Association between COVID-19 lockdown measures and the incidence of iatrogenic versus spontaneous very preterm births in the Netherlands: a retrospective study.

BACKGROUND: The COVID-19 pandemic led to regional or nationwide lockdowns as part of risk mitigation measurements in many countries worldwide. Recent studies suggest an unexpected and unprecedented decrease in preterm births during the initial COVID-19 lockdowns in the first half of 2020. The objective of the current study was to assess the effects of the two months of the initial national COVID-19 lockdown period on the incidence of very and extremely preterm birth in the Netherlands, stratified by either spontaneous or iatrogenic onset of delivery, in both singleton and multiple pregnancies. METHODS: Retrospective cohort study using data from all 10 perinatal centers in the Netherlands on very and extremely preterm births during the initial COVID-19 lockdown from March 15 to May 15, 2020. Incidences of very and extremely preterm birth were calculated using an estimate of the total number of births in the Netherlands in this period. As reference, we used data from the corresponding calendar period in 2015-2018 from the national perinatal registry (Perined). We differentiated between spontaneous versus iatrogenic onset of delivery and between singleton versus multiple pregnancies. RESULTS: The incidence of total preterm birth < 32 weeks in singleton pregnancies was 6.1‰ in the study period in 2020 versus 6.5‰ in the corresponding period in 2015-2018. The decrease in preterm births in singletons was solely due to a significant decrease in iatrogenic preterm births, both < 32 weeks (OR 0.71; 95%CI 0.53 to 0.95) and < 28 weeks (OR 0.53; 95%CI 0.29 to 0.97). For multiple pregnancies, an increase in preterm births < 28 weeks was observed (OR 2.43; 95%CI 1.35 to 4.39). CONCLUSION: This study shows a decrease in iatrogenic preterm births during the initial COVID-19-related lockdown in the Netherlands in singletons. Future studies should focus on the mechanism of action of lockdown measures and reduction of preterm birth and the effects of perinatal outcome.

High risk of long-term neurodevelopmental impairment in donor twins with spontaneous twin anemia-polycythemia sequence.

OBJECTIVES: To evaluate the long-term neurodevelopmental and behavioral outcomes in surviving infants of pregnancies with spontaneous twin anemia-polycythemia sequence (TAPS), to compare outcome between donors and recipients, and to investigate potential risk factors for neurodevelopmental impairment (NDI). METHODS: This was a retrospective study of a consecutive cohort of spontaneous-TAPS survivors delivered between 2005 and 2017 at the Leiden University Medical Center, The Netherlands. Neurological, motor, cognitive and behavioral development were assessed at a median age of 4 years. The primary outcome was NDI, which was a composite outcome of cerebral palsy, deafness, blindness and motor and/or cognitive delay. NDI was subdivided into two grades of severity: mild-to-moderate and severe NDI. Outcome was compared between surviving donor and recipient twins. Logistic regression analysis was used to assess risk factors for NDI. RESULTS: Forty-nine twin pregnancies complicated by spontaneous TAPS were eligible for inclusion. The perinatal survival rate was 83% (81/98) of twins. Neurodevelopmental assessment was performed in 91% (74/81) of surviving twins. NDI occurred in 30% (22/74) of TAPS survivors, and was found more often in donors (44%; 15/34) than in recipients (18%; 7/40) (odds ratio (OR), 4.1; 95% CI, 1.8-9.1; P = 0.001). Severe NDI was detected in 9% (7/74) of survivors and was higher in donors compared with recipients (18% (6/34) vs 3% (1/40)), although the difference did not reach statistical significance; P = 0.056). Donors demonstrated lower cognitive scores compared with recipients (P = 0.011). Bilateral deafness was identified in 15% (5/34) of donors compared with 0% (0/40) of recipients (P = 0.056). Parental concern regarding development was reported more often for donor than for recipient twins (P = 0.001). On multivariate analysis, independent risk factors for NDI were gestational age at delivery (OR, 0.7; 95% CI, 0.5-0.9; P = 0.003) and severe anemia (OR, 6.4; 95% CI, 2.4-17.0; P < 0.001). CONCLUSION: Surviving donor twins of pregnancies complicated by spontaneous TAPS have four-fold higher odds of NDI compared with recipient cotwins, are at increased risk of cognitive delay and have a high rate of deafness. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prevalence of placental dichotomy, fetal cardiomegaly and starry-sky liver in twin anemia-polycythemia sequence.

