Evaluation of the use of umbilical artery Doppler flow

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The Journal of Maternal-Fetal and Neonatal Medicine, March 2007; 20(3): 233–239

Evaluation of the use of umbilical artery Doppler flow studies and outcome of pregnancies at a secondary hospital

ELIZABETH J. C. HUGO, HEIN J. ODENDAAL, & DEBBIE GROVE Department of Obstetrics and Gynecology, University of Stellenbosch and Tygerberg Hospital, Cape Town, Republic of South Africa (Received 10 July 2006; revised 10 September 2006; accepted 16 October 2006)

Abstract Objective. To investigate the use of a personal computer (PC)-based, continuous-wave Doppler machine by a trained midwife at a secondary hospital to assess umbilical artery flow velocity waveforms (FVW) in referred women. Methods. Pregnant women referred for suspected poor fetal growth were evaluated from June 2002 through December 2004. The Umbiflow1 apparatus, consisting of a Pentium 3 PC with an ultrasound transducer plugged into the USB port and software, was used to analyze the FVW of the umbilical artery. Pregnancies in which the resistance index (RI) was 575th percentile (P75) were not further evaluated for fetal well-being unless the clinical condition of the mother changed. Pregnancies with an RI P75 were followed up according to a specific protocol. Primary end points were intrauterine death and intrauterine growth restriction. Results. A total of 572 singleton pregnancies were followed up. Significantly more infants were small-for-gestational-age when the RI was 4P95 (55.6%) than those between P75 and P95 (41.2%) or 5P75 (27.2%). Perinatal mortality rates were 13.2, 39.1 and 41.7 for women with RIs 5P75, P75–95 and 4P95, respectively. Conclusions. A normal Doppler FVW of the umbilical artery is less likely to be followed by perinatal death.

Keywords: Umbilical artery Doppler, placental insufficiency, intrauterine growth restriction, intrauterine death, flow velocity waveforms

Introduction Placental insufficiency is a major cause of intrauterine growth restriction (IUGR) [1–3]. In addition, it is also associated with the increased risk of intrauterine demise, intrapartum fetal distress, and neonatal morbidity and mortality [1–4]. The use of Doppler ultrasound to assess the flow velocity of the umbilical artery of the fetus with poor growth is the only method of antenatal surveillance that has improved perinatal outcome [5,6]. In a meta-analysis Thornton and Lilford [7] noted that a finding of absent or reversed end diastolic flow velocity is of particular importance as these fetuses were eighty times more likely to die than fetuses where end diastolic flow velocity was present. In another metaanalysis, Giles and Bisits [8] found a significant reduction (OR ¼ 0.54, 95%CI 0.32–0.89) of intrauterine deaths in normally formed fetuses in highrisk pregnancies where flow velocity waveforms (FVWs) of the umbilical artery were assessed.

A meta-analysis of 12 randomized control trials by Alfirevic and Neilson [6] demonstrated similar findings. In a high-risk pregnancy, the clinical action, guided by Doppler ultrasonography, reduced the odds of perinatal death by a phenomenal 38%. There was also a significant reduction in the number of prenatal admissions, inductions of labor, cesarean sections for fetal distress, and hypoxic ischemic encephalopathy. This decrease in perinatal mortality was achieved without an increase in the rate of inappropriate obstetric intervention. More recently Westergaard et al. [9] re-analyzed the data, using only well-defined studies. They concluded that the use of Doppler FVWs reduced the number of perinatal deaths and unnecessary obstetric interventions only in pregnancies with compromised placental function, i.e., those with suspected IUGR and/or hypertensive disease. There is no role for Doppler FVW as a screening test in low-risk pregnancies [10,11]. Pulsed-wave Doppler waveform analyzers are usually part of expensive ultrasound machines,

Correspondence: Hein J. Odendaal, University of Stellenbosch, Cape Town, South Africa. Tel: þ27 21 938 9601. Fax: þ27 21 938 9718. E-mail: [email protected] ISSN 1476-7058 print/ISSN 1476-4954 online Ó 2007 Informa UK Ltd. DOI: 10.1080/14767050601134926


