Prenatal diagnosis of sirenomelia in the late second trimester with three-dimensional helical computed tomography

Surgical Management of Sirenomelia: A Case Study

Background

Sirenomelia is a rare congenital condition characterized by fusion of the lower limbs. Patients with sirenomelia generally do not survive long after birth because the condition is associated with multisystem organ dysfunction due to developmental anomalies. Considering the low incidence and few cases surviving the neonatal period, there is minimal understanding regarding the surgical management of sirenomelia. We present a unique case of an infant born with type 1 sirenomelia, absence of external genitalia, presence of a cloaca, absence of the bladder, and presence of an imperforate and vestigial anus, who not only survived the birth process, but, at the age of 11 months, was determined to be a candidate for surgical separation of the lower extremities.

Methods

This case was approached much like a dorsal rectangular flap syndactyly release. Large Z-plasty flaps were designed and raised, and the soft tissue within the skin bridge was meticulously dissected to preserve anatomy and to provide adequate skin flaps without perineal skin grafting. A quadrangular flap was designed to reconstruct the perineum and produce a neo-vulva using de-epithelialization.

Results

Successful lower extremity separation was achieved. There were no major postoperative complications. The patient progressed with lower extremity function, and eventually achieved independent ambulation.

Conclusions

Management of sirenomelia is incredibly challenging, and data to guide surgical management are limited. This report details our approach to a successful lower extremity separation, repair, and neo-vulvar reconstruction in a case of type I sirenomelia.

Radiation dose reduction at MDCT with iterative reconstruction for prenatal diagnosis of skeletal dysplasia: preliminary study using normal fetal specimens

OBJECTIVE

The purpose of this study was to investigate to what degree the radiation dose can be reduced without affecting the ability to evaluate normal fetal bones at MDCT with iterative reconstruction.

MATERIALS AND METHODS

Fifteen normal fetal specimens immersed in containers (30- and 35-cm diameter) were scanned with a 64-MDCT scanner, with tube voltage of 100 kVp and tube current of 600, 300, 150, 100, and 50 mA. Images were subjected to adaptive statistical iterative reconstruction (ASIR). The fetal dose was measured using glass dosimeters. We calculated the relative ratio of the dose at 600 mA. Image quality was evaluated on maximum-intensity-projection and volume-rendering images. Two radiologists recorded the visualization scores of five regions. Images at 600 mA were considered to be standard.

RESULTS

With the 30-cm-diameter container, the fetal dose was 10.15 mGy (relative ratio, 100%) at a tube current of 600, 51% at 300, 25% at 150, 17% at 100, and 9% at 50 mA. With the 35-cm-diameter container the fetal dose was 10.01 mGy (relative ratio, 100%) at 600, 47% at 300, 24% at 150, 17% at 100, and 8% at 50 mA. Visual evaluation showed that in both containers, with ASIR 90%, there was a statistically significant difference between 50-and 600-mA images (p<0.01) but not between 600-mA images and those acquired at 100, 150, and 300 mA (p=0.08-1.00).

CONCLUSION

The fetal radiation dose for the evaluation of normal fetal bones can be reduced by 83% with ASIR 90%.