I found a few new articles (from just last month!) saying that CRS may be caused by an issue with the umbilical cord. This is what I’ve suspected all along because I did have a single umbilical artery (SUA). The umbilical cord is supposed to have two arteries and one vein, so SUA is when one of the arteries is missing. On one of my ultrasounds, they did say that they thought there was an issue with the umbilical cord, and they had me come back the next week for another look. They said then that there was no problem. However, when Jordan was born, they clearly saw the SUA. A few people in my online groups have said that they also had a SUA with their children with CRS.
It makes sense—the blood flow did not get to the entire fetus, so that affected growth of the lower portion, the “caudal” portion. Now, what causes the SUA...?
Here are the articles:
Duesterhoeft SM, Ernst LM, Siebert JR, Kapur RP: Five cases of caudal regression with an aberrant abdominal umbilical artery: Further support for a caudal regression-sirenomelia spectrum. Am J Med Genet 2007 Oct 26 [Epub ahead of print].
Abstract: Sirenomelia and caudal regression have sparked centuries of interest and recent debate regarding their classification and pathogenetic relationship. Specific anomalies are common to both conditions, but aside from fusion of the lower extremities, an aberrant abdominal umbilical artery (“persistent vitelline artery”) has been invoked as the chief anatomic finding that distinguishes sirenomelia from caudal regression. This observation is important from a pathogenetic viewpoint, in that diversion of blood away from the caudal portion of the embryo through the abdominal umbilical artery (“vascular steal”) has been proposed as the primary mechanism leading to sirenomelia. In contrast, caudal regression is hypothesized to arise from primary deficiency of caudal mesoderm. We present five cases of caudal regression that exhibit an aberrant abdominal umbilical artery similar to that typically associated with sirenomelia. Review of the literature identified four similar cases. Collectively, the series lends support for a caudal regression-sirenomelia spectrum with a common pathogenetic basis and suggests that abnormal umbilical arterial anatomy may be the consequence, rather than the cause, of deficient caudal mesoderm.
Stierkorb E, Hentschel J, Schneider G, Gortner L, Rohrer T: [Sonographic diagnosis of caudal regression syndrome.] Ultraschall Med 2007, 28(5):521–524.
Abstract: Caudal regression sequence (CRS) is a rare developmental defect of the lower spinal segments and the neural tube. Motor and sensory neurological deficits of the lower extremities as well as a reduced control of bowel and bladder functions are the main symptoms. Etiology and pathogenesis are widely unknown. This article discusses a newborn male with postnatal anomalies of the lower extremities. Sonographically, the spinal cord ended in the lumbar region. NMR confirmed the suspected sonographic finding of CRS. Sonographic examination of the abdominal vessel system depicted a common origin and junction of the hepatic artery, splenic artery and superior mesenteric artery from one common truncus. This points to a possible relict of a persisting vitelline artery. As previously described in sirenomelia, the findings in the present case indicate a possible vascular etiology of CRS.
Duh YC, Chia ST, Sheu JC, Peng CC: Crossed fused renal ectopia with segmental fusion of bilateral ureters and abdominal aortic anomalies in a patient with caudal regression syndrome. Eur J Pediatr Surg 2007, 17(5):370–372.
Abstract: Caudal regression syndrome consists of multiple congenital anomalies, mainly caudal segment defects. We describe a preterm baby born to a healthy mother with typical caudal regression picture, including imperforated anus with rectovesical fistula, sacral agenesis, multiple rib and vertebral anomalies, and club feet. Crossed fused renal ectopia with fused ureters resulting in urinary obstruction was managed with transureteroureterostomy and cutaneous vesicostomy. We also found a single large umbilical artery with high abdominal aortic insertion which usually presents in sirenomelia. Because of the anatomical diversity of the urinary and cardiovascular systems associated with multiple congenital anomalies, careful evaluation is mandatory.