OBJECTIVE: To investigate the prevalence of three additional ultrasound markers, placental dichotomy, cardiomegaly and 'starry-sky' liver, in monochorionic twin pregnancy with twin anemia-polycythemia sequence (TAPS). METHODS: All monochorionic twin pregnancies, diagnosed antenatally with TAPS at our center between 2006 and 2019, were reviewed retrospectively for the presence of placental dichotomy, cardiomegaly in the donor twin and a starry-sky liver in the recipient twin. TAPS was diagnosed based on delta middle cerebral artery (MCA) peak systolic velocity (PSV) > 0.5 multiples of the median. The primary outcome was the prevalence of placental dichotomy, cardiomegaly, starry-sky liver and at least one of these markers in both spontaneous and post-laser TAPS. The secondary outcome was the prevalence of these ultrasound markers according to the antenatal stage of TAPS. RESULTS: A total of 91 monochorionic twin pregnancies with TAPS were eligible for analysis. Placental dichotomy was observed in 44% (40/91) of TAPS cases. A total of 70% (64/91) of the TAPS donors developed cardiomegaly and a starry-sky liver was identified in 66% (53/80) of the TAPS recipients. The prevalence of cardiomegaly and starry-sky liver was roughly comparable between spontaneous and post-laser TAPS (69% (33/48) vs 72% (31/43) and 64% (25/39) vs 68% (28/41), respectively). Pregnancies with spontaneous TAPS showed a higher prevalence of placental dichotomy compared with post-laser TAPS (63% (30/48) vs 23% (10/43)). At least one of the three ultrasound markers was detected in 86% (78/91) of TAPS cases, meaning that 14% (13/91) of cases presented solely with discordant MCA-PSV values. There was a trend towards increased prevalence of all three ultrasound markers with increasing antenatal TAPS stage. CONCLUSIONS: Placental dichotomy, fetal cardiomegaly and a starry-sky liver are commonly found in TAPS pregnancy. Investigating the presence of these ultrasound markers can be of additional help in improving antenatal detection of TAPS in monochorionic twin pregnancy. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Right ventricular outflow tract obstruction in complicated monochorionic twin pregnancy.

OBJECTIVES: Severe right ventricular outflow tract obstruction (RVOTO) is a potential complication in recipient twins of twin-to-twin transfusion syndrome (TTTS) that requires postnatal follow-up or treatment. We aimed to evaluate pregnancy characteristics of neonates with RVOTO from complicated monochorionic twin pregnancies, determine the incidence of RVOTO in TTTS cases and construct a prediction model for its development. METHODS: This was an observational cohort study of all complicated monochorionic twin pregnancies with a postnatal diagnosis of RVOTO examined at our center. Cases were referred for evaluation of the need for fetal therapy or intervention because of TTTS, selective intrauterine growth restriction (sIUGR) or multiple congenital malformations in one of the twins. Ultrasound data were retrieved from our monochorionic twin database. Among liveborn TTTS recipients treated prenatally with laser therapy, those with RVOTO were compared with those without RVOTO (controls). We describe four additional cases with RVOTO that were not TTTS recipients. RESULTS: A total of 485 twin pregnancies received laser therapy for TTTS during the study period. RVOTO was diagnosed in 3% (11/368) of liveborn TTTS recipients, of whom two showed mild Ebstein's anomaly. Before laser therapy, pericardial effusion was seen in 45% (5/11) of RVOTO cases (P < 0.01) and abnormal A-wave in the ductus venosus (DV) in 73% (8/11) (P = 0.03), significantly higher proportions than in controls. Mean gestational age at laser therapy was 17 + 3 weeks in RVOTO cases compared with 20 + 3 weeks in controls (P = 0.03). A prediction model for RVOTO was constructed incorporating these three significant variables. One TTTS donor had RVOTO after the development of transient hydrops following laser therapy. Three larger twins in pregnancies complicated by sIUGR developed RVOTO, the onset of which was detectable early in the second trimester. CONCLUSIONS: RVOTO occurs in TTTS recipient twins but can also develop in TTTS donors and larger twins of pregnancies complicated by sIUGR. Abnormal flow in the DV, pericardial effusion and early gestational age at onset of TTTS are predictors of RVOTO in TTTS recipients, which suggests increased vulnerability to hemodynamic imbalances in the fetal heart in early pregnancy. These findings could guide diagnostic follow-up protocols after TTTS treatment. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of single fetal demise after laser therapy for twin-twin transfusion syndrome.