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normally operated by trained sonographers or obstetricians. The combined cost of the equipment and the training of the healthcare workers have put this technology out of reach of most smaller centers in developing countries. To reduce these excessive costs, the Medical Research Council (MRC) Unit for Perinatal Mortality at Tygerberg Academic Hospital (TBH), the MRC in Cape Town and the Centre for Scientific and Industrial Research (CSIR) in Pretoria developed a continuous-wave Doppler analyzer (Umbiflow1), which consists of a standard personal computer (PC) with an ultrasound probe plugged into the USB port and software, to analyze FVWs of the umbilical artery [12]. The waveforms are displayed on the computer screen; the resistance index (RI) is calculated and then plotted on a percentile chart against gestational age. Different colors are used to help the operator to easily identify the RI zone on the graph. The zone above the 95th percentile (4P95) is red, between P75 and P95 orange and 5P75 green. A comparative study at our unit has demonstrated that the accuracy of the Umbiflow1 compares favorably with that of a well-known commercial machine [12]. Patients and methods This prospective study was performed at the antenatal clinic of Paarl East Hospital, a secondary level hospital approximately 50 km from TBH in Cape Town. Doppler FVWs were assessed between June 2002 and December 2004 in 572 pregnant women. Indications for velocimetry were mainly poor symphysis fundus (SF) growth, hypertension, preeclampsia, poor obstetric history, and previous abruptio placentae. Mothers with multiple pregnancies were excluded from the study. Poor SF growth was defined as a measurement below the 10th percentile for gestational age according to the percentile chart for the local population [13]. Pregnancy-induced hypertension (PIH) was defined as blood pressure (BP) 4140/90 mmHg with no proteinuria on two separate occasions 6 hours apart occurring for the first time after 20 weeks of gestation. If hypertension was noted before 20 weeks or the patient had a previous history of this condition outside pregnancy, chronic hypertension was diagnosed. Preeclampsia was defined as BP 4140/ 90 mmHg on two separate occasions more than 6 hours apart with persistent proteinuria, more than 2þ on urine dipstick or 24-hour urine protein measurement 40.3 g. The gestational age of the pregnancies was determined by best clinical estimate, such as the last normal menstrual period, palpation of the size of the uterus in early pregnancy, early ultrasound, or SF measurement.

Pregnant women with one or more of the abovementioned abnormalities were immediately referred for the Umbiflow1 examination by a specially trained midwife in the prenatal clinic. As soon as the ultrasound probe was directed to the umbilical artery, the FVWs appeared on the screen. An audible signal of the heartbeat further aided in finding the umbilical artery. Once clear regular waveforms had been visualized on the screen, the recording was frozen and the RI was calculated. Reference values of TBH were used to determine the zone in which the RI index fell on the nomogram [14]. The patient was then managed according to the recommended protocol (Table I). Immediately after the examination, the midwife who had done the Doppler assessment entered the patient information onto a data sheet at the antenatal clinic. This included age, gravidity, parity, previous miscarriage, weight, height, date of first clinic visit, date of last normal menstruation, gestation at first visit, SF measurement at first visit, ultrasound examination before 24 weeks, the date as well as the gestational age at which the ultrasound was done, date of referral, indication for and date of the Umbiflow1 examination, and RI zone on the nomogram. Only the first RI obtained was used for the analysis. The information regarding pregnancy complications, mode of delivery and outcome of the newborns, as well as Apgar scores at 1, 5 and 10 minutes, was collated from the subjects’ hospital files and entered retrospectively. Pregnancy complications recorded included: abruptio placentae, hypertension, preeclampsia, eclampsia, and others. The date of the delivery was noted. Onset of labor was recorded as spontaneous or induced, and the indication for induction was noted. After delivery the birth weight, gender and gestational age at birth were recorded. Growth for gestational age was calculated [13]. If the

Table I. Management according to resistance index. RI

Management

5P75 P75–95

No further tests unless new clinical indication Repeat after 2 weeks No CTG No ultrasound Weekly Doppler Weekly CTG Admit to hospital Daily CTG Ultrasound Individualized management

4P95 AEDV

RI, resistance index; 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age; CTG, cardiotocography; AEDV, absent end diastolic velocity.


