Introduction

Any structural or functional abnormalities, including metabolic problems, that exist from birth are referred to as congenital malformations. These prenatal disorders are caused by intrinsic anomalies in the development process or by poor embryogenesis1. Birth defects remain a significant cause of morbidity and mortality in neonates and infants, and they can be isolated anomalies or components of a syndrome2.

Malformation, disruption, deformation, and dysplasia are the four primary categories of congenital anomalies. Morphologic flaws that arise from inherently aberrant developmental processes are known as malformations, and they take place early in development. A disruption happens when an initially normal developmental process breaks down or encounters interference. It can happen at any point during pregnancy. Deformations are anomalies in a body part’s shape or location brought on by non-disruptive mechanical forces. It typically appears in the latter part of pregnancy. An abnormal organization of cells into tissues, and its resulting morphological changes, are termed dysplasias3.

When a fetus weighs 500 g at birth, the World Health Organization (WHO) defines a stillborn as its death. If the birth weight is unknown, a gestational age of 22 weeks or a crown-to-heel length of 25 cm may be considered4.

The fetal autopsy is the gold standard procedure for determining the cause of fetal death. The fetal autopsy offers important details that aid in the parents’ emotional and psychological recovery, a precise diagnosis for appropriate counseling, and future pregnancy planning. When prenatal ultrasonography is unable to determine the cause of death, an autopsy is required5.

Congenital abnormalities frequently create psychological stress in the parents because they complicate a child’s entire existence. Modern obstetrics now requires the prenatal diagnosis of congenital abnormalities6. Antenatal ultrasonography is a highly effective technique to find significant congenital abnormalities. However, it lacks the specificity needed to diagnose a condition. Fetal autopsy is still essential for both confirming and identifying congenital abnormalities in spite of antenatal diagnostic methods7.

To raise awareness of congenital abnormalities, March 3rd of each year is designated as “World Birth Defects Day.” It is an educational initiative designed to promote congenital anomaly study, prevention, and monitoring8. The purpose of this study is to provide accurate counseling by emphasizing the value of concurrent fetal autopsy and prenatal ultrasound. To forecast and provide advice for safe future pregnancies, an autopsy examination must be performed on every stillborn fetus.

Objectives

Primary objective

To determine the pattern of distribution of congenital malformations according to the system of involvement.

Secondary objectives

  1. a)

    To determine the association between maternal factors and stillbirth

  2. b)

    To determine the association between fetal factors and stillbirth

  3. c)

    To determine the association between antenatal ultrasound and autopsy findings

Materials and methods

50 stillborn fetuses were the subject of this descriptive cross-sectional study. The Department of Obstetrics and Gynecology, JSS Medical College and Hospital, Mysuru, provided the stillborn fetuses. The total duration of the study was two years. The study was carried out in accordance with the guidelines provided in the most recent revision of the Declaration of Helsinki. The Institutional Ethics Committee approved this study with the approval number JSS/MC/IEC/02/660/2015–16.

Inclusion criteria

All fetuses that were stillborn at or after 22 weeks of pregnancy and whose parents provided informed consent were included.

Exclusion criteria

Fetuses having gestational ages of less than 22 weeks and autolyzed fetuses were excluded.

All procedures were conducted after obtaining informed consent from one of the parents before the autopsy. A complete history of the mother, including consanguinity, obstetric history, history of medical conditions, socioeconomic situation, the potential reason for the fetal death, method of termination, and antenatal USG report, was obtained using an autopsy proforma.

The modified Kuppuswamy socioeconomic scale, which is based on three variables—education, occupation, and income—was used to determine socioeconomic class. This led to the division of the population into the upper, upper middle, middle, upper lower, and lower classes9.

The prenatal ultrasound results and the autopsy proforma, which includes maternal and fetal variables, external and internal examination of the fetus, were validated by subject experts. The fetal radiological examination was done in suspected cases with musculoskeletal abnormalities.

Fetal autopsy procedure

Stillborn fetuses were preserved in 10% formalin. The organs were fixed by injecting formalin into the brain, abdominal, and thoracic chambers. An autopsy was conducted according to the standard procedure adopted by Edith L. Potter10.

The unique autopsy number was assigned to each fetus to identify any congenital abnormalities. The measurements were taken of the head, chest, and stomach circumferences, as well as the other morphometric characteristics such as birth weight, crown–rump length, and rump heel length. Additionally inspected were the placenta and umbilical cord. It was observed that the stillborn fetus had obvious abnormalities.

