Absent fetal hand: a case report.

Isolated congenital fetal hand malformation is a rare finding1. The prevalence of limb reduction deformities is about 3-8 per 20,000 births2. An isolated amputation of an extremity can be due to amniotic band syndrome, exposure to a teratogen or a vascular accident2. A comprehensive obstetric ultrasonographic assessment as well as genetic counselling are ideal when a fetal hand abnormality is detected, so as to determine whether a karyotype analysis is appropriate. We report a case of an absent left fetal hand and explore the parental distress with the diagnosis at almost 20 weeks of gestation. This case also highlights parental perception of medical inertia in terminating a pregnancy of this gestational age and complication.

Case report

A 29‐year‐old primigravida with a 19 week planned pregnancy was referred from a private ultrasound clinic to our maternity service, after an abnormal fetal morphology scan. She previously had a low risk combined nuchal translucency screening at 12 weeks. All booking investigations were within normal limits. There was no history of smoking or illicit drug use. She was well supported by her partner and other family.

Fetus In second trimester of pregnancy wIth absence of left hand longitudinal sonogram of fetal forearm showIng normal radius and ulna. None of phalanges of the hand can be Identified. The remainIng three extremities were normal In this fetus.

The pregnancy had been uneventful, but the mid‐trimester morphology ultrasound at 18 weeks and 6 days identified that the left fetal hand was absent. The left radius and ulna bones however, were visualised. The wrist bones appeared to be formed as well. No fingers or metacarpal bones were seen. The right hand seemed well formed and appeared normal. After a preliminary discussion, the parents were referred for an urgent tertiary level ultrasound and a second opinion.

The isolated absence of left fetal hand was confirmed, and no amniotic bands were detected.

The couple was, understandably, devastated and offered counselling and social worker review. They desired to know the gender of the baby, which was determined as female. This was relevant for their decision making. They were referred to the Limb Reduction Clinic at Westmead Children's Hospital, to help them prepare for the birth of the baby.

The clinic provides detailed information about prosthesis for the child and good before and after birth support. She was reviewed by a multidisciplinary team with a positive approach to the disability, particularly as the unborn baby appeared to have carpal bones that demonstrated movement.

Parents' perspective

The parents could not cope with the diagnosis and contemplated not continuing the pregnancy. After much deliberation, the couple requested to terminate the pregnancy, more so after knowing that it was female, as they felt the cosmetic impact would be far greater for a girl. They assumed that the high level of support provided to that point would translate into an automatic termination plan within the public health system .

Obstetrician's perspective

The primary focus was on recognition and confirmation of the disability, provision of care and counselling for the patient as well as referral to the limb clinic at Westmead Children's Hospital to help institute postnatal support for the family and their newborn once delivered.

It was initially difficult to find willing public obstetric cover for her termination within the narrow timeframe at our maternity/tertiary unit. We offered to liaise with other hospitals or to try and organise an obstetrician agreeable to provide care, but the couple were disappointed not to be accommodated immediately within the system and attended a private termination clinic. They proceeded with termination of the second trimester pregnancy performed by dilatation and evacuation following cervical priming.

Discussion

Fetal hand abnormalities include a wide variety of malformations. These can range from minor defects of the distal phalanges detected post delivery to gross malformations such as clubhand or complete absence of the hand. Certain specific hand anomalies may suggest a particular diagnosis including same length digits or trident hand (suggestive of chondrodysplasia), clenched hand with overlapping fingers (commonly found in trisomy 18) and “hitchhiker thumb” (diastrophic dysplasia) . Postaxial polydactyly of fetal hands may be seen in trisomy 13 as early as 14 weeks gestation .

Abnormalities of the fetal hand, as with other skeletal dysplasias, may often remain undetected after routine second trimester fetal ultrasound . Hence the need for a thorough and systematic approach to limb examinations. The antenatal ultrasonographic hand anomaly detection rate is understandably higher with targeted scans for a shortenend long bone, growth retardation or positive family history.

The onset of development of the fetal arm bud is around 27 days; the arm bud elongates at about 34–36 days. The hand paddle is formed at 38–40 days, with full separation of fingers at 50–52 days .

Anatomical ultrasonographic detail of the fetal hands includes the presence or absence, size, number, position, movement, morphology and relationship of:

Normal radius, ulna, and humerus.

Non ossified hypoechoic carpus

Five cylindric and echogenic metacarpal bones

Five independent digits of varying length (three ossified phalanges each but two for the thumb) .

The most common resting status of the fetal hand is a closed state with mild flexion of the hand and wrist, a neutral axis between forearm and the hand. Finger‐wrist flexion and extension should be checked as no fixed position of any joint is normal. Ideally bilateral fetal hands examination should be undertaken in axial and longitudinal views, while in an open configuration .

Congenital anomalies are found in 2% of live births. Of these limb reduction deficiencies occur only in 3–8 infants out of every 20,000 live births . Upper limbs are more often involved than lower limbs with a ratio of 2:1 . Unilateral defects are four times more common than bilateral . Chorionic villus sampling before day 66, vascular compromise, teratogens and intra uterine amniotic bands are the most common causes of isolated limb deficiencies

The majority of the isolated limb reductions are non genetic, but occasionally may occur as part of a genetic syndrome or chromosomal anomaly. A detailed ultrasound examination is essential to exclude other markers because of these associations. Karyotyping is recommended in such cases , .

In our case, a disability with the fetus was recognised, and referral to The Limb Reduction Clinic was done. The Limb Reduction Clinic at Westmead's children hospital is a multidisciplinary clinic for the assessment and treatment of children with congenital and acquired limb deficiencies. There was recognition and acknowledgement that this was an unfortunate disability and an understandably difficult situation for the prospective parents. The potential problem could be minimised by a limb prosthesis. The value of support groups to help parents cope is instrumental to their adjustment to the diagnosis.

The patient was partly disappointed with the public hospital system in that many doctors were uncomfortable doing a termination for this reason in a pregnancy just short of 20 weeks gestation and in the end, when an option materialised for obstetric termination cover in our unit, she preferred to go through a private termination clinic which she had liaised with and already booked. Chromosomal analysis of the products of conception was not done.

Conclusion

Fetal hand anomalies are rare, but should prompt a thorough search for other problems which might form part of a syndrome. There can be discrepancies in the views of parents and treating doctors in the “significance” of fetal abnormalities.