The following images show three cases of caudal regression syndrome (types II, III, and IV according to the classification of Renshaw at al. ) diagnosed in our department.
The first case represents type 2 of the caudal regression. It was a second pregnancy of a woman with non-contributive history. Her first trimester scan was normal (NT 1.2 mm, NB 2.0 mm). At 22 weeks absence of the sacral spine, club feet, hypoplastic leg’s muscles and simple umbilical artery were noted on the ultrasound scan. Karyotype was normal (46, XX).
The pregnancy was terminated and following pathological examination confirmed the diagnosis of the caudal regression syndrome. The spinal column was absent distally from the level of the fourth lumbar vertebra, the sacrum and coccyx were hypoplastic and the iliac wings were positioned close to each other. Both feet were deformed.
Images 1, 2: 22 weeks; the image 1 shows caudal part of the fetal spine. The sacral part of the spine is missing. The image 2 shows the lower extremities of the fetus with hypoplastic musculature.
Images 3, 4: 22 weeks; the image 3 represents a 3D scan of the lower fetal spine. The sacrum is missing and the iliac wings are positioned in midline close to each other. The image 4 shows transverse scan of the normally looking fetal head.
Images 5, 6: Pathological specimens showing hypoplastic musculature of the fetal legs, club feet (image 5) and deformed fetal pelvis with the absence of the sacrum and abnormally positioned iliac wings close to the midline (image 6).
The second case represents type 3 of the caudal regression. It was a second pregnancy of a woman with non-contributive history. Her first trimester scan was normal (NT 2.1 mm, NB 1.8 mm). At 16 weeks we found absence of the lumbar and sacrococcygeal spine, hypoplastic iliac bones and cystic spina bifida. Single umbilical artery and deformed feet were also noted. The lower limbs were akinetic, with popliteal pterygia, and were kept in a “frog legs” like position. Karyotype was normal (46, XX).
The pregnancy was terminated and pathological examination found 3 cm large cystic spina bifida (meningomyelocele) in the lumbar region of the spine. The sacrum was hypoplastic and there was aplasia of the coccyx. Bilateral popliteal pterygia were also present. X-ray scan revealed the absence of the lumbar, sacral and coccygeal regions of the spine, and hypoplastic iliac bones.
Images 7, 8: 16 weeks; the image 7 shows transverse scan of the fetal head. Note the lemon shape of the fetal skull, abnormal shape of the fetal vermis ("banana sign") caused by the lumbar myelomeningocele, the sac of which is visible on the image 8.
Images 9, 10: The images show X-ray (image 9) and 3D (image 10) representations of the fetal pelvis and legs. The legs are kept in fixed flexed position and the sacrum and lumbar vertebrae are missing.
Images 11, 12, 13: Pathological specimens showing the fetal pelvis and lower extremities of the fetus with the caudal regression syndrome. The image 12 shows the sac of the lumbar myelomeningocele that was also present in this case.
The third case represents type four of the caudal regression syndrome. The first sonography was done at 21st week and we found a fetus with the absence of the caudal spine distally from the fourth thoracic vertebra. Diaphragmatic hernia, aplasia of the left kidney, single umbilical artery, “frog legs” like positioned akinetic lower extremities, and popliteal pterygia were also present. Karyotype was normal (46, XY).
The pregnancy was terminated and following pathological study confirmed the diagnosis.
Images 14, 15: 21 weeks; the images shows sagittal scan of the fetal spine. Note that the caudal part of the spine distally to the thoracic vertebrae is missing.
Images 16, 17: The image 16 shows a transverse scan of the fetal abdomen. Note that the spine at this level is missing. The image 17 shows flexed lower extremity of the fetus. The arrow points at the popliteal pterygium.
Images 18, 19: Pathological specimens showing the hypoplastic deformed fetal pelvis with missing sacrum and medially positioned iliac wings. The image 19 shows the lower extremities of the fetus. Note the popliteal pterygia.
1. Renshaw TS. Sacral Agenesis. The Pediatric Spine - Principles and Practice. New York: Raven Press, 1994; 1:2214.