INTRODUCTION — Following birth of an antepartum or intrapartum fetal death, laboratory testing and gross and microscopic evaluation of the placenta and fetal tissues are important for determining the cause of death. The best strategy for evaluation is unclear, as high quality comparative data are not available to guide recommendations . Even with a comprehensive examination, a minority of parents will still be left without a definitive reason for their child's demise.
Procedures for evaluation of the stillborn ≥20 weeks of gestation will be reviewed here. The incidence, etiology, prevention, and management of antepartum and intrapartum fetal deaths and counseling the parent(s) are discussed separately. (See "Stillbirth: Incidence, risk factors, etiology, and prevention" and "Stillbirth: Maternal care".)
Early pregnancy loss (ie, first trimester) and early second-trimester pregnancy loss (ie, before 20 weeks of gestation) are also reviewed separately. (See "Pregnancy loss (miscarriage): Terminology, risk factors, and etiology".)
MATERNAL LABORATORY EVALUATION — The optimal laboratory evaluation of patients who have had a stillbirth is controversial. Many lists have been proposed, but the most cost-effective approach has not been determined [2-10]. Our approach is guided by clinical, sonographic, and histopathologic findings.
The author orders or reviews recent tests results for:
●Fetomaternal hemorrhage (eg, Kleihauer-Betke test, flow cytometry) in all patients who have an unexplained stillbirth since detection of a large fetomaternal hemorrhage may explain the cause of an otherwise unexplained fetal demise . (See "Spontaneous massive fetomaternal hemorrhage".)
●Urine drug screen (particularly cocaine and methamphetamine). (See "Testing for drugs of abuse (DOAs)".)
●Complete blood count (CBC). An abnormal CBC may prompt evaluation for an inherited hemoglobinopathy or other maternal disorder (eg, infection) as the cause of fetal death.
●Serologic testing for syphilis in patients with a history of sexually transmitted infections, or who live in areas of high prevalence, or who have not had the test performed earlier in pregnancy.
●A fasting glucose concentration or glycated hemoglobin level, which can be useful for excluding poor glycemic control as a cause of stillbirth in patients who have not been evaluated for gestational diabetes and in those known to have diabetes mellitus.
●Blood antibody screen to exclude red cell alloimmunization.
●Lupus anticoagulant and anticardiolipin and anti-beta2-GP I antibody titers (immunoglobulin M [IgM] and IgG) to exclude antiphospholipid syndrome. Such testing is suggested in patients with unexplained stillbirth or stillbirth associated with growth restriction or preeclampsia with severe features . (See "Diagnosis of antiphospholipid syndrome".)
Thyroid function tests and liver chemistries are obtained in selected patients in whom there is a clinical suspicion (eg, maternal signs/symptoms) of a specific underlying disorder and, rarely, to further evaluate unexplained stillbirths (stillborns with no gross or microscopic abnormalities). (See "Intrahepatic cholestasis of pregnancy" and "Overview of thyroid disease and pregnancy".)
Testing for inherited thrombophilias because of stillbirth is controversial; UpToDate suggests limiting testing to cases with evidence of substantial maternal vascular malperfusion in the placental examination (decidual arteriopathy or vascular thrombi with placental infarction), which is rare. The American College of Obstetricians and Gynecologists recommends not testing for inherited thrombophilias . If performed, testing should be done at least three months postpartum to exclude normal pregnancy-related effects on coagulation parameters. (See "Inherited thrombophilias in pregnancy", section on 'Selection of patients for screening'.)
Routine serologic testing for infection is unlikely to be useful because many individuals have positive serology from prior infections, which are unrelated to the stillbirth . Cytomegalovirus titer (IgM, acute and convalescent IgG), toxoplasmosis titer (IgM, acute and convalescent IgG), parvovirus B19 titer (IgM), and a Listeria culture are obtained if indicated by maternal clinical, prenatal sonographic, or histopathologic findings. Diagnostic studies for specific infections are reviewed separately:
●(See "Cytomegalovirus infection in pregnancy".)
●(See "Toxoplasmosis and pregnancy".)
●(See "Parvovirus B19 infection during pregnancy".)
●(See "Treatment and prevention of Listeria monocytogenes infection", section on 'Pregnant patients'.)
Aerobic and anaerobic cultures should be obtained by the delivering clinician or the pathologist. Culture of the fetal skin or placental surface may be misleading because of contamination during birth; culture of internal fetal organs and/or the area between the amnion and chorion is more reliable. (See 'Routine basic placental and noninvasive fetal evaluation' below.)
OVERVIEW OF THE AUTOPSY AND PLACENTAL EXAMINATION — Although discussing autopsy may be uncomfortable for some parents and caregivers, it is an important diagnostic procedure and requires written consent. Some insurance companies cover all or part of the cost. Many will cover the cost of maternal and placental tests but not tests on the stillborn. The health facility typically absorbs the cost of tests ordered in these situations. Histopathologic analysis (fetoscopy) of an abortus (induced or spontaneous) is billed like other surgical specimens. Molecular testing and cytogenetics are often not covered by insurance. These special tests often require consent by the family, with attestation of such by the clinician.
Clinical value — A complete clinical evaluation plus conventional autopsy with placental pathologic examination can diagnose the cause of death in the majority of cases. Determining the cause of death is important because sooner or later the parent(s) will want to know "Why did this happen?" and "Will it happen again?" Answers to these questions are often impossible without information gained from pathologic examination [12-16], as some diagnoses are only made by autopsy (picture 1).