From the chin to the pubic symphysis, which passes to the right of the umbilicus, a straight-line incision was performed. The rib cage’s skin and subcutaneous tissue were removed. The abdominal cavity was opened, and the abdominal organs were inspected in situ after the same incision. Together, the abdominal and thoracic organs were removed.

Using the tip of a scalpel blade and the index finger, the base of the tongue is separated from the inner edge of the jaw. A coronal incision was made on the head, beginning behind one ear and moving posterior to the vertex toward the other ear, to access the cranial cavity. The scalp was incised, and each side of the brain’s surface was examined. The brain was examined to check for any abnormalities.

Statistical analysis

MS Excel 2016 was used to enter the acquired data, and SPSS version 22 was used for analysis in order to produce pertinent statistics. The mean, standard deviation, percentages, and other descriptive metrics were computed. Descriptive statistics were used to assess the various maternal and fetal parameters. Every stillborn fetus was categorized according to its birth weight, gestational age, maternal age, mother’s gravida, and parents’ socioeconomic position. The corresponding parameters were depicted on the graphs.

To determine the relationship between a history of medical conditions like diabetes, hypertension, hypothyroidism, etc., and congenital abnormalities, inferential statistics such as the chi-square test were used. At P < 0.05, the data were considered statistically significant. The chi-square test was used to determine the correlation between autopsy results and prenatal ultrasonography. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were determined using the 2 × 2 contingency tables.

Results

The study included 50 stillborn fetuses, of which 44 (88%) had congenital abnormalities. Among the most frequently observed anomalies, central nervous system anomalies accounted for 10 (20%) and musculoskeletal system anomalies 18 (36%). A total of five (10%) cardiovascular system abnormalities, five (10%) gastrointestinal system anomalies, five (10%) genitourinary system anomalies, one (2%), and six (12%) miscellaneous cases were found in this study (Fig. 1).

Fig. 1
Fig. 1
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Classification of congenital malformations among the stillborn fetuses according to the system involved (The inner circle represents the number of stillborn fetuses, and the outer circle represents the percentage of stillborn fetuses).

The scalp and cranial vault were missing from a male fetus at 30 weeks of gestation, and the brain was exposed and deformed. Some basic brain tissue was visible, but the forebrain was completely lacking. The eyes were large and protruding. The nasal bridge was lowered, and the nose was wide. Low-set ears were seen, and the mouth was open (Fig. 2).

Fig. 2
Fig. 2
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Anencephaly in a 30-week male stillborn fetus.

In a 24-week male fetus, the dissection of the heart showed a deficiency of about 3 mm in the interatrial septum (Fig. 3).

Fig. 3
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Atrial septal defect (ASD) in a 24-week male fetus.

In a 24-week male fetus, overriding of the aorta with a membranous ventricular septal defect was observed in an antenatal ultrasound image. Overriding of the aorta, getting filled with both right and left ventricles in a case of tetralogy of Fallot (Fig. 4A, B).

Fig. 4
Fig. 4
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(A) Overriding of the aorta with a membranous ventricular septal defect as seen in an antenatal ultrasound image & (B) Overriding of the aorta getting filled with both the ventricles in a case of tetralogy of Fallot.

At 23 weeks of gestation, a male fetus was found to have thanatophoric dysplasia. The fetus showed a narrow thorax with short ribs, macrocephaly, a protuberant belly, short upper and lower limbs, a bent and short femur, and flattened vertebral bodies, all of which are indicative of thanatophoric dysplasia type I (Figs. 5A, B) and a radiograph of the same fetus (Fig. 5C).

Fig. 5
Fig. 5
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(A) A case of thanatophoric dysplasia in a 23-week male fetus (anterior view) & (B) A case of thanatophoric dysplasia in a 23-week male fetus (lateral view). (C) Radiograph of the fetus with thanatophoric dysplasia (Both anterior and lateral views).

There was a case of congenital diaphragmatic hernia in a female fetus at 29 weeks of gestation. Figure 6A displayed intestine coils in the thoracic cavity, hypoplastic lungs, and a developmental abnormality in the diaphragm. Figure 6B is a prenatal ultrasound image that displays the stomach and intestinal loops in the thoracic cavity.

Fig. 6
Fig. 6
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(A) A case of congenital diaphragmatic hernia observed in a 29-week female fetus and (B) An antenatal ultrasound image displaying intestinal loops and the stomach in the thoracic cavity.

A case of infantile polycystic kidney disease was found in a 35-week-old female fetus. It displayed the right kidney in its typical position and the left kidney in the pelvic area with polycystic alterations. The right fetal kidney seems to be normal. Multiple macrocysts measuring 0.4–1.1 cm have replaced the enormous (3.2 × 2.4 cm) embryonic left kidney (Fig. 7A).