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Evaluation of umbilical artery Doppler flow use mother had been referred to another hospital at any stage during the pregnancy, the necessary information regarding the pregnancy and neonatal outcome was obtained from the other hospital. According to the first RI, patients were divided into three groups: a normal group with an RI 5P75, an intermediate group with an RI P75–95 and an abnormal group here the RI was above P95. For statistical analysis the Statistical Package for the Social Science (SPSS) version 12 was used. The number and percentage of qualitative variables, and the mean and standard deviation (SD) of quantitative data were calculated. Comparisons between the mean values of quantitative variables were calculated using the Student’s t-test, while the Chisquare test was used for qualitative data. A 95% confidence interval was calculated where applicable. All tests of significance used were at the 5% level of significance. Results The study group consisted of 572 pregnant women for whom 927 Doppler examinations were done. Only the first Doppler FVW done was used for analysis. The RI was normal (P 575) in 314 women, P75–95 in 185 and above P95 in 73. Demographic details of the three groups did not differ significantly (Table II). Nearly a third of women in all three groups smoked cigarettes. Indications for the Umbiflow1 examination were mainly poor SF growth and hypertension (Table III). Hypertension and preeclampsia were the most common complications encountered during pregnancy (Table IV). There were 314 patients in the 5P75 group of whom 300 had live births. Ten patients delivered elsewhere and were lost to follow-up. In the P75–95 group there were 185 patients of whom 172 had live births and six were lost to follow-up. In the 4P95 group there were 73 patients of whom 69 had live births. One patient was lost to follow-up. In total there were three early and seven late intrauterine deaths and four early neonatal deaths.

Twenty-seven per cent of newborns in the normal RI group were small for gestational age (SGA) in contrast to 41.2% and 55.6% of the intermediate and abnormal groups, respectively. All these differences were statistically significant. Mean birth weights were 2739 g, 2553 g and 2260 g, respectively. The difference in weight was significant between all three groups (Table V). Apgar scores at 1 and 5 minutes were significantly different between the normal and abnormal group, and at 5 and 10 minutes between the intermediate and

Table III. Indication for referral for umbilical artery flow velocity waveform (FVW). RI 5P75 n (%) Poor SF growth Hypertension Preeclampsia Poor obstetric history Previous abruption Other

148 88 5 50 10 27

(47) (28) (2) (16) (3) (9)

RI P75–95 n (%) 91 60 4 23 7 11

(49) (32) (2) (12) (4) (6)

RI 4P95 n (%) 42 23 6 4 1 3

(58) (32) (8) (6) (1) (4)

RI, resistance index; 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age; SF, symphysis fundus. Some patients had more than one indication.

Table IV. Pregnancy complications.

Nil Abruption Hypertension Preeclampsia Eclampsia Other

RI 5P75 n (%)

RI P75–95 n (%)

RI 4P95 n (%)

198 3 54 40 1 17

117 2 32 20 1 10

39 2 10 14 1 7

(63) (1) (17) (13) (0.3) (5)

(63) (1.1) (17) (11) (0.5) (5)

(53) (2.7) (14) (19) (0) (10)

RI, resistance index 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age. Some patients had more than one complication.

Table II. Demographic details.

Maternal age + SD (years) Gravidity + SD Parity + SD BMI + SD Cigarette smoking Gestation at birth + SD (weeks)

RI 5P75 n ¼ 314

RI P75–95 n ¼ 185

RI 4P95 n ¼ 73

26.9 + 6.4 2.5 + 1.4 1.2 + 1.2 26.7 + 6.9 (n ¼ 264) 29.3% 37.8 + 2.8 (n ¼ 307)

26.2 + 6.3 2.2 + 1.2 1.0 + 1.1 25.6 + 6.8 (n ¼ 157) 32.4% 38.0 + 3.1 (n ¼ 180)

26.9 + 6.2 2.4 + 1.3 1.2 + 1.2 25.7 + 6.9 (n ¼ 61) 31.9% 37.3 + 2.9 (n ¼ 72)

RI, resistance index; 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age; SD, standard deviation; BMI, body mass index.


