Protocols for High-Risk Pregnancies. Группа авторов

Protocols for High-Risk Pregnancies

has not previously been routinely recommended include conditions such as maternal obesity, advanced maternal age, pregnancy resulting from assisted reproductive techniques or pregnancies in women self‐reported as being black. While each of these conditions is a weak but potentially independent stillbirth risk factor, they are common and may present specific logistical, sociological, and systemic challenges if they are included as indications for antenatal fetal testing. Indeed, all indications for antepartum fetal testing should be considered as somewhat relative and may vary in significance among different providers. However, in general, the conditions for which fetal testing are recommended are listed below.

Maternal conditions: pregestational diabetes mellitus, hypertension, systemic lupus erythematosus, chronic renal disease, antiphospholipid syndrome, poorly controlled hyperthyroidism, hemoglobinopathy (such as sickle cell anemia, sickle‐hemoglobin C or sickle‐thalassemia disease), and cyanotic heart disease.

Pregnancy‐related conditions: preeclampsia, gestational hypertension, decreased fetal movement, oligohydramnios (deepest vertical pocket less than 2.0 cm), moderate or severe polyhydramnios (deepest vertical pocket 12.0 cm or greater or an AFI greater than 30.0 cm), intrauterine growth restriction, pregnancy at or beyond 41 completed weeks of gestation, isoimmunization, history of stillbirth, dichorionic twins with significant growth discrepancy or beyond 36 weeks’ gestation, monochorionic/diamniotic twins, premature rupture of membranes, and third‐trimester uterine bleeding.

Potential other indications: maternal age of 35 years or greater, obesity, maternal black race, suspected or confirmed fetal structural or genetic abnormalities, pregnancies conceived by in vitro fertilization, intrahepatic cholestasis of pregnancy, abnormal first‐ or second‐trimester serum analytes used in genetic risk assessment, abnormal umbilical cord findings such as vasa previa, single umbilical artery or velamentous cord insertion.

The following general factors apply to testing.

Testing is generally initiated at 32–34 weeks for most patients; at 40 weeks for diet‐controlled gestational diabetics. However, it may begin as early as 26 weeks of gestation in pregnancies with multiple risk factors or when fetal compromise is suspected. The fetal heart rate reactivity may be diminished due to early gestational age and not necessarily reflect fetal compromise. Back‐up testing should be used whenever primary surveillance is of any concern.

Doppler velocimetry of the umbilical artery may be performed weekly in pregnancies complicated with suspected intrauterine growth restriction. This ultrasound procedure is generally performed in addition to biweekly nonstress testing.

A normal fetal surveillance heart rate test is typically repeated on a twice‐weekly basis.

Test should be immediately repeated in the event of significant deterioration in the clinical status regardless of the time elapsed since the last test. Intervention with delivery is always a clinical decision and may be indicated with either normal or abnormal testing depending upon the clinical circumstances.

PROTOCOL 9 Fetal Blood Sampling and Transfusion

Patricia Santiago‐Munoz

Department of Obstetrics and Gynecology, Division of Maternal‐Fetal Medicine, University of Texas Medical Center, Dallas, TX, USA

Clinical significance

Fetal blood sampling or cordocentesis is a straightforward procedure where fetal blood is typically accessed at the site of the umbilical vein, using a long, small‐gauge spinal needle. Access to fetal blood via the hepatic vein or heart (cardiocentesis) has also been described. Fetal blood sampling is performed for various indications such as cytogenetic diagnosis, congenital infection, and fetal anemia. It is rarely performed for the evaluation of fetal coagulopathies and platelet disorders, given the potential risk for fetal hemorrhage secondary to the pathologies suspected. Most of the time cordocentesis is performed as the precursor to fetal transfusion.

Cytogenetic diagnosis

As earlier and earlier identification of fetal anomalies with ultrasound has become more common, most patients who choose invasive diagnostic testing typically rely on chorionic villus sampling or amniocentesis, which can yield earlier results than cordocentesis would. In addition, the advent of noninvasive prenatal testing (NIPT) has also decreased patient requests for invasive testing overall, especially in the setting of normal sonographic findings. Cytogenetic analysis via fetal blood sampling is usually reserved for cases where quick turnaround of results is required, such as when a patient is nearing the gestational age for legal termination of pregnancy or when the results might affect delivery planning and neonatal management of a fetus with an anatomical abnormality.

Fetal infection

Cordocentesis is rarely used to evaluate or treat a fetus with congenital infection. Most diagnoses are suspected based on maternal serologies and ultrasound findings, and confirmed through polymerase chain reaction (PCR) in amniotic fluid. The one exception to this rule would be the evaluation and treatment of fetal parvovirus B19 infection, which causes fetal anemia via bone marrow failure.

Fetal anemia

Given current technologies and diagnostic tools, most cordocenteses are done in the evaluation of the fetus suspected to be anemic, the overwhelming majority typically due to maternal severe red blood cell alloimmunization. Fetuses at risk of anemia are identified by serial Doppler interrogation of the middle cerebral artery to measure peak systolic velocity. A distant second indication for cordocentesis is parvovirus B19 infection. The literature reports other potential indications for fetal transfusion, including fetomaternal hemorrhage, twin anemia polycythemia sequence, and

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Protocols for High-Risk Pregnancies. Группа авторов