Fig. 7
Fig. 7
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(A) Left kidney in the pelvic region and showing polycystic changes, and Right kidney in the normal position. (B) Kidney tissue with numerous cystic gaps that are bordered by thick stromal tissue and flattened epithelium (H&E, 400X). (C) A few primitive tubules and glomeruli are visible beside several well-formed glomeruli and tubules (H&E, 400X).

Histopathological analysis revealed kidney tissue with many cystic cavities surrounded by thick stromal tissue and flattened epithelium. A few primitive tubules and glomeruli were observed alongside several well-formed glomeruli and tubules (Fig. 7B, C).

Maternal factors

Maternal characteristics considered in this study included consanguinity, age, gravidity, socioeconomic status, delivery method, and medical conditions such as infections, diabetes, hypertension, and hypothyroidism. The chi-square test showed a significant association between congenital malformations and maternal diabetes, pregnancy-induced hypertension (PIH), and maternal hypothyroidism (P < 0.05) (Tables 1, 2, 3).

Table 1 Association between congenital malformations and maternal diabetes.
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Table 2 Association between congenital malformations and pregnancy-induced hypertension.
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Table 3 Association between congenital malformations and maternal hypothyroidism.
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The chi-square test did not display a significant correlation between maternal infection and congenital malformations (P > 0.05) (Table 4). The current study identified three maternal infections: measles, chickenpox, and HEV (hepatitis E virus) with positive IgM (immunoglobulin M) antibodies.

Table 4 Association between congenital malformations and maternal infections.
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The maternal age group of 26–30 years had the highest number of stillborn fetuses, followed by 21–25 years (Fig. 8). The primigravida had the highest number of stillborn fetuses, followed by the second gravida (Fig. 9). The lower middle class had the highest number of stillborn fetuses, followed by the upper middle class (Fig. 10).

Fig. 8
Fig. 8
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Distribution of maternal age among the stillborn fetuses.

Fig. 9
Fig. 9
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Distribution of the gravida of the mother among the stillborn fetuses.

Fig. 10
Fig. 10
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Distribution of the socioeconomic status of parents among the stillborn fetuses.

Fetal factors

The gender, birth weight, and gestational age of the stillborn fetus were the fetal parameters taken into account in this study. Fetal anthropometric measurements were taken, including head circumference, chest circumference, belly circumference, and crown-rump and rump-heel lengths.

Figure 11 shows the gender distribution of the stillborn fetuses. There were 28 (56%) and 22 (44%) stillborn male and female fetuses, respectively. In the current study, the male-to-female sex ratio was 1.27:1.

Fig. 11
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Distribution of gender among the stillborn fetuses.

500–1000 g was the highest weight range for stillborn fetuses, followed by 1001–1500 g (Fig. 12). The highest number of stillborn fetuses occurred between weeks 22–26 of gestation, followed by weeks 27–30 (Fig. 13).

Fig. 12
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Distribution of birth weight among the stillborn fetuses.

Fig. 13
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Distribution of gestational age among the stillborn fetuses.

The chi-square test showed a statistically significant association between autopsy findings and ultrasound reports (P < 0.05) (Table 5). The sensitivity, specificity, positive predictive value, and negative predictive value of the ultrasound reports were found to be 85%, 66%, 97%, and 22% respectively. The overall accuracy of the antenatal ultrasound reports observed in the present study was found to be 84%.

$${\mathbf{Sensitivity}} = {\text{TP}}/\left( {{\text{TP}} + {\text{FN}}} \right) = {4}0/\left( {{4}0 + {7}} \right) = {4}0/{47} = {\mathbf{85}}\%$$
$${\mathbf{Specificity}} = {\text{TN}}/\left( {{\text{FP}} + {\text{TN}}} \right) = {2}/\left( {{2} + {1}} \right) = {2}/{3} = {\mathbf{66}}\%$$
$${\mathbf{PPV}} = {\text{TP}}/\left( {{\text{TP}} + {\text{FP}}} \right) = {4}0/\left( {{4}0 + {1}} \right) = {\mathbf{97}}\%$$
$${\mathbf{NPV}} = {\text{TN}}/\left( {{\text{TN}} + {\text{FN}}} \right) = {2}/\left( {{2} + {7}} \right) = {2}/{9} = {\mathbf{22}}\%$$
$${\mathbf{Accuracy}} = \left( {{\text{TP}} + {\text{TN}}} \right)/\left( {{\text{TP}} + {\text{FP}} + {\text{FN}} + {\text{TN}}} \right) = \left( {{4}0 + {2}} \right)/\left( {{4}0 + {1} + {7} + {2}} \right) = {42}/{5}0 = {\mathbf{84}}\%$$
Table 5 Association between autopsy findings and ultrasound report.
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Discussion

There is a growing awareness of perinatal death and its preventable causes. As a result, finding the preventable causes of death during the prenatal period has increased. A number of the deformities can be avoided by taking a few easy steps, such as taking folic acid when you are pregnant. Doctors are interested in determining the likelihood of recurrence because congenital abnormalities are known to recur. A congenital abnormality in a baby has a significant emotional impact on the mother.