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abnormal group (Table V). Details of perinatal deaths are given in Table VI. In the 5P75 group there was only one intrauterine death at 28 weeks of gestation or more. The patient was a 22-year-old primigravida who booked late at 30 weeks. Duration of pregnancy was determined by SF height. The Doppler FVWs at 36 weeks demonstrated an RI of 0.62. The indication for the Doppler test was poor SF growth and uncertain gestation. On the same day the patient had an ultrasound examination after which the gestational age was changed to 32 weeks. As an RI of 0.62 at 32 weeks falls in the green zone, no further investigations were done. The patient went into spontaneous labor eight weeks after the Doppler examination and delivered a structurally normal macerated fetus of 3160 g. There were two early intrauterine deaths in the 5P75 group. The first case was a 31-year-old G4P1M2. She had type II diabetes mellitus and booked early at 9 weeks of gestation. Glucose value at booking was 11.6 mmol/L. Hemoglobin A1C (glycosylated hemoglobin) at 20 weeks of gestation was 6.9%, and detail-scan normal. At 25 weeks a

sharp decline was noted in the SF height and intrauterine demise was confirmed by ultrasound. A structurally normal fetus of 520 g was subsequently delivered. The second case was a 34-year-old G4P2M1. She booked early at 6 weeks of gestation and was known to have chronic hypertension and had had a previous mitral valve replacement for which she was on warfarin therapy. The 20 weeks detail-scan was normal. She had Doppler assessment at 25 weeks. At 27 weeks 2 days of gestation she presented with reduced fetal movements and intrauterine demise. A normally grown fetus of 1340 g was delivered. No obvious cause for the intrauterine death was present. It may have been related to the warfarin therapy. No autopsy was performed. In the intermediate group there were four intrauterine deaths 28 weeks. The first case was a 31year-old G2P1 who booked early at 15 weeks of gestation. She had a Doppler examination at 24 weeks for preeclampsia and abruptio placentae in her previous pregnancy. She presented 4 weeks later with an intrauterine death and subsequently had a breech delivery of a macerated fetus of 860 g. No abruptio

Table V. Pregnancy outcome. RI 5P75 (1) n ¼ 304

RI P75–95 (2) n ¼ 179

RI 4P95 (3) n ¼ 72

300 3 1 27.2%

172 5 2 41.2%

69 2 1 55.6%

2739 + 624

2553 + 636

2260 + 653

Apgar 1 min Apgar 5 min

9.4 + 1.2 9.8 + .0.7

9.3 + 1.5 9.8 + 0.7

8.9 + 1.8 9.4 + 1.3

Apgar 10 min

9.8 + 0.7

9.9 + 0.4

9.7 + 1

Live birth Intrauterine death Early neonatal death SGA

Birth weight + SD (g)

p Value

(1)/(2) 0.002 (1)/(3) 50.001 (2)/(3) 50.05 (1)/(2) 50.001 (1)/(3) 50.001 (2)/(3) 50.001 (1)/(3) 50.05 (1)/(3) 50.05 (2)/(3) 50.05 (2)/(3) 50.05 (2)/(3) 50.05

RI, resistance index; 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age; SGA, small for gestational age; SD, standard deviation.

Table VI (A). Perinatal losses—intrauterine deaths. Age

Gravidity/parity

31 34 22 19 31 17 24 27 19 25

G4P1M2 G4P2M1 G1P0 G1P0 G2P1 G1P0 G1P0 G2P0M1 G2P0M1 G3P1M1

RI 5P75 5P75 5P75 P75–95 P75–95 P75–95 P75–95 P75–95 4P95 4P95

Gestation (weeks) Delivery 25 27 40 24 28 33 33 35 32 36

NVD NVD NVD NVD Breech NVD NVD NVD NVD NVD

Birth weight (g) SGA 520 1340 3160 560 860 600 1220 Unknown 1260 1680

Yes No No Yes No Yes Yes Unknown Yes Yes

Possible cause

Maternal complication

Diabetes Warfarin Unknown Preeclampsia Unknown Plac insuff Unknown Plac insuff Plac insuff Plac insuff

Diabetes Hypertension/valve disease Nil Preeclampsia/HELLP Nil Hypertension Preeclampsia Nil Preeclampsia Nil


Evaluation of umbilical artery Doppler flow use

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Table VI (B). Perinatal losses—neonatal deaths.

