 results of treatment are dramatically different, and so we do not group these two defects into the same category .
Associated genitourinary defects
Important associated anomalies include genitourinary defects, which occur in approximately 50% of all patients with anorectal malformations. All patients must be evaluated at birth to rule out one of these defects, and the most valuable screening test is an abdominal and pelvic ultrasound. Urologic evaluation prior to colostomy provides the surgeon the necessary information needed to address the urologic problem at the time of the colostomy. The surgeon must be prepared to perform a urologic diversion if necessary.
Unfortunately, a common error in diagnosis occurs during the perineal inspection, when a female is thought to have "imperforate anus with rectovaginal fistula" when in actuality, all three structures, the urinary tract, vagina, and rectum all meet in a common channel and the baby has a cloaca [8–10] (Figure 1). The presence of a single perineal orifice is clinical evidence of a patient with persistent cloaca. Patients with these anomalies also have small genitalia. In patients with cloaca, examination of the abdomen may reveal an abdominal mass which likely represents a distended vagina (hydrocolpos), (Figure 2) present in 50% of patients with cloaca. An abdominal ultrasound determines the presence of an obstructive uropathy as well as the presence of a hydrocolpos. This misconception has important therapeutic implications that will be discussed below. It is vital to make the correct determination of cloaca because 90% of babies have an associated urologic problem, and 50% have hydrocolpos. Both the urinary tract and the distended vagina may need to be dealt with in the newborn period to avoid serious complications. Missing the diagnosis of cloaca frequently means that an obstructive uropathy is overlooked. The patient may then receive only a colostomy and subsequently may suffer from sepsis, acidosis, and sometimes death. The other implication of missing the diagnosis of cloaca involves repairing only the rectal component of the anomaly, leaving the patient with a persistent urogenital sinus.
Associated spinal anomalies
The sacrum is the most frequently affected bony structure. Traditionally, to evaluate the degree of sacral deficiency, the number of sacral vertebral bodies were counted. A more objective assessment of the sacrum can be obtained by calculating a sacral ratio. The sacrum is measured and its length is compared with bony parameters of the pelvis. The lateral film is more accurate than the anterior posterior view because its calculation is not affected by the tilt of the pelvis. A hemisacrum is always associated with a presacral mass, which is commonly formed of dermoids, teratomas, or anterior meningoceles. Hemivertebrae may also affect the lumbar and thoracic spine, leading to scoliosis.
Spinal anomalies including a tethered spinal cord can occur [11, 12]. This anomaly, which refers to the intravertebral fixation of the phylum terminale is known to occur in approximately 25% of patients. The prevalence of tethered spinal cord rises with increasing height and complexity of the anorectal anomaly. In addition, patients with a hypodeveloped sacrum and with associated urologic problems have a higher likelihood of having tethered cord. Motor and sensory disturbances of the lower extremities may result. Concerning bowel and urinary function, patients with anorectal malformations and tethered cord have a worse functional prognosis but they also have higher anorectal defects, less developed sacrums, associated spinal problems, and less developed perineal musculature. So, the actual impact of tethered cord itself on their functional prognosis is unclear. Untethering of the cord is indicated in the neurosurgical literature to avoid motor and sensory problems. There does not appear to be evidence that this operation will impact on the functional prognosis of a patient with anorectal malformation. Spinal ultrasound in the first 3 months of life and magnetic reso