The likelihood of finding an explanatory diagnosis depends on the completeness of the examination, the experience of the pathologist, and the gestational age at birth. For cases receiving an optimal evaluation, the frequency that a term stillbirth is unexplained after the evaluation is less than 30 to 40 percent [17-20].
Findings at perinatal autopsy can change the clinical diagnosis of the cause of death or yield additional findings . This new information often influences management of future pregnancies. As an example, a study including 1477 stillbirths reported that autopsy findings identified the cause of death in 46 percent of cases and yielded new information in 51 percent . This new information changed the estimated recurrence risk in 40 percent of cases, and changed recommendations for preconceptional care in 9 percent, prenatal diagnostic procedures in 21 percent, prenatal management in 7 percent, and neonatal management in 3 percent.
Unexplained cases can still provide useful information to the clinician and family, as anomalies and many diseases can be excluded as a cause of death. In addition, unexplained fetal death in the third trimester may be a form of sudden infant death syndrome (SIDS) in utero and may warrant emphasis of risk reduction measures after subsequent live births [21,22]. (See "Sudden infant death syndrome: Risk factors and risk reduction strategies", section on 'Prevention'.)
Role of the pathologist — Compassionate parental counseling is important to obtain informed consent before the pathologic examination and when communicating the findings. The practitioner seeking to obtain consent should be familiar with the procedure and have a simple but clear explanation of it for discussion with the parent(s). (See "Stillbirth: Maternal care".)
A full autopsy without restrictions and including placental pathologic examination is optimal for determining the cause of death, but restrictions on the procedure can be instituted upon the parental request. These can include, for example, consent for visual external examination or postmortem imaging studies only, restrictions to specific organs/regions, and restrictions about the disposition of the organs/tissues (eg, whether to return to body or retain for complete examination).
Ideally, the autopsy should be performed by an experienced perinatal pathologist. If a perinatal pathologist is not available at the hospital where the stillbirth occurred, the body can be transferred to a medical center with appropriate personnel and facilities (legal body transfers usually require a coroner, funeral home, or the police), or fetal and placental specimens or slides can be sent by mail for evaluation. If questions still persist or if the pathologist requests it, an expert perinatal pathologist can be consulted and sent all of the histologic slides and other materials (eg, photographs, radiographs) developed for the case.
Good documentation and careful dissection are essential. Photographs of any malformations or suspected malformations (especially when discrepancies between antenatal diagnoses and autopsy findings occur), results of laboratory and imaging studies, unusual findings, and pertinent negative findings are extremely important.
The autopsy should be completed in a timely way, as the parent(s)'s concerns and grieving period increase with delays. Autopsy reports should also be completed promptly so it is available for the meeting between the parent(s) and the clinicians. Including the pathologist in these meetings is very helpful for explaining the autopsy report and answering questions (see 'Report of findings' below). The pathologist is often thought of as an impartial specialist since they were not involved in the patient's antepartum or intrapartum management.
COMPONENTS OF THE PERINATAL AUTOPSY — The Autopsy Committee of the College of American Pathologists, with representatives of other interested organizations, prepared a guideline to assist pathologists in reporting perinatal autopsies . The judgment of the pathologist performing a specific case should guide the evaluation since there is no high-quality evidence establishing the optimum combination of tests that should be performed routinely on all stillbirths.
One study evaluating a protocol for postmortem examination of stillbirths concluded that gross examination, photography, radiography, and bacterial cultures should be performed in all cases, while karyotyping and microscopy could be reserved for stillborns that are abnormal on gross examination . This approach was less costly than performing these studies routinely, but still provided adequate information for genetic counseling since the prevalence of karyotype abnormalities is low (<2 percent) in the absence of dysmorphic features, growth abnormalities, structural anomalies, or hydrops after careful postmortem examination. However, this protocol might fail to detect some chromosomal abnormalities and some nongenetic disorders, such as viral infection . (See "The placental pathology report" and "Congenital cytogenetic abnormalities".)
The author's approach is described in the following sections.
Routine basic placental and noninvasive fetal evaluation — Most parents will consent to the following common components of stillborn evaluation:
●Review of the complete medical record to obtain the clinical history, with attention to medical, obstetric (past and present), and genetic conditions potentially associated with stillbirth. Informational gaps can be filled by the patient or their clinician. The author also reviews all previous obstetric and gynecologic specimens sent for pathologic examination. (See "Stillbirth: Incidence, risk factors, etiology, and prevention", section on 'Potential etiologies' and "Stillbirth: Incidence, risk factors, etiology, and prevention", section on 'Predicting risk for stillbirth'.)
●Measurement of birth weight and biometrics. (See 'Weights and biometric measurements' below.)
●Gross external examination of the stillborn, with detailed description and photographs of abnormalities, dysmorphic features, and pertinent negative findings. Detailed photographs of the entire fetus from several views (anterior, posterior, and lateral) and a facial photograph provide good documentation for future reference. Photographs of normal findings and pertinent negative findings can also be useful. As an example, a directed photograph of the fingers with nails can exclude many syndromes if the nail formation is normal. The facial photograph may be given to the parents, if requested.