Age

Gravidity/parity

36 24 21 31

G4P3 G3P1M1 G2P1 G4P1M2

Category

Gestation (weeks)

Delivery

Birth weight (g)

SGA

Age (day of neonatal death)

5P75 P75–95 P75–95 4P95

28 29 33 36

C-section C-section C-section C-section

658 970 1785 600

Yes Yes No Yes

4 3 1 4

Underlying obstetric problem Hypertension Hypertension Abruption Plac insuff

RI, resistance index; G, gravidity; P, parity; M, miscarriage; 5P75, less than 75th percentile for gestational age; P75–95, between the 75th and 95th percentile for gestational age; 4P95, above the 95th percentile for gestational age; SGA, small for gestational age; NVD, normal vertex delivery; C-section, caesarean section; HELLP, hemolysis, elevated liver enzymes, low platelets; Plac insuff, placental insufficiency. Perinatal mortality rate: 5P75, 4/304 (13.2/1000); P75–95, 7/179 (39.1/1000); 4P95, 3/72 (41.7/1000).

placentae or preeclampsia were noted. The second case was a 17-year-old primigravida who booked early at 13 weeks of gestation. At 15 weeks her blood pressure was 150/110 mmHg and the diagnosis of chronic hypertension was made, for which methyldopa, 500 mg three times daily, was prescribed. At 17 weeks her blood pressure was found to be normal and medication discontinued. At 28 weeks a blood pressure of 150/90 mmHg was noted but no proteinuria. A Doppler assessment was done. She did not attend the follow-up visit for repeat Doppler ultrasound examination and presented again in labor at 33 weeks. She was delivered of an SGA fetus that weighed 600 g. The third case was a 24-year-old primigravida who had a Doppler FVW examination at 24 weeks of gestation for unclassified hypertension. Subsequent examinations at 26, 28 and 30 weeks showed RI values of P75–95, 5P75 and P75– 95, respectively. A Doppler examination was not repeated at 32 weeks. She developed significant proteinuria (0.51 g/24 hours) and was admitted at 33 weeks 5 days of gestation, 21 days after her last Doppler assessment. She was delivered of a macerated growth-restricted fetus that weighed 1220 g. The cause of death was most likely placental insufficiency. The fourth case was a 27-year-old G2P0M1 who booked late and had Doppler ultrasound examination at 32 weeks because of a previous pregnancy loss. The patient was on epilepsy medication and suffered from a psychiatric disorder. She delivered at home at 35 weeks. No details about the delivery are available. The cause of death is unknown. One patient in the P75–95 group had an early intrauterine death. She was a 19-year-old primigravida who booked at 24 weeks of gestation. At booking she had unclassified hypertension, proteinuria and HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome. A termination of pregnancy was performed 2 days later. The fetus weighed 560 g. Two patients had RI values 4P95. The first was a 19-year-old G2P0M1. She booked after 20 weeks of gestation and developed unclassified hypertension at

26 weeks. Both the initial RI at 26 weeks and the follow-up RI at 27 weeks were 4P95. The patient was admitted for blood pressure control as well as exclusion of preeclampsia. She was discharged on antihypertensive medication. She did not return for follow-up and was seen again only at 32 weeks with severe preeclampsia and intrauterine death. Following induction of labor she was delivered of a macerated SGA fetus that weighed 1260 g. The second patient in this category was a 25-year-old G3P1M1. She had a Doppler examination at 34 weeks because of intrauterine death at 26 weeks in a previous pregnancy. An ultrasound at 34 weeks showed intrauterine growth restriction and oligohydramnios. Subsequent examinations at 35 and 36 weeks showed RI values 4P95. Intrauterine death occurred 4 days after the last Doppler examination. A structurally normal, SGA fresh stillbirth weighing 1680 g was delivered. In two patients the flow velocity worsened to absent end diastolic velocity (AEDV). The first was a 24-year-old G3P1M1 who booked at 20 weeks of gestation. The indication for her initial assessment at 24 weeks was chronic hypertension. The first RI was between P75 and P95. Two weeks later AEDV was detected. She was admitted to TBH for expectant management and was delivered electively by cesarean section at 29 weeks because of no interval fetal growth as measured by ultrasound. A 970 g male infant was delivered. Unfortunately the baby died on day three as a result of severe hyaline membrane disease. The second patient was a 36-year-old G4P3, who booked at 23 weeks of gestation. The indication for her Doppler examination was chronic hypertension with left ventricular hypertrophy. The first RI fell in the green zone. Repeat assessment at 26 weeks showed an RI value in the orange zone. At 28 weeks the flow velocity had worsened to AEDV. A cesarean section for fetal distress was performed at TBH. An infant weighing 658 g was born but he died on the fourth day as a result of extreme prematurity. Both these cases were managed at the tertiary center after referral from Paarl Hospital.


