Prenatal sonographic diagnosis of osteogenesis imperfecta

Clinical History

On routine prenatal ultrasound examination in the 35th gestational week, all extremities showed severe bowing deformities and there were marked fracture formations in the femur and humerus.

Imaging Findings

A -25 year old woman admitted for regular obstetric examination in the 35th gestational week. On obstetrical examination, the fetus was immobile during the examination. Heart rate was 120 /min. Biparietal diameter was in accordance with last menstrual period, but femur length was in accordance with 30th week. Brain, thorax and abdominal developments were detected within the normal limits. But all extremities showed severe bowing deformities. There were marked fracture formations at femur and humerus (Fig 1a-b). The pregnancy was terminated at the 39th week of the gestation by cesarean. The newborn was alive and male. After cesarean, the infant was examined by paediatrics. Except extreme bowing defects of all four extremities, no systemic abnormality was observed. On genetic counseling, it was learned that the mother had another infant that died immediately after birth 2 years ago. On babygram, we detected multiple fractures in upper and lower extremities with malunion and sclerotic callus formation. The cortices were thin and bones were radiolucent. The extremities severely defected and bowed (Fig 2). The intrauterine sonographic diagnosis was confirmed by physical, radiologic and genetic evaluations. At the 15th day of the labor, the infant died.

Discussion

Osteogenesis imperfecta is an inherited disease of connective tissue where basic pathology is of defective maturation of collagen. The clinical defects in osteogenesis imperfecta involve tissues with hight type I collagen content (bones, ligaments, tendons, fasciae, sclerae and teeth) (1). Osteogenesis imperfecta occurs in all races and affects both sexes with approximately equal frequency. The severe forms (10%) have high intrauterine and infant mortality rates. Most cases are diagnosed at birth or, with the use of ultrasonography, in utero. The mostly encountered sonographic finding in osteogenesis imperfecta is the short limbs when routinely measuring the lengths of the limbs in screening and dating of pregnancy (2). Amnios fluid changes especially polhydramnios can be seen. But most characteristic finding to osteogenesis imperfecta is the demonstration of factures and bowing deformities in the extremities. The fetus may be immobile as in our case due to multiple fractures. The most characteristic radiographic finding of osteogenesis imperfecta is a diffuse decrease in osseous density of variable degree, which involves axial and appendicular skeleton equally after birth. The cortices of the long bones may be abnormally thin or abnormally thick. The fractures that complicate the course of osteogenesis imperfecta occur most frequently in the lower extremities and usually are transverse. Micromelia and bowing deformities are the sequela of multiple telescoping fractures. Skull fractures are uncommon. Hyperplastic callus is well-described feature of osteogenesis imperfecta. Large masses of calcified callus, containing primitive woven bone, cartilage and fibrous tissue, form spontaneously of after injury (3). Because type II osteogenesis imperfecta results perinatal deaths in affected fetuses, prenatal diagnosis of this disease is important for termination of the pregnancy in a reliable stage and genetic counseling for future pregnancies in those mothers. Detailed evaluation of the limbs during sonographic examinations of first and second trimester of pregnancy can give important clues about this disease. MR imaging is a valuable complement to US and being the most acceptance method to evaluate especially intracranial pathologies at the fetus in recent years. Artifacts from fetal motion can limit the diagnostic validity of this method. But fast imaging techniques made it suitable in the evaluations of fetus. However, even small amounts of motion limit the depiction of extremities in their entirety.

Differential Diagnosis List

Final Diagnosis

Type II, subgroup B, osteogenesis imperfecta according to Sillence clasification

URL:	https://eurorad.org/case/1440
DOI:	10.1594/EURORAD/CASE.1440
ISSN:	1563-4086