In addition to genetic variables, environmental, teratogenic, and viral agents also have a significant influence on the development of abnormalities during the most sensitive stage of embryogenesis, which is the third to eighth weeks of gestation. Identification and confirmation of congenital abnormalities are aided by autopsy2.

In the present study, the percentage of congenital malformations is 44 (88%), which is very much higher when compared with all the other studies (Table 6). The prevalence of CNS anomalies was maximum among stillborn, whereas anomalies of the musculoskeletal system were maximum among live births11.

Table 6 Comparison of system-wise distribution of congenital malformations with other studies.
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System-wise classification of congenital malformations among the stillborn fetuses

In a study by Padma et al., congenital abnormalities were observed in 28 fetuses (27%) out of 102 autopsies performed. Anencephaly was the most prevalent of the central nervous system anomalies, accounting for 50% of all cases (12, 44%). They reported anencephaly linked to spinabifida in one fetus. The next most prevalent was the digestive system (9, 29.5%), and the most common in this group was omphalocele (50%). Horseshoe kidney was the most prevalent system, followed by the urinary system (6, 22%). Both of the fetuses had infantile polycystic kidneys, which were verified by histological analysis12.

In a study by Andola et al., out of 100 perinatal autopsies, 44 cases–25 females, 17 males, one case of female pseudohermaphroditism, and one case whose sex could not be determined had congenital anomalies. Defects in the central nervous system were the most prevalent congenital abnormalities; anencephaly was the most prevalent, followed by kidney abnormalities. In seven cases, several congenital abnormalities were found. One instance of Prune Belly syndrome per person. OEIS (Omphalocele-Exstrophy-Imperforate Anus-Spinal abnormalities) complex, Meckel Gruber syndrome, and Thanatophoric Dysplasia Type 1 were observed. There were two cases of congenital atrial septal defects and three cases of diaphragmatic hernias. Additionally, one case of infantile hemangioendothelioma of the liver and two cases of congenital cystic adenomatoid malformation of the lungs were observed13.

In a study by Hakverdi et al., a total of 274 fetuses were autopsied. A fetal abnormality was found in 160 cases, or 58.39 percent. Ten cases (6.25%) had no discernible sex among the cases with abnormalities, whereas 60 (37.5%) were female and 90 (56.25%) were male. The most common structural problems, which accounted for 79 (49.38%) of the cases, were neural tube anomalies and other central nervous system defects. Malformations of the musculoskeletal system followed in 36 (22.5%) of the cases, followed by those of the sexual organs and urinary system in 19 (11.86%). Central nervous system problems and bilateral adrenal agenesis were the most common multiple system anomalies. These were followed by musculoskeletal system abnormalities and urine system defects (renal dysplasia, polycystic kidney)14.

Kanchan Kapoor et al. reported in their study, there were 74 male and 76 female fetuses out of 150; the incidence of congenital abnormalities in males and females was 75% and 83% respectively. The overall number of congenital abnormalities was 104 (69%). Central nervous system problems (CNS) accounted for 49 (33%), gastrointestinal tract (GIT) disorders for 48 (32%), musculoskeletal (MS) disorders for 31 (21%), genito-urinary (GU) diseases for 25 (17%), and genetic abnormalities for 12 (8%). Forty (27%) fetuses have several abnormalities. The highest number of fetuses were aborted between weeks 18 and 20, then between weeks 20 and 25 of gestation. 60% of fetuses were born to mothers who were between the ages of 20 and 25. Congenital abnormalities were more common in the upper-lower income group9.

Gole et al. have reported in their study, 100 stillborn fetuses were dissected over the course of 18 months. Out of all the cases, 46 were female, and 54 were male. 13 males and 19 females were among the 36 individuals with congenital abnormalities. The central nervous system accounted for 36% of all malformations. Of the CNS abnormalities, anencephaly was the most prevalent (46%). A common condition in female fetuses was anencephaly. CNS abnormalities that were the second most frequent were spina bifida. Anencephaly connected to spina bifida was present in two cases. With polycystic kidneys being the most prevalent, genitourinary abnormalities were observed in 17% of individuals. One case of undifferentiated gonads and one case of horseshoe kidney were observed. Club foot, cleft palate, cleft lip, and diaphragmatic hernia were among the musculoskeletal abnormalities. A diaphragmatic hernia was found in 40% of the musculoskeletal abnormalities. Two cases (6%) had intestinal malrotation, and two cases (6%), had omphalocele. Three cases (eight percent) had cardiovascular system malformations. Two cases had atrial septal defects, while one case had a single ventricle15.