OBJECTIVE: Single fetal demise (SFD) occurs in up to 20% of monochorionic pregnancies treated with laser coagulation for twin-twin transfusion syndrome (TTTS). We aimed to determine the independent factors associated with SFD to improve outcome in the care of TTTS pregnancies in the future. METHODS: This was a case-control study on twin pregnancies treated for TTTS between 2007 and 2013. Data on ultrasound, laser surgery and outcome were retrieved from our monochorionic twin database. We analyzed separately cases of SFD in donor and recipient twins, and compared them with treated pregnancies that resulted in two live births. RESULTS: Of the 273 TTTS pregnancies treated with laser coagulation, SFD occurred in 30 donors (11.0%) and 27 recipients (9.9%). In 67% of pregnancies with SFD, the death occurred within 1 week after laser treatment. For SFD in donors, absent/reversed end-diastolic flow in the umbilical artery was the strongest predictor (odds ratio (OR), 3.0 (95% CI, 1.1-8.0); P = 0.01), followed by the presence of an arterioarterial anastomosis (OR, 4.2 (95% CI, 1.4-13.1); P = 0.03) and discordance in estimated fetal weight (OR, 1.0 (95% CI, 1.0-1.1); P = 0.04). For SFD in recipients, independent predictors were absent/reversed A-wave in the ductus venosus (OR, 3.6 (95% CI, 1.2-10.5); P = 0.02) and the absence of recipient-to-donor arteriovenous anastomoses (OR, 10.6 (95% CI, 1.8-62.0); P < 0.01). CONCLUSIONS: Our findings confirm earlier reports that suggest that abnormal blood flow is associated with SFD after laser treatment for TTTS. The association of SFD with the type of anastomoses is a new finding. We speculate that the type of anastomoses present determines the degree of hemodynamic change during laser therapy. Future strategies should aim at stabilizing fetal circulation before laser therapy to decrease the vulnerability to acute preload and afterload changes. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

'Superficial' anastomoses in monochorionic placentas are not always superficial.

Arterioarterial (AA) and venovenous (VV) anastomoses in monochorionic (MC) placentas lie on the placental surface and are termed as superficial anastomoses. The purpose of this study is to report the occurrence of an atypical form of superficial anastomoses which are partially hidden. Partially-hidden superficial anastomoses were defined as vascular anastomoses without visible direct connection on placental surface but with clear mixing of dye after colored dye injection. With analyzing 270 MC placentas, we found a prevalence of partially-hidden AA and VV anastomose of 3% and 5%, respectively. In conclusion, partially-hidden superficial anastomose are not infrequent in MC placentas.

Increased perinatal loss after intrauterine transfusion for alloimmune anaemia before 20 weeks of gestation.

OBJECTIVES: To evaluate and compare perinatal outcome after intrauterine transfusions (IUT) performed before and after 20 weeks of gestation. To analyse contributing factors. DESIGN: Retrospective analysis. SETTING: The Dutch referral centre for fetal therapy. POPULATION: IUTs for fetal alloimmune anaemia. METHODS: Fetuses were divided into two groups: fetuses requiring the first IUT before 20 weeks of gestation (Group 1) and those in which the IUTs started after 20 weeks (Group 2). The cause of perinatal loss was classified as procedure-related (PR) or not procedure-related (NPR). The cohort was divided into two periods to describe the change of perinatal loss over time. MAIN OUTCOME MEASURES: Perinatal loss of fetuses requiring the first IUT before 20 weeks of gestation, compared with perinatal loss later in gestation. RESULTS: A total of 1422 IUTs were performed in 491 fetuses. Perinatal loss rate in Group 1 was higher (7/29 24% versus 35/462 8%, P = 0.002). Especially NPR was higher for IUTs performed before 20 weeks (4/37 11% versus 19/1385 1%, P < 0.001). Kell alloimmunisation was overrepresented in Group 1 (7/29 24% versus 52/462 11%, P = 0.04). In a multivariate regression analysis, only hydrops was independently associated with perinatal loss (P = 0.001). In recent years, a decline in total perinatal loss was found (36/224 16% versus 6/267 2%, P < 0.001), but perinatal loss in Group 1 did not decline (4/224 1.8% versus 3/267 1.1%, P = 0.5). CONCLUSIONS: Perinatal loss after IUT performed before 20 weeks of gestation is increased compared with loss after IUT performed later in gestation. In addition, we confirmed earlier observations that hydrops is a major contributor to adverse outcome. Early and timely detection and treatment may prevent hydrops and improve outcome.

