indicated following an ectopic pregnancy, molar pregnancy, therapeutic termination of pregnancy and in some cases of uterine bleeding where this is repeated, heavy or associated with abdominal pain. A test for FMH is not required POTENTIALLY SENSITISING EVENTS IN PREGNANCIES OF 12 WEEKS TO LESS THAN 20 WEEKS OF GESTATION

For any potentially sensitising event, confirmed D negative, previously non-sensitised, women should receive a minimum dose of 250 IU anti-D Ig within 72 h of the event

presenting with continual uterine bleeding between 12 and 20 weeks gestation should be given at least 250 IU anti-D Ig, at a minimum of 6 weekly intervals

. A test for FMH is not required

POTENTIALLY SENSITISING EVENTS IN PREGNANCIES OF 20 WEEKS OF GESTATION TO TERM

For potentially sensitising events after 20 weeks gestation a minimum Anti D Ig dose of 500 IU should be administered within 72 h of the event

Appropriate tests for FMH should be carried out for all D negative, previously non-sensitised

The additional dose should be calculated as 125 IU if administered IM or 100 IU if administered IV for each mL of fetal red cells detected (minimum 500IU)

A follow-up blood sample should be taken at 48 h following each IV dose of anti-D and 72 h following each IM dose of anti-D to check if fetal cells have cleared.

In the event of continual uterine bleeding which is clinically judged to represent the same sensitising event, with no features suggestive of a new presentation or a significant change in the pattern or severity of bleeding, such as the presence of abdominal pain or another clinical presentation, a minimum dose of 500, IU anti-D Ig should be given at six weekly intervals. estimation of FMH should be carried out at two weekly intervals

ROUTINE ANTENATAL ANTI-D PROPHYLAXIS (RAADP)

If using the two-dose regimen, a minimum dose of anti-D Ig 500 IU is recommended at 28 and 34 weeks. Alternatively, a single dose of anti-D Ig, 1500 IU should be administered between 28 and 30 weeks.

PROPHYLAXIS FOLLOWING BIRTH OF AN D POSITIVE CHILD OR INTRAUTERINE DEATH

A dose of 500 IU, IM is considered sufficient to treat a FMH of up to 4 mL fetal red cells

Maternal samples for confirmatory ABO and Rh D type and FMH testing should be collected after sufficient time has elapsed for any FMH to be dispersed in the maternal circulation. A period of 30–45 min is considered and the samples should ideally be taken within 2 h of delivery primarily to ensure that the sample is taken prior to woman’s discharge from the hospital.

If an FMH >4 mL is detected, follow-up samples are required at 48 h following an IV dose of anti-D or 72 h following an IM dose to check for the clearance of fetal cells

dose calculation is traditionally based on 125 IU anti-D Ig/mL fetal red cells for IM administration.

When intra-operative cell salvage (ICS) is used for Caesarean section, reinfused blood may contain fetal red cells.

volume of fetal red cells in re-infused blood varies from 1 to 20 mL.

It is recommended that a minimum anti-D Ig dose of 1500 IU be administered after reinfusion of salvaged red cells if the cord blood group is D positive

Maternal samples should be taken for estimation of FMH 30–45 min after the re-infusion of salvaged red cells, and additional dose(s) of anti-D administered if necessary

If there is an intrauterine death (IUD) and hence no sample can be obtained from the baby, prophylactic anti-D Ig should be A minimum of 500 IU of anti-D Ig should be administered within 72 h following the diagnosis of IUD. Maternal samples should be tested for FMH and additional dose(s) given.

D positive platelet transfusions

A dose of 250 IU anti-D immunoglobulin should be sufficient to cover up to five adult therapeutic doses of D positive platelets given within a 6-week period (BCSH b, 2003) (Grade 2B). In severely thrombocytopenic patients with platelet count of ≤30 × 109/L, anti-D Ig should be given subcutaneously, or IV if a preparation suitable or IV route is available, to avoid the risk of IM bleed following IM injection

It is not necessary to administer anti-D Ig to D negative females without childbearing potential, or males who receive D positive platelets.

Inadvertent transfusion of D positive blood to D negative women of childbearing potential

When less than 15 mL have been transfused, the appropriate dose of IM anti-D Ig may be given.

When more than 15 mL have been transfused, it is preferable to use the larger anti-D immunoglobulin preparation (1500 or 2500 IU); however, IV anti-D immunoglobulin is the preparation of choice.

When more than one unit of D positive blood has been transfused, a red cell exchange transfusion should be considered to reduce the load of D positive red cells in the circulation and the dose of anti-D Ig required to prevent immunisation.

The quantitation of D positive red cells should be performed by flow cytometry (FC) after 48 h if an IV dose of anti-D has been given or 72 h if an IM dose has been given.

A single blood-volume red cell exchange transfusion will achieve a 65–70% reduction in D positive red cells; a double volume exchange will achieve an 85–90% reduction.

ROLE OF CELL FREE FETAL DNA TESTING

Using cell free fetal DNA (cffDNA) from maternal blood samples taken at 16–20 week gestation, have made it possible to determine fetal D type with a diagnostic accuracy of around 96% The risk of a false negative result (i.e. missing an D positive fetal blood group) by this technique, is small and currently estimated to be around 0•08 to 0•16%.