Case report: missed prenatal diagnosis of ‘mielo-meningocele’ .
In my experience with prenatal ultrasound diagnoses, I have observed several cases of fetal spina bifida and other neural tube defects, some of which were extremely serious and incompatible with life, such as the condition called ‘craniorachischisis’. I have documented these cases with pathologic slides, and have presented them at lectures and conferences.
All of this is water under the bridge, as thirty years ago folic acid’s role in the prevention of neural tube defects was discovered. Since that time, these types of malformations have only very rarely been seen in Ferrara. Thus, I was quite surprised a few years ago to learn from a patient that her
gynecologist (whose name has been withheld) doubted the efficacy of folic acid and was against its administration.
I report this episode because readers must understand that medicine is not always an exact science. Indeed, like many other gynecologists, I believe in the effectiveness of folic acid, and have prescribed it for the prevention of spina bifida as well as for other pathologies. However, in the case that I am going to discuss, in which folic acid was regularly taken by the patient, this did not prevent severe malformation.
I have been recently consulted as an expert witness in a legal proceeding that concerned the lack of prenatal diagnosis of spina bifida, ending with the birth of a male child with severe motor, functional and neurosensory deficit. His parents claimed compensation for past, present and future medical care, and for the educational and custodial support of their child. The pregnancy was followed at a public health facility in Northern Italy. From the available chart notes , it appears that a so-called “morphological ultrasound” was performed at the twentieth week.
The request by the parents for compensation was based solely on the impossibility of opting for an interruption of the pregnancy on the hypothesis that knowledge of the malformation had caused an illness to the patient. In fact, Italian law does not allow a pregnancy to be terminated for the declared purpose of suppressing the fetus, but only to protect maternal health. Therefore in this case it was not possible to ascertain whether the need for an interruption at the time of morphological ultrasonography would have occurred, since the patient was not then aware of the fetal pathology. It is certain, however, that this necessity did not take place in the 26th week, which is when the malformation was first diagnosed during hospitalization, due to the threat of premature birth.
We should ask ourselves: if this condition had occurred, would it have been permissible to terminate the pregnancy at week 26? The answer is yes, but only for a pathology that is so serious as to endanger the life of the mother. Is it therefore possible to hypothesize that this circumstance would have occurred in the 20th week? It would seem not, since it did not occur subsequently: but it is not my task to answer this question.
It is useless, however, to hide the real goal of the termination of the pregnancy (which is not allowed to be declared in order not to incur the crime of criminal abortion) which is the suppression of the fetus, in order to avoid the high cost of its survival for the family and for society. Maternal illness, true or vaunted, makes it legal to terminate a pregnancy, but ethically the parents and health professionals must appeal solely to their conscience.
As I have explained so far, it is therefore important that the diagnosis of a neural tube defect be made early in fetal development. In fact, obstetricians refuse to terminate pregnancies after the 22nd week because by that time point, the fetus can survive, and the neonatologist will be obliged to treat not only the basic pathology but also that caused by prematurity. The time point during fetal development in which spina bifida is diagnosed depends on the degree of the malformation and on the clinical acumen of the obstetrician.
A morphological ultrasound is usually carried out as soon as possible so that, in the event of a termination of pregnancy the fetus would not have otherwise survived, but as late as possible, so that a malformation becomes better clinically manifest: it is in order to comply with this second requirement that there is sometimes a risk to exceed the 22-week limit.
In our case, however, not even at this time point was the obstetrician able to detect with a degree of certainty the presence of significant spina bifida with protrusion of the meninges and spinal cord at the level of the lumbosacral vertebrae.
Sometimes there are mitigating factors for a failure to diagnose, for example, if there exists an unfavorable fetal position, or a shortage of the amniotic fluid that causes the attachment of the uterine wall to the fetal back.
However, in the case in question there were no extenuating circumstances, and in addition there were signs that should have alerted even an inexperienced sonographer, signs also present at the previous ultrasound performed in the 16th week, that were diligently recorded, but ignored in practice. These are fetal biometry data, and in particular the biparietal diameter and the head circumference, whose values were lower than the 14th and even the 3rd percentile, respectively.
In this regard it must be known that open spina bifida with protrusion of the meninges determines a downward traction of the whole cerebromedullary axis. In severe cases, the cerebellum partially engages the hole at the base of the skull, and due to the early compression it undergoes hypoplasia and deformation. The obstruction of the occipital foramen prevents the free circulation of the liquor, resulting in hydrocephalus, which is accompanied by hypoplasia, and generates a complex syndrome called ‘Arnold-Chiari malformation’, named after the researchers who first described it.
Cerebromedullary axis traction has repercussions on the shape of the cerebellum, which curves like a “banana;” of the cranium, by narrowing of the frontal drafts, resembling a lemon, or a projectile: all morphological and biometrics characteristics closely related to each other, and detectable by ultrasound.
Moreover, other morphological features have been recently reported which make open (i.e. high degree) spina bifida diagnosable, or at least highly suspected, even at the 11th-13th week of
pregnancy: this is the entire cranium occupation from the choroid plexuses (intra-ventricular vascular structures).
How come these alterations, certainly present in our case (given the registration of the values of the biparietal diameter and the head circumference, and the severity of the syndrome subsequently expressed), were not detected? Only one possible explanation remains: the sonographer’s inexperience.
At this point, further doubt must be contemplated and resolved: should the error consisting of a failure to diagnose be charged to the issue sonographer, or, more rightly, to those who have put him in charge of a function that he was not sufficiently experienced to perform? Who decides upon care tasks in healthcare facilities?
In my experience, I have noticed that often, for various reasons, prenatal ultrasound diagnostics are entrusted to specialists who have no experience in the diagnosis of fetal malformations. I am therefore not surprised by the failure of diagnosis of spina bifida by a specialist who in his clinical practice had perhaps never seen one. Nevertheless, I believe it is a serious fault not to send the patient to a so-called second-level echogram, i.e. to a check by an experienced sonographer, as early as the 16th week, given that the biometric parameters below the third percentile had been measured and registered.