●Gross and microscopic examination of the placenta. A sample of a placental worksheet is shown in the figure (form 1). Sections of placental tissues are processed for histological examination in all cases, even when severely autolyzed or structurally normal. Some pathologic findings can still be diagnosed in severely autolyzed tissues (eg, viral infections and tumors (picture 2)). Placental findings are often the most informative source for determining the etiology of the stillbirth as placental insufficiency and infection are the most common causative findings . A detailed discussion of placental findings is available separately. (See "Gross examination of the placenta" and "The placental pathology report", section on 'Findings'.)
•In a systematic review investigating the likelihood of diagnosing a cause of stillbirth from placental examination, histopathological examination provided useful information about the cause of death or contributing factors in 11 to 84 percent of cases . The wide range was attributed to variations in study methodology, completeness of placental investigation, classification systems, and clinical significance attributed to placental findings. The authors concluded that the precise role of various placental lesions in stillbirth remains uncertain. Determination of causality in an individual case is difficult because even though certain placental abnormalities are more common in stillbirths and complicated pregnancies, the same lesions can be seen in placentas from clinically normal pregnancies .
•A population-based study that used a standardized placental pathology protocol noted that all lesions found in the placentas of stillborns were also found in the placentas of live borns, but lesion prevalence differed between the two groups and also by gestational age at birth . Major findings included:
-Acute chorioamnionitis and funisitis were common findings in both stillbirths and live births before 24 weeks of gestation, and more common in live births (chorioamnionitis of the chorionic plate: 36 versus 82 percent; funisitis: 22 versus 43 percent).
-Retroplacental hematoma was most common before 24 weeks, and occurred with similar frequency in stillbirths and live births (36 percent in both stillbirths and live births).
-Fetal vascular thrombosis became more common with advancing gestational age at delivery, and was more common in stillbirths than livebirths after 24 weeks (at 24 to 31 weeks: 22 versus 11 percent; at 32 to 36 weeks: 26 versus 12 percent; at term: 35 versus 6 percent).
-Although an infrequent finding, diffuse placental infarction was far more common in stillbirths than livebirths. The overall prevalence in stillbirths and live births across gestation was 2.8 and 0.1 percent, respectively (odds ratio [OR] 43, 95% CI 5.6-328).
●Gross and microscopic examination of the umbilical cord, including measurement of the true complete cord length and number of vessels. A short cord can be a sign of neuromuscular compromise; a long cord can be a sign of heart failure or that a cord accident may have played a pivotal role in the demise, while a single umbilical artery can be associated with genitourinary anomalies (eg, renal agenesis, horseshoe kidney). (See "The placental pathology report", section on 'Umbilical cord'.)
A cord coil is a 360-degree spiral course of umbilical vessels. Cord coiling should be noted and reported as either the number of coils in 10 cm (2 is normal, ≤1 is hypocoiled, ≥4 is hypercoiled) or the cord coiling index (number of coils in the entire length of the cord divided by the length in cm; <0.07 is hypocoiled and >0.3 is hypercoiled). Because of regional differences in coiling density , we recommend using the coiling index from the total length of the cord as a more reliable measurement. Although most studies have reported that hyper- or hypocoiled umbilical cords are associated with increased perinatal mortality [30,31] and congenital anomalies , this has not been found universally . Hypercoiling can lead to kinking and strictures, especially at the abdominal insertion site, which may lead to fetal demise. This is most likely in the second trimester when the fetus can be very mobile because of the large relative amniotic fluid and uterine space. The pathologist should section through these strictures to identify any sign of chronicity (eg, thrombus, vascular wall necrosis, or inflammation) to feel confident that the stricture occurred antemortem and caused the demise. Otherwise, a comment about the finding and the possibility that it could be postmortem is prudent.
●Bacterial cultures should be performed on the placenta, especially if autopsy permission is declined. The placenta, although contaminated by the birthing procedures and handling after birth, can be cultured by peeling the amnion off of the chorion and swabbing this newly exposed chorionic surface or taking a small portion of the chorion using sterile technique. Both aerobic and anaerobic cultures should be performed. Pathogens responsible for the fetal death may be determined using these techniques; contamination has rarely been a problem. The author believe routine specialized cultures for viruses or Mycoplasma/Ureaplasma are unnecessary and not cost-effective. (See 'Additional tests' below.)
Microbiologic studies can also be performed on fetal blood taken from the heart, umbilical cord, or the placenta if a full autopsy is not performed.
Overview — There is no worldwide consensus as to when cytogenetic, biochemical, and molecular genetic studies and viral cultures of the fetus are indicated. The author follows a decision tree to decide whether to send tissue for genetic studies or tissues for other special studies (table 1A and table 1B) with the default decision to obtain the tissues.
●Genetic testing – The American College of Obstetricians and Gynecologists (ACOG) recommends genetic evaluation of all stillbirths after appropriate parental consent . If genetic testing is requested, the author routinely obtains tissue for microarray. The microarray is "held for karyotype" and is, therefore, available if needed in the future because of failure or inadequate information from a conventional karyotype. Skin or skeletal muscle are the preferred tissues for karyotype and microarray. In autolyzed cases, umbilical cord and/or chorionic plate may be substituted. Consent for these tests is usually required by the laboratory and, therefore, needs to be obtained. (See 'Options for genetic testing' below.)