Prabhala et al. have reported in their study, there were eight female (34.78%) and fourteen male (60.86%) fetuses, and one case (4.34%) had no discernible gender. Nineteen cases (82.60%) had gestational ages under 28 weeks. Ten cases (43.47%) included spontaneous intrauterine deaths, while 13 cases (56.52%) involved medical termination of pregnancy. In 15 cases (65.21%), prenatal ultrasound scanning was performed. Eleven cases (86.66%) showed a correlation between the autopsy and ultrasound results, whereas two cases (13.33%) had imaging study results that the autopsy was unable to identify. Eight cases (34.78%) had no ultrasound, and five of those cases (62.5%) had autopsy results that might have contributed to the fetal death. Only 14 cases (63.63%) involved the submission of placenta16.

In a study by Shanmuga et al., among 168 fetuses, 126 were spontaneous fetal losses, while 42 were terminated due to an abnormality found in the ultrasound. Fetal autopsies and internal organ analyses were performed in each patient. The results of the autopsy were compared with the ultrasound results for every fetus that had abnormalities. In all cases, fetal autopsy was able to issue a definitive final diagnosis. In every case, the fetal autopsy results showed a strong correlation with the ultrasound results. Although conventional ultrasonography can provide a reasonably accurate diagnosis, some deformities may not be picked up by the test. To confirm the diagnosis and check for related abnormalities, the terminated fetus should be examined for accompanying abnormalities. This aids in determining the reason for fetal death and is hence necessary before receiving genetic counselling17.

Choukimath et al. have reported in their study, 55 (52.4%) of the 101 cases had fetal causes, 21 (20%) had maternal reasons, and 11 (10.5%) had placental causes. In fourteen cases (13.3%), other reasons were identified. Of the 31 (29.5%) cases with a male: female ratio of 1:1.5, the most frequent congenital abnormalities were CNS anomalies. Ten cases (10%) had autopsy-added important findings to the prenatal diagnosis, and nine cases (9%) had autopsy-added and modified findings that helped classify them under a syndrome, so assisting with prenatal genetic counselling. Foetal autopsy is still useful in this day of advanced technology, since in the remaining 81 cases (81%) the clinical diagnosis was confirmed18.

40 (80%) of the fetuses in the present study had their ultrasonography results validated by autopsy. Three (6%) patients had their ultrasound diagnostic totally altered during the final autopsy procedure, while seven (14%) fetal autopsies included significant discoveries.

Limitations of the study

This study did not include the objective to perform the genetic evaluation of the stillborn fetuses. This would have provided a comprehensive evaluation of the causation of congenital malformations and the risk of recurrence in future pregnancies. We further plan to work in this direction and conduct future studies to evaluate the cause of fetal death as a multidisciplinary, holistic approach.

Conclusion

A comprehensive approach to the investigation of the nervous system, musculoskeletal, cardiovascular, gastrointestinal, genitourinary, respiratory, and other systems is necessary for the early detection of congenital malformations. In the present study, congenital central nervous system malformations are the most commonly observed congenital malformations, followed by musculoskeletal system malformations. The presence of external malformations serves as a clue to search for internal congenital anomalies in this study. A highly accurate diagnosis can be made with the use of histopathological analysis of the placenta and all the viscera. Antenatal ultrasonography should be performed in all pregnancies, particularly in cases of maternal diabetes, pregnancy-induced hypertension, hypothyroidism, etc., in view of the significant correlation observed between congenital malformations and maternal medical disorders in the present study.

The obstetrician plays a vital role in fetal autopsy and serves as the primary point of contact with the family, requesting consent, providing information, and facilitating the process. A pathologist plays a crucial role in a fetal autopsy by performing a comprehensive examination to determine the cause of fetal death, identify congenital anomalies, and assess the extent of malformations. A paediatrician is essential for interpreting the autopsy findings, especially when it comes to diagnosing congenital anomalies and understanding the overall clinical context, which aids in parental counselling and future pregnancy management. Radiologists play a crucial role in fetal autopsy by performing and interpreting postmortem imaging, such as X-rays, and also as part of prenatal screening to identify congenital anomalies.