Anamoly scan: A mandatory screening tool

Introduction

In 2013 the neonatal mortality rate was 29 per 1000 live births in India amounting to 7,53,000 neonatal deaths.^[1] Currently it is 28 per 1000 live births. Amongst the various reasons for neonatal deaths, 9% are due to congenital anomalies.^[2] Another study noted that congenital anomalies account for 8–15% of perinatal deaths and 13–16% of neonatal deaths in India.^[3] A second trimester ultrasonography provides important information about the number of fetuses, the gestational age, the location of the placenta, fetal anatomy (congenital anomalies) and maternal anatomy.

The current study is conducted to determine the rate of Congenital anomalies in a tertiary care hospital in Pune, Maharashtra in Western India by conducting a second trimester scan between 18 to 20 week of gestation and also determine the utility of second trimester anomaly scan in determining congenital anomalies.

Materials and Methods

This was a prospective study conducted after obtaining due ethical clearance from the institutional ethics committee, DY Patil Medical College, Pimpri, Pune, Maharashtra. Informed consent was obtained from the patients after explaining to them the objective and need for the study in their native language. 2000 mothers visiting the antenatal care were included in the study.

Results

The rate of fetal anomalies noted was 0.8% (16/2000 cases). 13 congenital anomalies were incompatible for viability of the fetus and hence were terminated. 3 congenital anomalies were minor in nature and hence continuation of pregnancy was advised. 2 mothers who were unbooked during antenatal period, delivered anomalous babies and were as well included in the evaluation.

Following major congenital anomalies were noted in the fetal scans as described below.

Case 1: Congenital cystic adenomatoid malformation with hydrops: This was noted in primigravida where left lung was replaced by multiple cysts.

Case 2: Anencephaly with craniorachischisis ([Figure 1]): This was noted in a subject who was second gravida. The earlier delivery was uneventful with no adverse neonatal outcomes.

Case 3: Phocomelia: This was noted in a primigravida where unformed limbs were noted. Both upper and lower limbs were not formed.

Case 4: Proximal urethral obstruction ([Figure 2]): This was noted in a primigravida. Urinary bladder was noted to be grossly distended and the mother was noted to have gross oligohydramnios. ([Figure 2] a) shows the antental USG picture of distended bladder. ([Figure 2] b) shows the fetus.

Case 5: Empty Sella turcica: This was noted in a primigravida patient where there was absence of pituitary gland.

Case 6: Meningomyelocele: This was noted in a primigravida where non closure of spinal canal and the backbone was noted. Non-compliant use of folic acid was observed in mother.

Case 7: Absent stomach bubble: This case was noted in a primigravida mother. The AFI was noted to be 22 cm.

Case 8: Gastroschisis: This was noted in a second gravida patient where abdominal contents were noted to be present outside in the amniotic fluid.

Case 9: Anterior abdominal wall defects: This was noted in a primigravida patient with anterior abdominal wall defects.

Case 11: Congenital CTEV ([Figure 4]): There was bilateral CTEV noted in the fetus of a primigravida subject. This was considered as a minor congenital anomaly and the pregnancy was subsequently continued.

Case 12: Polydactyly ([Figure 5]): This was noted in fetus of a primigravida subject with bilateral polydactyly. No other anomalies were noted in the fetus. This was considered as a minor congenital anomaly and the pregnancy was subsequently continued.

Case 13: Cleft lip and palate ([Figure 6]): This was noted in second gravida patient. The earlier child as well had cleft lip and palate which was surgically corrected. The pregnancy was suggested to be continued till term.

Case 14: Bilateral renal agenesis: Both the kidneys were not formed. This was noted in a primigravida patient. Additionally, oligohydramnios was noted.

Case 15: Anencephaly with ventricular septal defect: This was noted in a primigravida patient. The patient had history of exposure to antibiotics for upper respiratory tract infection during early phase of pregnancy.

Case 16: Renal agenesis with incompletely formed urinary bladder: This was noted in a primigravida patient. Patient had history of exposure to pain medication during first trimester. Additionally, severe oligohydramnios was noted.

Discussion

The rate of congenital anomalies was noted to be 0.8% in our study. This corresponds with different studies which noted the congenital anomaly rate to be 1.90% in a study by Taksande A et al.^[4] and 1.24% by Datta V et al.^[5]

Majority of the mothers whose children had congenital anomalies in our study were primigravida 76.92% (10/13) rest 23.08% (3/13) were second gravidas. In a study by Chaturvedi P et al.^[6] an increase in frequency was seen in advanced maternal age and in primigravida and fourth gravida mothers.

Only one patient of these 13 had given a positive family history of congenital anomalies where cleft lip and palate was noted in child born in previous pregnancy. Figueiredo JC et al.^[7] noted that a family history of clefts as well as having other biological children with a cleft were highly associated with increased risk of developing cleft lip and cleft palate in the current pregnancy.

The major professional societies throughout the world recommend that all pregnant women be offered a mid-trimester ultrasound scan for the detection of structural fetal anomalies.^[8], ^[9], ^[10] This is generally performed between 18 and 22 weeks, though ‘at risk’ women may receive additional scans. The majority of identifiable anomalies will be detected with 2D ultrasound, but in certain cases (such as facial clefts or talipes equinovarus) three-dimensional (3D) ultrasound may provide additional details.^[11]

Limitations of the Study

The study did not follow up all the patients until delivery of the fetus.

The data set is inadequate to extrapolate the data to regional and national trends.

Risk factors contributing to anomalies were not evaluated.

Chromosomal testing/ DNA analysis was not done.

Maternal characteristics contributing to development of congenital anomalies were not studied.

Conclusions

Second trimester anomaly scan is an important modality for diagnosis of congenital anomalies. This should be considered as an essential noninvasive procedure in providing ideal antenatal care. Detecting anomalies at an appropriate time before birth can prevent a huge amount of mental, social and physical turmoil to the couple and save the family from the future setback. Also, with the advent of fetal medicine we can identify, treat the fetus in utero which might reduce the future complications & further decrease the rate of neonatal as well as infant mortality rate. Though many congenital anomalies can be detected in first trimester scan, second trimester scan forms the corner stone in diagnosis of anatomical abnormalities in the fetuses. We suggest to conduct similar studies in correlation with first trimester scans and chromosomal/DNA analysis in a greater data set for further conclusive analysis.

Source of Funding

None.

Conflict of Interest

None.