Prophylaxis with low-dose low-molecular-weight heparin during pregnancy and postpartum: is it effective?

BACKGROUND: The optimal approach for venous thrombosis (VTE) prophylaxis during pregnancy and postpartum in women with an increased risk of VTE is not established. OBJECTIVES: To evaluate the effectiveness, represented as the incidence of pregnancy-related VTE, and safety, represented as incidence of postpartum hemorrhage (PPH), of a protocol recommending prophylaxis with low-dose low-molecular-weight heparin (LMWH) in women at intermediate to high risk of VTE. PATIENTS/METHODS: In this retrospective cohort study, we analyzed 34 women (44 pregnancies) with intermediate risk of VTE who received low-dose LMWH for 6 weeks postpartum and 57 women (82 pregnancies) with high risk of VTE who received low-dose LMWH during pregnancy and for 6 weeks postpartum. Pregnancy-related VTE was defined as VTE during pregnancy or ≤ 3 months postpartum. PPH was defined as blood loss >500 mL and severe PPH as blood loss > 1000 mL. RESULTS: The incidence of pregnancy-related VTE was 5.5% (95% CI, 2.4-12.3) despite prophylaxis with low-dose LMWH. All events occurred in women at high risk, with a postpartum incidence of 7.0% (95% CI, 2.9-16.7) and antepartum incidence of 1.8% (95% CI, 0.4-9.2). The risk of PPH was 21.6% (95% CI, 14.3-31.3) and severe PPH 9.1% (95% CI, 4.7-16.9), which was not different in women who started LMWH postpartum and those who used LMWH during pregnancy. CONCLUSIONS: Although prophylaxis with low-dose LMWH during pregnancy and postpartum proved to be safe, the risk of pregnancy-related VTE is considerable in women with a high risk of VTE. VTE prophylaxis with low-dose LMWH may not be sufficiently effective in these women.

Single-needle laser treatment with drainage of hydrothorax in fetal bronchopulmonary sequestration with hydrops.

Bronchopulmonary sequestration (BPS) is sometimes associated with hydrothorax and hydrops in utero. In the absence of fetal hydrops, perinatal outcome is favorable and justifies expectant management. In the presence of fetal hydrops, perinatal outcome is reported to be extremely poor and intervention should be considered. Therapeutic options include open fetal surgery, minimally invasive coagulation of the blood supply and thoracoamniotic shunting. We present the first case of fetal hydrops and a large hydrothorax due to BPS treated successfully with one ultrasound-guided thin needle insertion, through which both laser coagulation of the feeding artery and drainage of the hydrothorax were performed. Following the procedure the hydrothorax and hydrops gradually disappeared and the BPS diminished in size. A healthy neonate was delivered uneventfully at term. We describe the case and discuss the different therapeutic options.

[Treatment of foetal supraventricular tachycardia with antiarrhythmic medication administered through the umbilical vein]. / Behandeling van foetale supraventriculaire tachycardie met antiaritmica via de navelstrengvene.

Foetal supraventricular tachycardia (SVT) with hydrops foetalis is associated with a high morbidity and mortality rate. If SVT with hydrops foetalis persists despite transplacental therapy, direct foetal treatment can be initiated. One foetus was found to have SVT with hydrops foetalis during the 29th week of pregnancy, and the condition persisted despite transplacental treatment. Amiodarone was administered directly via the umbilical vein, and the SVT resolved. A second foetus was found to have SVT with hydrops foetalis during the 28th week of pregnancy. The condition persisted despite maternal antiarrhythmic medication. Direct treatment of the foetus with amiodarone was successful. Amiodarone is the treatment of choice for direct foetal therapy for SVT, and can be administered safely via the umbilical vein. Direct foetal therapy should be considered for the treatment of foetal SVT with hydrops foetalis that occurs in the first 31 weeks of pregnancy and persists despite adequate transplacental therapy.