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Discussion This study demonstrated that the use of a midwifeoperated continuous wave Doppler machine to measure the FVW of the umbilical artery identifies pregnant women at risk for poor perinatal outcome. Patients in the three different RI zones were comparable regarding age, gravidity and body mass index (BMI). Almost one-third of the pregnant women in all three groups smoked cigarettes. Patients in the abnormal RI zone were delivered earlier, and abruptio placentae occurred more frequently in the abnormal RI zone. This finding supports the fact that growth restriction is an independent risk factor for abruptio placentae [15]. Results show that there was a significant difference in the birth weights of the infants, as well as the rate of SGA (27.2%, 41.2% and 55.6%) in the normal, intermediate and abnormal RI groups, respectively. These differences cannot be explained by differences in parity, cigarette smoking or BMI as these were similar in all three groups. Study results therefore confirm independently the risk of IUGR in pregnancies with abnormal Doppler FVW [16]. Our finding that 55.6% of the newborns in the abnormal RI group were growth restricted correlates with the finding of Platt et al.[17] that an abnormal biophysical score (BPS) identified half of SGA newborns. This is a more efficient measure than the non-stress test, which identified only 20% of SGA newborns [17]. Tyrrell et al. [18] performed a randomized control trial that compared BPS and umbilical artery Doppler FVW. They found no patients had a persistently abnormal BPS if their Doppler tests were normal, and therefore concluded that FVW of the umbilical artery could be used on its own as a primary test. A normal Doppler FVW of the umbilical artery is strongly linked with a normal neonatal outcome. This is true even for very SGA babies. In comparison, Tyrrell et al. [16] found that AEDVs had a strong association with fetal hypoxia and acidosis at birth, with a sensitivity of 78%, specificity of 98%, and positive predictive value of 88%. We found a perinatal mortality rate of 13.2/1000 in women who had normal RI values compared with rates of 39.1 and 41.7/1000 deliveries for women who had intermediate and abnormal RIs, respectively. This concurs with Alfirevic and Neilson’s [6] meta-analysis finding that demonstrated that the odds for perinatal death are reduced by 38% (confidence levels 15–55%) with the use of Doppler studies in the high-risk pregnancy population. Developing countries like South Africa do not have the resources to provide neonatal intensive care for infants who are born earlier than a gestational age of 28 weeks. This is particularly the case at secondary hospitals such as Paarl Hospital. Whereas

