ectrum of defects, so every attempt to classify them is arbitrary and somewhat inaccurate. Consequently, the traditional classification of "high", "intermediate", and "low" defects renders the results dubious. The classification presented here attempts to group together defects that have common diagnostic, therapeutic, and prognostic features (Tables 1 and 2).
The posterior approach and direct visualization of the anatomy have allowed us to learn about important features. For instance, rectovaginal fistula are almost nonexistent, in retrospect it seems that most of the previously reported "rectovaginal fistula" cases were misdiagnosed cloacas. This assertion is supported by the authors' experience of cloaca reoperations where it has been found that most patients who were originally operated on by a surgeon who classified the defect as a "rectovaginal fistula" had only the rectal component of the cloaca repaired and had been left with a persistent urogenital sinus. Such patients have become categorized as instances of "rectovaginal fistula" and the true diagnosis of cloaca has become evident only many years later. In addition, many patients had undergone a abdominoperineal pull-through at another institution to repair a "rectovaginal fistula," and years later had been referred because of fecal incontinence. When these girls were examined, the little pouch of what used to be the rectum was found opening into the vestibule, indicating that these patients were been born with a rectovestibular fistula. The cloaca itself represents a spectrum and certainly defies the classification "high", "intermediate", and "low".
Also included in the "high" category in male patients were those with completely different defects requiring differing treatments and carrying a different prognosis (e.g., rectourethral fistula and rectobladderneck fistula). A rectourethral fistula can be treated without an abdominal approach, but a rectobladderneck fistula always requires the abdomen to be entered either with laparoscopy or laparotomy. The 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 