Kell alloimmunization in pregnancy: associated with fetal thrombocytopenia?

BACKGROUND AND OBJECTIVES: Kell haemolytic disease in pregnancies has been suggested to be associated with decreased fetal platelet counts. The aim of this study was to evaluate the incidence and clinical significance of fetal thrombocytopenia in pregnancies complicated by Kell alloimmunization. MATERIALS AND METHODS: In this retrospective cohort study, fetal platelet counts were performed in 42 pregnancies with severe Kell alloimmunization prior to the first intrauterine blood transfusion. Platelet counts from 318 first intrauterine transfusions in RhD alloimmunized pregnancies were used as controls. RESULTS: Fetal thrombocytopenia (platelet count < 150 x 10(9)/l) was found in 4/42 (10%) in the Kell group and in 84/318 (26%) in the RhD group. None of the fetuses in the Kell alloimmunized pregnancies, including 15 with severe hydrops, had a clinically significant thrombocytopenia defined as a platelet count < 50 x 10(9)/l. In the RhD alloimmunized pregnancies, 2/230 (1%) of the non-hydropic fetuses and 7/30 (23%) of the severely hydropic fetuses had a clinically significant thrombocytopenia. CONCLUSION: In contrast to fetuses with severe anaemia and hydrops due to RhD alloimmunization, fetuses with severe anaemia due to Kell alloimmunization are generally not at risk for substantial thrombocytopenia.

Twin-to-twin transfusion syndrome after 26 weeks of gestation: is there a role for fetoscopic laser surgery?

OBJECTIVE: To compare fetoscopic laser surgery with amniodrainage in the treatment of twin-to-twin transfusion syndrome (TTTS) diagnosed after 26 weeks of gestation. DESIGN: A retrospective cohort study. SETTING: Leiden University Medical Centre, a tertiary referral hospital for fetal therapy. POPULATION: Between January 1991 and February 2006, 21 TTTS cases were diagnosed and treated after 26 weeks of gestation. METHODS: Treatment of TTTS consisted of either amniodrainage or fetoscopic laser coagulation of vascular anastomoses. PRIMARY OUTCOME: adverse outcome (intrauterine or neonatal death, major neonatal morbidity and/or severe cerebral injury). Secondary outcome: gestational age at birth. RESULTS: Eleven TTTS cases were treated with amniodrainage and ten with laser surgery. Median gestational age at birth in the amniodrainage group and in the laser surgery group was 29 and 31 weeks, respectively (P = 0.17) All infants were born alive. Major neonatal morbidity occurred more often in the amniodrainage group than in the laser surgery group, 27% (6/22) and 0% (0/20), respectively (P = 0.02). Severe cerebral injury in the amniodrainage group and in the laser surgery group occurred in 23% (5/22) and 15% (3/20) of infants, respectively (P = 0.70). Neonatal mortality in the amniodrainage group and in the laser surgery group was 14% (3/22) and 0% (0/20), respectively (P = 0.23). Overall adverse outcome was 36% (8/22) in the amniodrainage group and 15% (3/20) in the laser surgery group (P = 0.17). CONCLUSION: In TTTS diagnosed after 26 weeks of gestation, amniodrainage and laser surgery both result in 100% survival. However, infants born after laser surgery have less major neonatal morbidity.

Successful ultrasound-guided laser treatment of fetal hydrops caused by pulmonary sequestration.

Microcystic or solid-looking fetal lung lesions associated with hydrops are associated with a high mortality rate. The most common of these lesions are microcystic congenital cystic adenomatoid malformations and pulmonary sequestrations (PS). Performing open fetal surgery by hysterotomy and lobectomy has, until now, been the only therapeutic option available following diagnosis of these lesions in the second trimester. Here we describe a new minimally invasive technique for the treatment of PS in the second trimester. Laser coagulation of the feeding systemic artery of the sequestration was performed under ultrasound guidance. The blood flow to the lung tumor was successfully arrested and hydrops reversed. The child was born at term and, at the time of writing, was alive and well at 2 years of age. Large PS with hydrops can be treated successfully by ultrasound-guided minimally invasive laser surgery. It is therefore important to utilize color Doppler ultrasound imaging for identification of a systemic feeding blood vessel in solid fetal lung tumors. Published by John Wiley & Sons, Ltd.