●Cultures – As discussed above, the author obtains aerobic and anaerobic bacterial cultures of the placenta and fetal lung in all cases (see 'Routine basic placental and noninvasive fetal evaluation' above). In her opinion, viral cultures are rarely indicated, as the histopathology of the placenta and fetal organs is diagnostic of viral infection in most cases (eg, cytomegalovirus (picture 3), parvovirus, herpes simplex virus (picture 4A-B)). Coxsackie virus can be passed across the placenta and should be suspected if myocarditis is found on histopathology; molecular studies can confirm this infection. Hydrops fetalis increases the likelihood of various bacterial and nonbacterial infections; appropriate studies are obtained based on the clinical scenario and other histologic findings. (See "Nonimmune hydrops fetalis", section on 'Infection'.)
●Metabolic studies – Ideally, metabolic studies would be obtained on all stillbirths, but such studies are costly. When obtained in selected patients at high risk of a metabolic abnormality, analysis of blood spots is feasible even on markedly autolyzed specimens. A Guthrie card for this purpose is usually available in the newborn nursery. It should be labeled that the specimen is from a stillbirth. It is difficult to find a laboratory willing to do these tests on stillbirths, and each institution should try to identify a laboratory able to do this important test.
●Imaging – Radiographs may reveal unrecognized skeletal malformations or further evaluate suspected skeletal abnormalities. The author recommends radiographs only for anomalous fetuses as the yield in a nonanomalous fetus is low. Plain whole body anteroposterior and lateral radiographs are taken with the stillborn's head "straight" (use cellophane tape to hold the head straight, nose in line with umbilicus, arms and legs in anatomic position) and the extremities extended (the legs are placed as if jogging, with one leg flexed above the other and with extended arms slightly separated). Fetal radiographs should be examined carefully by the autopsy pathologist for specific findings:
•Appropriate ossification of bones for gestational age.
•Documentation and timing of fractures, if present (which should be sampled histologically).
•Presence of ectopic mineralization/ossification of nonbony tissues (eg, heart, arteries, bowel lumen), which can be associated with a variety of in utero disorders (eg, TORCH infections, bowel abnormalities, hypoxic-ischemic encephalopathy, metabolic diseases).
Consultation with a pediatric radiologist is critical in evaluation of skeletal dysplasias or other skeletal anomalies .
Magnetic resonance imaging (MRI) and computed tomography (CT) may be useful as ancillary studies in addition to the conventional autopsy. MRI may be superior to the autopsy for some neurologic diagnoses ; the author recommends a postmortem MRI in cases of antenatally diagnosed or suspected neurologic malformations, even in cases of marked autolysis. MRI shows soft tissue well but not bone, whereas CT shows bone well but is less good for imaging soft tissue. Ultrasound examination is less useful. MRI or CT studies may be acceptable to parents who refuse conventional autopsy [36,37]. (See 'Minimally invasive autopsy as an alternative to standard autopsy' below.)
●Other special studies – Other special studies may be indicated in selected cases based on the clinical scenario and can be performed at evisceration. For example, tissue for biochemistry can be obtained to evaluate for storage disorders or for directed molecular studies (eg, Noonan's panel). Skin or skeletal muscle samples are best for molecular studies; liver, blood, or bile is preferred for biochemical analysis.
Options for genetic testing
●Microarray-based comparative genomic hybridization (aCGH) – Chromosomal microarray is more likely than G-banded karyotype analysis to provide a genetic diagnosis. It also has the advantage that it does not require dividing cells; therefore, it can be useful in fetal demise where failure of cell cultures is common. However, the test is costly and the hospital may not cover the costs. (See "Prenatal diagnosis of chromosomal imbalance: Chromosomal microarray", section on 'Fetal demise'.)
The advantages of microarray for genetic abnormalities in stillborns were illustrated in a study of 532 stillbirths in which both karyotype and microarray testing were attempted . Compared with traditional karyotype, microarray analysis was significantly more likely to:
•Yield a result (87.4 versus 70.5 percent)
•Detect genomic abnormalities (ie, aneuploidy plus pathogenic variants [8.3 versus 5.8 percent])
•Detect genomic abnormalities in both subgroups of patients studied: antepartum fetal demise (8.8 versus 6.5 percent), stillborn with structural anomalies (29.9 versus 19.4 percent)
Importantly, of the 157 stillbirths for which karyotype failed to provide a result, microarray yielded a definitive result in 125 cases (79.6 percent), and this result was abnormal in 9 cases (5.7 percent; aneuploidy 7 cases, pathogenic variant 2 cases). Conversely, microarray identified aneuploidy or a pathogenic variant in 44 stillbirths, of which 18 had a normal or failed karyotype.
The utility and clinical importance of microarray technology in the routine evaluation of stillbirth as part of the autopsy protocol is controversial. At the Massachusetts General Hospital, we have instituted this test as part of our routine autopsy protocol. We obtain the tissue for both karyotype and microarray on all perinatal autopsies but only run the tests with clinician/patient attestation/consent. We especially recommend microarray in cases when anatomic findings or history of multiple perinatal losses suggest a genetic cause of death (picture 5). While microarray has many benefits, issues to consider are cost (karyotype/fluorescence in situ hybridization [FISH] is less costly than microarray), logistics (both parents should have blood samples drawn when arrays are ordered, if possible), and uncertainty due to variants of unknown significance. The rate of variants of unknown significance can be decreased by comparison with the parental studies.