in a high-resource setting perinatal losses at between 24 and 27 weeks may be regarded as preventable, in this situation this is not possible. There was only one intrauterine death after 28 weeks in the normal RI group. In this case the uncertain gestation with the subsequent determination of gestation by late ultrasound could have led to an incorrect assessment of the RI zone. All four women in the P75–95 group who had late intrauterine deaths were not followed up correctly and therefore not seen again after two weeks for a second RI as suggested by the protocol. It is possible that intrauterine demise could have been prevented if the protocol had been followed. It is likely that an increase in the RI would have been noted and appropriate steps taken for additional monitoring. Two patients did not attend for follow-up visits. In the case of the patient in the intermediate group at 24 weeks of gestation, the attending physician might have felt that there was no need to do a follow-up Doppler examination until viability was reached at 28 weeks. In the other case where the attending doctor did not repeat a Doppler examination at 32 weeks, he or she could have been misled by the appearance of apparently good SF growth on the antenatal chart. This highlights the sensitivity of only about 30% of detection of IUGR by clinical palpation [19,20]. In the first case of intrauterine death in the abnormal Doppler group the patient failed to return for follow-up and presented five weeks later with severe preeclampsia and intrauterine death. This was also a preventable death, as early detection of maternal preeclampsia and of fetal compromise could have led to the timely delivery of the fetus. In the second case, the patient was appropriately followed up. The policy is to deliver IUGR at 38 weeks if everything else is normal. In the clinical notes a twice-weekly cardiotocogram was requested, but no notes could be found to confirm that it was done. An abnormal non-stress test would have led to earlier delivery. In this patient’s case the use of other Doppler indices such as the middle cerebral artery Doppler and ductus venosus studies could have provided additional information that would have forewarned the clinician about the extent of fetal compensation and decompensation [21,22]. Umbilical artery Doppler is only a test of placental function, but does not give information on the extent of fetal adaptation [4]. This study was done in a low socioeconomic population where nutrition is likely to be inadequate. In addition almost one-third of women smoked cigarettes during pregnancy. It is also likely that some of them drank excessive amounts of alcohol during pregnancy; it has been shown in a similar population in an adjacent town that 20% of women take a mean of 12.6 alcoholic drinks per week [23,24]. Under these difficult conditions, where


Evaluation of umbilical artery Doppler flow use some women book late for prenatal care and where early ultrasound is not readily available to determine the correct gestational age, a perinatal mortality rate of 13.2/1000 was achieved. When births below a gestation of 28 weeks are excluded the perinatal mortality rate is even better. It is also remarkable how much higher the perinatal mortality rate was in the P75–95 and 4P95 groups. We have demonstrated that a simple PC-based, continuous wave Doppler ultrasound device, operated by a midwife at the prenatal clinic, is effective in identifying patients at risk for placental insufficiency and in excluding pregnant women from additional tests for fetal well-being. A deficiency of the study is that the specific protocol to manage a pregnant woman with an abnormal RI of the umbilical artery was not actively promoted and followed. In addition, the number of patients investigated is still small. However, the results are encouraging and this service should be extended to busy prenatal clinics in communities where conditions associated with placental insufficiency such as poor fetal growth and hypertensive diseases of pregnancy are common. Acknowledgements Special words of thanks to Sister J. A. Nel and Sister H. K. Johnson for performing the FVWs and collection of data, Mrs P. Jonk for administrative help, and Dr S. Gebhardt, Head of the Department of Obstetrics and Gynaecology at Paarl Hospital. The Medical Research Council is thanked for financial support of the Perinatal Mortality Unit during which term the apparatus was developed. References 1. Pardi G, Marconi AM, Cetin I. Placental–fetal interrelationship in IUGR fetuses—a review. Placenta 2002;23(Suppl A):S136–141. 2. Regnault TR, Galan HL, Parker TA, Anthony RV. Placental development in normal and compromised pregnancies—a review. Placenta 2002;23(Suppl A):S119–129. 3. Sebire NJ. Umbilical artery Doppler revisited: Pathophysiology of changes in intrauterine growth restriction revealed. Ultrasound Obstet Gynecol 2003;21:419–422. 4. Divon MJ. Umbilical artery Doppler velocimetry: Clinical utility in high-risk pregnancies. Am J Obstet Gynecol 1996;174:10–14. 5. Pattinson RC, Norman K, Odendaal HJ. The role of Doppler velocity waveforms in the management of high risk pregnancies. Br J Obstet Gynaecol 1994;101:114–120. 6. Alfirevic Z, Neilson JP. Doppler ultrasonography in high risk pregnancies: Systemic review with meta-analysis. Am J Obstet Gynecol 1995;172:1379–1387. 7. Thornton JG, Lilford RJ. Do we need randomized trials of antenatal tests of fetal well-being? Br J Obstet Gynaecol 1993;100:197–200. 8. Giles W, Bisits A. Clinical use of Doppler in pregnancy: Information from six randomized trials. Fetal Diagn Ther 1993;8:247–255.

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