Fetoscopic laser surgery in 100 pregnancies with severe twin-to-twin transfusion syndrome in the Netherlands.

OBJECTIVE: In this prospective cohort study, we evaluated the initial results of fetoscopic laser surgery for severe second trimester twin-to-twin transfusion syndrome (TTTS) treated at our centre. METHOD: A total of 100 consecutive pregnancies with severe second trimester TTTS treated at our centre with selective fetoscopic laser coagulation of vascular anastomoses on the placental surface between August 2000 and November 2004 were included in the study. Perinatal survival was analysed in relation to Quintero stage. RESULTS: Median gestational age was 20 weeks at fetoscopy (range: 16-26) and 33 weeks at delivery (range: 18-40). Perinatal survival rate was 70% (139/200). The treatment resulted in at least one survivor at the age of 4 weeks in 81% of pregnancies. Perinatal survival was significantly higher when treatment was performed in the early Quintero stages (95% in stage 1, 76% in stage 2, 70% in stage 3, 50% in stage 4) (p = 0.02). CONCLUSION: Results of fetoscopic laser surgery for TTTS in our centre are similar to those in specialised centres in other countries. Diagnosis and treatment in the early Quintero stages resulted in significantly higher perinatal survival.

Fetal cardiac contractility before and after intrauterine transfusion.

OBJECTIVE: To evaluate the effect of fetal anemia and intrauterine transfusion on ventricular shortening fraction. METHODS: The end-diastolic and end-systolic transverse dimensions of the left and right ventricles were obtained using M-mode ultrasonography. The shortening fractions of both ventricles were calculated at three time points: before, immediately after and one day after intrauterine transfusion. The blood volume given at intrauterine transfusion was expressed as a percentage of estimated fetoplacental blood volume. RESULTS: Complete measurements were obtained from 49 transfusions in 23 fetuses. Intrauterine transfusion was performed at a median gestational age of 31 (range, 19-35) weeks. Median hemoglobin concentration before and after intrauterine transfusion was 7.9 (range, 2.7-13.7) g/dL and 14.3 (range, 12.7-16.1) g/dL, respectively. Both left and right ventricular shortening fractions differed significantly between the three time points. Left ventricular shortening fraction decreased immediately after transfusion in 43 (88%) of the 49 procedures. Right ventricular shortening fraction decreased immediately after transfusion in 42 (86%) of the 49 procedures. At the first intrauterine transfusion, there was only a weak correlation between the decrease in shortening fraction of both ventricles and the transfused volume (left: R(2) = 0.15; P = 0.20/right: R(2) = 0.005; P = 0.81). CONCLUSION: Transfusion significantly decreases the shortening fraction of both ventricles of the fetal heart. There is, however, little correlation between the decrease in shortening fraction and the volume of red cells given at intrauterine transfusion. Published by John Wiley & Sons, Ltd.

Non-invasive tests to predict fetal anemia in Kell-alloimmunized pregnancies.

OBJECTIVES: To compare test characteristics of ultrasound and Doppler parameters in the prediction of fetal anemia in Kell-alloimmunized pregnancies. METHODS: In this prospective study, 27 fetuses at risk for anemia due to Kell alloimmunization were evaluated with ultrasound and Doppler imaging. Spleen perimeter, liver length, middle cerebral artery (MCA) peak systolic velocity and intrahepatic umbilical venous (IHUV) maximum velocity were measured. Results were compared with fetal hemoglobin values at first intrauterine blood sampling or delivery. Severe fetal anemia was defined as a hemoglobin deficit of at least 5 SD below the mean for gestational age. RESULTS: Eighteen fetuses were anemic and required intrauterine transfusions. In the other nine pregnancies no transfusions were performed; one of these fetuses was severely anemic at birth. MCA and IHUV flow velocities were the best predictors of fetal anemia in Kell alloimmunized fetuses (sensitivity 89% for each test). Sensitivities for spleen perimeter (15%) and liver length (14%) were disappointing. CONCLUSIONS: Doppler evaluation of MCA peak systolic velocity and IHUV maximum velocity can be used to reliably predict severe fetal anemia in Kell alloimmunization.