●Conventional karyotype – Conventional G-band cytogenetic studies can be performed on the stillborn's blood or tissue as long as the cells are viable. Conventional G-band cytogenetic studies are a less costly alternative to microarray. Amniocentesis or chorionic villus sampling performed upon diagnosis of fetal demise appears to yield a higher rate of viable cells for successful culture and G-banded karyotyping than studies performed on the stillborn after birth (success rate: 80 to 100 percent from amniotic fluid obtained before delivery versus 10 to 30 percent from skin or umbilical cord blood after birth) [39,40]. With marked autolysis, fetal tissues are unlikely to be successfully cultured; the umbilical cord or placenta (eg, section of chorionic plate) provides a better alternative as it has more viable cells. (See 'Collecting blood and tissue for genetic testing' below.)
●Exome or targeted gene sequencing – Case reports have described the utility of exome and targeted gene sequencing to identify a monogenic cause for stillbirth or lethal anomalies when microarray analysis is normal [41-45]. However, the role of DNA analysis in explained or unexplained stillbirth or in determining the recurrence risk of lethal anomalies remains investigational.
In a study of 246 stillbirths without a well-defined cause (no multiple gestation, infection, maternal hypertension, maternal medical complications, or previously identified pathologic karyotype or microarray), exome sequencing yielded a plausible genetic diagnosis in 21 of 246 cases (8.5 percent) . A secure molecular diagnosis was identified in 15 cases (6.1 percent): In 9 cases the molecular diagnosis was across seven genes that were previously associated with stillbirth, and in 6 cases the molecular diagnosis was across six disease genes that were strong candidates for phenotype expansion; an additional 6 cases had a suggestive genotype in either a known stillbirth gene or a gene candidate for phenotype expansion.
Although a molecular diagnosis was more likely in cases with a structural anomaly than in those without (OR 8.80, 95% CI 1.7-38.4), the overall frequency of a molecular diagnosis was similar between cases with a probable cause of fetal death and those that were unexplained (OR 1.38, 95% CI 0.39-4.54). This suggests genomic sequencing may also have value in stillbirths that have been attributed to a potentially causal maternal or obstetric condition. In addition, the potential diagnostic yield of exome sequencing reported in this study is probably underestimated because of design limitations, such as the lack of trio sequencing analysis, omission of pregnancy terminations because of fetal demise, and exclusion of cases with a convincing nongenetic explanation for the fetal loss.
Collecting blood and tissue for genetic testing — Blood can be collected from the umbilical cord; at least 3 mL should be placed in a heparinized tube. Tissue samples of adequate size and depth are important for successful cell culture. We suggest removing a 1 cm2 specimen of the most viable and cellular tissue (eg, skin, lung, placenta; ACOG suggests costochondral junction or patella because of the longer viability of fibroblasts in these tissues ). Placental specimens should include the chorionic plate and can be taken from below the cord insertion site. Fresh tissue samples should be placed in a sterile medium (eg, Hanks balanced salt solution) from the cytogenetics laboratory, or sterile saline solution, and kept at room temperature (do not use fixatives such as formaldehyde). DNA can be extracted from a blood sample on a Guthrie card.
In cases of moderate or marked autolysis (retention of a stillbirth), two separate samples are collected for genetic analysis: one from fetal skin and the other from umbilical cord or chorionic plate. If culture fails and, therefore, karyotype analysis cannot be performed, directed FISH studies (eg, for trisomy 13, 18, or 21) might be successful on paraffin embedded blocks of fetal or placental tissues , or microarray can be performed. A limitation of using placental tissue for karyotype is the potential for confounding from confined placental mosaicism. (See "Chorionic villus sampling", section on 'Diagnostic uncertainty and misdiagnosis'.)
Invasive fetal evaluation — A detailed autopsy procedure is described in the table (table 2). Autopsy protocols are adapted according to available resources in resource-limited settings [48,49]. In any setting, it is helpful to consider broad categories of stillbirth (small for gestational age, anomalous fetus, intrapartum demise of term normally grown fetus) and direct the autopsy according to the differential diagnosis of the category [50-53].
Fetal autopsies should be performed with the care and respect that all autopsies are given. Also, it is not uncommon for a parent(s) to decide to view the body after the postmortem examination has been done; therefore, minimizing disfigurement during dissection is important. In the author's experience, even the smallest, youngest (in gestational age), and most autolyzed cases can receive a thorough postmortem examination and be returned in a condition suitable for viewing.
Performance of the fetal autopsy is nearly identical to that of the adult or pediatric autopsy, but the focus on the dissection is modified. Since one major goal is to detect and/or verify congenital malformations and diseases, it is important to perform the dissection with careful attention to detail, despite the fetus's size and level of autolysis (table 2).
Weights and biometric measurements — The following measurements are obtained:
●Placental weight (trimmed of cord and membranes)
●Weight of internal organs
●Crown-to-rump length (crown to ischial tuberosities, "sitting height")
●Crown-to-heel length (crown to heel of extended leg)
●Head circumference (ie, occipitofrontal circumference: above ears, as if wearing glasses)
●Chest circumference (around nipples)
●Abdominal circumference (at umbilical insertion)
●Inner canthal distance
●Outer canthal distance
●Measurement of potentially anomalous structures as directed by abnormal findings (eg, finger, lip, ear)
The weight, crown-to-rump length, foot length, and heart weight are compared with the range of values for gestational age in published tables, and a combination of these parameters are used to make a best estimate gestational age. This estimate is compared with the clinical estimate of gestational age using menstrual data, ultrasound examination, and/or physical examination. This helps to diagnose the small or large for gestational age fetus. However, demised fetuses lose weight between the time of demise, birth, and autopsy, potentially resulting in overdiagnosis of growth restriction . Visceral organs, such as the liver, are more subject to postdemise weight loss than the brain .
An accurate 0 to 500 g (in at least 1 gram increments) tabletop scale and a hanging 100 to 5000 g scale (in 10 gram increments) are essential. For very small fetuses or those with marked autolysis, an analytical balance is often needed for organ weights. Paired organs are weighed together. Many acceptable standards for weights and measurements are available [56-60] and should be posted at the bench where the autopsy is performed for quick consultation. If a weight significantly deviates from the norm, additional tests or sampling may be indicated. Brain weight is often facilitated by weighing a vessel of fixative, then allowing the brain to "slip" into the fixative while dissecting, then reweighing the vessel (with brain and fixative) and subtracting out the first weight. The author does not open the gastrointestinal tract or inflate the lungs so the contents of these organs are preserved for later analysis.
Dissection of the fetal heart for weighing can be difficult, especially in autolyzed cases; fixing the heart-lung block can be helpful. Dissection of the fetal heart starts with a thorough in situ examination looking at situs, pulmonary venous return, persistence of the left superior vena cava, and caliber of the aortic arch and the brachiocephalic vein. Any anomalies in these structures should warrant careful dissection, and consideration of consultation with a cardiac surgeon or a pathologist with expertise; such consultation should be performed before continuing the dissection. Removing the heart and great vessels from the lungs and dissection along lines of flow (being careful to cut away from the septa), observation of normal fetal structures (patent and competent foramen ovale, patent ductus arteriosus), and documentation of all valves should be completed before the great vessels are removed and the heart weighed. If possible, photographic documentation of findings and pertinent negatives should be performed.
Tissue sampling and culture — The author always obtains samples of all tissues for microscopy. Although one study suggested that histopathology had limited utility in determining cause of death when the internal organs appeared normal macroscopically , histopathology can detect contributing factors that are clinically important but not direct causes of death. For example, aspiration pneumonia and myocardial infection or infarction are not associated with gross abnormalities but can contribute to or cause fetal demise. Sampling the cardiac conduction system may reveal abnormalities, such as inflammation, calcification, or microscopic rhabdomyomas, that can explain sudden death.
Fetal cultures are best obtained from the fetal lung. After the chest wall is opened and before any evaluation of the contents is performed or organs handled, a sterile suture removal kit or equivalent sterile instruments are used to lift the right lower lobe of the lung and snip off a small portion (5 mm3 is sufficient). The tissue sample is placed in a sterile jar or in sterile medium for transport to the microbiology laboratory. Aerobic and anaerobic bacterial cultures are obtained in all cases; other studies for infection are obtained if indicated based on the clinical information and autopsy findings or if requested. Postmortem bacterial overgrowth in fetal organs should not be a problem as the fetus is sterile unless infected in utero. If blood is available, blood cultures can be performed as well, or a section of spleen can be cultured.
In addition, tissue may be frozen (at -80°C) for future examination and laboratory studies. (See 'Additional tests' above.)
Minimally invasive autopsy as an alternative to standard autopsy — The complete autopsy involves incisions, evisceration, and (usually and optimally) retention of organs for further evaluation. An alternative "minimally invasive autopsy" procedure has been proposed [62-65], which may be more acceptable to some parents . These procedures usually involve a combination of advanced imaging (MRI and/or CT) and tissue biopsy (brain, left and right lung, liver), but ultrasound is an acceptable alternative when there is no or limited access to MRI . The biopsies may be directed by imaging [68,69] or laparoscopy  or be "blind" and directed by anatomic landmarks . Sometimes only imaging is performed, without histology [35,71].
Accuracy rates of determining an anatomic cause of death vary amongst studies and techniques and range from 65 to 99 percent. In one study of minimally invasive autopsy (MRI with other ancillary postmortem investigations), cause of death or major pathological lesion detected by minimally invasive autopsy was concordant with conventional autopsy in 175 of 185 fetuses at ≤24 weeks of gestation (94.6 percent) and 88 of 92 fetuses at ≥24 weeks of gestation (95.7 percent) . Postmortem MRI was most accurate for detection of renal, neural, and cardiac abnormalities (with the exception of ischemic brain injury and myocarditis), while abdominal findings were nonspecific and lung imaging was inaccurate for diagnosis of most pulmonary abnormalities, except major structural lesions.
The minimally invasive autopsy technique is rapidly evolving and may represent a socially acceptable alternative to the conventional autopsy in certain situations. The author prefers the conventional autopsy as it still represents the gold standard for determining cause of death and for confirmation of antenatally diagnosed malformations. It is the only method to diagnose histologically relevant findings (eg, aspiration pneumonia, meconium ileus, specific infections, amongst others).
Estimating time of death — In most cases, fetal death is not witnessed on ultrasound examination or by fetal heart monitoring or caused by an acute maternal event (eg, trauma), so the exact time of death is not known. Examination of the stillborn fetus and placenta can help in estimating the time of death, but the reliability of postmortem changes in estimating time of death has not been systematically evaluated .
The following gross findings appear to be good predictors of the time of fetal death :
●Brown or red discoloration of the umbilical cord or desquamation ≥1 cm suggests the fetus has been dead and retained at least six hours before birth.
●Desquamation of the face, back, abdomen suggests the fetus has been dead and retained at least 12 hours before birth.
●Desquamation ≥5 percent of the body or ≥2 body zones suggests the fetus has been dead and retained at least 18 hours before birth (body zones = scalp, face, neck, chest, back, arms, hand, leg, foot, scrotum).
●Skin color that is brown or tan suggests the fetus has been dead and retained at least 24 hours before birth.
●Mummification (ie, reduced soft tissue volume, leathery skin, deeply grey-brown-stained tissues) suggests the fetus has been dead and retained at least two weeks before birth.
When this system was used to assign time of death in 26 cases with a good estimate of the time of fetal demise, 18 fetuses (69 percent) were correctly assigned to one of six intrauterine retention intervals (0 to 6 hours, 6 to 12 hours, 12 to 18 hours, 18 to 24 hours, 24 hours to two weeks, and more than two weeks) . The presence of a single gross change from the above list was not reliable; however, when two or more postmortem changes were present, 22 fetuses (85 percent) were correctly classified.
A number of histological changes in the placenta (eg, villous intravascular karyorrhexis, stem villous vessels luminal abnormalities) and fetal organs (eg, loss of nuclear basophilia) have also been correlated with time of fetal death (table 3) [72,74,75]. The development of fetal organ changes is affected by factors such as hydrops and a delivery-to-autopsy interval exceeding 24 hours, which hasten postmortem changes; and the gestational age (gestational age <25 weeks slows the development of postmortem changes) .
Cause of death — Specific causes of death include lethal congenital malformations, overwhelming congenital infection, sentinel events that cause acute anoxia, such as in uterine rupture or massive acute abruption, and placental insufficiency resulting in chronic anoxia.
Findings consistent with acute to subacute anoxia (duration up to approximately 24 hours before death) include:
●Intrathoracic petechial hemorrhages .
●Pseudo-cysts of definitive adrenal cortex.
●Visceral petechial hemorrhages (subcapsular liver, renal cortex, gonad).
●"Aspiration" of amniotic fluid and upper airway/oral cavity debris.
●"Starry sky" appearance of thymic cortex.
●Germinal matrix hemorrhage.
●Normoblastemia (ie, circulating late red cell precursors).
●Placental findings (eg, marked meconium pigment, intravillous hemorrhage, diffuse villous edema).
Findings consistent with chronic anoxia (duration more than 24 hours before death) include:
●Fetal adrenal cortical clearing ("fatty" change).
●Thymic ablation (either a small thymus by weight for gestational age or lymphocyte depletion [cortical involution]).
●Renal cortical mineralizations.
●Periventricular leukomalacia [52,77].
●Fetal growth restriction.
●Erythroblastosis (ie, early red cell precursors).
●Extramedullary hematopoiesis outside of the liver (eg, renal pelvis, placenta).
●Placental findings (eg, placental weight <10th percentile, placental infarcts, distal villous hypoplasia, decidual vasculopathy with/without atherosis, hydrops placentalis, chronic abruption, chronic villitis [infectious or of unknown etiology], massive chronic intervillositis/chronic histiocytic intervillositis, massive perivillous fibrin deposition, fetal vascular malperfusion).
Unknown cause of death — The published unknown cause of death rate is between 30 and 40 percent, even after a thorough autopsy investigation. Much of this unknown category lies in the interpretation of findings and whether a finding may be considered the cause of death. For example, the author believes that fetal growth restriction alone is not a cause of death (one needs to determine the etiology of the growth restriction), but large studies often include this finding as an explained cause of death.
When a specific cause of death is not identified, information about the timing of insult and pertinent negatives and positives identified at postmortem examination can still be helpful. The author believes that a constellation of factors may lead to fetal demise in many of these cases. Stillbirth may occur when a vulnerable fetus experiences a stress and/or maternal condition in a combination that is lethal . A relatively minor finding at autopsy, not lethal by itself or in a less vulnerable fetus, may be related to the demise of the vulnerable fetus, especially when multiple such findings are observed. For this reason, the author groups gross and histopathologic findings by category, for example, "nonanomalous stillbirth with features of chronic hypoxia and growth restriction" .
Report of findings — The following template for autopsy reports is simple and provides the key information for the clinician and family. The parent(s) usually read these reports; therefore, they should be carefully worded.
(Male/Female) fetus of estimated gestational age ____ weeks based on autopsy measurements of _____ grams body weight, _____ cm crown-to-rump length, _____ cm foot length. The fetus is appropriate/small/large for clinical estimation of gestational age of ____ weeks based on (first-trimester sonogram, last menstrual period, other).
●Best determination of anatomic cause of death:
●Congenital anomalies: no or yes (list)
●Dysmorphic features: if present (list)
●Other pertinent fetal findings:
●Placenta: full surgical pathology report
●Pertinent negative findings:
Pertinent maternal data:
The author follows this information with a comment stating whether or not an anatomic cause of death was determined by the autopsy. If no anatomic cause of death was identified, this is stated and a description and interpretation of all findings is provided.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Stillbirth".)
SUMMARY AND RECOMMENDATIONS
●Utility of perinatal autopsy – Perinatal autopsy may provide information about the cause of fetal death that is different from that derived from other clinical examinations. This information often changes the estimated risk of stillbirth recurrence and frequently influences recommendations for management of future pregnancies. For these reasons, we recommend offering perinatal autopsy to parents of stillborn infants. (See 'Clinical value' above.)
The frequency of unexplained stillbirth at term is less than 30 to 40 percent of cases receiving optimal evaluation. (See 'Unknown cause of death' above.)
●Components of the autopsy – Perinatal autopsy can include review of clinical records and patient interview, gross and microscopic examination of the infant and placenta, photographs and radiographs, bacterial and viral cultures, chromosome and other genetic studies. A detailed autopsy procedure is described in the table (table 2). (See 'Components of the perinatal autopsy' above.)
●Maternal laboratory evaluation – The optimal laboratory evaluation of mothers who have had a stillbirth is controversial. We suggest that the evaluation be guided by clinical, sonographic, and histopathologic findings. (See 'Maternal laboratory evaluation' above.)
●Fetal and placental evaluation
•A full autopsy without restrictions and including placental pathologic examination is optimal for determining the cause of death, but restrictions on the procedure can be instituted at the family's request. We suggest including the pathologist in family meetings in which autopsy performance and results are discussed. The family often has questions the pathologist can best answer. (See 'Role of the pathologist' above.)
An alternative "minimally invasive autopsy" procedure may be more acceptable to some parents. These procedures usually involve a combination of advanced imaging (magnetic resonance imaging [MRI] and/or computed tomography [CT]) and tissue biopsy. (See 'Minimally invasive autopsy as an alternative to standard autopsy' above.)
•When possible, the author obtains aerobic and anaerobic bacterial cultures of the placenta and fetal lung in all cases and follows a decision tree to decide whether to obtain tissue for karyotype or tissues for other special studies, with a leaning toward obtaining the studies (table 1A-B). Viral cultures are rarely indicated, as the histopathology of the placenta and fetal organs is diagnostic of viral infection in most cases. Metabolic studies are obtained in selected patients at high risk of a metabolic abnormality, and radiographs are obtained in anomalous fetuses. (See 'Additional tests' above.)
•Microarray is more likely than G-banded karyotype analysis to provide a genetic diagnosis. It also has the advantage that it does not require dividing cells; therefore, it can be useful in fetal demise where failure of cell cultures is common. (See 'Options for genetic testing' above.)
•Histologic findings can help to determine the approximate time of death, if fetal demise occurred antepartum. (See 'Estimating time of death' above.)
2 : Practice guidelines for autopsy pathology: the perinatal and pediatric autopsy. Autopsy Committee of the College of American Pathologists.
21 : Defining Sudden Infant Death and Sudden Intrauterine Unexpected Death Syndromes with Regard to Anatomo-Pathological Examination.
27 : Frequency and clinical significance of placental histological lesions in an unselected population at or near term.
30 : Umbilical cord hypercoiling and thinning: a rare cause of intrauterine death in the second trimester of pregnancy.
34 : Foetal radiography for suspected skeletal dysplasia: technique, normal appearances, diagnostic approach.
35 : Acceptance, reliability and confidence of diagnosis of fetal and neonatal virtuopsy compared with conventional autopsy: a prospective study.
36 : Post-mortem MRI versus conventional autopsy in fetuses and children: a prospective validation study.
37 : Diagnostic accuracy of postmortem MRI for musculoskeletal abnormalities in fetuses and children.
39 : A comparison of prenatal versus postnatal karyotyping for the investigation of intrauterine fetal death after the first trimester of pregnancy.
42 : Application of Whole Genome Sequencing Technology in the Investigation of Genetic Causes of Fetal, Perinatal, and Early Infant Death.
45 : Renal tubular dysgenesis: antenatal ultrasound scanning and molecular investigations in a Saudi Arabian family.
52 : Third trimester fetal demise occurring at time of delivery: correlation of autopsy findings and placental pathology with emphasis on antenatal central nervous system injury.
54 : Effects of intrauterine retention and postmortem interval on body weight following intrauterine death: implications for assessment of fetal growth restriction at autopsy.
55 : Organ weights and ratios for postmortem identification of fetal growth restriction: utility and confounding factors.
57 : Organ weights in human fetuses after formalin fixation: standards by gestational age and body weight.
58 : Autopsy standards of body parameters and fresh organ weights in nonmacerated and macerated human fetuses.
61 : Stillbirth and intrauterine fetal death: role of routine histological organ sampling to determine cause of death.
64 : Minimally invasive perinatal autopsies using magnetic resonance imaging and endoscopic postmortem examination ("keyhole autopsy"): feasibility and initial experience.
65 : Minimally invasive fetal postmortem examination using magnetic resonance imaging and computerised tomography: current evidence and practical issues.
66 : Acceptability of a minimally invasive perinatal/paediatric autopsy: healthcare professionals' views and implications for practice.
67 : Diagnostic accuracy of postmortem ultrasound vs postmortem 1.5-T MRI for non-invasive perinatal autopsy.
68 : Minimally invasive, imaging guided virtual autopsy compared to conventional autopsy in foetal, newborn and infant cases: study protocol for the paediatric virtual autopsy trial.
71 : Initial experiences of a minimally invasive autopsy service. A report of the techniques and observations in the first 11 cases.
73 : Estimating the time of death in stillborn fetuses: III. External fetal examination; a study of 86 stillborns.
74 : Estimating the time of death in stillborn fetuses: I. Histologic evaluation of fetal organs; an autopsy study of 150 stillborns.
75 : Estimating the time of death in stillborn fetuses: II. Histologic evaluation of the placenta; a study of 71 stillborns.
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